US3027912A - Actuating means for pressure responsive vessels - Google Patents

Description

April 3, 1962 E. w. CARR ETAL 3,027,912

ACTUATING MEANS FOR PRESSURE RESPONSIVE VESSELS Filed Sept. 30, 1959 2 Sheets-Sheet 1 jizz/ezz rs. ward Ck;

April 3, 1962 E. w. CARR ETAL 3,027,912

ACTUATING MEANS F OR PRESSURE RESPONSIVE VESSELS Filed Sept. 30, 1959 2 Sheets-Sheet 2 ilnited States Patent 3,027,912 ACTUATHNG MEANS FOR PRESSURE RESPONSIVE VESSELS Edward W. Carr, Cicero, and Raymond P. Setka, Chicago, Ill, assignors to Crane (30., Chicago, Ill., a corporation of Illinois Filed Sept. 30, 1959, Ser. No. 843,393 4 Claims. (Cl. 137-478) This invention relates generally to improvements in a pop safety valve and actuating means therefor. More particularly, it is concerned with the type of valve construction and actuating means lending itself to a performance in which a desirable high discharge capacity is accomplished. In this connection, it should be realized that boiler capacities are steadily increasing and safety valves should keep pace with such increase.

Heretofore, one of the weaknesses present in valves for this type of service, particularly Where such fluids as air or gases are involved which are expansible in character is that varying lengths of connected outlet piping will create varying back pressures tending to prematurely reseat valve disc resulting in fluttering and/ or chattering.

it is, therefore, an important object of this invention to provide for a baffle construction in which the discharge area past the baffle is deliberately sized so as to be less than the outlet piping transverse area. Thus, a deliberate but predefined back pressure condition is created which acts against a piston type disc imparting added lifting effort. At the same time, reasonable lengths of outlet piping are permitted to be applied as long as the latter is predetermined not to provide a reduction in pressure greater than the pressure drop induced by the restricted bafl le flow area.

Another object is to provide for an eflicient, fast accelerating actuating means of relatively low cost in which the side disposed lifting lever is independent of the pressure setting of the valve.

Another object is to provide for a valve in which an adjusting cap locks the adjusting screw as a locknut, while at the same time conveniently provides for a pressure-tight seal at the threads and holding simultaneously a suitable identification plate securely in position. In this connection, the previous means employed required the drilling of holes which ultimately became a source of leakage and therefore involved operational difliculties and added expense.

A further important object is to provide in a valve of this type for a unique spring design to eliminate the previous need for spacers and also reduce the travel of the adjusting screw for handling low to high settings of a spring-load range.

Other objects and advantages will become more readily apparent upon proceeding with the drawing, in which FIG. 1 shows a sectional assembly view of a preferred embodiment of our invention in a pop-safety valve construction;

FIG. 2 is a sectional view taken on the line 22 of FIG. 1;

FIG. 3 is a transverse sectional view taken on the line 33 of FIG. 1 with the valve in closed position; and

FIG. 4 is a view similar to that described in connection with FIG. 3, but with the valve in the open position.

Referring to FIG. 1, the valve casing generally designated 1 is of angular form as illustrated and is provided with the usual inlet 2 for attachment to a pressure vessel and a discharge outlet chamber 3. The inlet has suitable threads at 4 for attachment to a pressure vessel such as a boiler at 2, and the threads 5 provide a discharge connection either to atmosphere or point of safe disposal. The valve inlet 2 is preferably made with the venturi form illustrated at 6 and has the elongated tub- "ice ular body seat ring generally designated 7 with its threads 8 engaging similar threads in the body and preferably shouldering firmly at 9 in the fully assembled position within the valve. At its upper end, the seat ring 7 is provided on its outer periphery with the threads 11 receiving the lower regulating ring 12 with its outer serrated portion 13, as indicated. Preferably at its upper limit, the said regulating ring on the outer annular portion is of frusto-conical form, as indicated at 14, and on its inner periphery, similarly, as indicated at 15, it is oppositely tapered in frusto-conical arrangement to intercept and form the annular relatively sharp apex 16. The valve closure member 18 seats upon the annular surface 10 of the body seat ring 7.

