US 2051732 A
Description (OCR text may contain errors)
Aug. 18, 1936. J. F. M KEE 2, 1,732 H STEAM TRAP Filed June 3, 1933 3 Sheets-Sheet l Aug. 18, 1936. J. F. MCKEE 2,051,732
STEAM TRAP Filed June 3, 1955 s Sheets-Sheet 2 J. F. MCKEE STEAM TRAP 3 Sheets-Sheet 3 Aug. 18, 1936.
Filed June 3, 1933 ,67 6X I/I/I) Mu Patented Aug. 18, 1936 UNITED STATES PATENT OFFICE STEAM TRAP John F. McKee, Lansdowne, Pa.
Application June 3, 1933, Serial No. 674,253
The invention relates to a new method of trapping condensate and air from steam lines and to steam traps embodying my method for the automatic removal of condensate and trapped air 5 from steam lines and steam apparatus.
A purpose of the invention is to provide a steam trap that will be at once small, light and inexpensive to manufacture and that will effectively meet the needs of service in that, while 10 preventing steam discharge, it will have large capacity for discharging water, -for eliminating air when first turning steam into the trapped system and for maintaining the system free from air and water.
A further purpose is to use the variation in the heat content of the discharging liquid at a trap to control a valve regulating the discharge.
A further purpose is to permit leakage of condensate into an expansion chamber and to em- 20 ploy the change in expansion or control chamber'pressure to operate a valve.
A further purpose is to provide a continuous discharge through a plurality of throttlings and to use variations in pressure intermediate the throttlings to control the opening and closure of a discharge valve.
A further purpose is to provide a control chamber with a throttled inlet and a throttled outlet which cause reduction in pressure when con- 30 densate enters the control chamber, and to cause the'opening of a discharge valve by the pressure in the system acting against the control chamber pressure.
A further purpose is continuously to draw of! condensate and/or air from a steam system at a rate lower than that at which condensate ordinarily forms and to discharge any accumulated excess of condensate from the system periodically at a higher rate than that at which it forms. a
A further purpose is to provide a trap with a plurality of discharges, including a continu-' ous discharge of magnitude less than that of the condensate to be taken care of by the trap and an intermittent or/and an adjustable discharge using increase of temperature of the continuous discharge to control the intermittent or/and. adjustable discharge. A further purpose is to mount the valve ele- 50 ment of a steam trap on the outside of a'movable wall a control chamber of a control having throttled inlet and throttled outlet to the chamber from the inlet side of the trap and from the chamber to discharge and to control the operation of the valve 'by variant pressure withim the chamber of condensate leakage into the chamber and restriction of outlet from the chamber by reason of variant temperature of the condensate whereby with increase of temperature of the condensate leaking into the chamber the pressure is raised to move the valve toward closure and with reduction in temperature of the condensate leaking into the chamber the pressure within the chamber is reduced and the valve moves in an opening direction.
A further purpose is to place an impulse disc in the path of the liquid discharging through the trap valve and to use the impulse disc to assist in closing the valve.
A further purpose is to utilize condensate within the control chamber of a trap having a movable control chamber wall connected with an outlet valve to vary the pressure in the control chamber through variant flashing of the condensate as it leaves the control chamber, the variant flashing being due to different temperatures of the condensate.
Further purposes will appear in tion and in the claims.
A few only of the different forms of the invention have been shown selected from forms, however, that are practical and efllcient in operation and which well illustrate the principles involved.
Figure 1 is a sectional elevation illustrating a desirable embodiment of my invention.
Figure 2 is a sectional view taken upon the line 22 of Figure l.
Figure 3 is a perspective view illustrating a detail of Figure 2.
Figure 4 is a perspective view generally similar to Figure 3, but illustrating a modification.
Figure 5 is a sectional elevation generally similar to Figure 1, but illustrating a different form.
Figure 6 is a section taken upon the line 6-6 of Figure 5.
Figure 7 is a sectional detail of structure shown in Figures 5 and 6.
Figure 8 is a sectional perspective view illustrating a detail of Figures 5 and 6.
Figure 9 is a vertical section of a detail shown in Figures 5 and 6. Figure 10 is a top plan view of Figure 9.
Figure 11 is a longitudinal section 01 a somewhat difierent form of steam trap embodying the invention.
Figure 12 is a perspective view of the valve shown in Figure 11.
Figure 13 is a longitudinal sectionof a modified device to which the invention has been applied.
Figure 14 is a fragmentary section of a thermostatic device which may be applied to any of the forms of the invention.
Like numerals refer to like parts in all figures.
Steam systems, such as steam lines and steam devices generally, commonly contain air and condensate. The air is in the system when it is started up, and additional air enters the system in any one of manyways, as, for example, in the 60 the specificaform of air dissolved in the feed water to the boiler. Condensate is water produced whenever steam loses its latent heat of vaporization. Both air and condensate are undesirable, and must be removed from the system by a steam trap.
An expansion chamber is provided on one side of a movable wall and subjects the other side of the wall to the high pressure of the system. The
movable wall controls a steam trap valve. The.
control chamber has an inlet from the system at high pressure and an outlet at low pressure to atmosphere or some other low pressure space, the sizes of the inlet and outlet being so selected for a predetermined pressure drop when condensate or air enters the control chamber from the system. The pressure in the control chamber is thus intermediate between the high pressure in the system and the low pressure at the point of discharge.
The location of the inlet from the system to the expansion chamber is primarily a matter of design. The inlet may be through a stationary wall of the control chamber, through the movable wall or between the movable wall and the stationary wall of the control chamber. Likewise, the outlet from the control chamber may be arranged in any of a variety of ways, as for example, through the stationary wall of the control chamber or through the movable wall. Illustrations of these various forms are discussed later.
The control chamber appears to function in a manner which will now be briefly described, in order that the disclosure may be better understood. This is not considered to be necessarily the final theoretical explanation, although it seems to account for the action of my trap.
When the system is started, there will 01 course be air in it. As the pressure rises, the air will enter the control chamber inlet, and escape through the control chamber outlet.
As more and more condensate flows through the trap, the high pressure: steam (as distinguishedfrom steam, if any, formed in the control chamber) will come nearer and nearer to the trap, and the temperature of the condensate will rise. Eventually condensate which enters or is in the expansion chamber will have a temperature high enough to produce steam at the pressure of the expansion chamber. When the temperature of the condensate within the expansion chamber closely approaches the temperature of steam at the pressure in the system the heat of the liquid in the condensate entering the control chamber, while insuflicient to generate steam at the high pressure of the system, is more than the maximum heat of the liquid at the slightly lower pressure of the control chamber, so that the excess heat is available for latent heat of vaporization.
