Patent Publication Number: US-3876139-A

Title: Valve having integral filter

Description:
United States Patent 1 [in 3,876,139  
 Schmidt, Jr. Apr. 8, 1975 l5 l VALVE HAVING INTEGRAL FILTER 2.965.129 l2/l960 Faust 251/010. 3 3.620.449 11/1971 Hohn 236/56 [76] inventor: Peter N. Schmidt. Jr... 289 Gordon Ave. Fords, NJ. 08863 Primary E.\&#39;ammerW1lliam E. Wayner i Flledi 1973 Assisrun! Examinerw. E. Tapolcai. Jr.  
  2n Appl. No.: 389,386  
 [57] ABSTRACT [52] 236/56; 37/5473 [In/M413; A valve assembly is disclosed for use in steam systems. ZSHX-i The valve assembly is arranged with an integral filter [5 i] ll. Ci i t 4 v i i v t i i i i t is Flfit II) which i transparent t0 the p g of foreign material [58] Field of s 137/544 3 -l in the steam line during valve open conditions and 55/475; l0/497-l; m which is closed to such particles just prior to the time when the valve closes. The effect of such an arrange- References Cited ment being the protection ofthe valve from becoming UNITED STATES PATENTS stuck open clue to the wedging of a particle between 9513 7 3/1910 c 351/3 X the valve and valve seat. The integral filter is shown as LUZJ UW b11912 Atkinson ZSI/DIG 3 a coiled spring spiraled concentrically around the 2.068182 1H9]? Strindberg is 2lU/497.l valve, 2.3741672 FUN-15 Ncisingh l. Nil/4971 211163016 llHJSZ Carter. Jr A. 2lU/49Tl 7 Claims, 9 Drawing Figures FATENTECAP 8i975 3.876.139 sumlg &#39;gs&#39; FIG. I  
 STEAM l5 CONDENSATE mgmima 8125 3.8751139 sum 2 1 3 FIG. 8  
 VALVE HAVING INTEGRAL FILTER This invention relates to an improved steam valve as sembly and. more particularly, to a steam valve assembly having a continuously variable prefilter integral with the valve stem.  
 BACKGROUND OF THE INVENTION From the earliest days of the industrial revolution, steam has played an important, if not vital, role in the utiilization of mechanical forces to societys advantage. One use of steam has been for the purpose of delivering units of heat energy to a given location or number of locations from a central source efficiently. Typical of such uses are the well-known steam heating systems where pipes carry hot steam from a boiler to a number of radiators placed throughout a building or in a number of buildings. A not-so-well-known use of steam is for the purpose of maintaining a certain heat level in another material, usually for the purpose of lowering the viscosity of the other material so that it may be pumped through a pipeline easily and for the purpose of preventing the material from freezing. This use of steam is called tracing. Typically, the steam line and the pipe carrying the material to be heated are wrapped in common insulation and heat units given off by the steam are transferred to the other material through the walls of the abutting pipes or tubing.  
  As the steam gives up its heat energy. it begins to condense and turn back to water. The water is then returned to the boiler and reheated to again form steam. In order for such a closed loop system to be efficient, it is imperative that, before the steam is returned to the boiler. the heat units are removed and that only water and not steam is returned. This is accomplished by the use of a steam trap placed in the steam line somewhere near the end of the useful steam run and prior to the condensate line which runs back to the boiler. The steam trap operates to hold back the steam until condensate forms and only opens long enough to permit the condensate to enter the condensate line. The proper operation of such steam traps is critical if energy is to be conserved and if the system is to operate properly. Thus, if a steam trap remains open too long, steam will be wasted.  
  Commonly used steam traps have an inlet for steam and an outlet for water condensate. A valve assembly keeps the outlet closed when only steam is present in the trap. For this purpose a bellows is used in one type trap which expands in the presence of steam to hold the valve seated in the outlet port. When water condensate builds to a point where the bellows is cooled sufficiently, the bellows contracts and forces the valve away from the outlet port thereby allowing the accumulated condensate to flow into the condensate line. When the bellows is reheated by the steam, the bellows expands and the valve is again forced into the seat and the valve is once again closed.  
