CA1321572C - Drain valve device - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A drain valve device mounted on the bottom of a pressure tank for the purpose of disposing of unwanted, accumulated waste liquids in the tank. The valve portion of the device is of a type comprising a stem-mounted disc moving longitudinally against, or away from a valve seat in the process of closing or opening the valve, respectively. Movement of the stem is achieved by means of a pivotally mounted valve operating lever, or by air pressure. The valve includes as special features thereof limited contact between the disc and the valve seat; a specially positioned valve seat which provides a pressure relief safety feature; a non-jamming spring configuration with positioning means therefore, and a self-aligning stem. In one of the preferred embodiments, a constricted opening is provided in the outlet of the valve to create an audible signal and to reduce loss of pressure when the valve is in its open position, draining the tank.

Description

--` 1 321~72 D~ V~LVE DE~r(E

TECHNICAL FIELD
This ir~vention relates to a drain valve 1 device for vessels, particularly those containing gas under pressure greater than atmospheric. More particularly, this invention relates to a drain valve device equipped with a quick opening lump 1~ mechanism. Specifically, however, this invention relates to a seated disc-type val~e, operated automatically or with a manually operated lever opening device, in combination with, and for the purpose of draining contaminants from containers holding gas under pressure, especially gas storage vessels.

2~ BAC~GROUND OF T~E INVENTION
All gases, including air, contain moisture. When a gas is compressed to the point at which its moisture content caa no longer remain in a vapor state, it precipitates as a liquid.
This is a very serious problem in any compressed gas operation, and as a practical matter, compressed air must be kept as dry as possible in order for it to be of any commercial value. For e~ample, water interferes with air operated equipment by rusting components, mi~iD~ with any oil present to ~orm sludge and varnish, and free~ing the equipment in cold weatller. This results in the lelivery of less power than would :
, --- 132~L~72 otherwise be avail~ble, since water adds to the mass of the air flow and, therefore, to the f`riction withirl the cleliver~ system itse1f.
Furthermore, because water is inco~lpressible, it cannot contribute to -the prod~lction of power, f-or instance in air tools.
Water also causes damage by virtue of its accumulation in the co~pressed gas receivers with which virtually all compressors are associated.
Air receivers are required since they act as a storage vessel for the compressed g-as, so that the compressing eguipment ~Yill not over-heat due to continuous operation. In addition, the compressor motor and pump do not have to cycle as much each time there is a demand for air, inasmuch as air is already stored in the receiver, ready for use.
The latter factor is important since frequent start-up of the compressor is a major cause of motor failure. An air receiver also eliminates the pulsations generated by the compression equipment, allowing smoother power delivery.
Once the air is stored in the receiver, however, it has a :hance to cool, permitting water separation to occur in the receiver itself as the moisture precipitates durinp; cooling. This produces denser air, allowing more power to be delivered to the application; however, the watcr must be removed for reasons which include thos~
previously described. It is the removal of such water and associated waste to which the invention addresses itself.
~hen acqllisition of a compressed air system is under consideration, the pump. motor and rece;ver tnnl; si~ing are n~ en c~reful th-)u~ht.