With very high temperatures in the condensate within the control chamber, closely approaching the temperature of live steam in the system, flashing takes place in the control chamber and this flashing impedes outlet" of the mixed vapor and water through the leakage outlet from the control chamber, thus increasing the control chamber pressure and closing the valve. With lower control chamber condensate temperature much the same efiect is produced to close the valve at 11pmdetermined control chamber condensate temperature through variant flashing oi the condensate as it passes out to discharge from the control chamber. This flashing varies according to the temperature and causes retardation of flow of condensate from the control chamber. The
ratio between inlet and discharge opening may thus be set so that the flashing at some predetermined condensate temperature may be just sufllcient to close the valve or to move the valve toward closure sufliciently to tend to accumulate more condensate in the system and thus to lower the temperature of the condensate reaching the control chamber. With approach to uniformity of flow oi condensate the valve floats partly open, closing a little as the condensate increases in temperature due to discharge through the valve at a rate higher than the rate of supply of condensate and opening a little when condensate tends to back up in the system because of a discharge rate through the valve lower than that necessary to take care of the condensate as supplied. It is desirable to discharge the condensate through the trap at a temperature as high as possible, in many cases closely approaching the temperature of the steam system in order that condensate may not back up in the system and risk injury to apparatusfed from the system.
When the steam trap valve has closed, the escape of condensate and any entrained air preferably continues through the control chamber inlet to the control chamber, and out through the control chamberoutlet. Both the control chamber inlet and the control chamber outlet will of course be small and the leakage flow through the control chamber will preferably be selected to discharge condensate at a lower rate than the rate of formation of condensate. So long as the rate of formation of condensate does not exceed the capacity for flow through the control chamber leakage the valve will not open, condensate will merely leak through the control chamber and steam from the system (as distinguished from steam formed from excess heat of liquid in the condensate in the control chamber) does not normally enter the control chamber.
The ratio between the area of the movable wall (in Figure 1, the piston end) upon which pressure bears in the control chamber and the area within the cylinder but outside of the valve diameter, upon which pressure from the main chamber is effective, i. e. the relative areas subjected to control chamber and main chamber pressures, will largely control the pressure required in the control chamber to close the valve m-r any given initial steam pressure. The valve may thus be made to close with the relatively low pressure in the control chamber or may be made to depend upon the accumulation of a considerable pressure there.
When a temperature has been reached in the expansion or control chamber such that the valve closes, this high temperature will prevail in the control chamber as long as steam at high pressure is fairly near to the trap or condensate recently in contact with high pressure steam is continuously coming to the trap. In other words. the valve is controlled in opening or in closing by reduction or increase of the temperature the water immediately at the trap.
When condensate accumulates in the system, the high pressure steam will of course be more remote from the trap and condensaterecently in contact with high pressure steam will cease to enter the control chamber.
Under the conditions above the condensate in the control chamber will drop in temperature and the water in the control chamber will no longer flash to the same extent as at a higher pressure during its passage through the' control chamber to discharge, whether the flashing would take place within the control chamber or at the outlet to discharge. The pressure in the control chamber will then drop and the movable wall will be shifted by the high pressure of the steam (acting on the condensate, and through-the condensate as a piston) to the posi tion of valve opening.
With the steam trap valve open, condensate will flow from the trap through the open valve until the temperature of the condensate in the control chamber is high enough so that flashing takes place in the control chamber if the temperature be nearly enough that of live steam or additional flashing takes place at the outlet from the control chamber resulting in shifting of the movable wall toward closing or to effect actual closing. For convenience, in order that it may not be necessary to distinguish in most cases as to whether the flashing takes place within the control chamber or at the discharge outlet, this flashing will be referred to as occurring in the control system or through the control system.
This cycle repeats itself whenever a large slug of condensate accumulates in the system.
When the valve has been opened it will remain open until the pressure of condensate within the control chamber becomes high enough, operating against the upper face of the piston, to overcome the pressure in the main chamber or inlet chamber of the trap, operating against the under side of the piston as well as to overcome the effective back presssure upon the valve. This effective back pressure is greater of course with condensate flowing out through the valve than it would be if steam flowed out through the valve, which is one reason why the valve would close upon a lower pressure of steam within the control chamber than the pressure of condensate which would be required in the control chamber to close the valve. However, the pressure of condensate in the control chamber required to close the valve is reduced by partial balancing of this back pressure due to the impulse element shown in the impulse disc hereinaiter discussed. Flashing of condensate into steam takes place at the second (outlet) opening, that is, the opening from the control chamber to the exit whether flashing take place at the inlet opening to the control chamber or not.
The conditions in the expansion chamber control the steam trap valve; When the condensate temperature in the expansion chamber reaches a predetermined point, the expansion chamber pressure corresponding to this temperature closes the steam trap valve. On the other hand, when the condensate temperature in the expansion chamber drops below a predetermined point, the expansion chamber pressure decreases and'the steam trap valve opens.
The back pressure against the under face of the valve due to flow of condensate develops as the valve is opened and tends to hold the valve open, requiring a higher pressure in the control chamber to close the valve than the pressure in the control chamber at which the valve will be held closed. The valve therefore, will not both open and close at the same control chamber pressure, giving a slight range of control chamber temperature between its opening and closing movements. Because it is desirable to make this range of temperature difference small in order that it may be possible to discharge hot condensate at a close temperature approach to that of the live steam and because it is desirable additionally to ensure reliable closing of the valve without discharge of steam even where the close approach to steam temperature may endanger steam discharge, I use the pressure of the discharge steam against a projection in the path of the flowing condensate to somewhat offset the back pressure reaction of the discharge and to thus assist in closing the valve.
Having thus generally outlined the character of the invention, the preferred apparatus will now be described in more detail.
In each of the different illustrated embodi ments of my invention, the trap includes a hollow body I5 having an interior divided into an inlet space or compartment I6, an outlet space or compartment I1, and a control space, chamber or compartment I8. A ported division wall I9 is located between the inlet and outlet compartments, and a movable wall 20 of the control chamber, carrying a valve 2 I, controls the flow through the valve port, passage or other throat constriction 22. The control chamber It has throttled inlet at 23 from the inlet compartment I6 and tlhrottled outlet at 24 to the outlet compartment The threads 25 and 26 are intended for pipe connections 21 and 28, respectively, to a system requiring a trap to remove condensate, such as a drainage of structure under steam pressure, and to a waste or hot well.
Thus far the description applies generally to the various structures embodying my invention.
In the embodiment of Figures 1 to 3, inclusive, the control chamber I8 is within a removable bonnet 29 having a cylindrical interior, and threaded to the casing I5 at 30.
The passage 22 connecting the inlet and outlet compartments I6 and I1 through the partition I9 is the interior of a seat member 3| threading into the division wall I9 at 32.
A hollow movable valve unit 33 carries a piston 34 having a throttle fit with the bore 35 of the bonnet, the conical valve 2I, a stem' 36 extending loosely through the passage 22 and, in some of the forms, an impulse disc 31 located some little distance beyond the constriction at the throat.
It will be noted that the piston is guided by the cylinder walls and engages them. For this reason, because the stem is loose inthe throat constriction and because the impulse memberis located beyond the constriction (in the direction of discharge water flow) the combined piston and valve is free to wabble when the valve is open, centering about the contacts of the piston with the cylinder wall, tilting or canting'the piston, in directions comparable with the tilting of a butterfly valve, at the same time that the forward and. backward movement of the piston and valve unit scrape the piston over the adjoining cylinder surface,
The throttle connection between the inlet and control compartments I8 and I8, which provides the inlet 23 to the control chamber, is here around the piston 34, the diameters of the piston and cylinder being related to give the desired extent of throttling, which, for any individual case, can be determined by experiment. For example, in specific cases good results have been obtained with the piston diameter a few thousandths of an inch less than the cylinder diameter.
