US 3800878 A
Disclosed is a fluid pressure release mechanism including a primary seal hermetically sealed in a fluid outlet by a eutectic material, and an auxiliary seal isolating the eutectic material from the fluid pressure and opened thereby upon melting of the eutectic material.
Description (OCR text may contain errors)
United States Patent 11 1 1111 3,800,878
Poitras 1 Apr. 2, 1974 [5 RELEASE MECHANISM FOR 3,160,212 12/1964 Reid 169/20 PRESSURIZED VESSELS 556,631 3/1896 Johnson 169/26 3,261,404 7/1966 Merdlnyan 137/74  Inventor: Edward J. Poitras, 198 Highland St., Holliston, Mass. 01746 7 Primary Examiner-Allen N. Knowles  1972 Assistant ExaminerAndres Kashnikow  Appl. No; 220,790 Attorney, Agent, or Firm-John E. Toupal  US. Cl 169/20, 137/72, 169/9,
169/26, 169/31 R, 169/42  ABSTRACT Cl- Disclosed is a pressure release mechanism in  he d of 22 g eluding a primary seal hermetically sealed in a fluid I 7 [89 outlet by a eutectic material, and an auxiliary seal isolating the eutectic material from the fluid pressure and  References cued opened thereby upon melting of the eutectic material.
UNITED STATES PATENTS 5 1950 Doughty 169/26 17 Claims, 2 Drawing Figures RELEASE MECHANISM FOR PRESSURIZED VESSELS BACKGROUND OF THE INVENTION This invention relates generally to a fluid pressure release mechanism and relates, more particularly, to a device for automatically releasing a pressurized fire extinguishing medium in response to the detection of an elevated temperature indicative of either the presence or danger of fire.
A well known type of fire and explosion suppressor utilizes a vessel filled under pressure with a suitable fire extinguishing fluid and having a sealed discharge opening that is automatically opened in response to detection of fire. In many such devices the discharge port is closed by a frangible wall portion that is ruptured by detonation of an explosive squib disposed within the vessel. Generally, the internal explosive squib is detonated in response to an electrical signal produced by a suitable fire detector. Examples of detectors of this type are disclosed in U.S. Pats. Nos. 2,742,094 and 3,523,583. Other devices of this nature have discharge ports closed either by valves or sealed diaphragms. Devices of this latter type utilize various types of actuators including solenoids, pressure operated valves, etc. to open their discharge ports. Also well known are fire sprinkler heads with toggle valves that are released in response to fusing of an eutectic material.
Although many of the known suppressors of this type are generally quite reliable, they do exhibit certain disadvantages in particular fields of desired use. For example, the cost of automatically actuated highly reliable suppressor units limits their use to applications involving high risk of loss to either personnel or equipment. Also some kinds of actuators such as the explosive squib are objectionable in certain environments.
The object of this invention, therefore, is to provide for pressurized containers an improved automatic release mechanism that is highly reliable and of relative low cost.
SUMMARY OF THE INVENTION The invention is characterized by the provision in a pressurized fluid filled container of an outlet hermetically sealed by a release mechanism including both a temperature responsive eutectic material and an auxiliary seal that isolates the eutectic material from the pressurized fluid. The auxiliary seal prevents the escape of fluid through isolated paths created in the eutectic material while it is being melted in response to an increase in ambient temperature. Such an escape of fluid would induce cooling of the eutectic material and thereby inhibit complete melting thereof at a predetermined and desired release temperature. In the present invention, the auxiliary seal insures complete melting of the eutectic material after which the auxiliary seal is automatically opened by the pressure within the con tainer thereby permitting release of the fluid through the outlet.
In a featured embodiment of the invention, the outlet comprises a discharge orifice formed by the open end of a tube communicating with the interior of the container. Closing the open end of the tube is a sealing plug formed by a metallic cup-shaped member having cylindrical walls hermetically sealed to the internal walls of the tube by a fusible metallic alloy. The auxiliary seal is formed by an oppositely oriented resilient cupshaped member disposed within the tube between the sealing plug and the interior of the container. Upon initial creation of a leak path through the alloy, the fluid pressure within the container forces the cylindrical side wall of the auxiliary seal into sealing contact with the tube while the fluid pressure exerted on the end wall of the auxiliary seal member is retained by the oppositely disposed end wall of the metallic plug. However, after complete fusing of the eutectic material to release the metal plug, the internal pressure of the container acts to dislodge both seal members from the tube allowing a full release of its fluid content. In this embodiment the outlet can encompass a plurality of strategically oriented discharge openings each sealed by a separate release mechanism.