It should be noted that when the valve closure 18 is in the seated position shown, contacting at 10, the lower regulating ring 12 is then rotated on the threads 11, thereby to move the sharp crown 16 just in contact with the annular undersurface 30. Thus, the light contact is then broken by backing off the ring 12 a notch or two so that it is thus assured that the sharp annular edge 16 will not interfere with the proper seating of the valve at 10. The annular clearance between edge 16 and the surface 30 of the valve closure member 18 is thus intentionally made very small, for reasons that will hereinafter become apparent. The said annular contact of the closure member 18 with the seat ring surface 10 allows for the seating faces to be lapped by machine to extreme smoothness independent of and prior to assembly in valve, also permits renewing in the field which can be done without separating the valve body from its inlet and outlet attachments to respective pipe lines.

As indicated in the dotted lines, a suitable locking screw 17 extending transversely through the casing wall engages the serrated portion 13 thereby to lock the regulating ring 12 against rotation in the desired axial position when the closure member is seated as shown and as above qualified. The valve closure member is relatively closely received within the combined upper regulating ring and guide member 19, the latter member being serrated at 20 for locking adjustment and threadedly attached as at 21 to a fixed baffle 22 of generally annular configuration and integral with the casing 1. It will, of course, be appreciated that the closure member clearance within the guide surface 23 is of such dimensions as to eliminate any tendency for undue canting of the closure member to occur in the course of its reciprocal movement, While at the same time, allowing for smooth closure member movement in the course of such reciprocation in response to predetermined fluid pressures encountered within the inlet 2.

The upper end portion of the closure member 18 is preferably annularly flanged at 24 and at the underside thereof is provided with an annular surface 25. The latter surface predeterminately is engaged by the surface 26 which is of U-form when viewed in plan. It is an integral part of the actuating lever generally designated 27. The said actuating lever at an inner end portion thereof is journally mounted at 28 within the casing and at the outer end thereof is journaled within the bushing 2? as indicated at the inner surface 31, Thus to effect such surface engagernent by the surface 25 with the surface 26 and manually lift the valve closure member 18 from its seat contact at iii, the actuating lever bearings at 28 and 31 are predeterminately rotated by suitably actuating an angularly disposed handle 32 pinned at 33 to the shaft portion thereof 34. Such actuation of the handle 32 will cause the U-portion to be tipped upwardly to thereby cause the surface 26 at the lower portion of the U to abut the annular surface 25 and manually lift the valve closure member 18. The lifting handle 32 will swing approximately 30 to lift the closure member and is not affected 3 by different settings of the adjusting screw 47 as in conventional valves. Thus, the lifting lever is independent of adjustment and is installed at the initial assembly.

In further considering the details of the novel operation of the valve actuating means embodied in the U- shaped handle, attention is now directed to FIGS. 2, 3, and 4, and more particularly to FIG. 4, in which it will be apparent that the U-shaped actuating lever 27 is defined by the portions 57 and the curved area 58 being journalled at 31 in the threaded bushing 29 and in the casing at 28. Upon its rotation in said journalled portions, it will have its upper oppositely disposed corners defined at 61 contact the undersurface 25 of the rim or flange 24 of the closure member and such movement upwardly will occur until the lever stop at 59 shoulders in the casing as indicated in FIG. 4 immediately above the threaded portion 21 for receiving the adjusting ring 19. At the inner or open ends 61 of the U-shaped portion defined by the curved surface 58, as stated, the lever makes contact with the undersurface 25 of the rim 24 upon suitable pivotal movement of the lever 27 to ultimately lift the closure member 18 and open the valve.

The closure member 18 guided on its outer periphery by said ring 19 is guided also by the stem movable within the central threaded member 48, the stem being attached at 60 to the said closure member.

To hold the lever or handle 27 against endwise movement, the outer end limits of the U-shaped actuating lever are provided with the end thrust surfaces 62 oppositely disposed as indicated more clearly in FIG. 2. It will be noted, as also shown in the latter figure, that the journalling portion for the shaft 34 as at 31 and 28 are offset with respect to the vertical axis of the valve to allow for the desired thrust by the surface 61 against the surface 25 in opening the valve as previously described, thus accounting for the advantages in actuation of the closure member at a central annular portion as set forth previously. In summary, such benefits are that a substantial mechanical advantage is provided to overcome the load of the spring 42 and without the necessity for having high fluid pressure beneath the closure member 18 to assist in such unseating. Further, application of the oppositely disposed contact surfaces 61, 61 against the annular surface 25 provides for a straight upward lifting force at the central axis of the valve closure member.