~321~72 Such si~inp; is impol-tant beCa-l,S.? a ~ hOrSepOWer compressor canllot be used ~hen IllOt`~' COlllpresSill~
capacity is needed. Likewise, the use of a 20 horsepower compressor when a lO horsepower unit would be adequate is wasteful. Consequently, all of the demands on the compressed air system are taken into consideration at the time of svstem design, and the receiver size is usually matched to the compressor's capaci-ty to produce air, the latter, in turn, being matched to the rate at which compressed air is requirecl by the application.
While receiver size is usually dictated by the horsepower of the compressor, it's size may be varied somewhat, and there are general sizing guidelines com~only used in the industry. For instance an 80 gallon tank is considerecl standard for a 5 horsepower air compressor, and while a smaller or larger r~ceiver is sometimes used with such a compressor, experience has shown that a tank of that size strikes an optimum compromise between size, cost, and the amount of energy involved in filling it. It is understood, however, that if a larger storage ~essel is needed, a larger compressor is required to handle the application.
Air stora~-e requirements, the need to limit compressor cycling, and the provision of - 35 sufficient storage space to allow thf~ air to cool before use all influence receiver sizing;
corlst~ uently, different circumstances lictate the use of different receivers. Generally speaking, larger receivers are used with lar~er horsepower compressors, since the amount of air f IOWillg ' ,.~ 1?~3L57.
thro~l~ll tim?m is so JSreat that small~?r r(-~cei~--rs would not accomod~te influencin~ factors su(h as those described in the preceding.
While it is advantageous that the air in the receiver cooll and that the water separate from it, the accumulation of water in the receiv~;^
must be avoided. For e~ample, when the water accumulates, it takes up space in the tanl;, effectively reducing- the capacity of the receiver. Since water cannot be compressed, an 80 gallon tanl; half full of water has only ~}0 gallons of space left for air storage. It is apparent, therefore, that if the receiver capacity has been halved, and that it takes only half as m~lch time to empty, and half as much time to fill. This means that the compressor has to cycle on and off twice as often as would otherwise be the case, and that and it pumps only half as lon~- durin~ each cycle. It is this "rapid cycling" th~t destroys compressor motors since the inertial start-up loads are so e.~:tremely larg-e. The armature in larger integral horse power motors may, for instance, weigh as much as 100 pounds by itself, and the motor must also turn the compressor pump from a standing start, all of which creatf-~s a severe strain on the motor. If repeated too often, the strain causes the motor to wear out quickly, and it is, as stated, one of the problems associated with water accumulation inside air receivers-A fur-ther problem encounte~red when the receiver cap3city has been reduced by water is that it tal;es proE~orlionally læss timc~ for th~ air in the receiver to be consullled beca-ls~ there is less air stor-?-l to be)~in ~ith. The air in the receiver also has less time to cool, and as a consequellce, air leavin~ the tank is w,~srmer, less dense, and wetter, red~lcirlg the ~m~unt of air power delivered to the equipment, and increasing thé amount of water entering it. The result is the rapid destruction of air operated tools and equipment. For all the preceding reasons, therefore, it is important to assure that the receiver be kept as clean as possible.
While al~ receivers have provision for bottom drainage, it is difficult to find a valve 16 suitable for the purpose. In this regard, receiver tank drainage provides a severe test for any drain valve, due to the fact that the inside of the tank corrodes as a conse~uence of water condensing on its sides, resulting in the distribution of particulate scale matter over its bottom surface. At the same time, oil from the compressor intermi~es s~ith scale from the compressor head, and from the pipes leading to the receiver, forming a mi~ture that combines with the ~ater and scale present on the inside of the tank to form an acidic sludge which corrodes and plugs conventional drain valves, tending to render them inoperative. When allowed to dry, the sludge, particulatc matter, etc., forms a hard plaque not unlike cement, providing a dif~icult tasl; for an~
valve to accomodate.
The valve of tht~ invention i. desi~ned to handle this difficult application, however, and all features of the valve, from the tvpe of materials used in its construction, to the unique dished-out face, are intended for use s~here the ~ ~32~ ~7~
material tn ~e clr.lined is not clean wattr, bnt rather is a combination of substances, incl-lding particulate matter, and where the pressurized integrity of the vessel must be m3illtaine(i, as in the case of the receivers referred -to.

