Anti-water hammer flow regulator valve

Abstract

flow regulator valves that adjust to various fluid flow line pressure variations to stabilize flow to designed regulated flow rates in various flow line sizes and with fluid pressure build up in the line encountered such as with water hammer are combined with through flow relief valving to diffuse excessive line pressures. This includes the addition of a relief valve, of any of several configurations, to a flow regulating valve, in several configurations with the relief valve opening to relieve higher than flow regulating valve design working pressures.

Description

This invention relates in general to liquid flow through enclosed fluid flow systems including fluid flow lines having flow regulator valving and to the problem of water hammer, and more particularly, fluid flow regulators equipped with relief valving subject to opening to relieve line pressures higher than flow regulated valve design working pressures.

Presently existing methods for achieving flow regulation in Hydronic systems can include orifice plates used in the fluid flow line or manually adjustable valves that allow fine tuning of the fluid flow rate of a fluid flow system once it is functioning with such valves called circuit setters in the trade. Use of orifice plates with orifices one half the pipe inner diameter in fluid flow lines has potential for inducing water hammer as liquid with entrapped air volumns flows through the orifice. When this occurs the orifice, or valve, tends to dampen water hammer allowing induced energy to dissipate as the shock wave travels throughout the system, once the entrapped air volume has cleared the orifice. Water hammer is also induced with flow of fluid with entrapped air passing through a variable orifice fluid flow regulator where as the entrapped air passes through the variable orifice there is an immediate subsequent change as liquid again begins to flow through the orifice area the variable orifice area valve automatically adjusts itself by closing the variable orifice toward its smallest opening thereby intensifying induce water hammer.

In the case of an orifice plate used in a fluid flow line pipe the orifice will restrict the flow of fluid as a function of the change in pressure across the orifice and the viscosity of the fluid with viscosity a function of both temperature and fluid density. Assuming at a point in time water is flowing at a steady rate through the orifice at some ΔP=P₁ -P₂ (P₁ being upstream pressure and P₂ being downstream pressure relative to the orifice plate) with the fluid viscosity constant. At another point in time with a slug (volume) of air entrapped in the water reaching the orifice and with the density differences of air and water (air one two hundreth of water) there is also a corresponding viscosity difference. With the much lower viscosity of the air in the air pocket the pressure substantially equalizes across the orifice as long as the air pocket has not completed passage through the orifice and with the orifice within its confines. In this condition P₂ is increased and P₁ decreased in magnitude and with the upstream pressure P₀ remaining substantially the same fluid flow velocity increases with the increase in fluid flow pressure differential. This results in acceleration of fluid flow toward the orifice plate. Then when the air/water interface, as a wall of water, impacts the orifice plate there is a sudden increase of viscosity and a resultant high restriction at the orifice itself resulting in a significant velocity change of the upstream fluid coupled with inertial forces resulting in the creation of water hammer. With no other slugs of air in the fluid stream the shock wave propogates back through the fluid system until it encounters an obstruction to reflect off of. Each time the shock pressure wave returns to the orifice more fluid is forced through the orifice as the pressure increases until such time as the shock pressure wave has been dissipated. Each time the shock pressure wave is reflected to the orifice the consequent increased flow through the orifice lessens the intensity of the shock pressure wave. As a standard nearly all hydronic systems have a pressurized air over water surge tank located at or near the highest point in the system. If water hammer shock waves are allowed to travel to this tank pressure wave reflection back into the system would dampen very quickly eliminating the water hammer shock wave.

With some existing automatic flow control valves a resiliently deflectable spring structure is resiliently deflected by fluid pressure on a piston having a variable size orifice thereby sizing the variable orifice as a function of the pressure differential across the variable orifice ΔP=P₁ -P₂. This is with the variable orifice sized to maintain a specific flow rate (g.p.m.) within limits through some differential pressure range for a fluid of a constant viscosity. As an entained air slug volums begins to flow through the flow regulator control valve the spring reacts initially to the sudden viscosity change causing the orifice to become larger. Since the valve automatically enlarges the orifice under these conditions an even faster pressure equalization occurs across the orifice. This results in an upstream fluid velocity increase. Then as the air/liquid interface begins to flow through the variable orifice of the valve the orifice automatically begins to reduce the orifice opening area as the device senses the viscosity increase and the differential pressure increase and as the upstream pressure P₁ continues to increase the orifice continues closing toward it's smallest area state. This results in a significant upstream fluid velocity change in a very short time thereby inducing a water hammer shock wave. This water hammer will have greater pressure surges and will not tend to dampen as quickly since as the wave is reflected back to the flow regulator valve it will automatically close the orifice toward it's minimum area at the first indication of pressure increase. If two or more automatic flow control valves are located fairly close to one another the water hammer shock pressure wave could be reflected between valves for some period of time. Such shock pressure waves could be of such significant magnitude as to generate noise and possibly cause physical gamage in the piping system. Thus, it can be seen that this standard pre-existing automatic flow control valve is particularly susceptible to water hammer inducement and in some instances it tends to sustain such shock wave action once initiated as opposed to shock wave dissipation such as experienced with fixed orifice valves.