The throttled outlet 24 of the control chamber is at a small oriflce 38 into the hollow interior passage 39 through the valve 2I. On the end of the piston 34, a boss 40 is formed, to serve as a stop when the valve is in open position, and prevent the impulse disc 31 from closing the valve port 22. The boss 40 engages the inside of th bonnet at 4| when the valve is open.
The constructions shown in section in Figures 1 and are both full size illustrations of traps which have been constructed and successfully operated by applicant. It is not the intention to restrict the present inventionto any dimensions,
'and a considerable range of variation in sizes,
clearances and leakages has been found to be permissible. The best ratio cannot well be computed, perhaps because the two orifices have different coeflicients and because, ,the outlet handles water at one time and foam at another.
In order that the public may have the benefit of these specific examples as practical applications of the invention, it is stated that the form seen in Figure 1 operated upon pressures up to 600 pounds per square inch (and in any position of the structure, as'fshown, upside down, etc.) with a. difierence between the outside diameter of the piston and the inside diameter of the finished bonnet of 3/ 1000 of an inch and with a diameter of the outlet 24 of 76/1000 of an inch, and the form shown in Figure 5 operated successfully at pressures up to 250 pounds per square inch (likewise in any position of the structure) with a difference between the outside diameter of the piston and the inside diameter of the finished bonnet of 3/1000 of an inch and with a diameter of the outlet 24 of 42/1000 of an inch.
In any individual cases the number of 1000ths of an inch clearance between the piston and the bonnet, or size of other inlet, as well' as the diameter of the outlet 24 or other outlet most advantageousfor the purpose, may be'determined readily by experiment in view of the explanation herein made. The same is true of the forms, later to be discussed, in which the inlet to and outlet from the control chamber are through stationary walls of the control chamber.
Decrease in the size of the control chamber outlet with respect to the inlet tends to increase the water pressure in the expansion chamber in normal operation and to make the trap valve remain open until a higher condensate temperature in the control chamber is reached at which the condensate will vaporize in the control system to the extent required for suitable retardation of the condensate outlet. Increase in the size of the control chamber outlet with respect to the inlet tends to lower the water pressure in the expansion chamber in normal operation. The condensate temperature (and corresponding pressure) for closing must be the same for the same valve whatever the pressure and temperature at which vapor initially forms; but a valve may be selected having proportional opening and closing pressure areas such as to make the trap valve close when condensate at a, lower (but still a boilingi temperature enters the control chamber. In any case, however, whatever the inlet and the outlet leakage areas-selected, condensate pressure drops when condensate enters the control chamber. Y
If the outlet of the control chamber were grossly large with respect to the inlet, the pressure in the control chamber would never rise high enough to close the valve, and the valve would remain continuously open. If, on the other hand, the control chamber outlet were grossly too small with respect to the inlet, the pressure in the control chamber would never fall far enough to permit opening of the valve, and the valve would remain continuously closed. Between these extremes,
wide variation is permissible, and the best proportion for a particular installation may be determined by experiment, aided by the theoretical discussion given herein.
The actual size of the control chamber inlet and outlet (as distinguished from their relative sizes) is determined by the minimum rate of condensation in the system, since the control chamber inlet and/or outlet should be too small to take care of minimum condensation by continuous flow through the control chamber. Otherwise steam from the system may escape through the trap.
The area of the piston 34 plus the boss area, which in Figure 1 together form the control chamber pressure area are greater than the area of the annular enlarged portion of the valve 2| plus the exposed under flange of the piston, together forming the main pressure area v upon which the pressure of the system is acting to open the valve, The annular enlarged portion of the valve 2| is that portion of the valve which is exposed above the valve seat when the valve is closed. Therefore the pressure in the control chamber can, at the proper time, close the valve, notwithstanding that the system pressure is at all times higher than the control chamber pressure. In all the forms the movable wall constituting the control chamber pressure area must be larger than the movable wall constituting the main pressure area. 7
As the mechanism is necessarily closed in use but is also subject to high pressures and as the forces considered are difiicult to follow practically in their movements any statement of operation must rest upon theory supplemented by the noise made by fluttering or striking of the valve. The best explanation of-the operation of the trap known to applicant is as follows:
Inoperation the piping 21 on the high pressure side of the trap may be continuously full of condensate for permissibly a considerable but variant distance from the trap, with high pressure steam in the piping beyond the condensate and a continuous drainage of condensate out of the steam lines into the condensate seal of the trap, that is, into the continuous column of condensate in the piping 21 between the steam and the trap.
, If the system be just starting there will be air about the trap, and this will first be passed through the trap.
The temperature of a sealing column of condensate in the piping 21 will, at the steam end of the column, be that of the steam and, toward the trap, will be progressively lower by reason of progressive cooling. The opening and closing of the valve are made to depend respectively upon relatively low and high water temperatures, respectively, at the trap.
- Prior to opening the valve, the discharge of condensate has been merely the small continuous discharge through the control chamber, the pressure 01' the fluid within the control chamber holding the valve shut against opening forces exerted by fluid of the inlet and outlet spaces over areas determined by the dimensions of the piston and of the valve seat.
When a considerable slug" of condensate has accumulated, its outward pressure against the piston opens the valve, which allows the condensate to flow out rapidly until, as the water increases in temperature, a temperature point is reached at which the valve is closed. This pointis dependent upon the design of the valve and is aifected both by the ratio between the pressure areas subject to main and control cham- $051,739 ber pressures and by the inlet and outlet leakage areas to and from the expansion chamber".
When the water passing through the throttled inlet 23 into the reduced pressure of control chamber i8 becomes hot enough for its vaporization in the control system to retard outlet from the control chamber to the required extent, the pressure in the control chamber builds up. 'In' the above described operation the drop of temperature in the condensate discharged as compared with the temperature of live steam is a function of the distance to which the condensate is backed up in the passage leading to the trap.
When the trap is used to discharge condensate at very nearly the same temperature as that of live steam in the system the distance to which condensate seal of the trap extends is very much shortened, increasing the prospect of steam entering the inlet compartment of the trap from time to time and causing the extremely hot condensate to flash not only as it leaves the control chamber but also within the control chamber as it enters, both flashings being effective for the same result, namely, to increase the resistance to discharge of condensate from the control chamber and thus increase the pressure in the control chamber and close the valve. My trap facilitates operation of this character since even if steam reaches the inlet chamber of the trap it can do no harm as steam will not open the trap but when .and the control chamber temperature closely approaches that in the inlet compartment the valve is forced downwardly toward closure. Depending upon the quantity and temperature of the condensate the valve may close and be held closed.
and the condensate which has vaporized into steam be recondensed. This will reduce the pressure in the expansion chamber, whose fluid content is further reduced by fiuid'flow through outlet 24, because of which the valve again opens and the cycle is repeated. These fluctuations cause a flutter of the valve.
Though it is not essential to the operation of v the device, it is preferred that full opening movement of the valve shall close or restrict flow through outlet 24 by engagement of the boss against the interior surface II. This causes pressure to build up more rapidly within the control chamber than would otherwise be the case and increases the flutter of the valve.
