US 3237420 A
Description (OCR text may contain errors)
' March 1, 1966 B. J. MULHOLLAND 3,237,420
REFRIGERATION SYSTEM PURGING MEANS Filed July 8, 1964 30 28 /4 JIIJ U y [6b 22 l6 6? Q4 65 OondensingUnlt Evaporator I2 12 Bleeder Tool CI] J INVENTOR ATTORNEY Bernard J. Mulhollond rates Unite This invention pertains to methods and apparatus for purging refrigeration systems and more particularly to the purging of conduits in split system air conditioners.
. Generally, air conditioning systems include a condensing unit for liquefying refrigerant gas by compression (compressor) and removing the heat therefrom (condenser). The liquefied refrigerant is then fed to an evaporator, Where it absorbs heat and vaporizes. The gaseous refrigerant is then sucked back to the compressor, and the cycle repeats. Since the condensing unit and evaporator are displaced from each other, they are connected by a pair of conduits, one a liquid conduit from the outlet of the condenser to the inlet of the evaporator and the other a gas conduit from the outlet of the evaporator to the inlet of the compressor, If there are any contaminants, such as dirt, air or water vapor, in the system, malfunctions can occur. In particular, dirt particles can damage mechanical parts. Water vapor, on the other hand, will combine with the refrigerant under the influence of heat of compression to form acids which will damage the system components severely. In air conditioners wherein the condensing unit and the evaporator are pro-assembled in a unitary structure, precautions are taken at the factory to remove and eliminate contaminants from the system.
, However, there are available split-system unitary air conditioners, wherein the condensing unit and the evaporator are installed remote from each other. Accordingly, it is possible to make a versatile installation, wherein optimum thermal positioning of the separate units is obtained. For example, the evaporator can be located at the site where cooling is required and the condensing unit can be located in an efficient heat sink.
In the split system, it is necessary, on location, to establish and assure the proper system charge of refrigerant for optimum system performance. In certain split system designs, the manufacturer makes available a condensing unit and evaporator with a pre-established charge, held captive in these components by special sealing devices or couplers. In addition, since optimum system charge is, to a significant degree, affected by length of interconnecting conduits, the manufacturer makes avail able certain fixed lengths of liquid and vapor conduit charged with refrigerant in the necessary amount to compensate for the conduit length. These fixed lengths of conduits are similarly fitted with mating sealing devices or couplers. Although this system design assures a clean factory processed system, correctly charged with refrigerant, added expense is incurred in making and handling the specially sealed conduits. Further, some of the flexibility of the split system is lost, since the fixed tubing lengths rarely satisfy the exact requirement of the specific installation. This results in cumbersome excess conduit length, which must be tucked away in some unobjectionable area, or conduit shortage, which necessitates the addition of costly conduit extensions precharged and fitted with sealing couplers. The significant advantage of the above described type of system is that the installation may be made by any mechanically competent installer. It is not necessary to have broad knowledge in the refrigeration art.
In still other split system designs, the manufacturer supplies the condensing unit and evaporator and the installer interconnects these components with locally avail- 3,237,420 Patented Mar. 1, 1966 able commercial grade refrigeration copper tubing. In this case, however, it is necessary that the installer take the necessary precautions to process the components to assure that they are free from dirt, chips and contaminants. This usually involves a time consuming process of evacuation, flushing and/or purging. Further, the installer must establish the proper operating charge for optimum performance. This will involve weighing in a correct amount of refrigerant, based on system requirements and conduit length. In the case of condensing units which were precharged at the factory, the installer has to bleed off or add charge, based on operating pressure-temperature characteristics. This type of system design has the advantage of flexibility, with regard to the handling of refrigeration conduit. However, its significant disadvantage is that it requires installation by a competent mechanic thoroughly familiar with the refrigeration art.
It should, therefore, be apparent that it is extremely desirable to have a split system design, and this can be of either the remote condensing unit type, as described above, or the remote condenser type, and a processing method that would allow the use of locally available refrigeration copper tubing. This would eliminate the need for specially processed and charged tubing fitted with special sealing devices, and further, it would provide installation flexibility, since the installer is at complete liberty to cut the standard refrigeration tubing to suit the application. In addition, it is extremely desirable to have a system that can be properly installed, in a relatively short time, by mechanically competent installers who need not have knowledge or practice in the art of refrigeration.
It is, accordingly, a general object of the invention to provide a method which insures that a refrigeration system be free of contamination.