DISC~OSURE OF THE INVENTION
In view of the preceding, therefore, it is one aspect o~ this invention to provide a drain valve device uselul in intermittelltly draining liquid from pressure vessels, while otherwise - maintaining the vessel's pressurized integrity.
It is an additional aspect of the invent:ion to provide a drain valve device which is quickly activated to its open position, either automntically, or by a lever means operated by foot or hand pressure.
~ A further aspect of the invention is to provide a reliable device for draining unwanted effluent and waste from pressure vessels, which may be operated at required intervals determined 2~ by the time during which the pressure vessel has been accumulating such liquids.
Another aspect of this invention is to provide a drain valve de-ice of simple construction which is easy to install and maintain, and which is relatively free from the failures resulting from the adverse conditions of the environment in which the device is located.
~he foregoing and othcr aspects of the irlvention which will beconle apparent as the detailed description procetds, are achieved by a drain valve device comprising a val~e with a stem-mounted dis- activated hetween opened and "
-7~ 2~72 closed positionr, by longitudinal movement of the stem, and corresponding movement of the disc, against or away from the valve seat; a valve actuator mounted on said valve adapted to exert a force on said stem, thereby moving the stem and forcing said disc away from its seat, thus opening the valve, wherein said valve is equipped with a spring to return it to its closed position when said force is rem~ved, and wherein th~ valve seat is comprised of a replacable, pressure deformable, resiliant material, and wherein further, the inner surface of said disc facing said valve seat is recessed so as to provide a peripheral land on said inner surface, thereby limiting the area of ; contact between said valve seat and said disc in the valve's closed position to the surface area of the land.
Other aspects of the inventiun will be obtained by a combination comprising a drain valve device having a valve with a stem-mounted disc z~ activated between open and closed positions by longitudinal movement of the stem, and corresponding movement of the disc, against or away from the valve seat, the inner s~rface of said disc facing said valve seat being recessed so ~ as to provide a peripheral land on said inner i surface, thereby limiting the area of contact ~^~ between said valve seat and said disc in the valve's closed position to the surfac~? area of the land; a valve actuator mounted on said valv~ and adapted to e.Yert a force on the stem, thereby moving the stem and, therefore, moving the disc away from said seat, thus opening the val~e; a spring adaE~ted to force the disc back ap;.linst saill , ~
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, -8-- 132~2 seat~ thus closing the valve, and a vessel to which such valve i9 attachecl, whereby contaminants may be drained from the vessel when desired.

BRIEF ~ESCRIPTION OF THE nnAWINCS
The inv`ention will be more fully understood from the following detailed description, taken in connection with the accompanying drawings, wherein like-numbers refer to like-parts, and wherein:
Fig. 1 is a side elevation of two :- different embodiments of the drain valve device of the invention in their position of use attached to a vessel.
Fig. 2 is a cross-section of an automatic drain valve device of the invention showing the internal working details of the valve.
Fig. 3 is a partial cross-section of a manually operated drain valve device of the invention showing the interaction of the actuating levsr with the valve stem.

- BEST MODE FOR CARRYING OUT THE INVENTION
Referring to the drawings, Fig. 1 shows a r 30 sidc elevation of a pressure receiver vessel or tank 11 to which are mounted two different embodiments of the invention, generally 10, and 10a, respectively. An automatic dump valve 10 is shown attached to the bottom of a pressure vessel lI and to a dump valve contro] llnit 13, the latter also being attached to the pressure vessel. A
manual dump valve l0a connected to the vessel is also shown.