Flutter of the valve has another cause. Impulse disc 3'! lies in the path of movement of the fluid flow through the valve, with the result that the impact of the fluid against the disc tends to pull the valve shut. Looked at from another standpoint the projection represented by the impulse disc oifsets part of the back pressure upon the lower surface of the main valve, making the pressure upon the movable (preferably piston) control chamber wall easily effective to move the 'wall toward valve closure. This may completely close the valve if the action be abrupt or may partly close it, relatively backing up condensate until the cooling of the leakage condensate passing into the control chamber lowers the control chamber temperature and pressure resulting in a wider opening of the valve and resulting in "floating" of the valve until a more sudden increase of temperature in the control chamber results in closing of the valve.
The impulse disc performs a further service, in
that in cases of sticking of the valve for any 5 reason until the condensate has been drained and live steam or steam from revaporized condensate begins to flow out through the valve, the much higher velocity of flow of steam would give higher impact against the disc and cause the valve to close, additionally safe-guarding against leakage of steam through the valve.
The present invention additionally protects the trap against steam passage through the valve by reason of the fact that the inlet to the control 15 chamber is an aperture rather than a passage, facilitating the flow of steam in case of possible access of the steam to the under face of the piston and thus immediately increasing the pressure in the control chamber and against the control 20 chamber side of the piston to drive the valve shut before the water has been drained from the inlet chamber. This action is further improved by the extremely light weight of the valve and piston unit made possible by the use of a thin-edged or 25 wafer type of piston.
When the temperature of the water is on the border, just about hot enough for its reevaporation in the control chamber to cause the valve to close, the latter flutters, opening for flow .of 30 some of the water and closing again as the valve ceases to flutter. The valve then remains closed until the water is cooled sufliciently to start operation again.
The valve may thus be balanced, partly open, 35 while the water is, drained off and until the high temperature of the water in the control system causes closing of the valve by re-evaporation (flashing) in the system, whether this act by pressure or by foam interference with the discharge.
Subject to the control of the designer the operation of my trap lies between two extremes. On the one hand, it. can be designed to open at relatively low temperatures down much below the temperature of the steam in the system, backing up the condensate in the system deliberately and letting the cooler condensate out constantly while the hottest condensate cools as it approaches the trap. On the other hand, it can be designed to discharge condensate so nearly at "the temperature of steam of the system as to allow steam to enter the trap at intermediate times of low condensate supply, never opening upon steam but only upon flooding of the trap by condensate and closing on' condensate substantially at the steam temperature or on steam and remaining closed on steam. Whether the designer approach either of these limits or plan the trap to work at an intermediate part of this range must depend upon the needs of the particular installation or type of installations which are being considered, the trend being strongly toward discharge at a very high temperature.
It is desirable in normal operation that the trap discharge water at as high temperature as possible without allowing steam to reach the trap, in practice at least ten degrees below steam temperature. In order that the discharge may be at high temperature, it is desirable that the pressure within the expansion chamber" i8 during normal operation, shall be as nearly the pressure of the .main system as possible and that the area upon which the closing pressure is exerted shall be as little larger than the area upon which the main pressure is exerted as possible.
There are other features which aifect the question, including the weight of the valve, whether it be lowered for closure or lifted for closure, friction and the back pressure in the chamber II (which may be considerable). The light weight of the piston-valve unit as well as the wafer piston and wabbling character of the piston facilitate operation of the present valve upside down or in any angular position desired.
In connection with conditions of operation resulting in successive openings and definite closures of the valve, the relation between the pressure and leakage areas is seen from the following discuss1on:
The fluid pressure within the control chamber will be intermediate in magnitude between the high pressure within the inlet space and the low pressure within the outlet space and will be variant according to the relative variations of density at the inlet and outlet of the expansion chamber. The pressure within the control chamber increases and decreases respectively with fall and rise of the ratio 62/61 if 61 and 6: represent the densities at the inlet and outlet of the control chamber. 1
Let P1, P2 and P: be the absolute pressures in the inlet space, control chamber and outlet space of the trap, and t1 the temperature of the condensate as it reaches the inlet to the control chamher.
If t1 is greater than that corresponding to saturated steam at the pressure P2, there will be generation of vapor in the control chamber and a correspondingly increased specific volume and lowered density at the control chamber outlet, variant according to the extent the heat of the liquid at t1 is greater than the heat of the liquid at a temperature t1 corresponding to that for saturated steam at the pressure P2. It will be understood that P: rises with rise in t1.
Let A and A1 equal'the areas respectively across the piston 34 and across the valve at its line of engagement with the valve seat.
As later explained, the valve will operate regardless of its angle with respect to the horizontal. I will, however, assume for the moment that the valve is upright. When the valve is closed, it is pressed shut by a force (PaA-i-w) where w is the weight of the valve, and urged open by a force (P1(A-A1) +P1A1). In order that the valve may remain shut, (P=A+w) must be greater than The pressure P: (at outlet I'I) may be very considerable, especially with high P1 pressure or when discharging into a system having back pressure.
When the valve is shut, t1, and therefore P2, progressively fall, since the condensate is accumulating faster than it discharges through the outlet of the control chamber.
When P: has fallen so far that the closing force (PzA+w) is less than the opening force (P1(AA1)+P:A1), the valve lifts and suitably rapid discharge takes place through the valve port While the valve is open, the condensate discharges faster than it accumulates, and t1 and P1 both rise until the valve again closes. The dimensions of the control chamber inlet and outlet and of the valve are so selected, as by test determination of suitable dimensions, that the closure is at a sufliciently low temperature 121 to avoid danger of having live steam reaching the trap.
While the valve is open, the opening force has a value greater than (P1(A--A1) +PaA1, since a somewhat indefinite portion of the area A1 now receives all or part of the pressure Pi.
It is desirable to provide for an increase in the closing force during the period that the valve is open and to suitably offset a portion at least of the increase in the opening force due to the fact that the outlet flow bears against the under face of the valve which lies within the valve opening when the valve is closed but is exposed to the outflow of condensate when the valve is open. This increase in the closing force may be supplied by the use of a projection such as impulse disc 31 within the path of flow. The impulse disc is supported upon the extension of the valve stem at 36 and at a point beyond the valve seat in the direction of flow of the valve. The disc is in the path of the discharge and exerts a corresponding pressure upon the valve toward closure as long as the valve is open, in part offsetting the back pressure due to condensate discharge. The impulse disc also avoids any tendency of the valve to stick in open position due to scale and other impurities in the condensate.
The closure of the valve port by the impulse disc 31 when the valve is in open position is prevented by the boss 40 which engages the inside of the bonnet 29. g
It is usually desirable to have the force holding the valve open sufiiciently high to avoid valve closure until there has been a material increase in the value of the temperature t1 of the condensate.
As elsewhere explained the impulse disc can be used for various advantages. It can be used for its impulse function alone or it can be used to prevent the valve from striking at the top of its stroke or it can be used to throttle the outlet somewhat where the valve is balanced in normal discharge and floats without fully closing by its position controlling the outlet flow to agree substantially with the rate of formation of condensate and thus maintaining the temperature ,of the condensate at the trap nearly constant.
While the impulse disc is usually desirable and decidedly my preference the rest of my invention can be used without it.
