Pilot operation pressure release valve assembly

Abstract

A pressure relief valve assembly may include a valve body having a valve inlet and a valve outlet, a pilot valve, a dome, and a valve trim. The pilot valve may control the pressure in the dome as a function of the monitored pressure at the valve inlet. The valve trim may be arranged to be urged on a valve seat within the valve body by pressure within the dome to prevent flow between the valve inlets. The valve trim may include a flow passage bypassing the pilot valve fluidly coupling the valve inlet and the dome.

Description

Background Technology

[0001] Valve assemblies, including pilot-operated pressure relief valves, can be used in a variety of industrial, commercial, and other applications to relieve pressure in a system. In some applications, transient pressure events can cause the valve to open prematurely or unexpectedly. Summary of the Invention

[0002] Some examples of this disclosure provide a pressure relief valve assembly. The pressure relief valve assembly may include a valve body having a valve inlet and a valve outlet, and a dome. A pilot valve may be provided to control the pressure in the dome based on a monitored pressure at the valve inlet. Valve internals may be arranged to be pushed against a valve seat within the valve body by the pressure within the dome to prevent flow between the valve inlet and the dome. The valve internals may include a flow passage bypassing the pilot valve to fluidly connect the valve inlet and the dome.

[0003] Some examples of this disclosure provide valve internals for a pressure relief valve assembly. A main valve member is movable and controls the flow rate between the valve inlet and outlet of the pressure relief valve assembly by being mounted on or raised from the main valve seat. A flow passage extends through the main valve member. An intermediate valve is arranged along the flow passage to control the flow rate from the upstream side of the main valve member to the dome of the pressure relief valve assembly.

[0004] Some examples of this disclosure provide a method for operating a pilot-operated pressure relief valve. A pilot valve can be used to provide a pilot flow path between the monitored pressure and the dome of the pilot-operated pressure relief valve. Between the monitored pressure and the dome, an internal valve flow path parallel to the pilot flow path can be provided along a flow passage through the internal valve components of the pilot-operated pressure relief valve. When the pilot valve is closed to maintain the pressure within the dome at the monitored pressure, when the monitored pressure rises below the set pressure of the pilot-operated pressure relief valve, an intermediate valve along the internal valve flow path allows fluid to flow from the monitored pressure through the internal valve flow path to the dome. When the pilot valve is open to discharge pressure from the dome, the intermediate valve prevents fluid from flowing from the monitored pressure through the internal valve flow path to the dome. Attached Figure Description

[0005] Figure 1 This is an isometric view of a pressure relief valve, based on an example of the disclosed technology.

[0006] Figure 2 yes Figure 1 A cross-sectional view of the pressure relief valve under dome loading.

[0007] Figure 3 yes Figure 2 A detailed view of the check valve of the pressure relief valve, with the check valve in the open position.

[0008] Figure 4 yes Figure 2Detailed view of the pressure relief valve / check valve, with the check valve in the closed position.

[0009] Figure 5 This is a schematic cross-sectional view of another pressure relief valve, based on an example of the disclosed technology. Detailed Implementation

[0010] The concepts disclosed in this discussion are described and illustrated with reference to exemplary arrangements. However, the application of these concepts is not limited to the structural details and component arrangements in the examples, but can be implemented or performed in a variety of other ways. The terminology used in this document is for descriptive purposes and should not be considered restrictive. Words such as “including,” “comprising,” and “having,” and variations thereof, as used herein, are intended to cover items listed below, equivalents, and other items.

[0011] As described above, pressure relief valves can be used in a variety of industrial, commercial, and other applications to release fluid pressure in a system. Pressure relief valves, such as pilot-operated pressure relief valves, can have a set pressure at which the main valve component of the pilot-operated pressure relief valve assembly opens to vent the monitored system. During valve opening, fluid can flow from the valve inlet to the valve outlet as the monitored pressure increases. Conversely, the main valve component should remain closed until the monitored pressure (e.g., the pressure at the valve inlet) reaches or exceeds the valve set pressure.

