CA1237630A - Safety relief valve - Google Patents
Safety relief valveInfo
- Publication number
- CA1237630A CA1237630A CA000461669A CA461669A CA1237630A CA 1237630 A CA1237630 A CA 1237630A CA 000461669 A CA000461669 A CA 000461669A CA 461669 A CA461669 A CA 461669A CA 1237630 A CA1237630 A CA 1237630A
- Authority
- CA
- Canada
- Prior art keywords
- disc
- safety relief
- relief valve
- seat
- orifice
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000007788 liquid Substances 0.000 claims abstract description 21
- 230000000694 effects Effects 0.000 claims description 4
- 241000169624 Casearia sylvestris Species 0.000 claims description 3
- 239000012530 fluid Substances 0.000 abstract description 9
- 238000010276 construction Methods 0.000 description 7
- 241000282320 Panthera leo Species 0.000 description 1
- 210000003423 ankle Anatomy 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000013022 venting Methods 0.000 description 1
Landscapes
- Safety Valves (AREA)
Abstract
SAFETY RELIEF VALVE
Abstract of the Disclosure A safety relief valve for relief of overpressure in an incompressible liquid having a displaceable disc cooperating with an annular valve seat for opening and closing the valve to fluid flow. Included is a cylindrical orifice defined in the flow passage coaxially surrounding the valve seat immediately downstream of the seat and in series flow relation thereto. The orifice is of controlled size and length able to substantially maintain the overpressure value of liquid flow exposed to said disc in the disc area immediately beyond the valve seat to significantly increase disc lift after only initial disc lift occurs.
Abstract of the Disclosure A safety relief valve for relief of overpressure in an incompressible liquid having a displaceable disc cooperating with an annular valve seat for opening and closing the valve to fluid flow. Included is a cylindrical orifice defined in the flow passage coaxially surrounding the valve seat immediately downstream of the seat and in series flow relation thereto. The orifice is of controlled size and length able to substantially maintain the overpressure value of liquid flow exposed to said disc in the disc area immediately beyond the valve seat to significantly increase disc lift after only initial disc lift occurs.
Description
I
SAFETY RELIEF VILLAGE
Technical Field The field of art to which the invention pertains come proses the art of fluid handling as applies to relief of overpricer from incompressible liquids.
Background of the Invention _ Safety relief valves are widely used with incompressible liquids in the relief of o~erpressure by venting controlled quantities of fluid flow from the system. In a conventional construction, such valves utilize a displaceable disc that is spring biased against a nozzle seat for normally maintaining the valve closed to fluid flow. The spring force imposed against the disc is adjustable preset for the "set pressure"
at which the disc is to "lift" for relief of an overpricer encountered in the system being monitored. Typically, the disc or its associated structure includes an excess of surface area over that -to which it is exposed when seated that functions to enhance the lift force imposed against the disc after initial disc lift has occurred. While this excess surface area effectively aids in liftoff, it also has a drawback in that it tends at the same time to impose a negative effect on "slowdown"/ i, e., to delay closing of the valve at a pressure Rowley of the relieved liquid increasingly below set pressure.
As a consequence of the foregoing ! the quantity of excess surface area about the disc has generally represented a come promise such that for liquid service, full lift of the disc for maximum flow does-not normally occur until the o~erpressure ~3~7~3~
value of the fluid reaches approximately 15 percent above set pressure. During the interim, however, particularly when over-pressures approximately correspond to set pressure, the disc incurs only a marginal degree of lift at which there is a tendency of the valve to become dynamically unstable. An aspect of the instability is a phenomena known as "chatter" which is characterized by repeated contact between the disc and valve seat that imposes a destructive force on one or both. Chatter is obviously undesirable, and an approach for overcoming its effect in such valves is disclosed in prior US. patent 4,130,130.
This invention relates to safety relief valves operable with incompressible fluids for relief of overpricer.
More specifically, the invention relates to an improved con-struction for such valves able to substantially if not come pletely eliminate the chatter problem previously associated with such valves, while enabling slowdown to be continually obtained within acceptable operating limits.
The safety relief valve of the present invention includes a body defining a liquid passage between an inlet and an outlet axially offset from each other with an annular seat surrounding the passage at an intermediate location thereof.