The valve automatically closes as soon as the pressure P2 reaches a value sufficient to make the closing force greater than the force pressing the valve open, this increase in P1 being due to the rising temperature t1, which is in turn incident to the condition that the discharge through the trap is faster than the accumulation of condensate in the piping before thetrap. 1
It will be understood that the opening and closing pressures of the valve are dependent upon proper relations between the areas A and A1, and also within fairly wide limits, on the relative areas of the inlet and outlet of thecontrol chamber.
The relation between A/A1 and a1/a:, where 01 and a2 represent the areas of the inlet and outlet of the control chamber, may be quite widely varied. A rough indication of the way in which the dim nsional characteristics of the control chamber inlet and outlet and of the valve are.
related may be had from a brief theoretical discussion. Assuming no change in the density along the orifices themselves and the same discharge coeflicients for both orifices:
whence where S, 6, q and r are respectively the specific volume of steam, the specific weight of water, the heat of the liquid and the heat of vaporization, with subscripts 1 and 2 referring to pressure conditions respectively before and after the inlet to the control chamber.
If P1 were 300 pounds per square inch and the inlet and outlet of the control chamber for example are given dimensions such that (oi/a2) has a value of 3, the pressure within the control chamber in accord with the above equations might range between 229 and 261 pounds per square inch. Ifthe inlet and outlet of the control chamber are given dimensions such that (tn/a2) has a value of 0.04, P2 might range from 26 to 265 pounds per square inch, showing that if the valve is dimensioned (as by making A/A1=4) to operate at any pressure range between 229 and 261 pounds per square inch (assuming P1 of 300 pounds per square inch), (ai/az) may have any value between 3 and 0.04 and even lower than 0.04 without affecting the automatic operation of the valve.
If, however, the valve is dimensioned to operate at a low range of control chamber pressure, as between 2'7 and 30 pounds per square inch, theory would indicate that control chamber inlet and outlet should be dimensioned to give (oi/a2) a value not greater than say 0.04.
The two valves, dimensioned to make A/A1 respectively say 4 and 1.04, would automatically discharge at relatively high and low temperatures, respectively near to and far from that of saturated steam at P1, and the operation of the first valve would be far less under the influence of variations in the ratio of the control chamber inlet and outlet areas than that of the second. and would satisfactorily operate on the same inlet and outlet areas as the second. Since high temperature discharge is also usually preferable to low temperature discharge, the first valve would usually be much preferable to the second.
It has been found that in practice, a relation of 4 to 1 between A and A1 is very satisfactory, but am aware that lower ratios than 4 to l are not only suitable but in special cases may be preferable.
Good results have been obtained with the pressure in the control chamber at the time that the valve is closed about 50 pounds per square inch below the pressure in the system, when the sys tem is under pressure of the order of 300 pounds per square inch. The valve should preferably close when the temperature of the condensate in the control chamber is about 10 F. below the saturated steam temperature in the system. For this purpose in Figs. 1 to 4 the area of the inlet, about the piston should preferably be about one and one-half times that of the outlet.
Because the inlet is a circumferentially long and very narrow annulus its resistance to water flow will be quite different for the same ultimate cross-section from that of the outlet of circular section. This affects the starting of the valve on cold condensate. It is to be noted that the'inlet leakage past the piston is handling condensate, i. e. water, whereas after the trap begins handling hot water the outlet will handle a mixture of water and vapor or steam of much larger.
volume for the water content. It'is the intention to provide for a lower rate of flow through the control-chamber than the minimal rate of formation of condensate in order that the inlet compartment may be kept filled with condensate.
Considering again theconditions for opening and definite closing of the valve, it will be evident that, when the condensate temperature reaches a predetermined value, the valve closes due to the rise in control chamber pressure. The closure of the valve is sudden, eliminating wire drawing in the valve port. The impulse disc assists in producing an instantaneous closure of the valve, even when dirt and grit are present.
If the condensate at system pressure could get entirely beneath the valve when the valve opened,
it would be impossible for the control chamber pressure to close the valve because of excessive back pressure. To prevent this, the valve stem 36 is extended for a substantial distance through the valve port 22 even when the impulse disc is not used.
In Figure 4 the valve is shown without an impulse disc, but having a long stem. The pressure acting on the lower end 42 of the valve stem 33 to hold the valve open is well below system pressure even when the valve is in open position, and is probably always close to the outlet space pressure. When the valve is open fluctuation of the path of flow of the discharging condensate contributes to wabbling of the valve in this form also.
Wherever the words pressure or fluid pressure or the like in control chamber l8 are mentioned in this description, it is intended to mean the pressure of water of varying densities or the pressure of water mixed with its vapor formed by the excess of the heat of the liquid at the reduced pressure; all in distinction to dry, Saturated or superheated steam pressure.
The form of the invention shown in Figures to 10, inclusive, is well suited to use in systems having large amounts of scale. The condensate entering the trap must pass through slots 43 in a strainer 44 comprising annular ribs 45 joined by unslotted portions 46 to the bonnet 29'. v
The valve 2| has a large bore 41 at the piston end, with a smaller communicating bore 48 nearer the stem end, and an outlet 24' at the stem end. The impulse disc 31' is threaded on the stem 36 at 49, and can be removed quickly if desired. The same type of leaky piston inlet here 23'to the control chamber is used in the form of Figures 5 to 10, inclusive, as in-,the form of Figures 1 to 4, inclusive.
Instead of forming the stationary walls of the control chamber on the inside of the bonnet in Figures 5 to as in the form of Figures 1 to 4, inclusive, the'valve reciprocates in a separate housing in the form 01 Figures 5 to 10, inclusive. The housing contains a valve seat-3|, threaded into the body l5 at 32. and a cylindrical wall 50 having openings at 5| and threaded at 52 to a cap 53. The interior diameter of the cylindrical wall 50 is properly chosen with respect to the diameter of the piston 34, so as to give the desired clearance as previously explained.
In thetrap of Figures 5-10 it will be noted that 1 "the cylinder within which the wafer piston opermanner as that of Figures 1 to 3, inclusive, ex-
cept that there is no boss 40 to limit the valve in open position, this function being performed by the piston itself, which comes into contact with the cap 53. The impulse disc is adjustable in the form of Figures 5 to 10, inclusive, so that it need not close oif the valve port 22 when the valve is fully open.
From the steam trap of Figure 11, it will be seen that the traps may be used in inverted position, or at any desired angle to the horizontal, as they do not open or close by gravity. It will also be seen from this form that the control chamber inlet and outlet need not be in the clearance between the movable wall and the stationary walls of the control chamber or through the movable wall of the control chamber, but may be entirely through the stationary walls of the control chamber. Clearance between the piston 34 and the bore 35' has been minimized in Figure 11, and. leakage around the piston has been further reduced by labyrinth rings 54 spaced by annular grooves 55. The inlet 23' to the control chamber is controlled by a needle valve 56 having a thumb screw 51, while the outlet iscontrolled by a needle valve 58 provided with a thumb screw 59.
The form of Figure 11 operates in the same way as that of Figures 1 to 3, inclusive. The operator may change the control chamber inlet and outlet areas by means of the-needle valves, to suit the conditions of the particular installation.