According to another embodiment of the invention, the above described release mechanism is utilized to operate a pilot valve that controls discharge of a pressurized fluid from a supply reservoir. The release mechanism communicates with a pilot volume separated from the reservoir by a piston type valve. A leak path through the valve establishes equal pressures on either side thereof thereby maintaining the valve in a position that seals a primary discharge orifice. The conductance of the leak path between the reservoir and the pilot volume is less than that provided by the tube retaining the release mechanism. Consequently, upon actuation of the release mechanism the pressure in the pilot volume falls producing across the piston valve a differential pressure that actuates the valve and opens the primary discharge orifice. In this embodiment a plurality of release mechanisms can be strategically distributed throughout a protected region and all connected for communication with the pilot volume. Actuation of any individual release mechanism will produce release of fluid from the supply reservoir.
DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1 there is shown a first embodiment 11 of the invention including an hermetically sealed container 12 filled with a pressurized fluid agent 13. In a preferred fire suppressor embodiment of the invention, the pressurized fluid 13 can be, for example only, methyl bromide or similar halogen suppressant. The suppressant l3 enters the container 12 through an inlet valve 14 positioned in a discharge tube 15 communicating with the interior of the container 12. The valve 14 can be, for example, of the type used in tubes for tires and prevents vaporization and escape of the liquid suppressant 13. One open end 16 of the tube 15 terminates near the bottom 17 of the container 12 while the other end is bifurcated to form a pair of discharge orifices 18 and 19.
Disposed within each of the discharge orifices 18 and 19 is a release mechanism 21 only one of which is shown in detail, it being understood that the two are identical. The release mechanism 21 comprises a cupshaped sealing plug 22 and an oppositely oriented cupshaped auxiliary seal element 23. The plug 22 possesses an end wall 24 that closes the discharge orifice 19 and a cylindrical side wall 25, the outer surface of which is hermetically sealed to the inner surface of tube by a eutectic material 26 such as a fusible metallic alloy. The auxiliary seal element 23, preferably made of a resilient elastomeric material, similarly includes an end wall 27 in contact with the end wall 24 of plug 22 and a cylindrical side wall 28 the outer surface of which engages the inner surface of the tube 15. Extending between and secured to both the seal plug 22 and the container 12 is a retaining cord 29 made of a strong material such as nylon.
During typical use of embodiment 11, the container 12 is suitably mounted with the discharge orifice 19 directed toward a region in which fire protection is desired. For example only, the container 12 could be mounted on a cabinet housing (not shown) electrical equipment such as an electrostatic copying machine. In that case the tube 15 would extend through an opening in the cabinet with the orifice 19 pointed toward the equipment to be protected. It will be apparent that a single discharge orifice might suffice for many applications in which case a tube 15 with only one outlet could be used. The embodiment shown, however, is particularly useful for protecting compartmented volumes separated by partitions of some kind. Under those circumstances a single container 12 can be used to protect multiple areas each of which is occupied by a different discharge orifice.
In response to either a fire or an excessive heat condition that could result in fire, the ambient temperature in the protected volume rises to above the fusing temperature of the material 26 which accordingly begins to melt. Typically, this melting process is not uniform because of localized variations in the temperature to which the material 26 is subjected and also due to some non-uniformity in the temperature response of the material itself. For these reasons, isolated leaks are generally created through the annularly distributed eutectic material 26 before it is completely melted to release the plug 22. The premature flow through these leak paths of pressurized suppressant vapor 30 is prevented by the auxiliary seal member 23. Accordingly, localized cooling of the eutectic material 26 by escaping vapor is prevented and the entire body of material 26 is quickly melted to release the plug 22. This melting process is further enhanced by the cup-shape of the plug 22 which minimizes the thermal mass in contact with the eutectic material 26. Correspondingly, the shape and resiliency of the auxiliary seal 23 enhances its sealing function. The pressure of vapor 30 within the tube 15 forces the resilient outer surface of the side wall 28 against the internal surface of the tube 15 thereby providing a substantial fluid seal therebetween. However, upon complete melting of the eutectic material 26, the internal pressure exerted by the vapor 30 against the end wall 27 forces both the auxiliary seal member 23 and the plug 22 out of the discharge orifice 19. The internal vapor pressure within the container 12 then rapidly forces the extinguishing liquid 13 up through the open end 16 of the tube 15 and out of the discharge orifice 19 into the protected region. Damage of the protected equipment by the expelled plug 22 is prevented by the retaining cord 29.