A disc is movable from between an urged first position engaging the seat to prevent liquid therapist toward a second position removed from the seat to permit liquid flow to the outlet in response to a liquid overpricer encountered against the disc.
Means defines a sectionally elongated orifice in the flow passage adjacent to the valve seat in downstream series flow relation therewith. The orifice is of substantially uniform cross-sectional dimension and sized to substantially maintain the liquid pressure flow exposed to the disc at a crack open lift condition of the disc to at least be on the valve seating area of the disc.
It is therefore an object of the invention to provide an improved construction for a safety relief valve able to substantially if not completely eliminate the chatter mob/
~.~3t763~D
problem previously associated with the prior art construction in the relief of overpricer with incompressible fluids.
It is a further object of the invention to effect the previous object in an effective yet inexpensive manner as to resolve a long standing problem associated with such valves.
- pa -mob I
Brief Description of the Drawings Fig. 1 is a sectional elevation of a safety relief valve of a type incorporating the inventive improvement hereof;
Fig. 2 is an enlargement of the encircled portion 2, 3 of Fig. l;
'it. 3 is an alternate embodiment of the encircled port lion 2, 3 of Fig l; and Fig. 4 is a graphical representation of the valve char-acteristics hereof as compared to valve characteristics of the prior art.
Referring now to Fig. 1, the valve thereof is of a basic type as disclosed, for example, in US. patent 3,520,326 as modified to incorporate the instant invention.
Briefly, the valve is comprised of a bonnet 10 supported on a base 12 that includes a bottom inlet passage 14 and a gasket seal 16. The inlet communicates with an internal flow passage 18 leading to a discharge outlet 20. Threads 22 and 24 at the outlet and inlet, respectively, permit mounting the valve in the system with which it is to be employed, it being understood that the valve is generally mounted upright with the axis of passage 14 in a vertical orientation At the downstream end of passage 14 there is provided a terminal end section defining a primary orifice I about which is formed an annular planar extending valve seat 28.
Cooperating with valve seat 28 in a normally closed relation as to prevent liquid flow therapist is a displaceable disc 30 having an annular seat 32 formed in its undersurface generally coextensive with valve seat 28. Integral of disc 30 on its topside is a shank 34 extending within a cylindrical disc holder 36 and secured thereto via a retainer ring 38. The disc holder in turn is slide ably contained within cylindrical disc guide I secured to bonnet 10 my means of a cross pin 42.
For imposing a closing force against disc 30 there is provided a coaxial spindle or stem 44 extending centrally upwardly from within shank 34 and urged in a downward direction by a reloaded coil spring 46 contained between spring washers 38 and 50. The degree of spring force imposed on disc 30 for presetting the valve set pressure is effected by means of an adjustment screw 52. By this arrangement, 3~3~
therefore, pressure of the incompressible fluid contained in inlet 14 acts upward against the exposed area on the under-side of disc 30 until fluid pressure exceeds the set pressure setting. At that point, disc 30 is Cossack to begin movement upward and away from nozzle seat I
pro better understand achievement of chatter prevention in accordance with the invention, reference is now made to additional Figs. 2 and 4. Shown in Fig. 2 for that purpose is a cylindrical orifice I coccal located with respect to inlet I The orifice is of restricted radial dimension A and axial length B defined in this embodiment between the outside diameter of adjusting ring 56 and the internal diameter of an overlapping skirt 58. The skirt is integrally a part of disc holder 36 and terminates at its lower end with an angle of about 35 degrees. By virtue of the relatively narrow flow passage afforded through orifice 54, the liquid pressure thereat being imposed against disc 30 beyond seat 32 is substantially maintained. This in turn enables a lift force to be generated on the underside of disc 30 radially beyond seat I to lift the disc a distance above seat 28 at which chatter would otherwise occur. Orifice length B afforded by skirt 58 continues to be effective in this manner until after length B has been exceeded by con-tinting lift. At such time greater liquid pressure is avail-able for forcing the disc toward its full lift position.
The foregoing can be appreciated by reference to Fig. 4 in which curve A represents the operating characteristics of a conventional similar type valve of the prior art, curve B
represents the operating characteristics of a valve as disk closed in US. patent 4 r 130,130, and phantom line 3 repro-sets the operating characteristics in accordance herewith It can he noted specifically, as represented my curve C, that approximately 35 percent lift is achieved by the construction of the instant invention with even a minimum flow representing the incipient or cracked open position of valve disc 30 at the onset of overpricer relief.