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~ 1~21~72 The dischar~e of automati(- dulnp valve 10 is determined by controller 13, ~hich may be of a type designed to activate the valve at regular intervals, for specific periods of discharge. The intervals of time ~ay depend upon the conditions of operation, the type of equipment involved, and similar factors, and may, for example, be set to discharge at intervals of from about 1 to 100 minutes. The length of the discharge will likewise depend upon operating factors; however, discharge periods will ordinarily not e~ceed several seconds.
The manually operated valve lOa is activated by an operator, either by foot or by hand, until the accumulated waste in vessel 11 has been discharged. Completion of discharge can quickly and easily be determined by observing the absence of liquid discharge, or in the case of a vessel under pressure, by the sound of gas escaping under pressure. In a preferred embodiment, the valve is proided with an effluent discharge nipple 3~, fitted with a whistle device 33 which may, for e~ample, be a plug fitted with a constri.cted opening such as a small hole drilled in its center. The constricted opening reduces the amount of gas escaping before the valve can be closed, after all the waste has been drained.
However, it also increases the velocity of the gas esca~ing at the end of the draining operation, and mal;es its escape more audible. While the size of the hole is not critical, depending upon the pressures involved, the size of the valve, and similar considerations, the diameter of the hole may desirably vary from abont :3/:3~ inch to about -10~ ?J1~7~
l'l6 irm:!l, with particular a-lvantage~ being obtained from 3 hole abo~lt 7,~1~ inch in diameter.
When draining has been completed, the lever is released, allowin~ the valve to returll to its closed position.
The time at which discharge of effluent waste from the vessel should be undertaken is influenced by such factors as the length of time since the last discharge, the amo~lnt of usage of the system in the intervening period, the nature of the gas and waste being handled, the .. temperatures involved, and similar considerations.
In the case of compressed air storaga tanks, such discharge is usually performed at least on a daily basis.
Fig. 2 shows a crt~ss-sectional view of an automatic valve 10 having a circular cross-section transverse to the horizontal a~is of the Figure.
The external body portions of the valve comprise a valve housing 12, a valve stem housing 14, and an end cap 42, all of which are held together hy si~
bolts 44 equally spaced adjacent to the circular periphery of the valve. A valve stem, generally 16, is positioned within a center bore 3- in valve stem housing 14, and is provided with O-rings 24 as a seal therefor. The valve stem 16 includes a piStOIl portion 38, a shaft 3~, and a valve stem : disc 17. The valve stem disc 17 is provided with a dished-out, face recess 20, leaving a face land 18 adjacent the periphery nf the disc. The valve stem disc 17 is also provi.ded with a disc cont~ 22 on its lower or pressure face, and a valve spring 28 positioned adjacent to the disc rone. A valve seat ~6 is located in an annular grooie at the smaller diallletel, Lcwer enri of the v~ e stem housin~ . A circular actuator piston ~ is ... : pos~tioned between a flexible diaphragm ~7 and the encl of the stem piston 38, while a sealing gasl;et 34 is posi.tioned between valve housing 1 and valve stem housing 1'~.
The valve is connected to the receiver vessel to be drained at effluent inlet 30, the effluent waste leaving the valve through the effluent discharge port 32.
The valve is actuated to its discharge, or dump position by air entering air control inlet 40, which pushes against diaphragm 27 and actu.ttor piston 29 moving the latter away from end cap stop--ridge 43, and agains-t the end of stem piston 38. The force thus generated pushes the disc face land 18 away from valve seat 26, allowing the discharge effluent to flo~ through the inlet 30, around the space created between the land 18 and the seat 2~, around the stem shaft 39, and finally, out the effluent discharge port 32. When the control air supply is shut off, the process is reversed, the valve spring ~8 forcing the disc face land 18 back against the valve seat 26, shutting off the effluent discharge.
While drain valves are essential in pressure vessels, for the reasons previously stated, it is e~-tremely difficult to assure the positive seating of such valves in their closed pOSitiOII, which is essential to the maintenance o~
pressure in the vessel. This is due to the accumulation of sludge, scale, and other cont~-tminating seclimcnts in the val~e. Such sediments, for e~an~ple, have a tendenc~ to hec(Jme 2 ~ ~ 7 h lodr;ed hetween the seat of tht- valv.~ and thl clisc eace, preventing the valve from completely closing`. FurthermQre, the sedimcnt problem also hinders the action of c~lindrical valve springs, sometimes accumulating on the coils of such springs, interfering with spring compression, and thus obstructing the proper opening of the valve.
The valve shown is provided with a number of important improved features, described in the following, which avoid these difficulties, and make the valve highly reliable in drain service.
The recess 20 provided in the disc face surface, for e~ample, limits the area of the face in contact with the disc 17 to the area of land 18. The limited surface of valve seat contact thus afforded greatly minimizes the area available for accumulation of particulate contamination, and it also increases the unit-loading of the contact surface against the disc. Both effects tend to provide reliable seating, irrespective of the amount of sediment contained in the discharge effluent. With respect to the si~e of the land 1~, it has been found desirable to limit to it a width of from about 0.03.; inch to 0.045 inch, a width of about 0.040 inch, however, being preferr-ed.
Related to the elimination of sedimentation within the valve is the provision of the disc cone 22, which not only serves to securely position the smaller diameter, upper end of valve spring 2~ against the disr: 1-, but also importantly, acts as an air spoiler to reduce the turbulence created b~ sudden changes in the effluent discharge stream, thus maintaining a ~ .t~t~ 72 smc.otll flow of the ~iaste ma-terial, and accolllpan~ing air discharged. The smovth flow thus .: induced permits the complete purging of the valve, and greatl~ reduces the likelihood of sediment accumulation in the dead air spaces, which often results from flow turbulence. While cones with taper angles having different values can help to provide the effects described, it is preferable that the cone have a taper of from about. ~0~ to 45, relative to the vertical a~is of the valve stem 16, and a taper angle of about 30 is -. commonly employed.
- 15 Although a variety of springs can be employed in dump valves, it has been determined that a conical spring is unusall~ beneficial in avoiding interference of accumulated sediment on the surface of the spring with the spring's compression. As stated, when a cylindrical spring is used, sediment tends to accumu1.ate on the exposed surfaces, jamming the spring by limiting the degree to which the spring can be compressed.
It has been found, however, that such an accumulation poses no problem wit.h a conical spring, since adjacent coil surfaces do not contact each other, even when the spring is eompressed. Provision of a conical spring, therefore, is an .~dditional feature which provides notable advantages for the valve in receiver vessel draining service.
~ further aclvantaP;- o:f the valve of the invention is to be found in the provision of the annular groove in which valve seat '~ rests. The groove as constructed forms an annular lip 21 on the valve stem housing. The liE~ func:t ions a~ a l 1 1 3 ~ ~ ~5 7 i safet~ relief valve when the valve stem disc is subjected tc~ danl,crl>-:sly elevate-l pressur--s. Lll such cases, the face lan(i lR compresses the valve seat '?6 to sucll an e~tent that the s-lrf`acl-: of the S face recess 20 is forced against lip ?1, and no more compression of the valve seat is possible.
This limits the sealing ability of the contact between the face land 18 and the valve seat 26, so that further pressure escapes at the contact point and discharges safely through discharge port 3'?.
Proper operation of the valve requires that the valve stem 16 move parallel tv the :- longitudinal a~is of the center bore 37 of valve stem housing 14. In other words, if the movement of valve stem 16 occurs at an angle to the bore 37, a wobbling movement can occur, sometimes resulting in the valve stem being placed in a "cocked" position which interferes with proper seating of the valve. While close fabrication tolerances can help eliminate the problem, it has been found that the ratio of the length of the valve pis-ton 38 to the piston's diameter can have an important beneficial affect in helping to eliminate the problem. Specifically, it has been found that the stem is self-aligning and stem wobb~e is virtually eliminated if such ratio is not less than about 1.~ to 1, with about 1.8 to 1 being particularly advantageous.