It is another object of the invention to provide a method of processing or purging the conduits of a refrigeration system, and to establish a proper operating charge to insure optimum performance.
It is the further object of this invention to provide a simple, rapid and reliable mechanical method of purging the variable lengths of field supplied and installed conduit in a refrigeration system.
Generally, the invention contemplates a refrigeration system which includes a condensing section charged with refrigerant in an amount in excess of the required system charge in consideration of its maximum interconnecting con-duit length. The condensing unit includes a liquid line refrigerant outlet valve, which is initially closed, thus, containing the refrigerant in the condenser. The condensing unit also includes a suction line valve, which, similarly is closed, containing the refrigerant in the condensing unit. The interconnecting liquid and suction conduit connects to the liquid and suction valves on the condensing unit and to the evaporator. The liquid and suction valves are common refrigeration components designed to have a front seating (sealing) and back seating position. When front seated (closed), the refrigerant is contained in the condensing unit, and the port to which the interconnecting conduit is attached, is open to a service port. When the valve is fully opened (back seated), the service port is shut off, and there is free passage between the condensing unit and interconnecting conduit.
The invention contemplates that the installer will use and provide locally available standard refrigeration tubing, which is dehydrated and/or cleaned, sealed or capped. Therefore, the only contaminant to the system will be the volume of moisture laden air and minute airborne particles that will enter at the time the tubing is cut and the mechanical joint made to connect to the condensing unit and evaporator.
It is an object, of another aspect of the invention, to provide a special tool to further simplify and make safe the practice of the invention.
Another object of the invention is to provide an inexpensive, re-usable tool for accurately purging the refrigeration system at the time of installation, wherein, by use of the tool, the process becomes a series of simple mechanical steps requiring the minimum of mechanical competent from the installer.
Briefly, according to this aspect of the invention, there is contemplated a tool for use in bleeding, at a constant known rate, pressurized gas from the outlet of a fiuid system. The tool comprises a capillary tube of precise bore, a strainer assembly upstream of the capillary tube, a valve means upstream of the strainer assembly and a connection means to adapt to the condensing unit valve service port by means of a flexible conduit.
According to a feature of this aspect of the invention, the apparatus is housed in an insulated metal box structure having perforated side panels. A further feature of this aspect of the invention contemplates that the box would also contain a timing device to provide a signal on completion of the process.
Other objects, features and advantages of the invention will be apparent from the following detailed descriptions, when read with the accompanying drawings, which show, by way of example, and not limitation, the now preferred embodiments of the invention.
In the drawings:
FIG. 1 shows, partially in schematic representation, and, partially in cross section, a refrigeration system used in practicing the invention; and
FIG. 2 shows in perspective the tool employed in practicing the invention, wherein a portion of the housing of the tool is broken away.
Referring to FIG. 1, there is shown a condensing unit 10, located in a heat sink, and an evaporator 12, located in a region to be cooled. These two units separated from each other by a distance predicated on the location of the heat sink and the region to be cooled comprise the major elements of a refrigeration system and, more particularly, a split system air conditioner. By way of example, the system may have a capacity of 2 4,000 B.t.u. The condensing unit has a pressure outlet 14 which includes a manually operable valve 16 and a suction inlet 18 which includes a manually operable valve 20. Condensing unit 10 is initially installed with valves 16 and 18 closed as shown in FIG. 1. At this time, the condensing unit 10 contains a charge of liquid refrigerant which is, for example, nine and one-half ounces in excess of the amount required for a split system having a twenty-five foot separation between the condenser and the evaporator.
It will be noted that valve 16 has an inlet 16a connected to the pressure line of condensing unit 10 and an outlet 16b; and valve 20 has an inlet 2011, a first outlet 20b connected to the suction line of condensing unit 10 and a second outlet 20c connectable to the atmosphere as will hereafter become apparent.
Evaporator 12 includes an inlet 22 and an outlet 24. A required length of conventional refrigerant tubing is cut and connected by means of fittings 26 and 28 to the outlet 16b of valve 16 and inlet 22 of evaporator 12, respectively, to provide a first conduit therebetween. Another required length of conventional refrigerant tubing is cut and connected by means of fittings 32 and 34 to the inlet 20a of valve 20 and the outlet 24 of evaporator 12, respectively. A calibrated bleeder tool 36 is connected to the outlet 20c of valve 20. For the present, it is only necessary to know that tool 36 includes a manually operable valve 38 (FIG. 2). When valve 38 is closed, outlet 200 is effectively sealed, and when valve 38 is open outlet 200 is connected to the atmosphere.