[0012] In some conventional pilot-operated pressure relief valves, a sudden increase in pressure at the valve inlet can cause the main valve to open prematurely, even if the pressure of the monitored system does not exceed the set pressure. For example, during startup, the pressure at the valve inlet may rise rapidly, at which point the initial fluid pressure introduced into the system is generally lower than the set pressure of the pressure relief valve. However, the sensing line (e.g., a Pitot tube) between the valve inlet and the pilot valve of the pilot-operated pressure relief valve can transmit pressure between the sensing position and the corresponding dome, with a time lag.

[0013] Therefore, the main valve of a pressure relief valve may briefly open due to a momentary increase in system pressure before the pilot valve can deliver sufficient pressure to the valve dome to balance the monitored pressure increase and reclose the valve. Thus, systems and methods that provide more direct pressure application to the valve dome to bias the main valve towards the closed position may be useful when the monitored pressure is below the set pressure, including during relatively sudden pressure increases that might be delayed by conventional pilot valve assemblies.

[0014] Conventional methods to counteract premature opening of a pilot-operated pressure relief valve may include preloading the dome of the main valve. That is, the dome can be preloaded (e.g., to a set pressure or slightly below a set pressure) before the pressure relief valve is installed in the system or before the system is pressurized. Therefore, the dome pressure preventing the valve from opening may not initially depend on the pressure sensed at the pilot valve; as long as the monitored pressure balances the preloaded dome pressure, the dome can accordingly push the main valve component toward the closed position.

[0015] However, preloading the dome of a pressure relief valve can have drawbacks. For example, after a pressure relief event or other operation causes a decrease in dome pressure, the valve may lose its protective function against premature opening unless it is reloaded. Repeated preloading operations can be costly, time-consuming, or simply impractical (e.g., for remote or large-scale installations).

[0016] Embodiments of this disclosure address these and other drawbacks of conventional valves and methods to reduce premature valve opening, including premature opening that may result from a sudden increase in pressure at the valve inlet (below a set pressure). For example, embodiments of this disclosure may provide a pilot-operated valve assembly having a direct flow passage extending between the valve inlet and the dome, rather than being operated via a pilot valve. For instance, fluid from the monitored system can bypass the pilot valve and flow from the valve inlet to the valve dome via a passage in the spindle assembly. This allows the dome to be rapidly pressurized when the monitored pressure suddenly rises (below a set pressure) to prevent premature valve opening.

[0017] In some examples, the bypass passage through the pilot valve may include an intermediate valve that selectively blocks flow toward the dome. For example, such an intermediate valve can help ensure proper overpressure protection by blocking fluid flow toward the dome along the flow path when the pressure at the inlet reaches or exceeds the main valve set pressure or other relevant pressure conditions are met.

[0018] In some examples, the bypass passage through the pilot valve can extend, in particular, through the valve internals of a pilot-operated pressure relief valve. For example, the flow passage can extend through a main valve element configured to seal the main valve of the pressure relief valve, through a piston assembly or other spindle assembly of the main valve element, through a diaphragm of the main valve, or through various other components. Similarly, some examples may include an intermediate valve, which may be mounted or formed in the main valve element, in the piston assembly or other spindle assembly of the main valve element, or in various other components.

[0019] Now refer to the example in the figure, Figure 1 A pilot-operated pressure relief valve assembly 100 according to an embodiment of the present disclosure is shown. The valve assembly 100 includes a main valve having a valve body 102, a valve inlet 104, a valve outlet 106, and a dome 110. Similarly, as... Figure 1 As shown, valve assembly 100 also includes a pilot valve 108 in fluid communication with valve inlet 104 and dome 110. Generally, valve assembly 100 is configured to release fluid pressure at valve inlet 104 when the pressure monitored by pilot valve 108 reaches a set pressure of valve assembly 100. More specifically, in use, when pilot valve 108 detects a set pressure (e.g., at valve inlet 104, such as...), Figure 2 As shown), the pilot valve assembly opens to release the pressure in the dome 110 (e.g., to release the pressure into the atmosphere). The main valve element (such as a piston) can then be lifted from the valve seat to open the main valve, discharging the pressurized fluid through the valve outlet 106.