As indicated, the closure member is open on its upper end portion to provide the chamber 35, the lower limits of the latter being defined by the integral button 36. It is preferably tapered annularly at 37 to receive and center the similarly tapered lower portion 38 of the spring washer 39, annularly recessed to receive and support as at 41 the coil spring 42. The latter member is provided at it upper end limit with the upper spring washer $3 similarly recessed annularly at 44 for receiving the upper end portion of the spring 42. At its upper annular extension 45, the casing is provided with a threaded cap generally designated 46, having the central threaded portion 48 for receiving the spring adjustment screw 47. The cap 49 internally threaded engages the threads 48 thereby to lock the spring adjusting screw 47 in position. At the upper end portion, the screw 47 may be suitably slotted transversely as at 51 to allow for rotatable adjustment of the adjusting screw 47 upon removal of the closing cap 49. The outer portion of the cap 49 is preferably of polygonal form at 52 to receive a sealing washer 53 superposed over a suitable name plate as shown. Thus, an adjusting screw locknut is eliminated as the cap 49 seals the screw 47 and acts as a locknut as well. This arrangement further guards against tampering by reason of the use of sealing wires at 54 connected to the conventional seal element 55. The sealing wires have preferably continuous engagement with the threaded locking screw 56 engaging the serrated portion 20 of the adjusting guide 19 to hold the latter securely against rotation in the course of service. Thus, the entire locking mechanism, such as the members 17, 56, and 53, are continuously held in place by a simple sealing means, thereby to avoid tampering in the field.

As previously mentioned in connection with the sharp annular edge 16 in relation to the closure surface 30, the overall effect is to permit the establishment of an annular huddling chamber 4-0 which aids materially in effecting the desired high lift of the valve with resultant large discharge capacity by the valve. The construction provides an impulse factor which is apparently responsible for such desirable high valve lift being obtained. While an accurate calculation of this force has not been determined, test results show that when coupled with high lift readings and calculated spring loads the impulse force actually does exist. It has also been found that compensation for this additional force may take place by increasing the area between the lower popping ring or adjusting ring member 12 and the upper regulating ring 19 to bring about satisfactory blow-down in the operation of the valve in compliance with the Power Test Code of the American Society of Mechanical Engineers.

As inferred previously, the type of seating construction between the closure member 18 and the seat ring 7 permits of a lapping of the seat faces easily by a simple machining operation to accomplish desirable smoothness in the facing. When installed in a valve, the overall resuit is a valve having tightness at very near the set pressure. This is a vast improvement over prior hand lapped relief or safety valves requiring an oil seal in many cases to obtain the same results.

It has also been found that by making the annular baffie 22 integral with the casing, there is such strength and rigidity as to eliminate the usual leakage at the body joints arising from vibration or pipe strain. It also eliminates transmission of distortion of the joint to the valve seat, which obviously could cause objectionable valve leakage.

It will further be appreciated that in using the form of lower regulating ring, as exemplified at 12, there is thus created means for effecting the initial low lift to the valve disc. Concurrently therewith, the flow of fluid discharging therepast has been found to exert an additional lifting force to the disc due to the restraining effect exercised by the upper regulating ring which thereby produces a secondary pressure. It has been found that the fluid flow is approximately of the theoretical maximum flowing through an orifice to atmosphere, and to handle such large flow, it is necessary to have the valve discharge outlet two sizes larger than the inlet, as, for example, one and one quarter inches (1%) as against two inches (2"). It is also desirable to provide a baffle at the outlet which provides for a valve discharge passage less than the area of the pipe used. It will also be understood that the use of integral baflie makes the valve setting and its operation consistently uniform and independent of the piping employed in the outlet.

In obtaining a better understanding of the performance of the valve of this design, it should be appreciated that valves in their compliance with the prescribed code of the American Society of Mechanical Engineers previously mentioned must also comply with blow-down requirements thereof which are 4% for steam and 5% for air service. Since the discharging fluid impinges directly under the disc, it thereby imparts an impulse factor which is desirable because it has been found to aid materially in lifting the disc or closure member and also hold it up predeterminately to prevent premature reseating.

To compensate for this additional lift, it has been necessary in the past to enlarge the flow area between the upper regulating ring and the adjusting or popping ring 12, which thereby reduced the effective fluid pressure below the closure member and thereby diminished the impulse force correspondingly. In this invention,

the valve design assures of a proper balance of pressure under the closure member controlled by the regulating ring and the impulse generated by the flow results in the desired blow-down to meet flow requirements.