When the system has been assembled as described above, it is necessary to purge the conduits 30 and 37.
4 As supplied, valve is closed, its piston 20d blocks outlet Ztib, which also results in communication of inlet 20a with outlet 2iic. The installer then opens valve 38. Accordingly, conduit 37 communicates via valve 20 and tool 36 with the atmosphere. Making note of the time, the installer opens valve 16. Liquid refrigerant flows via conduit 30 and inlet 22 to evaporator 12 where it expands to a gas. Gaseous refrigerant flows via outlet 24, conduit 37, valve 20 and tool 36 to the atmosphere propelling with it contaminants. After a given period of time, the installer closes valve 38 and refrigerant flow stops. The installer then opens valve 20 until piston 29d is in its back seated position. Accordingly, the refrigerant circuit of the refrigeration system is serially connected in a closed loop and the system is ready for operation. The installer can disconnect tool 36 from outlet 29c at his convenience.
At this point, it may be appropriate to discuss system I charge and the timing sequence between opening valve assures a constant bleed rate.
16 and blocking of the communication of conduit 37 to the atmosphere by the closing of valve 38. It may be recalled that one major purpose of the invention was to purge the conduits by bleeding a certain quantity of refrigerant through the system, as a vehicle for contaminants. This requires that a minimum amount of refrigerant be bled, regardless of conduit length. In the system cited, by way of example, the minimum bleed will be three ounces.
A second major purpose of the invention is to establish proper system charge to achieve optimum performance from the system. Systems, of the type described, may be sensitive to plus or minus one ounce of refrigerant. In the system cited, by way of example, the condensing unit and evaporator would require three lbs. five and nine-tenths ounces of refrigerant charge, if closely coupled. However, since this is a split system, there will be separation between the condensing unit and evaporator. This system will then be joined by means of liquid and suction conduits. With the addition of interconnecting conduit, there will be the requirement of 0.26 ounce additional refrigerant for each foot of separation, as determined by the liquid line length. The liquid line conduit is the primary consideration, in determining the added charge, because it will contain liquid refrigerant. The suction conduit carries gaseous refrigerant whose mass is generally inconsequential for the lengths under consideration.
In normal application of a system, as cited, the distance of separation might vary up to fifty feet. Therefore, in practice of the invention, the condensing unit would be charged with refrigerant contemplating fifty feet of separation, and, in addition, the minimum three ounce bleed to purge. In the system cited, this would be a total of four lbs. five and nine-tenths ounces of refrigerant charge.
If, in a given installation, the actual distance of separation were only twenty-five feet, then the required charge for that specific application would be three lbs. twelve and four-tenths ounces. The condensing unit charge is, herefore, nine and five-tenths ounces overcharged for the system requirement.
T 0 accurately release the excess refrigerant, the bleeder tool 36 is used. This tool is calibrated to release gaseous refrigerant at a rate of one ounce per ten seconds. Accordingly then, in the system cited, by way of example, the bleed off process would require a ninety-five second purge. In other words, the time lapse, between opening of valve 16 and closing of valve 38, is ninety-five seconds.
The bleeder tool 36, which is used to simplify the method of purging a system, will now be described primarily with respect to FIG. 2. Tool 36 includes a capillary tube 44 formed to be contained in an enclosure, and in a manner to avoid distortion in the tube. Precise internal diameter and flow rate test of the capillary tube A conventional strainer assembly 50 has its outlet connected to the inlet of capillary tube 44 to prevent dirt particles from entering tube 44. The inlet of strainer assembly 50 is connected to the outlet of valve 38. Valve 38 is opened or closed by rotating valve stem 52. The inlet of valve 38 is connected to a threaded connector 54. The installer uses a standard service conduit to connect from outlet port 20c of valve 20 to the bleeder tool connector 54.
A housing 56 encases the capillary tube 44 and the major portion of valve 38. Shaft 52 of valve 38 extends through an opening in housing 56. The valve and capillary assembly are held in the housing 56 by a mounting bolt engaged on the underside of the valve body. The threaded connector 54 extends through an opening in the housing.
