US2022722A - Train-line relief valve - Google Patents

Description

Dec. 3, 1935. L. c. HYATT 2,022,722

TRAIN LINE RELIEF VALVE Filed April 3, 1931 awveuto'c 100/; C. Hyaff Patented Dec. 3, 1935 UNITED STATES PATENT OFFICE TRAIN-LINE; RELIEF VALVE Application April 3, 1931, Serial No. 527,575

5 Claims.

For a detailed description of the present form of my invention, reference may be had to the following specification and to the accompanying drawing forming a part thereof, wherein Fig. 1 is a plan of my valve;

Fig. 2 is a vertical section thereof.

My invention relates to an automatic relief valve for removing condensate from the trainline of a steam-heating system either for railways or from any other condensing agency.

In a steam-heating system for railways one feature of the operation is the continuous condensing into water of the steam which gives heat to the cars. As the steam, which ordinarily comes from the locomotive, gives up its heat to the several cars of the train, that loss of heat is constantly causing reconversion of the steam back into water. That is to say, the condensation is not merely an incident, but is a necessary and continuing part of the car-heating operation. The condensate, if not removed as rapidly it is formed, remains in the pipes, particularly in the main supply pipe which extends from the locomotive through the train. The customary connections of this train-line from car to car is by a loop of hose, usually of rubber, containing on each of its two half lengths a separable coupler-part. The said loop, being at a lower level than the rest of the train-line, naturally receives the water of condensation from the train line. In cold weather it is liable to freeze, unless carefully watched, and the water therein drawn off at frequent intervals. Heretofore many attempts have been made to provide an automatic valve near the coupler that would open periodically to evacuate the water and then close to retain the steam. All of these, so far as I know, have been arranged to close from theinside by virtue of the internal steam pressure, and to open only when the steam pressure on the valvehas been so reduced, by the accumulation of water in the loop or by turning off the steam, that the valve will open in response to a spring or gravity when the steam pressure thereon is relaxed. These have not been reliable agents, particularly in severe weather, and it has hitherto been necessary in practice for a trainman, at every stop of the train, to go out and manually drain the train pipe by opening a valve therein at the rear end of the train and permitting the live steam in the pipe to blow out the water. The said hand valve is also left partly open so that the steam may continue to blow the water out through it while the train is running.

One of the objects of the invention is to provide a balanced pressure type automatic relief valve that will keep the train line entirely free of water at all times regardless of the steam pressure therein, being dependent for its action, not on the pressure of the steam, but on the pressure of the condensate itself. A further object is to provide a relief valve of the character mentioned so constructed and arranged that the slightest accumulation of the condensate water will cause the valve to open, if the steam pressure the time is 200 pounds or even if it is zero or less as may occur when the condensation is more rapid than the steam supply and a vacuum is thereby formed in the pipe. The trouble with the previous systems which have gone into general V has been not merely the liability of the trainline to be frozen up and thereby closed against the flow of steam to the cars. In fact, in such systems the train-line may be partly closed by the accumulation of condensate therein even if such 5 condensate is not frozen. In that case a heavy steam pressure is required to force steam through the clogged train-line. Such heavy steampressure, in turn, puts a strain on the rubber coupler-hose, particularly in long trains. The frequent bursting of such rubber hose has required it to be made thicker and larger and much more costly than formerly and in some cases it has been replaced by metallic hose which presents its own line of costs and difficulties. My invention has for a further object the provision of a device which will keep the train-line always free of the water of condensation and thereby prevent the clogging of it by that water and the complete stopping of it by ice are both prevented. The relief valve in my construction is operated by a. small sealed and flexible container responsive, not to the mere presence of the steam but to its temperature conditions and the effects incident to the conversion of the steam from a vapor to a liquid and vice versa. This container is sealed while in its compressed and contracted state after being filled with a suitable liquid, which, in this instance, is water. Since this container is usually immersed in the steam, the small, isolated amount of water inside of it will experience approximately the same pressure and temperature conditions as the steam outside of it and therefore will change from vapor to water and vice versa synchronously with those same changes in the enveloping steam. As the condensation of the steam starts, this container will start to contract, thereby opening the outflow valve to evacuate the condensate. Conversely, as steam condensation stops, the container will start the impact of steam from the coupler.

to expand and close the said valve. The action is an extremely delicate one, the container acting, in effect, as a condensation meter for the steam. If the steam should be derived from some other liquid than water the container vessel should, in that case, be filled with such other liquid instead of with water. If that other liquid evaporated atsay 150 degrees, instead of at 212 degrees, the container would then expand at 150 degrees. So I may employ this feature of my invention in other situations where its action is to correspond to the boiling or vaporizing and the condensing of a liquid.