In Figure 13 is shown a slightly variant form in .which the movable wall comprises a diaphragm 60 clamped by bolts 6| between the bottom portion 62 and the top portion 63 of the diaphragm casing 64, which is threaded into the main body of the trap. The diaphragm has an opening at 65, through which a threaded end of the valve 2| passes, to be gripped by a nut 66.
The valve 2| contains both the inlet and the outlet of the control chamber. The inlet 23 is through a passage 61 and the outlet 24' is through a passage .68.
In operation and in general character, the form of Figure 13 is like that of the earlier figures.
While the desirability of having continuous escape of condensate at a rate lower than the minimum rate of condensation in the steam system has been discussed, it will be understood that escape of condensate need not be continuous, but may be intermittent.
In Figure 14 a form is shown which is generally similar to that of Figures 1 to 3, inclusive, except that a bimetallic thermostatic element 69 is secured at 10 to the inside of the bonnet 29 and carries a valve 2 I which acts upon the upper end of the outlet 24*- As long as the temperature of the condensate is high, the thermostatic element remains expanded in the position shown in Figure 14, closing the control chamber outlet 24 and preventing opening of the valve 2l When tne condensate cools below a predetermined temperature, the bimetallic thermostat contracts, opening the outlet 24 of the control chamber. As long as the thermostatic element is contracted, the valve is capable of operating inexactly the same manner as the valve in Figures 1 to 3, inclusive, but when the thermostatic element again expands, it forces the valve closed (whether or not it has previously closed due to the action of the control chamber) and closes the outlet 24 It will be evident that various modifications of my steam trap may be made, with or without the impulse disc.
It will further be evident that, by bypassing the condensate through the control chamber, the temperature (pressure) of the bypassed stream of condensate in the control chamber can be used to control the main stream of condensate through the steam trap valve. By making the rate of bypassed flow less than the minimum rate of condensation, any undesirable effects through having steam enter the trap are avoided. Should steam enter the trap, however, under unusual conditions,
the loss will be slight, as my control chamber inlet and outlet are quite small and will not permit rapid flow through the control chamber.
It will also be evident that, after the valve has been designed with the proper proportions of areas, the valve may be used without regard to variation in the steam pressure of the system.
The trap is not in any way dependent for operation upon accurate determination or adjustment for the pressure of the steam. This is an important feature, as many steam systems undergo wide pressure variation during normal operation.
It will be evident that among the various forms shown there are several parts performing the same function, as for example, the inlet passage which may result from a loose piston fit or a port in either the fixed or movable member. These parts have been given the same reference character in many cases with distinguishing superscripts which it has not been considered necessary to refer to specifically in the specification. The grouping for this purpose applies the reference character without superscripts in Figures 1-4 with primes in Figures 5-10, seconds in Figures 11 and 12 and the number 3 in Figure 13.
It will be evident that condensate at a temperature very close to that of the steam at system pressure will pass through the leakage space from the main chamber to the control chamber without foaming until it has reached the control chamber, and will therefore pass through the inlet port 23 at approximately the same speed as that of colder condensate passing through this port. However, when the hot condensate reaches the control chamber and foams it exerts a higher pressure upon the movable wall than before; and
this for two reasons. Because of the pressure due to vaporization the control chamber immediately becomes full of a mixture at the pressure due to the evaporation, Because the condensate is now in the form of foam due to the evaporation it cannot longer pass out of the orifice 38 at the same water speed as before and, relatively, condensate can now leak in at a faster rate than it can leak out. Both of these tend to increase the pressure in the expansion chamber. There may be a still further reason for increase here in that access to the orifice 38 may be cut oii or restricted by location'of the end of densate discharged.
with the same efiect. The flashing would seem to take place after the condensate leaves the control chamber and enters orifice 38, passing from It will be evident that with a large quantity of condensate to be handled the valve will not close during normal operation but will stay open in a position to handle the condensate progressively and continuously with slight variations either for more rapid discharge or for less rapid discharge.
It has been noted that the fluctuation of the valve is more rapid and greater in extent when the system is started up and the trap is handling air or cold water first than is the case after the air and cooler water have been eliminated and. the trap is operating consistently upon very hot water.
It will be evident thatthe impulse disc 31 may be of such size or of such proportion that as soon as a slug of condensate starts to pass out through the valve port and strikes the (preferably annular) projection the back pressure upon the valve will be equalized in part and the valve will be closed, and consequently, the condensate will be discharged through the valve by successive openings and closings of the valve with intermediate small flows of condensate. However, it is my understanding that in the form shown in Figures 1 and 2, for example, the impulse against this disc balances the valve in partly open position and the flow is nearly uniform from the time the valve opens until almost all of the condensate has been discharged and until, by reason of the approach of live steam to the trap, the discharge temperature approaches closely the temperature of live saturated steam within the system.
The position and diameter of the disc with respect to the lower edge of the outlet port 22 may be used to throttle the discharge as the valve rises so as under normal circumstances to prevent engagement of the top of the valve with the interior surface ll It will further be evident that it is ordinarily not necessary nor even desirable to guide .the lower end of the valve unit nor to prevent this lower end from wabbling within the port 22 when the valve is open. The freedom to wabble at the lower end has merit in that the surface of the valve and seat and of the edge of the flange forming part of the movable wall in Figure 1 are scoured by the wabbling as well as by the longitudinal movement of the valve, the piston is canted or tilted and any scale lodged between the movable parts is readily eliminated by the combined movements.
In view of the invention and disclosure varla tions and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the structure shown, and, therefore, all such are claimed in so far as they fall within the reasonable spirit and scope of the invention.
Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:
1. In the art of removing condensate from a steam system, the method which comprises withdrawing liquid condensate continuously from the system as leakage discharge of a small stream along a constricted passage and reducing or increasing withdrawal through' another stream thereof by variation of the pressure of the continuously discharging condensate at a portion of the constricted passage.
2. In the'art of removing condensate from a steam system using a condensate discharge valve, the method which comprises discharging from beneath the surface of the condensate a small stream of the condensate, reducing the cross-section of the small stream at spaced points, urging the condensate discharge valve toward closure by fluid pressure exerted by the small stream at an intermediate point between the points of reduced cross-section and urging the condensate discharge valve toward opening by pressure of the steam system and controlling the opening and closing of the discharge valve by variation in pressure at the intermediate point due to variation'in-reevaporation of the condensate.
3. In the art of trapping an incoming stream of condensate out of a steam system to a discharge region of pressure lower than that within the said. system, the method which comprises continuously diverting one portion of said stream of condensate, as distinguished from steam, along a passage to discharge, reducing the cross-section at spaced points below that of the adjacent parts of said passage, providing orifice flow at that reduction nearer the inlet, opening or increasing the opening of a second passage through a discharge valve when the pressure from revaporization reduces and closing the valve .opening or reducing the opening of said second passage by variation in pressure from condensate at a portion of the passage intermediate the portions of less crosssection when the pressure from revaporization increases, while maintaining the point of diversion full of condensate.