Housing 56 is made of rigid material such as sheet steel. At least a portion of the housing 56 includes perforations, to permit unrestricted egress of air and gaseous refrigerant from within the housing to the atmosphere. The purpose of the housing is to prevent the installers hands coming in contact with the discharging refrigerant at the outlet of the capillary tube. Lining the inner surface of housing 56 is a layer 62 of porous insulating material such as rock wool or Fiberglas batting. The function of layer 62 is to deaden sounds generated by the flow of pressurized gases from the capillary tubes outlet 46. Mounted on housing 56 is a conventional mechanical timer 63 of the type which is hand set for a particular elapsed time, steps back to a home position with the passage of time, and sounds a bell when the home position is reached. Accordingly, timer 63 includes a combination handset and indicator 64 opposite a calibrated scale 66. Timer 63 relieves the installer of the task of timing the purging period. He need only set the timer 63 to the time established for the particular length of conduit as discussed above. However, to even further simplify the timing step, it is advantageous to calibrate the scale 66 in units of length of conduit. Accordingly, the installer need only position indicator 64 opposite the appropriate length of graduation on 66 and the timing becomes automatic.
There has thus been shown an improved method for purging the conduits in a refrigeration system. The method is simple in that it merely involves the opening and closing of particular valves in a given sequence with a given time interval between the opening of one valve and the closing of another valve. The time interval chosen insures that suflicient refrigerant has circulated so that all contaminants in the conduits of the system are expelled into the atmosphere.
There has also been shown a tool which includes a capillary tube which permits the bleeding of gaseous refrigerant at a constant known rate to simplify the purging and to assure correct operating charge for optimum system performance.
While only a single embodiment of each aspect of the invention has been shown and described in detail, there will now be obvious, to those skilled in the art, many modifications and variations thereof, which satisfy the objects of the invention without departing from its spirit as defined in the appended claims.
What is claimed is:
l. A method of charging an air conditioner system which comprises a condenser precharged with a predetermined quantity of liquid refrigerant in excess of the requirements of the system and having a liquid refrigerant outlet and a gaseous refrigerant suction inlet, a first valve initially closed coupled to the liquid refrigerant outlet of said condenser, a second valve initially closed coupled to the gaseous refrigerant suction inlet of said condenser, an evaporator including an inlet and an outlet, a first conduit coupling said first valve to the inlet of said evaporator, a second conduit coupling the outlet of said evaporator to the atmosphere through the second valve, said method comprising the steps of opening said first valve to allow refrigerant to flow from the condenser through the first conduit to the evaporator and then through the second conduit to the atmosphere, allowing said second conduit to communicate with the atmosphere for a given interval of time after the opening of said first valve sufficient to allow a quantity of refrigerant equivalent to the refrigerant in excess of the requirements of the system to escape to the atmosphere, sealing said second conduit from the atmosphere after a given interval of time sufiicient to permit refrigerant in excess of the requirements of the system to escape to the atmosphere, and opening said second valve to provide a passageway for refrigerant from the second conduit to the gaseous refrigerant suction inlet.
2. A tool for bleeding at a constant known rate a pressurized gas from an outlet of a fluid system comprising a capillary tube including first and second ends, an outlet orifice at the first end of said capillary tube, an inlet orifice at the second end of said capillary tube, said tube being bent in a convolution, a manually operable valve means including an outlet connected to the inlet orifice of said capillary tube, an inlet adapted to be connected to the outlet of said fluid system and a valve stem extension including a handle extending therefrom, a housing for containing said capillary tube and said valve means, said inlet of said valve means extending through said housing and said valve stem extension extending through said housing so that said handle is accessible for manual operation and a manually settable timer fixed to said housing to time a bleed operation.
3. The tool of claim 2 wherein said housing is of a rigid material including perforations.
4. The tool of claim 3 further comprising a layer of porous insulating material lining the inside of said housing for mufiling the sound of pressurized gas escaping from the outlet orifice of said capillary tube.
5. The tool of claim 2 wherein said timer includes setting means calibrated with respect to the capacity of said fluid system.
References ited by the Examiner UNITED STATES PATENTS 1,687,597 10/1928 Springer 62--195 2,215,717 9/1940 Rea 62475 X 2,341,429 2/ 1944 Elsey 62-77 2,518,212 8/1950 Wilson 62-149 2,934,915 5/1960 Morse 6277 X 3,006,155 10/1961 Vanderlee et al 62149 X 3,125,867 3/1964 Rath 62157 X MEYER PERLIN, Primary Examiner.
LLOYD L. KING, Examiner,