Referring to the drawing, A represents a coupler'to which my device is applied. B is a small casing that may be screwed onto the coupler by a screw C. Through that screw passes, from the casing B into the interior of, coupler A, a short tube E which has, on its coupler end, a gauze strainer D and on its casing end opens into the casing just inside of a guard-plate F which protects the expansion chamber in the casing from At the top and bottom of said guard-plate is a free passageway into casing B. G is the aforesaid ex' pansible container in the form of a corrugated, bellows-like, vessel that is expansible and contractible in the line of its vertical axis. At its upper end vessel G is secured to the inside top may be closed by a perforated cap 0 screwed on the outside of it and carrying a lug adapted to fit the said opening. Four ribs L with guard-plate F on the inside of casing B guide the vessel G as it plays up and down.

From the foregoing, it will be understood that I have produced a train-line relief valve of the balanced pressure type. That is, the parts are so constructed and arranged, and the volume of the thermally responsive liquid so proportioned to the capacity of the vessel G, that at the normal temperature of the vapor surrounding said vessel, the nternal pressure is balanced by the external pressure applied by said surrounding vapor. In other words, in the particular embodiment designed for use in. connection with a steam trap, the pressures are balanced when the traps are filled with steam and contain no condensate.

In the balanced pressure type of steam trap, water is the liquid which must be sealed in the bellows, although it is obvious that other liquids may be substituted if the device is to be used as a trap in connection with the flow of vapors other than steam.

In constructing the thermostat element, the vessel or bellows G is first compressed longitudinally by suitably applied endwise pressure, until it has been collapsed to its minimum length. While the vessel is maintained in this compressed and collapsed position, it is filled with the: desired thermally responsive liquid, (such as distilled water, if it is to be used as a steam'trap), and while maintaining the collapsing pressure and the vessel is still in its minimum length condition, the bellows is sealed. Upon removal of the collapsing pressure, the bellows is prevented from expanding to its full free length, until some partof the water is changed to vapor. This is because it could not expand without creating a vacuum inside, which is prevented by the atmospheric pressure. In practice, the walls of. the bellows are of resilient metal, so that the spring action thereof tends to extend it to its full free length, but until there has been a vaporation to some extent, of the thermally responsive liquid, atmospheric pressure exerts a much greater external force than the spring action of the bellows. Assuming that the device is employed in a steam trap and that the liquid in the bellows is water, it will be readily understood that the pressure inside of the bellows for a predetermined steam pressure can never exceed that of the steam surrounding it. For example, with five pounds of steam pressure surrounding the bellows, the pressure within a bellows containing Water could not exceed five pounds. Similarly, with one hundred and five pounds of steam pressure surrounding the bellows, the pressure within the bellows containing water could not exceed one hundred and five pounds. It will, of course, be understood that these pressures willvary with the different types of thermally responsive liquid employed, and that the specific examples above given do not apply, for instance to a bellows which contains alcohol. This explains why a bellows filled with water does not have to be made as heavy as a bellows containing alcohol. It also explains why the same water filled bellows can operate satisfactorily in both high and low pressure traps, without any adjustment whatever.

The operation of a steam trap constructed in accordance with the invention is as follows:

When initially installed and at room temperature, the bellows G is under compression and the valve H is in the open position, due to the predominating atmospheric pressure above explained. Steam and condensate from the steam line enter the chamber B through the inlet channel E. Obviously, condensate and some steam are at first discharged from the trap through the outlets N and 0 until all of the condensate is discharged. a In a short time, however, usually a few seconds, the bellows G, because its walls are thin, becomes heated to the approximate temperature of the steam. The heat thus generated causes a sufficient portion of the water within the bellows to be changed to steam, and to thereby develop an internal pressure corresponding to the temperature of the steam surrounding the bellows. Since the steam inside and that outside of the bellows are at the same temperature, the pressures must be equal, and because of this fact, the

inherent spring pressure of the bellows is now free to exert itself so as to extend the bellows to its full free position, and thereby seat the valve H to prevent the escape of steam.

When condensate collects in the trap, or comes into contact with the bellows, the temperature of the bellows falls below that of the steam, and because the bellows walls are at a lower temperature than the steam, namelythe temperature of the condensate, heat flows from the steam inside of the bellows to the bellows walls. Therefore, the steam inside the bellows gives up some of its heat, and as a consequence, said steam condenses and thereby reduces the pressure inside of the bellows- When this internal pressure has been reduced sufiiciently below the pressure of steam, the now greater external steam pressure compresses the bellows from its free, length, i. e.

closed position, thereby moving the valve H from reheats the bellows to the steam temperature, thereby establishing equalized internal and external pressures, and permitting the closing of the valve, due to the expansible resiliency of the wall of the vessel. It is in this closed position that the pressures inside and outside of the bellows are referred to as being balanced, that is, in the closed. position of this type of trap, the bellows is under neither compression nor expansion, but is at its free length. This condition does not prevail with the other types of valves such as those of the unbalanced pressure type and the liquid expansion type. In other words, in the device herein described, the valve is closed by the inherent bellows spring pressure, and not by internal vapor pressure.

In practice, the parts are so constructed and arranged that the valve H will be seated before the full free length of expansion of the bellows is reached, so as to maintain a slight pressure on the valve to finally seat it. After the valve is seated, the spring pressure holds it in its seated position as long as the pressures within and without the bellows are balanced.