[0020] like Figure 2 As shown, valve assembly 100 is configured as a diaphragm-type pilot-operated pressure relief valve, with dome 110 correspondingly including a diaphragm 116 that engages with main valve assembly 130. Similar to some conventional pilot-operated pressure relief valves, dome 110 is in fluid communication with pilot valve 108, which in turn is in fluid communication with valve inlet 104 via sensing path 122 (e.g., for sensing the monitored pressure at valve inlet 104, as shown).

[0021] As described above, in conventional valves, pressure communication between the pilot valve and the dome of the conventional pilot-operated pressure relief valve is achieved only through a sensing path between the valve inlet and the pilot valve 108. Therefore, for conventional valves, when the pressure at the valve inlet suddenly increases, the sensing path may not be able to transmit the pressure change to the pilot valve and then to the dome quickly enough to keep the main valve seated. Thus, even if the inlet pressure is lower than the set pressure, the main valve will briefly open and discharge fluid.

[0022] like Figure 2 As shown, valve assembly 100 also includes a flow passage 124 that extends through the valve internals of the main valve. Specifically, in the illustrated example, flow passage 124 passes through the shaft 126 of the piston assembly 128 of the main valve, as well as the diaphragm 116 and the main valve member 130. Therefore, flow passage 124 can bypass the pilot valve 108 and supply fluid directly from valve inlet 104 to dome 110. Thus, for example, when the pressure in the monitored system suddenly rises (below the set pressure), flow passage 124 can quickly transmit pressure to dome 110, preventing the main valve member 130 from prematurely lifting off its seat.

[0023] In particular, for a given monitored pressure below the set pressure, channel 124 transmits pressure from inlet 104 to dome 110 faster than the pressure transmitted via sensing path 122 of pilot valve 108. In this respect, valve assembly 100 has advantages over conventional pilot-operated pressure relief valves. For example, when the pressure at inlet 104 is below the set pressure of valve assembly 100, the direct path between inlet 104 and dome 110 can more effectively and efficiently transmit pressure fluctuations at inlet 104 to dome 110, thereby preventing (or reducing) unnecessary valve opening events.

[0024] exist Figure 2 In the diagram, arrow 136 indicates a unidirectional flow of fluid from inlet 104 to dome 110 through channel 124 in shaft 126 of piston assembly 128. Therefore, for example, even if the pressure in dome 110 exceeds the monitored pressure, pressure leakage back to valve inlet 104 from dome 110 can be prevented.

[0025] In general, while the combination of sensing path 122 and channel 124 provides parallel pressure communication from inlet 104 to dome 110, channel 124 allows a larger volume of fluid to flow to dome 110 compared to sensing path 122, suitable for monitoring pressures and pressure differentials between dome 110 (e.g., at some or all of the monitored pressures below the valve 100 set pressure). In some embodiments, sensing path 122 may include a Pitot tube with a relatively small flow diameter and various bends, as well as portions defined by internal components of pilot valve 108. Therefore, sensing path 122 can provide a relatively indirect flow path for transmitting fluid pressure between valve inlet 104 and dome 110. In contrast, channel 124 can provide a direct flow passage between the upstream side of main valve 130 and dome 110, thus efficiently delivering fluid at valve inlet 104 to dome 110, thereby increasing the fluid pressure in dome 110 as needed.

[0026] In some examples, as follows Figure 3 and Figure 4 The valve assembly 100 also includes an intermediate valve 140. When the inlet pressure is lower than the set pressure of the valve assembly 100, the intermediate valve 140 allows fluid to flow from the inlet 104 to the dome 110, while preventing unwanted backflow from the dome 110 to the inlet 104. Conversely, arrow 144 indicates the direction of flow from the inlet 104 along the sensing path 122 to the pilot valve 108. Therefore, the combination of sensing path 122 and channel 124 can provide parallel flow and pressure communication from the inlet 104 to the dome 110, with the fluid bypass indicated by arrow 136 passing through the pilot valve 108 to pressurize the dome 110.

