US1754782A - Air-relief valve - Google Patents

Description

J. M. BARRETT AIR RELIEF VALVE Filed Nov. 26, 1926 Patented Apr. 15, 1930 UNITED STATES PATENT oFFicE JOSEPH M. BARRETT, OF 'FOSTORIA, OHIO, ASSIGNOR TO THE SWAR'IWOUT COMPANY,

OF CLEVELAND, OHIO, A CORPORATION OF OHIO AIR-RELIEF VALVE Application filed November 26, 1926. Serial No. 150,867.

This invention relates to air relief valves and more particularly to the class of valves designed to remove air from high pressure steam systems.

It has long been appreciated in the art that the presence of air in asteam system is detrimental to the elliciency of the system and in many instances is dangerous. In the use of control apparatus which is sensitive to the heat content and temperature of steam, the presence of air in place of steam causes non-performance of the apparatus which may lead to harmful results. In the control of condensation traps, the presence of air may cause the trap to become inoperative and bring about a harmful accumulation of condensate to the damage of the plant. In the high pressure steam lines, air displaces useful steam with the result that the prime movers operate at a low efliciency.

It is among the objects of my invention to provide an air relief valve which is simple in construction,which may be easily installed,

which is positive in operation and which can be depended upon to start itself and continually free the system of whatever air accumulates.

It is also among the objects of my invention to provide a valve which will be extremely sensitive to small accumulations of air and to cause the expulsion thereof from the system and also to be sensitive to the presence of live steam so that a minimum of steam will be lost whenever air is discharged.

Other objects will appear from the following more detailed description of my invention, reference being had to the accompanying drawings, the essential characteristics are summarized in the claims.

In the drawings Fig. 1 is a side elevation of the valveyFig. 2 is a partial section of the apparatus shown in Fig. 1.

I show at 1 a container which may be a steam line, radiator or other vessel from which it is desired to expel air to the exclusion of the hot and useful steam contained therein. Mounted above the container 1 and connected thereto by the pipe 2, I show a trap 3 which is provided for the purpose of maintaining a small water seal, above which the air from the container. may be accumulated and isolated from the movement of steam in the container below. At upper end of the conduit 2, I provide a valve body 10 having an outlet pipe 11 through the check valve 12. Mounted above the valve and carried by the body of the valve, I show a frame structure 15 extending co-axially with the valve actuating rod 16. The valve may be of single seat type arranged so that the valve member is urged from its seat 21 by the fluid pressure thereon and by the spring 25 positioned between the cross-member of the frame 15 and the nut on the valve rod 16.

Carried on the upper end of the frame 15, I provide a diaphragm chamber 35, wherein is received a diaphragm 36 which is exposed on its under side to atmosphere and is engaged by a mushroom like member 37 carried by the end of the valve rod 16. Leading into the diaphragm chamber 35, I show a conduit 40 through which pressure is transmitted so that the valve 21 is urged downwardly onto the seat 21 in response to the pressure exerted in the diaphragm chamber. Thus when the effective diaphragm pressure exceeds the pressure of the spring 25, the valve will be positively closed. When the diaphragm pressure falls below the spring and fluid pressure, the valve is raised from its seat a distance proportional to the difference in pressures.

Surrounding the pipe 2. I provide a pressure generator 41, comprising a cylindrical casing 42 adapted to lie concentric with the pipe 2 and forming a closed chamber with the heads 43, which are braised or otherwise sealed to the outside of the pipe 2. Mounted externally of the cylindrical portion 42, I provide radiating fins 44. In the upper of the heads 43, I provide a filling plug 45 and in the lower of the heads 43, I provide a connection 46 for the conduit 40. Within the casing 42 and without the pipe 2 is formed an annular cylindrical chamber in which is con tamed a volatile and expansible fluid, the nasuch as alcohol which has a low point of va orization. Conversely if the generator is to be used in conjunction with steam of very high temperature, I may find it advisable to use mercury for the working fluid. For the ordinary usage and even for handling what we now term high pressure steam, I prefer to use water for the working fluid.