Since the walls of the bellows can be made very thin, because the device does not have to withstand heavy pressures, the unit as a whole is very sensitive. Observations of its action, through a glass-walled trap demonstrate that a little trickle of condensate, on the bellows causes it to contract. As a matter of fact, the movement of the walls is very small and rapid, and after the trap is once heated, the valve movement is very slight. Therefore, the level of the condensate in the valve is maintained just below the bottom of the bellows. In order that the excessive radiation of heat from vessel G may be prevented, I have added on the inside of the casing a set of four small ribs M in contact with the top of vessel G and with the inside of casing B, which ribs will add sufficient surface exposed to the heat of the steam to neutralize the flow of heat outward from vessel G to the atmosphere through the metal forming the top of casing B to which top the vessel G is attached.

It may be observed that my relief valve above described acts more frequently than the so-called traps heretofore attempted and that the small amount of water exuded at one time is immediately vaporized as it emerges, by reason of its escape from the pressure inside the train pipe. This might lead an observer to think that it Was emitting steam instead of water. On the contrary, live steam does not escape; before it could do so the valve closes. The above described action takes place regardless of the steam pressure that may exist in the train pipe. It will act if that pressure is 290 pounds or if it is down to 5 pounds or zero. Indeed, the train-line pressure differs in the prior systems on different cars as the train-line becomes clogged by the condensate. The usual allowance is pounds per car as the steam pressure required to force steam through the water-clogged train-line making 160 pounds difference in the train-line pressure between the first and last ca:s of a lG-car train. During operations at temperatures as low as below zero, no attention whatever to the train line is required. Its Water free condition produces a steam-pressure-difference between adjoining cars ranging from a maximum of approximately ten pounds to a minimum of approximately two pounds, While the car temperature does not vary more than approximately 3 between the different cars of the train. Thus, the relief valve acts in normal fashion even if the steam pressure from the locomotive were cut off and regardless of such pressure difference as may exist. At frequent intervals each trap will silently emit a small quantity of hot water which appears like a gentle wisp of vapor, the effect being to discharge the hot water as rapidly as it is produced by the continuing condensation without allowing the live steam to escape.

What I claim as new and desire to secure by Letters Patent is:

1. A condensate relief valve comprising a casing having an inlet opening and an outlet opening, an expansible and contractible vessel supported within said casing and having a Valve controlling the outlet opening, said vessel containing a thermally responsive liquid of the same boiling point as the condensate, the volume of said liquid being equal to the internal volume of the vessel while said vessel is in contracted condition, a guard plate associated with said inlet opening so as to protect said vessel from impact of incoming vapors and fluids, and ribs cooperating with said guard plate for guiding said vessel during its expanding and contracting movements. i

2. A condensate relief valve comprising a casing provided with a removable top plate, said casing having an inlet opening and an outlet opening, an expansible and contractible vessel supported by said topplate and located within said casing, said vessel having a valve controlling said outlet opening, a thermally responsive liquid within said vessel, said liquid being of the same boiling point as the condensate and the volume of the liquid being equal to the internal volume of the vessel while in its maximum contracted condition, and ribs carried by said top plate and contacting with said vessel so as to neutralize the flow of heat outwardly from said vessel to the atmosphere through the metal of the casing.

3. A condensate relief valve comprising a casing having an inlet opening and an outlet opening, an expansible and contractible vessel supported within said casing and having a valve controlling the outlet end, said vessel containing a thermally responsive liquid of the same boiling point as the condensate and of a volume equal to the internal volume of the vessel while in its maximum contracted condition, and ribs located within said casing and contacting with said chamber to neutralize the flow of heat outwardly from the vessel to the atmosphere through the 5 metal of the casing.

4. A condensate relief valve comprising a casing having an inlet opening in its side wall and an outlet opening in the bottom wall, said outlet opening being provided with a valve seat, a removable top plate for said casing, an expansible and contractible vessel attached to said top plate and located within said casing, said vessel containing a thermally responsive liquid of the same boiling point as the condensate and of a volume equal to the internal volume of the vessel while in its maximum contracted condition, a valve carried by said vessel and complemental to said valve seat, ribs on said top plate contacting with said vessel to neutralize the flow of heat outwardly from the vessel to the atmosphere through the metal casing, ribs within said casing for guiding the vessel in its expanding and contracting movements, and means for protecting the vessel from impact of incoming vapors and fluids.

5. A condensate relief valve comprising a casing having an inlet opening and an outlet opening, an expansible and contractible vessel supported within said casing and having a valve controlling said outlet opening, said vessel contain ing a thermally responsive liquid of the same boiling point as the condensate, the volume of said liquid being equalto the internal volume of the vessel while contracted to its minimum the vapor surrounding said vessel the internal pressure is balanced by the external pressure applied by said surrounding vapor, and a guard plate extending across the inlet opening in such manner as to protect the vessel from the impact of the incoming vapors and fluidS said guard 5 plate having passages therethrough connecting said inlet opening with the interior of the casing, said vessel being so constructed and arranged as to expand from its contracted state while said pressures are balanced.

LOUIS C. HYA'I'I.

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