Dimensions A and B can, of course, be varied to suit the specific operating characteristics sought to be achieved.
A represented in the embodiment of Fig. 2, length B can be ~Z3~3~
threadedly adjusted by axial positioning of adjusting ring 56.
In a preferred embodiment, a mean value for dimension A of about 0c012 inches has been found suitable, while a mean length for dimension B of approximately 9.5 percent ox the nozzle bore diameter 26 measured with disc 30 in the closed position has been found suitable. In this manner, the cross sectional area of dimension A is proportional to the outside diameter of the adjusting ring, while length is proportional to the throat diameter of the nozzle. Ankle a further aids in liftoff after dimension B has been conned As shown by the alternative embodiment of jig. 3, adjusting ring 56 is of reduced dimension, and the annular orifice 54 is defined directly between the outside diameter of the base 12 and the inside diameter of the skirt 58.
By the above description there is disclosed novel apparatus for a safety relief valve able to completely eliminate or substantially eliminate the chatter problem previously associated with such valves. The construction is relatively simple and inexpensive to implement and yet is able to achieve a solution to a longstanding problem which has hampered such valves of prior construction Since many changes could be made in the above construe-lion and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the drawings and specification shall be interpreted as illustra-live and not in limiting sense.
SAFETY RELIEF VILLAGE
Technical Field The field of art to which the invention pertains come proses the art of fluid handling as applies to relief of overpricer from incompressible liquids.
Background of the Invention _ Safety relief valves are widely used with incompressible liquids in the relief of o~erpressure by venting controlled quantities of fluid flow from the system. In a conventional construction, such valves utilize a displaceable disc that is spring biased against a nozzle seat for normally maintaining the valve closed to fluid flow. The spring force imposed against the disc is adjustable preset for the "set pressure"
at which the disc is to "lift" for relief of an overpricer encountered in the system being monitored. Typically, the disc or its associated structure includes an excess of surface area over that -to which it is exposed when seated that functions to enhance the lift force imposed against the disc after initial disc lift has occurred. While this excess surface area effectively aids in liftoff, it also has a drawback in that it tends at the same time to impose a negative effect on "slowdown"/ i, e., to delay closing of the valve at a pressure Rowley of the relieved liquid increasingly below set pressure.
As a consequence of the foregoing ! the quantity of excess surface area about the disc has generally represented a come promise such that for liquid service, full lift of the disc for maximum flow does-not normally occur until the o~erpressure ~3~7~3~
value of the fluid reaches approximately 15 percent above set pressure. During the interim, however, particularly when over-pressures approximately correspond to set pressure, the disc incurs only a marginal degree of lift at which there is a tendency of the valve to become dynamically unstable. An aspect of the instability is a phenomena known as "chatter" which is characterized by repeated contact between the disc and valve seat that imposes a destructive force on one or both. Chatter is obviously undesirable, and an approach for overcoming its effect in such valves is disclosed in prior US. patent 4,130,130.
This invention relates to safety relief valves operable with incompressible fluids for relief of overpricer.
More specifically, the invention relates to an improved con-struction for such valves able to substantially if not come pletely eliminate the chatter problem previously associated with such valves, while enabling slowdown to be continually obtained within acceptable operating limits.
The safety relief valve of the present invention includes a body defining a liquid passage between an inlet and an outlet axially offset from each other with an annular seat surrounding the passage at an intermediate location thereof.
A disc is movable from between an urged first position engaging the seat to prevent liquid therapist toward a second position removed from the seat to permit liquid flow to the outlet in response to a liquid overpricer encountered against the disc.
Means defines a sectionally elongated orifice in the flow passage adjacent to the valve seat in downstream series flow relation therewith. The orifice is of substantially uniform cross-sectional dimension and sized to substantially maintain the liquid pressure flow exposed to the disc at a crack open lift condition of the disc to at least be on the valve seating area of the disc.
It is therefore an object of the invention to provide an improved construction for a safety relief valve able to substantially if not completely eliminate the chatter mob/
~.~3t763~D
problem previously associated with the prior art construction in the relief of overpricer with incompressible fluids.
It is a further object of the invention to effect the previous object in an effective yet inexpensive manner as to resolve a long standing problem associated with such valves.