It is, therefore, a principal object of thie invention to minimize the development of water hammer shock waves in a liquid piping system

Another object is to provide a liquid piping system with liquid flow regulator valving having shock wave valve diffusing of excessive line pressures.

A further object is to eliminate water hammer pounding noises vibration and destructive forces.

Still another object is to provide a flow regulation valve equipped with a relief valve that opens in response to excess line pressure above a selected pressure level and that immediately returns to the through flow automatic flow regulation mode immediately after the excess line pressure is relieved.

Features of the invention useful in accomplishing the above objects include, in an anti-water hammer flow regulator valve, a fluid flow regulator valve, with an automatically variable orifice, equipped with a relief valve that opens to relieve fluid flow media pressures higher than flow regulatng valve design working pressures and particularly to diffuse water hammer shock wave impact pressures.

Specific embodiments representing what are presently regarded as the best modes of carrying out the invention are illustrated in the accompanying drawings.

In the drawings:

FIG. 1 represents a perspective view of an anti-water hammer flow regulator valve in a fluid flow line pipe of a fluid flow system;

FIG. 2, a cut away and sectioned view taken along line 2--2 of FIG. 1 showing interior detail of the anti-water hammer flow regulator valve of FIG. 1;

FIG. 3, a cut away and sectioned view taken along line 3--3 of FIG. 2 showing further detail of the valve of FIGS. 1 and 2;

FIG. 4, an additional cut away and sectioned view like that of FIG. 2 with, however, on the bottom half the piston moved toward a less orifice area position in flow regulation in response to increased upstream fluid line pressure exerted thereon;

FIG. 5, an additional cut away and sectioned view like that of FIGS. 2 and 4 with, however, the relief valve body moved to the right against the resilient force of the relief valve body spring for excess pressure shock wave valved passage of fluid for shock wave pressure relief.

FIG. 6, a cut away and sectioned view like FIG. 2 of another anti-water hammer flow regulator valve embodiment;

FIG. 7, a partial cut away and sectioned view of the antiwater hammer flow regulator valve embodiment of FIG. 6 with the relief valve open for excess pressure shock wave valved passage of fluid for shock wave pressure relief;

FIG. 8, a partial cut away view taken along line 8--8 of FIG. 6 showing some internal detail of the valve of FIGS. 6 and 7;

FIG. 9, a cut away and sectioned view like FIG. 2, of another anti-water hammer shock wave relief valve;

FIG. 10, a cut away and sectioned view like FIG. 9 of another anti-water hammer shock wave relief valve with a position settable orifice;

FIG. 11, a partial cut away and sectioned view of the valve of FIG. 10 with the position settable orifice set to a restricted through flow state; and

FIG. 12, a cut away and sectioned view like FIG. 2 of another anti-water hammer shock wave relief valve with a flow metering orifice piston in the low pressure position, and in a high pressure position in phantom and also in phantom high pressure shock wave opening of butterfly relieve valve doors.

Referring to the drawings:

The anti-water hammer flow regulator valve 20 is shown in FIG. 1 to have opposite end caps 21 and 22 that, as shown in FIG. 2, have internal threads 23 and 24, respectively, into which pipe sections 25 and 26 of liquid flow system piping are threaded. Referring further to FIGS. 2-5 for more valve 20 detail the opposite end caps 21 and 22 have external threads 27 and 28, respectively, that thread into opposite end internal threads 29 and 30 of valve body housing 31 that is provided with a plurality of fluted ribs 32 spaced one from the other around the interior of the body housing 31. The fluted ribs 32 have a shoulder 33 upon which ring 34 seats to back one end of relief valve spring 35 the other end of which engages shoulder 36 of relief valve body 37 that is resiliently pressed by spring 35 with conical surface 38 in sealing engagement with conical surface 39 of end cap 21 within valve body housing 31. Relief valve body 37 is cylindrical with a reduced diameter cylindrical shank 40 that is a sliding fit within the inner surfaces 41 of fluted ribs 32 and a cylindrical valve head 42 that is sliding fit within the inner surfaces 43 of fluted ribs 32. The relief valve body 37 is also formed with an inner cylindrical surface 44, within which valve piston 45 is slidably held, and an inner cylindrical surface 46, of greater diameter than surface 44, that receives the radially extended support legs 47 of valve ring 48. Valve ring 48 is held in place within relief valve body 37 with ring support legs held between relief valve body inner shoulder 49 and a snap ring 50 inserted in body groove 51. The valve piston 45 that is part of a flow regulator valve 52 held within relief valve body 37 is formed with a cylindrical shank 53 having a closed bottom 54 and at least one side valve opening 55 is a slidable fit within valve ring 48 positioned such that longitudinal movement of the cylindrical shank 53 of valve piston 45 within valve ring 48 varies the cross-sectional area open for fluid flow through side valve opening 55. Such movement is induced by variance in upstream fluid pressure acting on the valve piston 45 against the resilient bias of regulator valve spring 56 that is resiliently compressed between ends 57 of valve ring support legs 47 and valve piston shoulder 58. A snap ring 59 mounted in body groove 60 limits the upstream movement of valve piston 45 to its most open position of side opening 55 as would occur when the upstream pressure is low. It should be noted that the side valve opening 55 is "T" shaped such that as the piston 45 comes to its most open position such as shown in FIG. 2 the valve opening with last increments of movement as the head 61 of the "T" shaped opening is moved to clear valve ring 48 the opening increases in crosssectional area very quickly.

Operation of the water hammer dampening automatic flow control valve 20 of FIGS. 1-5 is controlled in large measure by the relative resilient compression rates of the regulator valve spring 56 and the relief valve spring 35. The regulator valve spring 56 is preselected to resiliently permit the valve piston 45 of the flow regulator valve 52 to start moving from the zero upstream pressure state of FIG. 2 and the top half of FIG. 4 to the right after the upstream pressure has risen to the point such as to maintain the through liquid flow rate desired with maximum orifice opening through side valve opening 55. While referring to opening 55 in the singular for balanced liquid flow there are a plurality thereof generally two, three, or four all similarly shaped. As the valve piston 45 starts to move to the right at a differential pressure between upstream and downstream pressures relative thereto of between, for example, five to twenty five pounds an initial small movement of the piston 45 to the right quickly materially restricts the cross-sectional area of the "T" shaped side valve opening 55 (or the total area of the plurality of such openings in the piston 45) to thereby meter liquid through flow to substantially the same rate out through the opening(s) 55 to the spring 56 chamber 62 on through the channels 63 between valve ring support legs 47 to beyond the piston cylindrical shank 53 on downstream into and through the inner diameter of outlet pipe 26. Thereafter as the upstream pressure is raised to a designed for pressure limit of, for example, fifty pounds per square inch with a differential pressure between upstream and downstream pressures, typically, in the range of twenty to thirty pounds per square inch the piston is moved to a position of maximum restriction of the "T" shaped side valve opening(s) 55 such as shown in the bottom half of FIG. 4, with substantially a constant metered through flow rate of liquid being metered through the flow regulator valve 52 through the range of settings thereof. Then if there is a shock pressure increase in upstream liquid on the order of fifty five to sixty five pounds per square inch as encountered with shock waves such as engendered with water hammer the resilient resistive force of relief valve spring 35 is such as to permit resiliently biased to close openings of relief valve body 37 with movement thereof like a piston to the right valve concal surface 38 unseating from the valve conical surface 39 seat of end cap 21 to a degree from the closed state of FIGS. 2 and 4 to as much space therebetween as shown in FIG. 5 where relief valve passage area of liquid flow runs to as much as one half or more the cross-sectional open inner area of inlet pipe 25. This relief valve passage area flow runs into and through the chambers 64 between fluted ribs 32 to downstream from the flow regulator valve 52 within valve body housing 31 and on out the inside of outlet pipe 26. The relief valve opening is a relatively large area of liquid flow for pressure relief to an area as much as equal to the nominal inside pipe area of inlet and outlet pipes 25 and 26. The only restriction offered to the fluid flow by this valve is the differential pressure required to open the relief valve on the order of fifty five to one hundred p.s.i. A water hammer shock pressure wave running to a maximum pressure of one hundred p.s.i. will not cause pipe expansion and/or pipe joint parting and only on rare occasions is such as to generate noise problems.

In understanding the phenomenon known as "Water Hammer" the term is used to define the destructive forces, pounding noises and vibration that develops in a piping system when a column of relatively non-compressive fluid flowing through a pipe line at a given pressure and velocity is stopped abruptly or undergoes a significant velocity change. When water hammer occurs, a high intensity pressure wave travels back and through the piping system until it reaches a point of some relief such as a large diameter riser or piping main. Then the shock wave travels back and forth between the point of relief and the point of origination until the destructive energy content has been dissipated in the system. Common causes of water hammer shock wave are the quick closing of electrically controlled, pneumatic or spring loaded valves or closure devices as well as quick manual closure of valves or fixture trim with the speed of valve closure, especially the speed of the last fifteen percent of valve closure, directly related to the intensity of the pressure wave or surge. Water hammer shock wave intensity is a function of quick valve closure equal to or less than two times the length of pipe in feet divided by the velocity of pressure waves in water (i.e. in the 4,000-5000 ft/second range-speed of sound in water) if water is the liquid. The maximum pressure rise in such shock waves equals the specific weight of fluid (lbs/ft cubed) times the pressure wave velocity and the change in flow velocity ft/sec. divided by (144 times acceleration due to gravity 32.2 ft/sec squared).

The anti-water hammer relief flow regulator combination valve 20' embodiment of FIGS. 6,7, and 8 has many structural features and functions duplicating to some extent those with the valve 20 embodiment of FIGS. 2-5 yet with a number of differences. With the valve 20' embodiment opposite end caps 21' and 22' have internal threads 23' and 24', respectively, into which pipe sections 25 and 26 of liquid flow system piping are threaded. The end caps 21' and 22' have external threads 27' and 28', respectively, that thread into opposite end internal threads 29' and 30' of valve body housing 31'. Housing 31' has an upstream end inner cylindrical chamber 65 within which the head 66 of valve piston 67 of liquid flow regulator valve 68 is a sliding fit. The cylindrical shank 53' of piston 67 that is closed at the bottom end by an over pressure valve relief ball 69 is a sliding fit in cylindrical surface 70 of valve body housing internal boss 71 and cylindrical surface 72 of the innermost end 73 of end cap 22' that is positioned within internal chamber 74 of valve body housing 31'. A regulator valve spring 56' is resiliently compressed between piston head 66 and housing internal boss 71. A plurality of orifice regulator valve openings 75 are provided in piston cylindrical shank 53' to permit regulated flow of fluid therethrough to chamber 74 of valve body housing 31' and therefrom through openings 77 to the interior of end cap 22' and on out through outlet pipe 26. At the upstream end of piston 67 three armed 78 pressure overload valve 79 support plate 80 mounted in rescess opening 81 allows fluid bypass flow into the interior of the piston 67. The plate 80 has a center opening 82 through which over pressure valve relief ball 69 mounting rod 83 is a sliding fit and between which and a rod end nut 84 and washer 85 pressure relief valve coil spring 86 is resiliently compressed. Regulator valve openings 75 are shown to be circular openings although they could be "T" shaped openings such as shown with the embodiment of FIGS. 2-5.

With the embodiment of FIGS. 6-8 operation of this water hammer dampening automatic flow control valve 20' is in like manner controlled by the relative resilient compression rates of the regulator valve spring 56' and the relief valve spring 86. The regulator valve spring 56'is preselected to resiliently permit the valve piston 67 of the flow regulator valve 68 to start moving from the zero upstream pressure state of FIG. 6 to the right after the upstream pressure has risen to the point such as to attain the through liquid flow rate desired through side valve openings 75. Movement of the valve piston 67 to the right as a function of the differential pressure between upstream and downstream pressure meters the liquid fluid through flow to the desired predetermined flow rate. Such movement of valve piston 67 to the right lifts it from the limit position with piston head 66 in abutment with the inner end 87 of end cap 21' through a metering range to a position of valve piston 67 displaced to the right as shown in FIG. 7 with spring 57' compressed and the regulator valve openings 75 in a maximum through flow restricted state by cylindrical surface 72 covering most of the orifice space of regulator valve openings 75. After the valve piston 67 has moved to the limit position to the right, as shown in FIG. 7, if there is a shock pressure increase in upstream liquid on the order of fifty five to sixty five pounds per square inch over downstream pressure relative to the valve 20', such as encountered with shock waves typical of water hammer, the resilient resistive force of relief valve spring 86 is such as to open relief valve 79. In doing so over pressure relief ball 69 is lifted out of ball seat surface 88 in the downstream end of piston cylindrical shank 53'.

Once water hammer shock wave action is induced the valve 20' acts to dampen such shock waves through the relief valve much the same as has been described hereinbefore. It should be noted that valve 20' in the relief open state presents effectively only opening area approximating one half the pipe inside diameter as a flow orifice like that described herein in accord with present design criteria. With this valve 20' the only possible water hammer induction and/or initiation will be the narrow span range between the operating pressure and the relief pressure setting, that for all practical purposes should never exceed one hundred p.s.i. and usually in the order of fifty five to sixty five p.s.i. depending on operation design discretion.

When an air/water interface impacts the variable orifice 75 metering area the regulator piston 68 moves to close the orifice openings 75 to their smallest openings, but then with a sudden build up in pressure with liquid again impacting the orifice area the sudden reduction in liquid velocity, the ball relief valve 79 opens at a predetermined pressure setting between fifty five p.s.i. and one hundred p.s.i.. With the relief valve open an area approximately equal to one half the nominal pipe 25 and 26 internal diameter is available for relief valve fluid flow as driven by the high pressure build up associated with fluid flow sudden velocity change. Depending on the volume of an entrained air pocket that is an influencing factor in upstream fluid velocity and thereby a factor in the magnitude of the shock/pressure wave generated, there is a high probability that water hammer would be generated and if so the relief valve in the open position acts to defuse lessen water hammer shock pressure in much the same way as with a fixed orifice valve as has been described.

Referring now to the anti-water hammer shock wave relief valve 20" of FIG. 9 other than for a fixed orifice opening 89 in an orifice plate 90 that is an internal part of relief valve body 37" in place of regulator valve 52 in relief valve body 37 of the FIGS. 2-5 embodiment. The exterior of valve body 37" is identical to the exterior of valve body 37 and the other parts of valves 20 and 20" external to valve bodies 37" and 37 are the same and as a matter of convenience are numbered the same and some description is not repeated again. When an excessive liquid pressure is exerted on orifice plate 90 and the relief valve body 37" such as encountered with water hammer rising above a predetermined upstream to downstream pressure differential the relief valve body 37" is moved to the right against the resilient bias of relief valve spring 35 to a position such as indicated in phantom and like body 37 in FIG. 5.

With the anti-water hammer shock wave relief valve 20" of FIGS. 10 and 11 the orifice plate 90 of FIG. 9 is replaced by a thickened orifice plate 90' that supports an adjustable orifice member 91 with through orifice opening 89'. The adjustable orifice member 91 is a cylindrical member seated in truncated transverse cylindrical opening 92 in orifice plate 90' and is provided with an adjustment drive worn screw 93 longitudinally fixed in place in orifice plate opening 94 positioned for adjustment drive engagement with worm gear sector 95 whereby the adjustable orifice member 91 may be adjustably positioned through a range of settings from maximum orifice opening of FIG. 10 to minimum restricted orifice opening of FIG. 11. The adjustment drive worm screw 93 is provided with a tool engagemable head 96 that may be turned for the desired orifice 89' setting before pipe 25 is threaded into end cap 21. If it is desired that the orifice member 91 be adjustable after the valve 20"' is assembled with pipes 25 and 26 then the valve 20"' is modified. This includes a tool engageable head 97 external to valve body 31 drive connected as schematically indicated by drive connection 98 extended from head 97 through valve housing 31 and the inner nose end portion 99 of end cap 21 to the drive end head 96 of adjustment drive worm screw 93. Drive connection 98 is flexible enough to accomodate the valve relief movement of valve body 37"' from the position of FIG. 10 to that of FIG. 11. Other than the orifice opening adjustment for different liquid through flow rates operation of this embodiment is substantially the same as with the embodiment of FIG. 9. It should be noted that the opposite cap ends 21, 22, 21' and 22' of the various embodiments have different size external threads 27 and 28 that conveniently insure that they never are threaded into the wrong ends of valve housing 31. The adjustable orifice member 91 could be spherical instead of cylindrical in shape and the opening 92 surface could be a spherical section instead of cylindrical with the thickened orifice plate 90' being made in two halves for assembly (detail not shown) and fixed in place within through cylindrical opening 100 of valve body 37"' by bonding or by position fixing structure (detail not shown).

The previously described combination liquid flow regulating and anti-water hammer shock wave relief valves 20, 20', 20" and 20"' are suited for use, respectively, with ranges of pipe sizes FIGS. 2-5 one half to five inches, FIGS. 6-8 one half inch to five inches, FIG. 9 one half inch to thirty inches or more, and with respect to the embodiment of FIG. 12 described hereinafter six inches to seventy two inches or more.

The anti-water hammer shock wave relief valve 101 of FIG. 12 is shown to have a valve body 31" into the upstream end of which end cap 21" is threaded 102 and into which inlet pipe 25" is threaded 23" and while broken off at the other end a downstream end cap is threaded into valve body 31" in the manner of valve caps 22 in other embodiments. Housing 31" has an upstream end inner cylindrical chamber 65" within which the head 66" of valve piston 67" of liquid flow regulator valve 68" is a sliding fit. The cylindrical shank 53" of valve piston 67" that is closed at the bottom end by over pressure relief valve 103 is a sliding fit in cylindrical surface 70" of valve body housing internal boss 71" and cylindrical surface 72" of valve ring 104 positioned within internal chamber 105 of valve body housing 31". A plurality of regulator valve springs 106 are resiliently compressed between piston head 66" and housing internal boss 71" with the piston head 66" limited in upstream movement to the left by snap ring 107 inserted in valve housing groove 108 within inner cylindrical chamber 65". A plurality of orifice regulator valve openings 75" are provided in piston cylindrical shank 53" to permit regulated flow of liquid therethrough to chamber 109 of valve body housing 31" and therefrom through openings 110 in valve ring 104 into valve body housing chamber 105. The valve ring 104 is mounted in chamber 105 held in place between shoulder 111 and snap ring 112 inserted in groove 113 within valve housing chamber 105. The liquid pressure overload relief valve 103 is a butterfly type valve with two semi-circular halves 114 and 115 that are resiliently biased toward the closed state by transverse spring 116 that has opposite arms 117 and 118 backing the valve halves 114 and 115 that have outer beveled edges 119 that seat in the closed state in the annular beveled surface 120 of piston end opening 121. A valve mounting rod 122 extends through the loops of transverse spring 116 to opposite end mounting in opposite side ears 123 of piston shank 53".

Operation of the water hammer dampening automatic flow control valve 101 of FIG. 12 is controlled in large measure by the relation between the combined compression rate of regulator valve springs 106 and the resilient resistance to opening of over pressure relief valve 103 exerted by pressure relief valve transverse spring 116. The regulator valve springs 106 are selected to resiliently permit the valve piston 67" to start moving from the zero upstream pressure state shown to the right after the upstream pressure has risen to a point such as to maintain the through liquid flow rate desired with maximum opening through side valve openings 75". As the valve piston 67" moves to the right at a predetermined differential pressure between upstream and downstream pressures relative thereto it may move to a position such as indicated in phantom with through flow cross-sectional area of the side valve openings 75" materially restricted. Thereafter as the upstream pressure is raised to a higher pressure generating an upstream to downstream differential pressure in the order of 55 to 65 p.s.i. such as would occur with shock pressure increase typical of water hammer induced pressures the resilient resistive force of relief valve spring 116 is such as to permit the butterfly relief valve 103 to open.

Whereas this invention has been described with respect to several embodiments thereof, it should be realized that various changes may be made without departure from the essential contributions to the art made by the teachings hereof.