In operation the system, including the diaphragm chamber 35 the generator proper and the conduit 40 are filled, or nearly filled with working fluid, a small amount of air being trappe in the system for the purpose of cushioning or tempering the operation of the gen erator. It will be seen that when the pipe 2 contains live steam, there will be a rapid heat exchange between the contents of the pipe and the contents of the generator so that the fluid in the nerator is vaporized and pressure is created i n the generator system, which in turn builds up pressure in the diaphragm chamber 35 and forces the valve into the seat 21. The heat exchange from the conduit 2 to the generator is balanced by the radiation through the fins 44, so that for steam of a given temperature a certain maximum pressure is exerted on the diaphragm 36. When however, the pipe 2 is filled with fluid having a heat content such that the working fluid in the generator will not be vaporized, then the working fluid will be chilled both by external and internal conduction of heat so that the pressure in the diaphragm chamber 35 is lowered and valve 22 is raised from its seat by the spring 25 and the fluid. pressure exerted on the valve member. The fluid in the pipe 2 is forced outwardly through check valve 12 by the pressure of the steam in the container 1. As the fluid with the lesser heat content is expelled, steam moves upwardly into the conduit 2 and heats the generator again creating a 1pressure on the diaphragm 36 and closing t e valve.

It will further be seen that if the whole systern be chilled, including the contents of the container 1, that the valve 20 assumes an open position and remains open permitting the discharge of all fluid, the temperature or heat content of which is less than the amount necessary to volatilize the working fluid. It will further be seen that as long as the contents of the ipe 2 contain enough heat to maintain the wor ing fluid under suflicient pressure, the valve will be held closed. For the purpose of air relief, since the air which is separated from steam does not have as high a heat content as the steam, air accumulating in the pipe 2 in suflicient quantity to reduce the pressure of the working fluid, will cause the valve to open so that the air will be expelled.

From the foregoing it will be seen that in the operation of the device all of the air coming near the lower end of the conduit 2 is tra ped in the upper portion of the conduit so t lat a column or volume of air is built up in the upper portion of the conduit 2 immediately below the valve 20. As the proportion of air to steam in the conduit adjacent the generator increases, the temperature of the working fluid is lowered by rea son of the decreased rate of heat exchange as the air displaces the steam. The pressure in the diaphragm chamber is reduced so that the opposing pressures which eii'ect movement of the valve 20 are brought toward a condition of equilibrium, then a further increase of quantity of the air will. just break the state of equilibrium so that the valve is slightly opened, which permits the escape of air. As soon as the air begins to escape the proportion of steam to air is increased and it is easily conceivable that this action can be made so fine that there is always trapped in the upper part of the conduit 2 above the generator a small quantity of air and that as the valve operates no steam ever escapes through the device.

I find a practical advantage in using the trap 3 in that a trap of this nature tends to collect and hold all of the air coming into the container 1 in the conduit 2, and prevents the circulating or mixture of air or steam in the conduit to the detriment of the working of the valve.

Regarding the trap 3, I am able to achieve further advantages beyond those described above. I find in the operation of the valve that when the system including the container 1 is large enough and the piping extends over quite a portion of the plant, or where there are odd piping arrangements where there are apt to be air pockets, that even if no air is trapped in the container 2 of my device, it is advantageous to blow down the entire system at predetermined intervals.

I find that it lies within the nature and i construction of the trap to accomplish this result in the following manner. I provide a downwardly extending lip 50 on one side of the trap as shown in 2, an upwardly extending lip 51 as shown on the other side 01' Fig. 2. The diflerence in elevation between the edges of the lips may be great or small and as will appear, I find that this difference is one of the factors in determining the time element in the intermittent action of the trap under the collection of air. The trap is sealed, when the condensate collects up to the level of the lower edges of the lip 50 so that a further condensation breaks the seal and allows steam to enter the conduit 2. The water in the trap may surge downwardly but is held in the trap by reason of the elevation of the lip 51. Further condensation draws water upwardly into the conduit 2 until the level of the water in the trap is down to the level of the lower edge of the lip 50 when the unsealing and surging process is repeated. As this action continues, there comes a time dependent upon the relation between the quantity of water which is held in the horiwr Aux.

zontal space between the edges of the lips, and the volume of the conduit 2, that as the steam condenses in the conduit 2, enough water is raisedcin the conduit before unsealing the trap to chill the generator and cause the valve to open. When the valve is opened under this circumstance all of the water is blown out and a momentary pressure drop is established between the container and the rest of the system so that a sharp fluid movement through the whole system results which tends to break up any air pockets in the system. It will be seen that the volume of water held be tween the horizontal limits of the edges of the lips and 51 determine the time element of the operation, if no air is collected in the conduit 2.

From the foregoing, it will be seen I provided a highly dependable air relief valve which is particularly adapted to function in connection with high pressure and high temperature steam, by which by a mere change of working fluid may be adapted to strcnu-- ous use.