3~ In a preferred embodiment, the control air inlet 40 is supplied s~ith compressecl air from the vessel being drained. Therefore, the air pressure forcing the valve stem clisc l7 against valve seat ~, is the same as that being applied to cliaphra~m ~7. In such case, sl~ lollg a. the dialneter of actuator piston ~ is grPate: than that of the valve stem disc 1l, the air pressllrt entering air inlet ~0 from the controller 13 will alwa~s he sufficient to open the valve fnr draining.
Fig. 3 is a partial cross-section of a manually operated valve of the invention, generally lOa, showing details o~ the actuating mechanism. The portion of the valve relating to valve seat 26, the valve stem disc 1/, and related structure is identical to that previously -. discussed in connection with Fig. 3. In the : Figure, a valve stem housing 14a is connected to valve housing 12 by bolts identical to the bolts 44 of Fig. ~, but which, however, are not shown in Fig. 3. The valve stem housing l~La has a vertical slot 46 which e~tends thr~ugh the end thereof, with an actuating lever 48, a plate-like e~tension provided with a lever pedal 50, usually round, mounted thereon. The lever is pivotable about pivot pin .52 which extends through the lever slot 46, and is attached to valve stem housing l~La.
The valve is actuated when an operator mnves the actuating lever 48 by stepping on lever pedal oO, or moves the lever by hand. When le-er 4~ is thus depressed, lever face 4~ pushes valve stem 16 within its associated bnre 37, forcing the disc face land 18 away from valve seat 26, openinp; the valve. When the operating force is removed from lever 48, the valve spring 28 fnrc~s tne valve stem 1~ in the reverse direction, resto:i:lg the lever to its original position, and fvrcing the disc face land 18 back against valve seat 26. ~s in the case of the valve of Fig. 2, gasket 34 ic 13 2 71 r 1.~
positioned between valvf- h(-u~-ing 12 and va]ve stf-n ho~lsin~ 14a, and O-rings 2~ sf-al the valve St~
`~ witl1in the bnrf~ 37 of thf valve stem housing.
Discl1arge thrl)ugll the valve is froDI port 3~, as previously described.
Valve seat Z6 is formed from relatively resilient, pressure deformable materials in order to assure a substantially liquid-tight seaL with disc face land 18. Elastomeric materials, for exa~nple, natural and synthetic rubber, as well as other resilient substances having similar - properties may all be successfully employetl for the purpose. The selection will depend upon the nature of the liquids to be encountered, and the conditions of the service to which the drain valve device is tc~ be e~posed.
The difnensions of the valve, other than as described, are not particularly critical and are governed by such things as the volumes of liquids to be handled, the pressures to which the drain ~alve device is to be subjected, and similar considerations.
In the draining process, the operator presses valve operating lever 48 until the accumulated waste in the vessel ll has been discharged. Completion of waste discharge can quickly and easily be determined by observing the absence of liquid discharge, or in the case of a vessel under pressure, the sound of gases escaping under pressure can provide an audible signal as well, as previousLy described.
While the invention described is illustrclted in connection with particular valve operating cvml)onent, and fittinos. showin~-13~ Cr~"
preferre(l design embodimtn~, it wilL b-apE~reciate(l that details of sucll (omp-Jnents1 - includin~ their manner of their interconnecti-n with each other, and with the associated vessel to be drained, m~y be varied without departin~ from the spirit of the invention disclosed.
Furthermore, while the drain valve device is particularly advantageous when sued with pressure vessels, it may also be employed with vessels not under pressure, particularly where valve spring 28 is strong enoug-h to force the disc face land 18 ti~htly against valve seat 26, unassisted by pressure.
While in accordance t~ith the patent statutes only the best mode and preferred embodimen-t of the invention has been illustrated and described in detail, it is to be understood that the invention is not limited thereto or thereby, but that the scope of the invention is defined by the appended claims.