  A serious problem with such a valve is that particles of foreign material. which are always present in steam lines. can become wedged between the valve and the valve seat of the steam trap when the valve is closing thereby preventing the valve from seating. When this occurs, live hot steam continues to keep the bellows expanded which. in turn, keeps the trapped material wedged between the valve and the seat and thus steam continues to escape through the opening into the con densate line. The trap is then rendered useless.  
  To overcome this problem in the past. a strainer has been placed in the steam line upstream from the trap to remove the dirt and scale from the line. In addition to being costly. such strainers must be frequently cleaned or the steam flow is stopped. In order to clean these strainers, a blow-down valve is installed in the line and is opened periodically by a steam fitter to clean the screen. The labor costs alone to do this job are enormous even assuming that all of the blow-down valves of a given installation are accessible and known. This is not always the situation and, even when it is. the need for constant attention requires that steam traps and blow-down valves be located in easy-to-reach places, This is often not possible.  
  In addition, even when a strainer is cleaned in this manner, the operation is rarely successful in cleaning all the pores and only enough pores may be opened to allow a certain volume of condensate to pass. However, when the atmospheric temperature drops. more condensate is produced in a given period of time and this increased volume of condensate may not pass the cleaned strainer. Under this condition. in outside installations a costly freze-up is likely to occur ifthe outside temperature drops below freezing. In indoor installations it may result in the failure of thermoset products to cure properly or, in other such costly malfunctions.  
  Accordingly, a need exists for a steam trap valve arranged to prevent the jamming of the outlet valve in the open position while at the same time preventing the buildup of foreign material in the steam line.  
  A still further need exists for a valve assembly arranged to insure proper seating of the valve in the presence of fluid flow having therein the ever-present particles of foreign material up to approximately [/16 of an inch in diameter.  
  A further need exists in the art for a valve assembly for use in installations, such as safely bypasses, which are used only periodically, which assembly is not subject to the accumulated backup of foreign material.  
 SUMMARY OF THE INVENTION By recognizing that it is unnecessary to prevent the passage of foreign particles through the steam trap valve when the valve is in the opened position, I have designed a valve having an automatically adjusting prefilter so that, as the valve starts to close. the prefilter openings become progressively smaller, thereby preventing the passage of particles into the discharge stream at the instant just prior to the time when the valve seats. The prefilter is designed to reduce in size as fast as the valve closes to insure that particles do not become wedged between the valve and the valve seat at the instant of valve closure. The prefilter is further arranged so that, at the instant just prior to valve closure, only clean steam flows through the reduced valve opening, thereby clearing the seat of foreign particles just as the valve closes.  
  In one embodiment the prefilter takes the form of a coiled spring mounted concentrically around the valve stem. When the valve is opened, the bottom coil of the spring lies around the valve seat and the top coil of the spring is secured to the top of the valve stem and/or to the bottom of the contracted bellows. The spring coils are formed in such a manner that, when the valve is open, there is at least one gap between the coils to allow the condensate to enter the outlet port and be discharged into the condensate line. The opening between the spring coil is such that particles in the condensate will flow through the valve opening unim peded. The steam trap is self-cleaning in that, during the open valve interval, any accumulated particles are free to pass through the valve opening and into the discharge line. Thus, during the discharge. period. the fil ter is transparent to foreign particles.  
  As the bellows begins to expand, the valve shaft moves the valve toward the valve seat. Since the spring coils are also mounted to the same shaft and also controlled by the movement of the bellows, the coils of the spring move closer together. This movement has the effect of continuously reducing the size of the openings between the coils and thus reduces the openings through which foreign matter can pass, The spring is arranged so that the coils completely close just prior to the time when the valve seats. However, some live steam passes through the closed spring coils and this steam has the effect of leaving a clean valve seat to insure that the valve will completely close.  