- pa -mob I
Brief Description of the Drawings Fig. 1 is a sectional elevation of a safety relief valve of a type incorporating the inventive improvement hereof;
Fig. 2 is an enlargement of the encircled portion 2, 3 of Fig. l;
'it. 3 is an alternate embodiment of the encircled port lion 2, 3 of Fig l; and Fig. 4 is a graphical representation of the valve char-acteristics hereof as compared to valve characteristics of the prior art.
Referring now to Fig. 1, the valve thereof is of a basic type as disclosed, for example, in US. patent 3,520,326 as modified to incorporate the instant invention.
Briefly, the valve is comprised of a bonnet 10 supported on a base 12 that includes a bottom inlet passage 14 and a gasket seal 16. The inlet communicates with an internal flow passage 18 leading to a discharge outlet 20. Threads 22 and 24 at the outlet and inlet, respectively, permit mounting the valve in the system with which it is to be employed, it being understood that the valve is generally mounted upright with the axis of passage 14 in a vertical orientation At the downstream end of passage 14 there is provided a terminal end section defining a primary orifice I about which is formed an annular planar extending valve seat 28.
Cooperating with valve seat 28 in a normally closed relation as to prevent liquid flow therapist is a displaceable disc 30 having an annular seat 32 formed in its undersurface generally coextensive with valve seat 28. Integral of disc 30 on its topside is a shank 34 extending within a cylindrical disc holder 36 and secured thereto via a retainer ring 38. The disc holder in turn is slide ably contained within cylindrical disc guide I secured to bonnet 10 my means of a cross pin 42.
For imposing a closing force against disc 30 there is provided a coaxial spindle or stem 44 extending centrally upwardly from within shank 34 and urged in a downward direction by a reloaded coil spring 46 contained between spring washers 38 and 50. The degree of spring force imposed on disc 30 for presetting the valve set pressure is effected by means of an adjustment screw 52. By this arrangement, 3~3~
therefore, pressure of the incompressible fluid contained in inlet 14 acts upward against the exposed area on the under-side of disc 30 until fluid pressure exceeds the set pressure setting. At that point, disc 30 is Cossack to begin movement upward and away from nozzle seat I
pro better understand achievement of chatter prevention in accordance with the invention, reference is now made to additional Figs. 2 and 4. Shown in Fig. 2 for that purpose is a cylindrical orifice I coccal located with respect to inlet I The orifice is of restricted radial dimension A and axial length B defined in this embodiment between the outside diameter of adjusting ring 56 and the internal diameter of an overlapping skirt 58. The skirt is integrally a part of disc holder 36 and terminates at its lower end with an angle of about 35 degrees. By virtue of the relatively narrow flow passage afforded through orifice 54, the liquid pressure thereat being imposed against disc 30 beyond seat 32 is substantially maintained. This in turn enables a lift force to be generated on the underside of disc 30 radially beyond seat I to lift the disc a distance above seat 28 at which chatter would otherwise occur. Orifice length B afforded by skirt 58 continues to be effective in this manner until after length B has been exceeded by con-tinting lift. At such time greater liquid pressure is avail-able for forcing the disc toward its full lift position.
The foregoing can be appreciated by reference to Fig. 4 in which curve A represents the operating characteristics of a conventional similar type valve of the prior art, curve B
represents the operating characteristics of a valve as disk closed in US. patent 4 r 130,130, and phantom line 3 repro-sets the operating characteristics in accordance herewith It can he noted specifically, as represented my curve C, that approximately 35 percent lift is achieved by the construction of the instant invention with even a minimum flow representing the incipient or cracked open position of valve disc 30 at the onset of overpricer relief.
Dimensions A and B can, of course, be varied to suit the specific operating characteristics sought to be achieved.
A represented in the embodiment of Fig. 2, length B can be ~Z3~3~
threadedly adjusted by axial positioning of adjusting ring 56.
In a preferred embodiment, a mean value for dimension A of about 0c012 inches has been found suitable, while a mean length for dimension B of approximately 9.5 percent ox the nozzle bore diameter 26 measured with disc 30 in the closed position has been found suitable. In this manner, the cross sectional area of dimension A is proportional to the outside diameter of the adjusting ring, while length is proportional to the throat diameter of the nozzle. Ankle a further aids in liftoff after dimension B has been conned As shown by the alternative embodiment of jig. 3, adjusting ring 56 is of reduced dimension, and the annular orifice 54 is defined directly between the outside diameter of the base 12 and the inside diameter of the skirt 58.