[0027] Figure 3 and Figure 4 A detailed example configuration of the intermediate valve 140 in piston assembly 128 is shown, although other valve assemblies could be used in other examples to provide similar flow control. In particular, Figure 3 The diagram shows a valve 140 in the open position, with a seal 152 (e.g., a ball) positioned between and spaced from a dome-side seat 140A and an inlet or valve-side seat 140B. Fluid can thus flow from inlet 104 to dome 110 through passage 124. In some examples, such as... Figure 3 As shown, fluid flowing through channel 124 can exit valve 140 at valve outlet 150, which is located inside dome 110 (e.g., as shown, the two outlets 150 extend in opposite directions).

[0028] On the contrary, Figure 4 The valve 140 is in the closed position, with the seal 152 abutting against the dome-side valve seat 140A. Therefore, from inlet 104 (see...) Figure 2 Fluid flowing through channel 124 to dome 110 is blocked. In some examples, as discussed further below, this is when the dome pressure is significantly lower than the monitored pressure (e.g., when pilot valve 108 (see...)). Figure 2 When the valve is opened to vent the dome 110, valve 140 can be configured to move to the closed position. Thus, for example, a significantly higher pressure in valve inlet 104 can cause seal 152 to prevent flow from valve inlet 104 to the dome 110, and the main valve can accordingly release the monitored pressure. Conversely, for example, when the pressure in the dome 110 is lower than but relatively close to the monitored pressure (e.g., when the inlet pressure suddenly rises but remains below the set pressure of the pressure relief valve 100, keeping pilot valve 108 closed to maintain pressure within the dome 110), valve 140 can be configured to remain open.

[0029] In particular, Figure 3 In the example shown, seal 152 is suspended in the fluid flowing through intermediate valve 140 by local pressure forces corresponding to the flow rate through valve 140 when the flow rate through intermediate valve 140 is relatively low. For example, seal 152 can be suspended by the local forces of turbulent vortices and other flow structures, which are often generated by the relatively small pressure difference between inlet 104 and dome 104 driving the flow through valve 140. In particular, in the example shown, seal 152 can be suspended against the force of gravity. Conversely, in Figure 4 In the example shown, the relatively large pressure difference between inlet 104 and dome 110 results in a relatively large flow rate through intermediate valve 140. This resulting flow rate (and pressure difference) can overcome the levitation forces on seal 152 (e.g., as...). Figure 3(In the middle), causing the seal 152 to move onto the dome-side valve seat 140A. In this respect, for example, the seal 152 allows flow (such as... Figure 3 (as shown) or prevent flow (such as) Figure 4 The specific pressure differential (as shown) can be adjusted as needed during manufacturing, installation, or maintenance. For example, specific operating characteristics of valve 140 can be achieved through a specific configuration of its flow passages or by adjusting the size of the relevant orifices (e.g., as described below). However, in other examples, other flow structures or mechanical arrangements known in the art may be used to allow or block flow between the monitored location and the dome selectively.

[0030] like Figure 3 and Figure 4 As shown, in one example configuration, the intermediate valve 140 also includes an adjusting screw 156. In use, the adjusting screw 156 can be used to adjust the operating characteristics of the intermediate valve 140 (i.e., control the pressure drop across the valve 140 between the monitored pressure and the dome 110) by changing the orifice size within the flow passage 124. Therefore, by selectively adjusting the adjusting screw 156 (e.g., by helical movement of the screw 156 relative to the valve 140 body), the user can control the flow rate of fluid from inlet 104 to dome 110 to accommodate a given pressure difference between the two locations. Adjustment of the adjusting screw 156 can also correspondingly set a pressure difference between inlet 104 and dome 110 beyond which fluid will no longer be allowed to flow through passage 124 to dome 110 (see [reference]). Figure 4 In the example, the adjusting screw 156 can be secured in a specific position using the lock nut 154, but other configurations can also be used.