  I have arranged the prefilter spring in a concentrically decreasing spiral so that the valve is free to move in relationship to the prefilter thereby giving the over travel necessary for proper operation. Also, I have surrounded the entire assembly with a gross filter having the effect of keeping particles larger than 1/16 of an inch away from the assembly. This is an added precaution to insure proper operation. since the number of such particles present in a steam system is relatively small, having been removed during the initial blowdown of the line prior to installing the various traps.  
  Using this arrangement, the necessity for a strainer in the line prior to the steam trap is eliminated. By eliminating the strainer, I have also eliminated the need for the costly blow-down valve and attendant piping and couplings. I have also thus greatly reduced the possibility of system leaks, because of the reduced number of connections necessary, and of system failures due to the clogging of permanent inline strainers.  
  Accordingly. it is a feature of my invention to replace steam line fixed filters with a continuously variable fil&#39; ter having the capability of being transparent to the movement of foreign particles through the line during valve open conditions and of being closed to such particlesjust prior to the time when the valve closes. These and other objects and features of my invention will be more fully appreciated from a description of the drawing in which FIG. 1 shows a cut-away sectional view of a steam trap utilizing my new valve assembly;  
 FIG. 2 shows my valve assembly in the open position;  
  FIG. 3 shows my valve assembly in the closed position;  
 FIG. 4 shows the valve;  
  FIGS. 5 through 8 show the valve and prefilter in various stages of closure; and  
  FIG. 9 shows a cut-away view of a safety release de vice utilizing my new valve assembly.  
 DETAILED DESCRIPTION FIG. 1 shows a steam trap 10 having an inlet port 11 and an outlet port I8. Contained within the steam trap is a bellows 15 which acts in the well-known manner such that, below a certain fixed temperature, the bellows contracts, thereby pulling valve away from valve seat I3. Above a certain fixed temperature, the  
 bellows, because of the vaporization inside the bellows of a fluid 51, expands and drives valve 20 downward causing the valve to mate with valve seat I3, thereby closing output port 18.  
  Before discussing my invention, I will first describe the operation of a typical steam trap. In operation, live steam enters the trap at input 11 and causes bellows 15 to expand thereby closing output 18. Thus, steam is held within the trap causing a backup of steam down the inlet. line (not shown) which, in turn, forces the steam to discharge heat units along the input line. As heat is given up, condensate forms in the line and collects along the bottom ofthe line. The steam pressure forces this condensate to flow along the line and into steam trap 10. As the condensate builds up in the trap, atmospheric temperature causes the condensate to cool. Eventually, the cooled condensate cools the bellows causing the bellows to contract and open the outlet valve. The condensate then flows into the condensate line (not snown) and back to the central boiler.  
  Since more steam arrives at input 11 when the outlet valve is open than does condensate, the bellows soon warms up and expands again closing the outlet valve. This expansion takes place in a very short period of time and thus the valve in effect snaps into a closed mode.  
  Under the operation just described, if the input steam contains foreign particles, which are present in all steam installations, at least one of these particles is bound to become trapped between the valve and the valve seat at the instant the valve is forced closed. In fact, experience has shown that, if the live steam is not prefiltered, the steam trap cannot be expected to oper ate properly for long. Thus, in the prior art, as discussed above, strainers are placed in the line prior to the steam trap to clean the steam to avoid this problem. Of course, it should be noted that. once the valve becomes stuck open steam will continue to flow into the trap and continue to keep the bellows expanded thereby keeping the particle trapped between the valve and the valve seat.  