By the above description there is disclosed novel apparatus for a safety relief valve able to completely eliminate or substantially eliminate the chatter problem previously associated with such valves. The construction is relatively simple and inexpensive to implement and yet is able to achieve a solution to a longstanding problem which has hampered such valves of prior construction Since many changes could be made in the above construe-lion and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the drawings and specification shall be interpreted as illustra-live and not in limiting sense.
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a liquid safety relief valve for relieving liquid overpressure including a body defining a liquid passage between an inlet and an outlet axially offset from each other, an annular seat surrounding said passage at an intermediate location thereof, and a disc movable from between an urged first position engaging said seat to prevent liquid therepast toward a second position removed from said seat to permit liquid flow to the outlet in response to a liquid overpressure encountered against said disc, the improvement comprising:
means defining a sectionally elongated orifice in said flow passage adjacent to said valve seat in downstream series flow relation therewith, said orifice being of sub-stantially uniform cross-sectional dimension and sized to sub-stantially maintain the liquid pressure flow exposed to said disc at a crack open lift condition of said disc to at least beyond the valve seating area of said disc.
means defining a sectionally elongated orifice in said flow passage adjacent to said valve seat in downstream series flow relation therewith, said orifice being of sub-stantially uniform cross-sectional dimension and sized to sub-stantially maintain the liquid pressure flow exposed to said disc at a crack open lift condition of said disc to at least beyond the valve seating area of said disc.
2. In a safety relief valve according to claim 1 in which the orifice of said improvement is cylindrical and is located coaxially surrounding said valve seat.
3. In a safety relief valve according to claim 2 in which the size of said orifice is defined by a radial clearance and a predetermined length as measured with the disc in said first position to effect a disc lift of in excess of 10 percent when said crack open lift condition of said disc occurs.
4. In a safety relief valve according to claim 2 in which said valve seat and at least one of said surrounding surfaces comprises the inside diameter surface of an annular skirt downwardly depending about said disc.
5. In a safety relief valve according to claim 4 in which the other of said concentric surfaces comprises the outside diameter of wall means enclosing the inlet of said passage.
6. In a safety relief valve according to claim 4 in which there is included an adjusting ring threadedly secured about wall means enclosing the inlet passage and presentably position able axially thereon, and the other of said concentric surfaces comprises the outside diameter of said adjusting ring.
7. In a safety relief valve according to claims 2, 3 or 4 in which the dimensions of said orifice includes a radial dimension having a mean value of approximately 0.012 inches and a length dimension as measured in the fist position of said disc having a mean value of approximately 9.5 percent of the nozzle bore of said inlet passage.
8. In a safety relief valve according to claim 5 or 6 in which the dimensions of said orifice includes a radial dimension having a mean value of approximately 0.012 inches and a length dimension as measured in the first position of said disc having a mean value of approximately 9.5 percent of the nozzle bore of said inlet passage.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US52744883A | 1983-08-29 | 1983-08-29 | |
| US527,448 | 1983-08-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1237630A true CA1237630A (en) | 1988-06-07 |
Family
ID=24101504
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000461669A Expired CA1237630A (en) | 1983-08-29 | 1984-08-23 | Safety relief valve |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS6069369A (en) |
| CA (1) | CA1237630A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024215537A1 (en) * | 2023-04-13 | 2024-10-17 | Curtiss-Wright Flow Control Corporation | Relief valve |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4130130A (en) * | 1976-11-15 | 1978-12-19 | Crosby Valve & Gage Company | Valve with variable secondary orifice |
-
1984
- 1984-08-23 CA CA000461669A patent/CA1237630A/en not_active Expired
- 1984-08-29 JP JP18024084A patent/JPS6069369A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024215537A1 (en) * | 2023-04-13 | 2024-10-17 | Curtiss-Wright Flow Control Corporation | Relief valve |
| US12504083B2 (en) | 2023-04-13 | 2025-12-23 | Curtiss-Wright Flow Control Corporation | Relief valve |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6069369A (en) | 1985-04-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |