US2837308A

US2837308A - Fluid control valves

Info

Publication number: US2837308A
Application number: US513558A
Authority: US
Inventors: Shand Stanley Grapes
Original assignee: Saunders Valve Co Ltd
Current assignee: Crane Process Flow Technologies Ltd
Priority date: 1955-06-06
Filing date: 1955-06-06
Publication date: 1958-06-03
Anticipated expiration: 1975-06-03

Description

June 3, 1958 s. G. SHAND 2,837,308

FLUID CONTROL VALVES I Filed June 16, 1955 by @WM ATTORNEY FLUID CONTROL VALVES Stanley Grapes Shand, Hereford, England, assignor to flaunders Valve Company England, a British company Application June 6, 1955, Serial No. 513,558

Claims. (Cl. 251-474) This invention relates to fluid control valves such as plug cocks of the kind having the joint between the obturating member and the body of the valve made by means of at least one seating ring supported against the obturating member by a flexible diaphragm sealed to the obturating member and sealed at its periphery within the body and exposed on its outer surface to fluid pressure, pressure of the seating ring upon the obturating member being maintained in the absence of fluid pressure by spring means. I

In the specification of Patent No. 2,520,288 a plug cock oi the above kind is disclosed in which the plug, conveniently of spherical form, rotates between seatings which are separate from the cock casing and free to rock a little about the axis of the plug.

A development is disclosed in the specification of my application Ser. No. 73,238 filed January 28, 1949 now Patent No. 2,751,185 in which to enable a diaphragm of convenient size to be used without excessive fluid pressure acting on the seatings an annular abutment surface is provided rigid with and extending inwardly from the internal surface of the valve body and of such Limtied, Monmonthshire,

States Pater radial width that its internal diameter is less than the ex- 7 ternal diameter of the seating ring, this abutment surface ICE pressure will overcome the spring pressure and force its way between the diaphragm and the ring, thereby escaping to the low pressure side of the valve.'

It will be seen that the relief of pressure does not involve discharge of liquid outside the valve and the line, a point of some importance where highly inflammable fluids such as petrol are being controlled. It will be understood that the line itself must permit pressure relief on one side of the valve but usually the line on one side of the valve is open to the atmosphere at some point or at any rate is only under low pressure. If necessary, it could be provided with a safety valve discharging at a point where provision can be made to avoid'danger.

The cock may desirably be constructed on the lines of Patent No. 2,751,185, in which case the fluid pressure has access to the plug side of the ring by a counter-borein the ring which is of greater diameter than the internal diameter of the abutment against which the outer part of the flexible diaphragm is pressed by the fluid pressure..

An embodiment of the present invention is illustrated by way of example in the accompanying drawing, which.

is an axial section.

phragm is effective to press them towards the plug. The

effective diameter over which the fluid has access to the-- back of the diaphragm is the internal diameter of the: washer 15 and has been marked B in the drawing. The

fluid pressure also has access between the rings 13 and the plug 12 by way of a counter-bore indicated at 16 in the rings. The effective diameter of the counter-bore has been marked A in the drawing and in the construction according to the present invention diameter A is greater than diameter B, so that the net effect of the fluid pressure acting along is to lift the rings 13 away from the plug 12. To maintain sealing contact springs 17- are used and 1 since larger spring pressures are necessary than in conto make the counter-bore of such diameter as to reduce the effective fluid pressure to zero.

Where plug cocks of this kind are used in lines in which very high pressures are likely to be developed, for example fuel lines on aircraft where very large temperature changes are encountered, it has been found necessary to provide means for allowing excessive pressures to be released to avoid damage to components, joints, piping etc. According to the present invention, in a plug cock of the kind above set forth the fluid pressure also has access to the plug tide of the ring over an area greater than the area over which the pressure is effective on the back of the diaphragm to press the ring towards the plug so that the net effect of fluid pressure is to lift the ring away from the plug and the necessary seating pressure is struction disclosed in my Patent No. 2,751,185 afore said, it is convenient to provide a series of helical compression springs arranged in circular formation, these springs being located in pockets 18 in metal ring members 19, each having a tubular extension 21 centered in the diaphragm 14 and seating ring 13. Desirably the inner margin of the diaphragm is of dove-tail section on the ring side as at 22 so thatthe material is under volume compression thus ensuring a good fluid-tight joint between "the diaphragm 14 and ring 13. A similar section as at 23 may be used to clamp the outer margin of the diaphragm between the inwardly extending washer 15 and the end fitting 24 by which connection is made to the "14 and if after excess pressure on the high pressure side provided bysprings strong enough to'ensure a good plug side of the diaphragm over an adequate area, the

has been relieved as above described into the body space, thepressure in the body space builds up to a high value, the fluidwill press the diaphragm 14 on the low pressure side back against the action of the springs 17, the tubular extension 21 being a sliding fit in the ring 13 for this purpose. The liquid in the body space escapes between the diaphragm 14 and the ring 13 and between the ring 13 and the tubular extension 21 into the low pressure side of the line, thus relieving the pressure in the body space. The necessary volume of fluid which has to escape to relieve the pressure is quite small espe- Patented June 3, 1958- outside at the location of the valve. -The low pressure linezmust' be: open to the atmosphere at some point or at any rate provided with some means to limit the maximum pressure. If need be it can be provided with a safety valve at a point where discharge can be allowed without danger.

The invention has been described in its application to a plug cock of symmetrical construction with the passagestraight through its body and a spherical ducted plug but it will be understood that the invention is not limited tolsuch an. arrangementand'is applicable to fluid control through, a ducted obturating member movable within the bodybetweena position in which-the passage is obturatcd: and a position in which the duct therein aligns with. the passage, at least one seating ring surrounding the". passage at the high pressure side thereof and coacting with saidobturatin'g member, a flexible diaphragm sealed to the body and to the seatingring, thefluid pressure; in the passage at the location of the ring having access to the back of the diaphragm and also'to aportion of the; surfacezofi the ring fa'cing the obturating member, theeifective area: at the backof the diaphragm to which thefluid pressure-rhas accessbeing less than-the area of ther portionof thetsurface of the ring facinglthe obturat ing member to which the fluid pressure has access so that:the.-net etfect of the fiuid'pressure is'in a direction to lift:the;ring away from -the obturatingmember, and spring means urging'the ring: against the obturatingmember with a.v force; adequate'to, provide a good seal'b'etween;

the ringzandthe obturatingmember'when the fluid pressureisnot above a determined value correspondingto normal operating: conditions;

2. A plugcockcomprising a body having a passage therethrough, a; ducted plug rotatablein said body between' the position in which: it obturates the passageand thepositioninwhich the'duct in: the plug aligns'with the passage,:. at leastaone seating: ring surrounding the passager atlthelhigh pressure side thereof and having an' annulus :irncontact withssaid plug, a flexible diaphragm sealed tothebody and to'the: seating ring, the fluid pressure inthepassage at=thelocation of the ring having access to the back of the diaphragm and also to aportion ofthe surfaceof thesringr on the plug side of the ring, the effective area of "the back of the diaphragm to which the fluid pressure has access being less than the area on theportion oftheplugiside of the ring to which the fluid. pressure'hasa access so that the net effect of the fluid pressure. isin-a direction to lift the ring away from the plug,; and springmeans urgingrthe ring towards the plug-with a force adequate to provide a good'seal between the:- ring and the plug whenthe fluid pressure is notabove adetermined value corresponding tonormal operating conditions.

3. A plug cock asset forth in claim 2' comprising two 4 sealing rings respectively cooperating with the plug at opposite ends of the duct therein, the diaphragms and rings being separate members the seal between which is effected solely by pressure of the one against the other and any fluid which leaks into the body having access to the plug side of the diaphragm so that if the fluid pressure in the body rises above a predetermined value it forces back the diaphragm sealing the ring on the low pressure side and escapes between the diaphragm and the ring from the body space into the passage on the low pressure side.

4. A plug cock as set forth in claim 2 including an annular abutment rigid with the body located at the plug side of the diaphragm against which the diaphragm bears when the ring is against the plug, the internal diameter of the abutment being less than the internal diameter of the annulus of contact between the ring and the plug.

5. A plug cock as" set forth" in' claim 2 including a sealing' ring surrounding the: passage in the'body at each end of the du'ct'in the plug, an annular abutment rigid with the body locatedonv the plug side of each diaphragm against which the diaphragm bears when the ring is against the plug,'.the diaphragms and rings being separate members the seal between which is effected solely by thepressure of the one against the other, the internal diameter of the abutment" beingless than the internal diameter of the annulus of contact between the ring-and the plug, and the externaldiameter of the part of the ring extendingthrough the abutment being of smaller diameter than the internal diameter of any abutment so that the fluid" leakinginto'the body between the rings has access to the plug side of-thei diaphragm and if its value rises sufliciently can-force its way between the'diaphragm and-ring on the low pressure side.

6'. A plug cock" asset forth in claim 5 in which the passage throughthe body is straight and the plug is spherical, the two'ring, diaphragm and abutment assemblies being'symmetrically dimensioned and disposed.

7. A- plug-cock-as set forth inclaim 6in which the spring means comprises a} series of helical springs arranged in circular formation around the passage;

8: A plugcock as set forthinclaiml7 also comprising a ringmember carried' by each sealing ring and diaphragm, said ring member having pockets in which said springs are housed.

9; A --plug cock asset forth in'claim 8 in which the inneremargin of the diaphragm is'of dove-tail sectionand is clamped to the-sealing ring by the pressure of the springsi'acting tlirough said ring member.

10'. AL plug cocl as -set"forth in claim 12 including a main body portion and a separable endfitting, and a rigid annular-abutment held between said main body portion and end fittingand located on the plug side of the diaphragmagainstwhich the diaphragm bears when the ringis against the plug, the internal diameter of the abutment being less than the internal diameter of the annulus of contact between the ring and the plug, the outside marginof the diaphragmbeingof dove-tail section" and being clamped between said end fitting'and said abutment.

Refrences fiitedzin the 'flle of this patent FOREIGN PATENTS 655,077 Great Britain July 11, 1951 655,078 Great Britain July 11, 1951 1,094,708" France Dec. 8, 1954