  I have eliminated the need for fixed pre-strainers by the use of the valve assembly I am about to describe. Again, with reference to FIG. 1, I have mounted a prefilter in the form of a coil spring 17 concentrically around valve 20. As will be more fully described hereinafter, the spacing between the coils is such that, when the valve is fully open, particles in the condensate and in the steam are free to pass through the space and into the condensate line. Since I have determined that the foreign matter only causes trouble when the valve is closing, I have arranged the coil spring in a manner so that, as the bellows begins to expand, the spacing between the coils begins to decrease and decreases in proportion to the decrease in the outlet opening between the valve and the valve seat. At the instant just prior to the time when the valve closes, only fully filtered steam is allowed to pass through the spring coils, thereby leaving a seat without particles. Thus, it is assured that the valve will seat properly, even in the face of unfiltered steam entering the steam trap.  
  To protect the bellows and valve assembly even further, I have surrounded the entire mechanism within the steam trap with a gross filter 14 having openings 14A, 14B, to pass only particles smaller than 1/16 of an inch in diameter. Foreign matter of larger size are not prevalent in steam systems and will not clog the line lying on the outside of the gross filter between the gross filter and the trap housing. In time, these particles will break down and pass through the trap.  
  Note that the coil spring diameter is shown relatively larger than is intended. This is done for the purpose of clarity. It is to be understood that light wire is contem&#39; plated, on the order of 0.050 inches diameter, to give the desired movement. Note also that the smallest opening between the coils when the prefilter is fully opened must be at least as large as the openings in the gross filter.  
  As shown in FIG. 2, valve is fastened to collar 2I which, in turn, is connected to the bottom of bellows 15. Spring coil prefilter 17 is shown fastened also to collar 21 via an upper coil 24. Lower coil is shown in contact with the outer surface 23 of valve seat 13. Lip 27 of valve seat 13 serves the purpose of keeping the lower coil uniformly concentric around valve opening 18. Several alternatives are available for this purpose. For example, a groove can be cut into surface 23 of valve seat 13 to receive the spring. or the spring could ride on a shaft around the seat.  
  As shown in FIG. 2 when the valve is in the fully open position (bellows contracted), the opening between the coils of the spring, such as opening 22, between coils 25 and 26, has a slightly smaller opening than the open area between valve head 42 and outlet opening 18. Accordingly, any material which passes through the coils is free to pass through the valve and valve seat opening, even if the valve begins to close at this instant. Thus, in the open position, the prefilter coil is transparent to foreign material. Although there is shown only one opening between the coils, my invention could be constructed with many openings between different ones of the coils, all arranged to close prior to valve closure.  
  In FIG. 3 my valve assembly is the closed position with valve 20 seated fully in valve seat 13 and with the openings between all of the coils fully closed. I have constructed the coils of the spring in a decreasing spiral to permit the minute valve travel override necessary after all particles of consequence are filtered from the seat area.  
  FIG. 4 shows the construction of valve 20 having a sloping surface 42, a screw base 41 for attachment to the bellows and hexagonal portion 40 for use in installation of my assembly.  
  FIG. 5 shows the relative spacing between the coils and the opening between the valve and valve seat when the valve is fully opened. As the valve begins to move downward. as shown in FIG. 6, the valve and valve seat spacing decrease and so does the spacing between the coils of the spring. In FIG. 7 the coil spacing is closed, allowing only clean steam through, while there still remains a small opening between the valve and valve seat. However, since the spring prefilter is closed prior to this time, only clean steam passes the valve.  
  In FIG. 8 the valve has seated and the coil remains closed. The fact that the coil is spiraled allows the coil to close the instant before the valve and yet have enough override to allow the valve to continue moving downward. Thus. the valve is free to move longitudinally with respect to the coil. This is important if the coil is to close prior to the closure of the valve and still be motivated by the same closing force, namely, the bellows. The spiral shown is arranged having concentrically decreasing diameter coils, each coil small enough to fit just inside the immediately lower coil and still maintain contact with the attendant adjacent coil.  