[0031] In some examples, a check valve or other intermediate valve in the bypass flow path can prevent fluid from flowing to the dome when the pilot valve is open to vent the dome, or when there is a significant difference between the dome pressure and the monitored pressure (i.e., when the dome pressure is 50% or less of the monitored pressure). Therefore, for example, in the event of a rise in the monitored pressure, the corresponding pilot valve can appropriately vent the dome during a pressure relief event. Conversely, a check valve or other intermediate valve can also allow fluid to flow to the dome when the pilot valve is closed to maintain the dome pressure relative to the monitored pressure, or when the dome pressure is not significantly different from the monitored pressure (i.e., the dome pressure is 50% or more of the monitored pressure and less than or equal to the set pressure).

[0032] In some examples, the intermediate valve can be adjusted to allow or prevent flow at a specific pressure drop based on the weight of the seal. For example, in the illustrated embodiment, fluid flows through intermediate valve 140 in a vertically upward direction toward dome 110. Accordingly, when the pressure difference between dome 110 and valve inlet 104 is large enough that the force flowing toward seal 152—and the corresponding static pressure difference ultimately passing through seal 152—is sufficient to resist gravity lifting seal 152 onto the dome-side valve seat 140A, seal 152 can prevent fluid from flowing through intermediate valve 140. In other words, if the pressure from inlet 104 is greater than the sum of the pressure from dome 110 and the weight of seal 152, seal 152 can prevent flow through valve 140. Conversely, when the pressure difference between the dome 110 and the valve inlet 104 is sufficient (i.e. large enough) to lift the seal from the valve-side seat 140B, but not sufficient to allow the seal 152 to sit on the dome-side seat 140A, the seal 152 allows fluid to flow through the intermediate valve 140.

[0033] In some examples, a biasing element can be configured to push the seal 152 in a specific direction relative to the flow direction from inlet 104 to dome 110. For example, as Figure 3 As shown, a spring or other biasing element 160 may be arranged upstream or downstream of the seal 152 to bias the seal 152 toward one of the respective valve seats 140A, 140B. For example, the biasing element 152 may be various types of springs (such as helical springs or wave springs), composites (such as rubber rings or other composite elastic structures), or other structures known in the art for biasing valve assemblies with relatively sealing contacts. The addition of the biasing element 160 can improve performance; for example, it can selectively reduce the pressure differential that the seal 152 prevents from flowing between the inlet 104 and the dome 110, or improve the sealing between the inlet 104 and the dome 110 during valve ejection. Alternatively, when the pressure differential between the dome 110 and the inlet 104 is relatively small, the biasing element 160 helps to increase the flow rate toward the dome 110.

[0034] Figure 5Another example is shown, namely a pilot-operated pressure relief valve assembly 200 according to an embodiment of this disclosure. Generally, valve assembly 200 can monitor and release pressure similarly to valve assembly 100, and therefore the above discussion regarding valve 100 generally applies to valve 200 as well. However, valve assembly 200 differs from valve assembly 100 in some respects. For example, valve assembly 200 includes a main valve having a valve body 202, a valve inlet 204, a valve outlet 206, and a pilot valve 208, configured to control the pressure in the main valve dome 210, similar to valve assembly 100. However, unlike valve assembly 100, valve assembly 200 includes a dome 210 without a diaphragm between the dome 210 and the valve inlet 204. Conversely, the valve internals of valve assembly 200 include piston assembly 228, which is formed into a movable piston (main valve) body. The piston is directly exposed to pressure in the dome 210 on the dome side of the piston body, while the valve side of the piston body sits on a valve seat of valve body 202.

[0035] like Figure 5 As shown, similar to valve assembly 100, valve assembly 200 includes a flow passage 224 that bypasses pilot valve 208 and extends through valve internals to dome 210. Furthermore, in some cases, intermediate valve 240 may be arranged along flow passage 224 (e.g., at its downstream end) to selectively allow or block flow along flow passage 224 from valve inlet 204 to dome 210. For example, valve 240 may be configured similarly to valve 140, discussed in detail above, to allow pressure fluctuations (below a set pressure) to be rapidly transmitted from valve inlet 204 to dome 210.