4. In the art of trapping an incoming stream of condensate out of a steam system to a discharge region of pressure lower than that within the said system, the method which comprises continuously diverting one portion 'of said stream of condensate, as distinguished from steam, along a passage to discharge, having at spaced points parts of-cross-section less than the cross-section of said passage between these points, the earliest of which points in the direction of said stream travel provides orifice flow, opening or increasing the opening of a second discharge passage when the pressure from revaporization reduces and closing the second passage when the pressure from revaporization increases, by variation in said streams by reason of the progressively inant increasing pressure at a part of the throttled stream between the points at which throttlin takes place, as the temperature of said stream rises progressively nearer an .upper limit corresponding to the temperature of saturated steam at said pressure and before the temperature reaches the said upper limit and opening the other of said streams by the system pressure as the condensate in the continuously flowing stream cools and the pressure reduces.
6. The method of discharging condensate through a piston-connected valve operating in a control cylinder, which comprises surrounding the piston-connected valve by condensate constantly in contact with the piston, continuously bleeding condensate through a reduced pressure in the control cylinder whether the valve be closed or opened, the extent of bleeding into said cylinder varying with different positions-of the valve when the valve is open, opening the valve by the main pressure of the system operating through the condensateand closing the valve by pressure upon the piston due to revaporization of the condensate in the system before the condensate has been wholly discharged through the valve, whereby the piston and the valve are continuously in contact with condensate.
7. In the art of trapping condensate from a steam system through a piston-controlled steam trap valve, the method which comprises continuously discharging condensate from the system at a rate lower than the average rate of formation of condensate through a passage about the piston providing orifice flow and through a control space having reduced pressure and, from said space, through a restricted passage to a point of discharge at lower pressure, and opening and closing another passage controlled by the piston for rapid withdrawal of condensate from the system at a rate higher than the average rate by variation of pressure in the control space due to variant re-ev aporation of condensate within the control space as compared with the main system pressure. i
8. In the art of trapping condensate from a steam system through a piston-controlled steam trap valve, the method which comprises continuously discharging condensate from the system through a passage about the piston providing orifleeflow and a control space having reduced pressure and from said space through a restricted passage to a point of discharge at lower pressure, varying the section of the orifice by movement of the piston and varying the pressure in the control space by variant re-evaporation of condensate within the control space as compared with the main pressure to eflect opening and closing of another passage controlled by the piston for withdrawal of condensate from the system.
9. In the art of removing condensate from a steam system, the method which comprises continuously withdrawing condensate as such, as distinguished from steam, through a by-pass at a rate lower than the minimum rate of formation of condensate and in periodically withdrawing condensate by a different path at a rate higher than the maximum rate of formation of condensate, controlling the periodic withdrawal by the change in ratio between the re-evaporation pressure of the condensate and the pressure of the steam in thesystem.
10. The method of trapping condensate by a condensate charged trap and a piston within acylinder for control therefor, which comprises continuously surrounding the valve on the piston side of the valve seat and the piston with condensate, passing a small quantity of condensate to discharge through the space on the side of the piston away from the valve, opening the valve by the main system pressure engaging the piston through the condensate, closing the valve by increasing re-evaporation pressure of the condensate as the temperature of the condensate rises,
while maintaining the piston against sticking by rigid with the valve and located in the path of the condensate main discharge and on the opposite side of the yalve throat constriction, using a cylinder enclosing the piston, which comprises opening the valve by the main pressure of the system through the condensate and in part counterbal ancing the reaction pressure exerted upon the valve by theflow when the valve is open by pressure against the projection connected with the valve, thus assisting the valve toward closed position by discharge of condensate against the projection.
12. The method of trapping condensate from a steam system by a valve located on one side of a valve seat and adjacent valve throat constriction and having a projection rigid with the valve and located in the path of the condensate main discharge and on the opposite side of the valve throat constriction and by a cylinder-enclosed piston movable with the valve, which comprises opening the valve by the main pressure of the system acting upon one side of the piston through the condensate, in part counterbalancing the reaction pressure exerted by the flow upon the valve when the valve is open by the discharge pressure upon the projection and thus assisting the valve toward closed position with discharge of condensate, whereby the valve is caused to flutter in partly open position by the variation in flow of the discharge, and assisting in closing the valve by pressure of the condensate upon the opposite side of the piston, varied because of viiriant re-evaporation of the condensate.
13. In the art of eliminating condensate froni' a steam system, the method of opening and closing a steam trapvalve controlling the discharge of the condensate through the valve opening and throat thereof, which comprises continuously withdrawing condensate along a constricted passage, opening the valve by the pressure of the main system acting through the condensatathe valve opening in a direction opposite to the direction of the discharge, closing the valve in part by pressure due to revaporizatlon of condensate. acting in the direction of the closure at an intermediate point in the passage and varying with the temperature of the condensate, andasslsting in closing the valve by discharge impingement beyond the throat constriction of the valve upon a surface connected with the valve and projecting into the path of discharge.
14. In the art of eliminating condensate from a steam system, the method of balancing in partly openposition a steam trap valve unit controlling the discharge oi the condensate throughgthe valve opening and the throat thereof, which comprises continuously withdrawing the condensate along a constricted passage, opening the valve by pressure from the main steam pressure acting continuously throughthe condensate, and balancing the valve in variant partly open position by the pressure of high temperature condensate leakage along said passage, and the pressure of the discharge at a point beyond the throat constriction of the valve, upon a surface connected with the valve, the valve opening more widely as the condensate reaching the trap cools by reason of increased rate of formation and closing partly as a slower rate of condensate formation causes hotter condensate to reach the trap.
15. In the art of eliminating condensate from a steam system, the method of opening and closing a valve unit controlling the discharge of the condensate through the valve opening and the throat thereof, which comprises pressing the valve toward opening by the main stream pressure, continuously surrounding the valve by condensate, balancing the valve unit between said opening pressure and a closing pressure from a control chamber continuously receiving and discharging condensate and pressing the valve unit toward valve closure through the condensate, by the combined efiects of leakage pressure in the control chamber and impulse effect of the discharge exerted upon the valve unit at a point beyond the valve throat in the direction of discharge flow.
16. In the art of eliminating condensate from a steam system, through a discharge valve, the steps in the method which comprise continuously discharging a small quantity of the condensate independently of the valve closure against its seat, utilizing the re-expansion'of the condensate when the temperature of the condensate becomes hot enough for that purpose as the means of closing the valve and progressively reducing the outlet flow through the valve with continued opening movement of the valve when the valve opening has become excessive.
1'7. In the art of eliminating condensate from a steam system through a discharge valve and its seat having a throat, the steps in the method which comprise continuously discharging a small quantity of condensate through a control system independently of the valve closure against its seat, varying the pressure tending to close the valve by the re-expansion of the condensate in the control system, when; the temperature of the condensate becomes hot enough for that purpose and progressively cutting off the flow through the valve, at a point after it has passed the valve throat, with excessive opening movement of the valve, whereby the reaction opening pressure upon the valve is reduced and movement of the valve toward'closure is hastened.
18. In the art of eliminating condensate from a steam system, the method of eliminating condensate from a steam system through a steam trap valve unit, which comprises providing a larger area of valve unit exposure in the control chamber than in the main chamber for the closed position of the valve, continuously filling the main chamber with condensate, moving the valve unit by'the main pressure of the condensate to open the valve, allowing inlet from the main chamber to the control chamber in all valve positions and at rates variant when the valve is open, and from the control chamber to discharge in all except fully open valve positions, whereby the pressure within the control chamber progressively increases with rising condensate temperature by reason of vaporization of a progressively greater portion of the condensate and restricting outlet in fully open position of the valve by the position of the unit.