Referring now to FIG. 2 there is shown another embodiment 31 of the invention in which components identical to those utilized in embodiment 11 have been given the same reference numerals used therefor in FIG. 1. As above, a plurality of release mechanisms 21 each including a sealing plug 22 and auxiliary seal number member 23, hermetically seal discharge orifices formed by open ends of a tube 15. An opposite open end 32 of the tube 15 communicates with a container 33 formed by a cap member 34 and a piston valve member 35.
A vessel 36 serves as a reservoir for a fluid 37 which again comprises a pressurized liquid fire extinguishing agent. In this embodiment, the container 33 provides a pilot volume 38 for the valve 35 which is controlled by the difference between the pressure in the pilot volume 38 and that within the vessel 36. A neck portion 41 on the vessel 36 has external threads that receive the cap 34. Extending to near the bottom of the vessel 36 is an open end 42 of a dip tube 43 that is accommodated by the inner surface 44 of the neck portion 41.
The outer surface of the piston member 35 possesses an annular groove that receives an O-ring gasket 45 that provides a seal with the interior surface of the cylindrical cap 34. Fixed to the bottom of the piston 35 is a circular gasket 46 that seals against the top edges of the neck portion 41 and the dip tube 43. A recessed portion 47 in the neck 41 forms with the cap 34 an annular space 48 that is in fluid communication with a primary discharge tube 49 that is accommodated by an opening in the cap 34. Extending through both the piston member 35 and the gasket 46 is an orifice 51 that provides a leak path between the pilot volume 38 and the interior of the vessel 36. The top surface of the piston member 35 possesses a small annular ridge 52 encircling the orifice 51 and an annular groove 53 that retains a spring member 54.
During installation of the embodiment 31, the release mechanisms 21 are distributed throughout an area to be protected and interconnected with the tubing 15. To facilitate this operation, the release mechanisms 21 are preferably connected to the tubing 15 with threaded couplings 61. Typically, the release mechanisms would be located near the ceiling of a room for which protection is desired. Next, the tubing 15 is connected to the vessel 36 which has been mounted in a convenient location and with the primary discharge tube 49 opening into the protected zone. The vessel 36 is filled by coupling a suppressant supply tank to the primary discharge tube 49 after removing at least one of the release mechanisms 21 to create atomospheric pressure in the tubing 15 and accordingly in the pilot volume 38. Pressure created by suppressant flow into the annular region 48 overcomes the bias force of the spring member 54 and forces the piston 35 upward. This opens the tube 43 to allow suppressant flow -into the vessel 36. The resultant high pressure exerted on the surface of gasket 46 forces the annular ridge 52 into contact with the cap 34 and establishes therewith a relatively good seal because of high unit loading provided by the limited surface area of the ridge. Upon completion of the filling process, the primary outlet 49 is closed by a suitable valve (not shown) on the supply tank (not shown) and all release mechanisms 21 are mounted to seal the tubing 15. In a short period, molecular leakage through the orifice 51 and the limited seal created by the annular ridge 52 establishes within the tubing and the pilot volume 38 a pressure substantially equal to that within the vessel 36. Consequently, the pressure induced forces on both sides of the piston 35 are equalized and the additional force provided by the spring member 54 causes the piston to move into the position shown in FIG. 2. An extremely tight seal between the gasket 46 and the vessel 36 is insured by the larger surface area that is exposed to fluid pressure on the top of the piston 35.
In response to a predetermined ambient temperature at any of the release mechanisms 21 produced, for example, by a fire within the protected region the above described discharge of the cup-shaped plugs 22 and 23 will occur. This will result in an immediate reduction of pressure within the pilot volume 38 in that the fluid conductance to atmosphere provided by the opened tubing 15 is substantially greater than that provided to the pressurized vessel 36 by the orifice 51. Accordingly, the piston 35 is forced upward to open the vessel 36 and allow pressurized discharge of the suppressant 37 through the primary discharge tube 49.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example, the primary outlet 49 can comprise a plurality of strategically located discharge outlets. Also, the release mechanisms 21 can be used to control the release of pressurized fluids other than the fire suppressants specifically described herein. It is to be understood, therefore, that the invention can be practiced otherwise than as specifically described.
What is claimed is:
l. Pressurized fluid release apparatus comprising:
a pressure sealed container means for retaining under pressure a fluid medium;
outlet means defining a discharge orifice for accommodating release of the fluid medium from said container means; temperature responsive hermetic seal means sealing said discharge orifice, said hermetic seal means comprising an eutectic material adapted to melt at a predetermined temperature; and
auxiliary seal means isolating said eutectic material from the fluid medium in said container, and adapted in an unbroken state to prevent fluid discharge out of said hermetic seal means, said auxiliary seal means comprising a pressure responsive portion adapted to be automatically opened by the fluid pressure in said container means in response to opening of said hermetic seal means, and wherein said pressure responsive portion is engaged and retained in sealing position by said hermetic seal means.
2. Pressurized fluid release apparatus according to claim 1 wherein said container means is filled with a pressurized fire extinguishing medium.
3. Pressurized fluid release apparatus according to claim 1 wherein said eutectic material comprises a fusible metallic alloy.
4. Pressurized fluid release apparatus according to claim 1 wherein said hermetic seal means further comprises a plug having a periphery hermetically sealed to said outlet means by said eutectic material.
5. Pressurized fluid release apparatus according to claim 1 wherein said outlet means comprises a tube with an open end forming said discharge orifice, and said hermetic seal means further comprises a cupshaped plug disposed in said tube and having a cylindrical wall hermetically sealed thereto by said eutectic material.
6. Pressurized fluid release apparatus according to claim 1 wherein said outlet means comprises a tube with an open end forming said discharge orifice, said auxiliary seal means comprises a resilient cup having a cylindrical side wall portion engaging an internal wall of said tube and an end wall forming said pressure responsive portion.
7. Pressurized fluid release apparatus according to claim 4 including retainer means for retaining said plug after melting of said eutectic material.
8. Pressurized fluid release apparatus according to claim 6 wherein said hermetic seal means further comprises a cup-shaped plug disposed in said tube and having an end wall engaging said resilient cup end wall and a cylindrical side wall hermetically sealed to said internal wall of said tube by said eutectic material.
9. Pressurized fluid release apparatus according to claim 8 wherein said cylindrical side wall portion of said resilient cup is no greater in height than about the diameter of said pressure responsive end wall thereof.
10. Pressurized fluid release apparatus comprising:
a pressure sealed container means for retaining under pressure a fluid medium;
outlet means defining a discharge orifice for accommodating release of the fluid medium from said container means; temperature responsive hermetic seal means scaling said discharge orifice, said hermetic seal means comprising an eutectic material adapted to melt at a predetermined temperature;
auxiliary seal means isolating said eutectic material from the fluid medium in said container, and adapted in an unbroken state to prevent fluid discharge out of said hermetic seal means;
a reservoir means for retaining under pressure a fluid medium;
second outlet means defining a primary release orifice for accommodating release of the fluid medium from said reservoir means; and
valve means for controlling fluid flow through said primary release orifice in response to the differential fluid pressure retained by said pressure sealed container means and said reservoir means.
11. Pressurized fluid release apparatus according to claim 10 including means defining a fluid leak path between said pressure container means and said reservoir means.
12. Pressurized fluid release apparatus according to claim 11 wherein said auxiliary seal means comprises a pressure responsive portion adapted to be automatically opened by the fluid pressure in said container means in response to opening of said hermetic seal means.
13. Pressurized fluid release apparatus according to claim 12 wherein said pressure responsive portion is retained in sealing position by said hermetic seal means.
14. Pressurized fluid release apparatus according to claim 13 wherein said outlet means comprises a tube with an open and forming said discharge orifice, said auxiliary seal means comprises a resilient cup having a claim 15 wherein said tube is dimensioned to provide substantially greater fluid conductance than that provided by said leak path.
l7. Pressurized fluid release apparatus according to claim 16 including attachment means to facilitate integral mounting of said outlet means, said hermetic seal means and said auxiliary seal means to said container means.