I claim:

1. In an air relief valve for a chamber containing steam, the combination of a valve, a conduit leading from the chamber to the valve, means tending to force the valve open, pressure responsive means for closing the valve, means including a compartment con taining an expansible fluid surrounding the conduit between the chamber and the valve adapted to create a pressure depending upon the heat content of the fluid in the conduit. whereby the valve is actuated according to the heat content of the fluid in the conduit.

2. A system for ridding steam of air comprising in combination, a steam container, a conduit extending upwardly from the container in which air from the container collects, pressure generator means associated with the conduit and comprising a closed chamber surrounding the conduit, said pressure generator means being responsive to the heat content of the fluid in the conduit, a pres sure actuable valve controlling the flow through the conduit and positioned at the top thereof above said pressure generator, and means connecting said pressure generator means with said valve whereby the valve is actuated dependent upon the heat content of the fluid in the conduit, and whereby the presence of air in the conduit causes said valve to open.

3. In combination, a container for steam, a conduit extending upwardly from the container, pressure generator means associated with the conduit, a trap for condensate associated with the conduit below the pressure generator means, said pressure generator means being responsive to the heat content of the fluid in the conduit, a pressure actuable valve controlling the flow through the conduit and means connecting said pressure generator means with said valve whereby fluid of lesser heat content than steam is trapped in the conduit and the valve actuating pressure is influenced by the heat content of the fluid so trapped.

4. In combination, a container for steam, an air relief valve associated with the container adapted to permit the outflow of air but the retention of steam in the container, a conduit disposed between said valve and said container, thermo-responsive means associated with the conduit for actuating said valve, a trap in the conduit positioned between the said thermo-responsive means and the container whereby air from the container is trapped in the conduit adjacent said thermo-responsive means before being discharged through said valve.

5. In combination, a container for steam, an air relief valve associated with the container adapted to permit the outflow of air only from the container, a conduit disposed between said valve and said container, thermo-responsive means associated with the conduit for actuating said valve, a trap in the conduit positioned between the said thermo-responsive means and the container whereby air from the container is isolated in the conduit before being discharged through said valve.

6. In a device of the character described, the combination of a valve adapted to control the outflow of fluid from a vessel normally containing steam, a valve actuating rod, a diaphragm positioned to exert a pressure on said rod to close the valve, resilient means associated with the rod and opposing the pressure exerted by the diaphragm, a conduit disposed between said valve and said vessel, pressure generator means comprising a closed chamber containing an expansible fluid surrounding the conduit and associated with said conduit, said pressure generator means being heated by presence of steam in said conduit and chilled by the presence of air in the conduit, whereby the pressure exerted on said diaphragm is inversely proportional to the ratio of the air to the steam held in the conduit.

7. In combination, a steam system, an air relief valve associated with the system, a conduit disposed between said valve and said system, thermo-responsive means associated with the conduit for actuating said valve and means associated with the conduit disposed between said thermo-responsive means and said steam system for intermittently opening said valve at spaced intervals.

8. In an air relief valve for a container for steam, the combination of a conduit extending upwardly from the container, a pressure actuable valve at the top of the conduit, and a pressure generator for actuating said valve comprising a chamber surrounding the conduit and positioned between the container and the valve.

9. An intermittently acting relief valve for a container comprising a vertically extending conduit, a trap for condensate at the base of the conduit and connected to the container and adapted to collect condensate to be drawn into the conduit, a valve at the top of the conduit, thermo-responsive means associated with the conduit between the trap and the valve, said valve being resiliently forced to open position and held closed when the thermo-responsive means are heated by the presence of steam in the conduit and permitted to open when condensate rises in the conduit and chills the said thermo-responsive means.

10. An intermittently acting relief valve for a container comprising a vertically extending conduit, a trap at the base of the conduit connected to the container and disposed above the container, a Valve at the top of the conduit, thcrmo-responsive means comprising a closed chamber with an expansible fluid associated with the conduit above the trap, said valve being resiliently forced to open position and held closed when the thermo-responsive means are heated by the presence of steam in the conduit and permitted to open when condensate rises in the conduit, said trap bein adapted to collect condensate from the con uit and hold a column of condensate in the conduit until the proportion of condensate to steam in the conduit is such that the thermo-responsive means are chilled, whereby the valve is opened and the contents of the conduit are discharged.

In testimony whereof, I hereunto aflix my signature.

JOSEPH M. BARRETT.

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