19. In the art of eliminating condensate from a steam system, the method of operating a steam trap valve unit by condensate engaging opposite faces of the unit within a main chamber and within a control chamber, respectively, which comprises providing a larger area of valve unit exposure in the control chamber than in the main chamber for the closed position of the valve, filling the main chamber with condensate, moving the valve unit by the main pressure of the condensate to open the. valve, allowing inlet of condensate from the, main chamber to the control chamber in all valve positions and at rates variant when the valve is open, and from the control chamber to discharge in all valve positions, whereby the pressure within the control chamber progressively increases with rising condensate temperature by reason of vaporization of a progressively greater portion of the condensate and restricting outlet through the valve in fully open position of the valve by the position of the unit. Y
20. In the art of eliminating condensate from a steam system, the method of controlling the position of a steam trap exhaust valve unit, which comprises subjecting one area of the valve unit continuously to the main condensate pressure, tending to open the valve, continuously providing condensate leakage through a control system including a passage securing orifice flow and engaging a larger area of the same valve unit and then to discharge from said larger area, pressing the unit in a direction opposite to that caused by the main condensate pressure and controlling the opening and closing of the valve by the 'extent of pressure on said larger area, variant by reason of variant re-evaporatlon.
21. In a steam trap, a body having inlet and outlet chambers, a hollow cylinder, a thin-edged piston closely fitting the interior of the cylinder and fulcruming against the wall of the cylinder, between which cylinder and piston leakage from the inlet chamber is free to take place, avalve on the piston, a valve seat cooperating with the valve and forming a discharge outlet through a valve throat, ,a valve stem extending beyond the valve and loosely through the valve throat, providing room for substantial lateral movement of the stem when the valve is open and walls forming an outlet leakage connection from the cylinder to the outlet chamber.
22. In a steam trap, a tapered valve, a valve seat within which the valve can move laterally when the valve is open, a piston connected with the valve, a cylinder within which the piston operates and by whose walls the piston is. guided, connections for supplying condensate to one side of the valve and withdrawing it as leakage past the piston from the opposite side of the valve, the piston being thin at the edge and free-to tilt and the valve being free to shift laterally with respect to its seat when lifted to a substantial extent to permit wabbling of the piston within the cylinder and side movement of the valve, whereby the cylindrical surface of the piston'is scoured, and means carried by the valve, extending beyond it and engaged by the discharge so that the valve and piston are made to wabble,
densate to the inlet chamber on one side of the 7 5 piston and withdrawing ittrom the opposite side thereof, the piston being thin at the edge and free to tilt, whereby wabbling of the piston within the cylinder is facilitated and the perimetral' surface or the piston is scoured.
24. In a steam trap, walls forming inlet and discharge chambers, a tapered valve, a valve seat thereior, a piston connected with the valve, a cylinder 'within which the piston operates and by whose walls the piston is guided, and connections for supplying condensate to the inlet chamber between the valve and piston causing it to leak past the piston into the cylinder and walls providing leakage from the cylinder to discharge, the piston being thin at the edge and free able in the cylinder, a valve connected with the piston, a valve seat engaged by the valve communicating with the discharge chamber through a valve throat, a valve stem extending in a direction 'away from the piston beyond the valve throat and loosely through the valve opening and whereby the stem is surrounded by discharge passing through the valve opening, and an annulus located on the valve stem beyond the valve throat within the path of discharge through the valve and effective to reduce opening movement 01 the valve.
26. In a steam trap, a body having inlet and outlet spaces and a control chamber, a movable wall by its position varying the volume of the control chamber, a valve connected to move with the movable wall, a valve seat cooperating with the valve to control flow through the valve from the inlet to the outlet space, leakage means for providing flow from the inlet to the control chamber and from the control chamber to discharge providing variant pressure in the control chamber according to the.revaporization oi the leaking condensate opposing the varying pressure in the control chamber against the inlet pressure to determine the position of the movable wall, and an impulse member secured to the valveon the outlet sides of the valve and prol'ecting outwardly from inside the discharge stream into the stream for oilsetting the pressure upon the impulse member against the reaction pressure upon the valve when the valve isopen and thus tending to close the valve.
' 27. In a steam trap, a body having inlet and outlet spaces, a valve seat between the two spaces, a valve unit having portions of different diameter including an annular thin-edged piston at one end, a valve at a point intermediate the extremities of the unit, a valve stem extending through the seat to the outlet side oi the seat and a proiection on the valve stem extending from the inside outwardly into the discharging stream, cylinder walls surrounding the piston and having clearance for leakage from the inlet space to the cylinder and stop means for preventing the valve aosmss from opening far enough so that the impulse projection will unduly restrict the valve opening.
28. In a steam trap, walls forming inlet and discharge spaces and a cylinder, a thin-edged piston dividing the cylinder from the inlet space having its only guidance within the cylinder eiiected by the piston perimeter bearing against the cylinder walls and having clearance allowing leakage past the piston into the cylinder, a valve connected with the piston and a valve seat for the valve within which the valve has substantial clearance when the valve is open to move laterally to an extent greatly in excess of the extent of piston clearance. to permit swinging movement about an edgeoi the piston when the valve is open, and to secure scouring movement 0! the piston.
29. A steam trap having inlet and discharge compartments, a cylinder connected therewith, a wabbly piston in said cylinder having clearance from the cylinder walls and through the clearance providing leakage ior inlet condensate past the piston and into the cylinder, there being outlet from said cylinder for said leakage, a discharge valve from the inlet compartment connected with the wabbly piston and laterally loose when the valve is open to an extent of movement greatly in excess of the piston clearance, a seat for the discharge valve and means carried by the valve engaged by the discharge through the valve seat to wabble the piston and valve during discharge.
30. In a steam trap, a body having inlet and outlet spaces and a valve seat, a valve unit, adapted to close against the seat, cooperating to control communication between the inlet and outlet spaces through the valve opening, stationary walls forming part of a control chamber, a piston forming part or the valve unit, surrounded and laterally supported by the control chamber walls, having leakage clearance from them and rigidly connected to the valve, whereby the pressure of the system is continuously applied against that side of the piston toward the valve, and walls forming an outlet from the control chamber to the outlet space substantially fixed in use, the piston being thin and loosely guided by the valve when the valve is open and the valve free to wabble when the valve is open, whereby the thinness of the piston cooperates with the lateral freedom of the valve to provide wabbling.
31. In a steam trap, walls forming an inlet space connected with a main steam system, a valve seat providing a main discharge from the space through a valve throat and a control chamber having orifice leakage connection with the main system and leakage connection with the discharge, a longitudinally movable valve unit for the seat having an area exposed to the main pressure as an opening pressure and a larger area connected therewith exposed to the control chamber pressure as a closing pressure, the area exposed to the main pressure and that exposed to the control chamber pressure, respectively, bearing a ratio or the order of 3 to 4, and a pressure element on the valve having a surface beyond the valve throat in the line or discharge adapted to be engaged by the discharging condensate to restrict valve opening movement and to assist in movement oi the valve toward closure.