[0036] Therefore, examples of the disclosed technology can provide improved pressure relief valve assemblies, improved pressure relief valve internals, and improved pressure relief valve operation methods. In particular, some examples can improve the transmission of monitored pressure fluctuations to the dome of the pilot-operated pressure relief valve (e.g., by bypassing the flow passage of the corresponding pilot valve). Thus, for example, it is generally possible to prevent the corresponding pressure relief valve from opening when the monitored pressure fluctuation does not exceed the pressure relief valve's set pressure.

[0037] In some embodiments, the devices or systems disclosed herein may be utilized, manufactured, installed, etc., using methods embodying various aspects of the disclosed technology. Accordingly, unless otherwise stated, any description herein of a particular feature, function, or intended purpose of a device or system is intended to include disclosure of: methods of using such device for its intended purpose, methods of otherwise implementing such function, methods of manufacturing related components of such device or system (or device or system as a whole), and methods of installing disclosed (or otherwise known) components to support such purpose or function. Similarly, unless otherwise stated, any discussion herein of any method of manufacturing or using a particular device or system (including installing the device or system) is essentially intended to include, as an example, disclosure of the features and capabilities of using the device or system as an example of the disclosed technology.

[0038] Some methods of the disclosed technology may list operations in a specific order above or below. Unless otherwise required or specified, the operations of these methods may be implemented in a different order, in parallel, or as a selected subset of one or more individual operations (e.g., implementing the specific operations listed alone, rather than in combination with other operations).

[0039] As stated above, the illustrations in this disclosure are merely illustrative, and the features described herein or elsewhere can be used in other pressure relief valve configurations. Therefore, the examples of the technology disclosed herein can provide an improvement over conventional systems and methods to accommodate rapid increases in pressure at the valve inlet. The foregoing description of the disclosed examples is intended to enable any person skilled in the art to make or use the disclosed technology. Various modifications to these examples will be apparent to those skilled in the art, and the general principles defined herein can be applied to other examples without departing from the spirit or scope of the disclosed technology. Therefore, the disclosed technology is not limited to the examples shown herein but should be given the broadest scope consistent with the principles and novel features disclosed herein.

[0040] As used herein, unless otherwise limited or defined, "or" indicates a non-exclusive list of components or operations that may appear in any different combination, rather than an exclusive list of components that can only appear as substitutes for each other. For example, a list of "A, B, or C" indicates the following options: A; B; C; A and B; A and C; B and C; and A, B, and C. Accordingly, the term "or" as used herein indicates an exclusive alternative only when preceded by an exclusive term (such as "any," "one of," "only one," or "exactly one"). For example, a list of "one of A, B, or C" indicates the following options: A excluding B and C; B excluding A and C; and C excluding A and B. A list beginning with "one or more" (and its variations) and containing "or" to separate the listed elements indicates that one or more of any or all of the listed elements can be selected. For example, the phrases “one or more of A, B, or C” and “at least one of A, B, or C” indicate the following options: one or more A’s; one or more B’s; one or more C’s; one or more A’s and one or more B’s; one or more B’s and one or more C’s; one or more A’s and one or more C’s; and one or more A’s, one or more B’s, and one or more C’s. Similarly, a list of listed elements beginning with “multiple” (and its variations) and separated by “or” indicates that multiple instances of any or all of the listed elements can be selected. For example, the phrases “multiple A’s, B, or C” and “two or more A’s, B’s, or C” indicate the following options: A and B; B and C; A and C; and A, B, and C.

[0041] Furthermore, unless otherwise limited or defined, "monolithic" and its derivatives (such as "monolithic") describe a component manufactured as a single piece, without fasteners, adhesives, or the like holding the individual parts together. For example, a single component formed by stamping, casting, or otherwise shaping from a single sheet of metal or other continuous monolithic material, without rivets, screws, other fasteners, or adhesives holding the separately formed parts together, is an integral (monolithic) component. Conversely, an element composed of multiple parts that were initially formed separately but were later fixed together is not an integral (or monolithic) component.