While only a single embodiment has been illustrated and described, it will be appreciated that this is only for purpose of illustration and in no sense should be understood to limit the scope of the invention as expressed by the appended claims.

We claim:

1. In actuating means for a safety valve, the combination of a body with an inlet and outlet and a movable closure member therefor normally seated between said inlet and outlet having an upper annular outwardly projecting portion thereon, the said actuating means including a transversely extending pivotally movable lever, the lever having a substantially U-shaped portion when viewed in plan for engagement of oppositely disposed outer ends of the said U-portion with the said annular outwardly projecting portion of the said closure member, means for pivotally moving the said lever at one end portion thereof, the pivotal axis of rotation of said lever being in a vertical plane removed from the central axis of the said body whereby upon predetermined pivotal movement of the lever another end portion of said lever in a lower plane thereof relative to the first named end of the lever and remote from said pivotal axis of rotation contacts a shoulder portion of the said body and an opposite end portion thereof in an upper plane relative to said'last named end portion contacts an undersurface of the said annular outwardly projecting portion of the said closure member to unseat the latter member in said body.

2. In an actuating mechanism for a pressure actuated valve, the combination of a body with an inlet and outlet, and a reciprocally movable closure member therefor normally seated between said inlet and outlet and having an upper flanged rim portion, the said actuating mechanism including a transversely extending pivotally movable lever journalled in oppositely disposed portions of the said body, means for moving said pivotally movable lever, the lever having a U-shaped portion when viewed in plan for engagement of oppositely disposed outer ends forming the side disposed opening of the said U-portion, said latter engagement being with an annular undersurface of the said flanged rim of the closure member at approximately the central axis of the valve, the body having an inner shoulder with an upper surface thereon serving as a stop to receive an opposite end of the lever adjoining the end of the U-shaped portion of the lever in a plane below the plane of the axis of rotation of the said pivotally movable lever upon predetermined pivotal movement of the said lever.

3. In an actuating mechanism for a safety valve or the like, the combination of a body chamber with an inlet and outlet and a reciprocally movable closure member therefor having an upper outwardly projecting rim, the said actuating mechanism including a transversely extending pivotally movable lever journalled in opposite wall portions of the said body chamber, the lever having a U-shaped portion when viewed in plan for cooperation by the inner opposed ends of the U-portion with a reduced neck portion immediately below the said outwardly projecting rim of the closure member, the said inner opposed ends of the U-portion being defined by transverse shoulders for locating the said lever axially with relation to an undersurface defining the lower limits of the projecting rim of said closure member, the pivotal axis of the lever being disposed off-center relative to the central axis of the body chamber whereby to provide for an outer end limit of the lever adjacent the U-portion to bear against a radially disposed shoulder surface portion in the body chamber and whereby said inner ends of the U-portion bear against said undersurface of the projecting rim of the said closure member at substantially the central axis of the valve when the pivotal lever is predeterminately moved in lifting the closure member.

4. In an actuating mechanism for a pressure actuated valve or the like, the combination of a body with an inlet and outlet and a reciprocally movable closure member therefor having an annular outer rim portion at its upper limits and an annular reduced portion for substantially its remaining height below said rim portion, the actuating mechanism including a transversely extending pivotally movable lever having a U-shaped recess for receiving said annular reduced portion of the closure member immediately below the said outer rim portion of the closure member, an outer limit of the lever substantially defined by the U-shaped recess contacting an inner shoulder in the body to serve as a stop therefor and opposite ends of the U-recess having upper substantially corner surfaces in the plane of the vertical axis of the valve closure member for contacting opposite sides of undersurfaces defining lower limits of the said rim portion upon predetermined pivotal movement of the lever, the latter member substantially at the end portion thereof making said contact with the closure member rim.

References Cited in the file of this patent UNITED STATES PATENTS 287,131 Iarecki Oct. 23, 1883 374,750 Orme Dec. 13, 1887 498,803 Lunken June 6, 1893 524,208 Kunkle Aug. 7, 1894 525,963 McNeil Sept. 11, 1894 1,685,866 Raymond Oct. 2, 1928 1,696,452 Raymond Dec. 25, 1928 1,743,430 'Coffin Jan. 14, 1930 2,035,129 Hopkins Mar. 24, 1936 2,592,673 Folmsbee Apr. 15, 1952 FOREIGN PATENTS 23,500 Great Britain of 1892 255,223 Great Britain July 22, 1926 1,159,335 France Feb. 10, 1958 499.241 Italy Nov. 10, 1959

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