Claims (7)

1. A drain valve device, comprising:
a valve with a stem-mounted valve disc activated between opened and closed positions by longitudinal movement of the stem and corresponding movement of the valve disc against and away from a valve seat, said valve seat comprising a replaceable, pressure deformable, resilient annular disc having an opening therein through which a flow of material may axially pass, and said valve disc having an inner surface facing said valve seat, said inner surface being recessed to provide a peripheral land on said inner surface, thereby limiting an area of contact between said valve seat and valve disc in the valve's closed position to the surface area of the land;
a valve actuator mounted on said valve and adapted to exert a force on said stem, thereby moving the stem and forcing said disc away from said valve seat and thus opening the valve, wherein said valve is equipped with a spring to return it to its closed position when said force is removed; and wherein said valve disc has a pointed tapered cone extending from a center of a surface of said disc opposite said valve seat, said pointed tapered cone being axially aligned with said annular disc with a pointed end of said cone positioned upstream of said flow of materials to said annular disc, and wherein said spring is conical in shape and is positioned within said valve so that its smaller end is seated against said cone.

2. A drain valve device according to claim 1 wherein said land has a width of from about 0.035 inch, to about 0.045 inch.

3. A drain valve device according to claim 2 wherein said stem includes a piston portion at the end of the stem opposite the end at which said valve disc is located, said position portion having a ratio of length to diameter of not less than about 1.2 to 1.

4. A drain valve device according to claim I wherein said valve seat is maintained within an annular groove within a housing such that when said disc is subjected to a predetermined pressure, said disc compresses said seat sufficiently against said housing to allow pressurized gas to escape through said valve.

5. A drain valve device according to claim 1 wherein said valve actuator comprises a lever pivotally mounted on said valve adapted to exert a force on said stem, and thereby to open said valve.

6. A drain valve device according to claim 1 wherein said valve actuator comprises a diaphragm mounted on said valve which is adapted to exert a force on an actuator piston in contact with said stem when said diaphragm is actuated by a controlling gas pressure, thereby exerting a force on said stem, and thereby opening said valve.

7. The drain valve device of claim 1 in which discharge of the valve occurs through a hole in a fitting attached to the valve, said hole having a diameter of from about 3/32 inch, to about 1/16 inch.