Claims

1. A combination liquid flow regulating and anti-water hammer shock wave relief valve insertable in a liquid flow piping system comprising: a valve housing having open fitting ends; an upstream end cap, and a downstream end cap inserted into opposite ends of said valve housing; first valve means and second valve means mounted within said valve housing; one of said first and second valve means being a liquid flow regulating valve, and the other of said first and second valve means being a predetermined upstream to downstream differential pressure opening valve; and one of said first and second valve means is mounted in the other of said first and second valve means; wherein said predetermined upstream to downstream differential pressure opening valve is a pressure relief valve; resiliently deflectable overload valve spring means mounted in said pressure relief valve with resilient bias force of said overload valve spring means biasing said pressure relief valve toward the closed state and with sufficient upstream to downstream differential pressure, relative to said pressure relief valve, resilient deflection of said overload valve spring means with opening of said pressure relief valve; said liquid flow regulating valve is mounted within said pressure relief valve; said pressure relief valve includes a relief valve body slidably mounted in said valve housing; housing liquid passage means in said valve housing spanning the longitudinal length of said relief valve body; relief valve seat means; and resiliently compressible spring means contained in chamber means between said valve housing and said relief valve body resiliently biasing said relief valve body toward and into seating engagement with said relief valve seat means closing said relief valve from through flow of liquid to said housing liquid passage means and out through said downstream end cap; said relief valve seat means includes a conical surface on the inner end of said upstream end cap; and a conical surface on the upstream end of said relief valve body matching and seatable in said conical surface of said upstream end cap.

2. A combination liquid flow regulating and anti-water hammer shock wave relief valve insertable in a liquid piping system comprising: a valve housing having open fitting ends; an upstream end cap, and a downstream end cap inserted into opposite ends of said valve housing; first valve means and second valve means mounted within said valve housing; one of said first and second valve means being a liquid flow regulating valve, and the other of said first and second valve means being a predetermined upstream to downstream differential pressure opening valve; and one of said first and second valve means is mounted in the other of said first and second valve means; wherein said predetermined upstream to downstream differential pressure opening valve is a pressure relief valve; resiliently deflectable overload valve spring means mounted in said pressure relief valve with resilient bias force of said overload valve spring means biasing said pressure relief valve toward the closed state and with sufficient upstream to downstream differential pressure, relative to said pressure relief valve, resilient deflection of said overload valve spring means with opening of said pressure relief valve; said liquid flow regulating valve is mounted within said pressure relief valve; said pressure relief valve includes a relief valve body slidably mounted in said valve housing; housing liquid passage means in said valve housing spanning the longitudinal length of said relief valve body; relief valve seat means; and resiliently compressible spring means contained in chamber means between said valve housing and said relief valve body resiliently biasing said relief valve body toward and into seating engagement with said relief valve seat means closing said relief valve from through flow of liquid to said housing liquid passage means and out through said downstream end cap; said liquid flow regulating valve includes upstream to downstream liquid flow through orifice means; wherein said liquid flow regulating valve includes valve piston means slidably mounted in a through opening extended from the upstream end to the downstream end of said relief valve body; said valve piston having a piston head and a reduced diameter cylindrical shank; valve means mounted in said through opening; position restraining means holding said valve ring means longitudinally in place in said through opening; liquid through flow means through said valve ring means; regulator valve spring means resiliently compressed between piston head and said valve ring means resiliently biasing said valve piston in the upstream direction to an upstream limit position in said relief valve body against piston travel limit means mounted in said relief valve body; and said through flow orifice means is orifice opening means through the wall of said reduced diameter cylindrical shank positioned to clear an inner ring position of said valve ring when said valve piston is in its upstream limit position and when the piston is moved in the downstream direction against the resilient bias of said regulator valve spring means said orifice opening means is increasingly restricted in through flow area by said inner ring position of said ring as said reduced diameter cylindrical shank is slid through said inner ring portion in the downstream direction for liquid flow regulation through the orifice opening means to a spring chamber and on through said liquid through flow means through said valve ring means and on out through said downstream end cap.

3. The combination liquid flow regulating and anti-water hammer shock wave relief valve of claim 2, wherein said orifice opening means includes at least one opening in the form of a "T" with the head of the "T" shape in the downstream direction.

4. The combination liquid flow regulating and anti-water hammer shock relief valve of claim 2, wherein said orifice opening means includes a plurality of openings spaced around the circumference of said reduced diameter cylindrical shank of said piston.

5. The combination liquid flow regulating and anti-water hammer shock relief valve of claim 2, wherein said regulator valve spring means and said overload valve spring means are preselected to present such resilient compressive bias that said regulator valve spring means is resiliently compressed through the longitudinal downstream movement of said piston through a range of upstream to downstream differential pressures before the differential rises to a level such as to move said relief valve body against the resilient bias of said overload valve spring means in opening said overload pressure relief valve.