  In FIG. 9 I have shown another use for my valve. The device shown is for the purpose of safety to prevent costly freeze-ups which would occur if the steam, which normally travels from the inlet 96 through screen 99 to outlet 97, is stopped by a plugged screen or other blockage down stream of the device. To insure only emergency discharge, the bellows of this device would have a liquid fill with a boiling point slightly lower than the conventional trap bellows. In this arrangement my spring assembly would be placed in outlet 98 which discharges to atmosphere, or to a signal detector, whenever bellows contracts. The bellows, of course. will remain closed as long as hot steam passes from inlet 96 to outlet 97. When a blockage occurs. condensate forms and cools the bellows thereby opening the valve. Steam thus escapes intermittently to atmosphere as an indication of a malfunction.  
  Since, as discussed above, my valve assembly is transparent to particles when in the open position. there is no danger that a buildup of such particles would pre vent it from operating as would be the case if a strainer were needed in the line ahead of the valve.  
 CONCLUSION I have disclosed a valve assembly having the charac teristics of being self-cleaning and transparent to foreign particles while in the open position while at the same time filtering the input at a time when filtering is necessary. Such an assembly has the great advantage that no strainer is necessary prior to the input to the valve, no blow-down valve is necessary to clean the strainer. no costly downtime is required to clean a strainer which will not respond to blow-down techniques, and which maintains a constant opening size in the open position since it is not subject to accumulated backup of foreign material.  
  Although I have shown my valve in conjunction with a steam system, the usefulness of this valve is not limited to such systems. Because of the widespread applications I envision for my new, self-cleaning, variable prefilter valve, several alternatives, each directed to a particular application, are bound to be used each trading upon the principles herein discussed all without departing from the spirit and scope of my invention. For example, several alternatives may be used to achieve valve override instead of the spiraled coils I have shown. Also, the coils could all be held together and when the valve is open the steam would pass under the spring and not through the spring. This would be particularly so if the coil were to be mounted on a shaft.  
 What is claimed is:  
 l. A valve assembly comprising a valve seat,  
 a valve arranged for mating relationship with said seat,  
 means for moving said valve into said mating relationship,  
 a filter constructed having a variable filter size said filter arranged for mating relationship with said seat, said filter consisting ofa spring coil mounted concentrically around said valve, said valve being free to move in longitudinal relationship therewith, and  
 means linked to and controlled by said moving means for reducing said filter size in direct proportion to the opening between said valve and said valve seat, whereby when said valve is open. said filter is open and when said valve is closed, said filter is closed 2. The invention set forth in claim 1 wherein said filter reducing means is arranged to close said filter just prior to the time when said valve and said valve seat are mated.  
  3. The invention set forth in claim I wherein said coiled spring is spiraled in decreasing concentric fashion around the body of said valve.  
  4. The invention set forth in claim 3 wherein said valve seat is arranged to receive said spring coil of said filter in mating relationship 5. The invention set forth in claim 4 wherein said moving means is temperature sensitive.  
  6. The invention set forth in claim 1 wherein said valve is an elongated shaft having one end connected to said moving means and said other end free to move into said mated relationship with said valve seat,  
 said filter spring coil having one end connected to said moving means and the other end adapted for mating relationship with said valve seat.  
  7. A steam trap arranged for the passage of condensate therethrough and for the blockage of steam, said trap comprising an inlet through which steam and condensate enters said trap,  
 an outlet through which said condensate flows,  
 valve seat associated with said outlet.  
 valve for movement against said valve seat to prevent said steam from passing through said outlet. heat-sensitive element operable at a certain temperature to move said valve against said valve seat and further operable at a certain lower temperature to move said valve away from said valve seat thereby creating an opening between said valve and said valve seat for the passage of steam or con densate through said opening into said outlet. filter constructed having a variable filter size. said filter arranged for mating relationship with said valve seat, said filter consisting of a spring coil mounted concentrically around said valve. said valve being free to move in longitudinal relationship therewith, and  
 means linked to and controlled by said heat-sensitive element for reducing said filter size in direct proportion to the movement of said valve relative to said valve seatv