[0042] Unless otherwise specified, the numbering used herein is for ease of reference and is generally based on the order in which specific components are presented in the relevant sections of this disclosure. In this regard, terms such as "first," "second," etc., generally only indicate the order of the identified components introduced into the discussion and do not generally indicate or require a particular spatial, functional, temporal, or structural priority or order. Relatedly, similar or identical components may be represented by different numbering in different contexts.

[0043] Furthermore, unless otherwise limited or defined, "configured as" indicates that a component, system, or module is particularly suited to the relevant function. Therefore, for example, ZZ configured as YY is specifically suited to YY, not just generally capable of doing so.

[0044] Although the currently disclosed techniques have been described with reference to preferred examples, those skilled in the art will recognize that changes may be made to the form and details of the disclosed examples without departing from the spirit and scope of the concepts discussed herein.

Claims

1. A pressure relief valve assembly, comprising: Valve body, the valve body having a valve inlet and a valve outlet; Dome; A pilot valve, the pilot valve being arranged to control the pressure within the dome based on a monitored pressure at the valve inlet; as well as Valve internals, which are arranged to be pushed onto a valve seat inside the valve body under pressure within the dome to prevent flow between the valve inlet and the valve seat. and The valve internals include a flow passage that bypasses a pilot valve to connect the valve inlet to the dome fluid.

2. The pressure relief valve assembly of claim 1 further comprises: The intermediate valve within the flow channel allows unidirectional flow from the valve inlet to the dome along the flow channel when the monitored pressure is at or below the set pressure of the pressure relief valve assembly.

3. The pressure relief valve assembly according to claim 2, wherein, When the monitored pressure is higher than the set pressure of the pressure relief valve assembly, the intermediate valve prevents flow from the valve inlet to the dome along the flow channel.

4. The pressure relief valve assembly according to claim 2, wherein, The intermediate valve includes: Dome-shaped valve seat; Valve side seat; and A seal that is movable between a position located on a valve-side seat and a position located on a dome-side seat. When the seal is in the position seated on the valve side, it prevents flow from the dome to the valve inlet along the flow channel; When the seal is positioned on the dome-side valve seat, it prevents flow from the valve inlet to the dome along the flow path.

5. The pressure relief valve assembly according to claim 2, wherein, The intermediate valve includes: A seal capable of moving in response to a pressure difference between the dome and the monitored pressure to impede flow along the flow path from the valve inlet to the dome; and An adjusting screw, which is rotatable to adjust the orifice size within the flow channel so that flow from the valve inlet to the dome.

6. The pressure relief valve assembly according to claim 5, wherein, The adjusting screw extends into the dome.

7. The pressure relief valve assembly according to claim 5, wherein, The intermediate valve includes multiple outlets disposed within the dome to guide fluid from the flow channel into the dome.

8. The pressure relief valve assembly of claim 1, wherein the valve internals further comprise: The main valve component is movable to the valve open position to allow flow between the valve inlet and the valve outlet, and is movable to the valve closed position to prevent flow between the valve inlet and the valve outlet. as well as A piston assembly for moving a main valve element between a valve open position and a valve closed position; The flow channel extends through the main valve and piston assembly.

9. The pressure relief valve assembly as claimed in claim 8, wherein, The piston assembly engages with the dome-shaped diaphragm to move the main valve element between the valve open and valve closed positions; and The flow channel extends through the diaphragm into the dome.

10. The pressure relief valve assembly according to claim 1, wherein, The pilot flow path extends through the pilot valve between the valve inlet and the dome, parallel to the flow passage; and Specifically, when the monitored pressure is lower than the set pressure of the pressure relief valve assembly, the flow channel flows from the valve inlet to the dome at a higher volumetric flow rate than the pilot flow path.

11. A valve internal for a pressure relief valve assembly, the valve internal comprising: The main valve assembly is movable to control the flow between the valve inlet and valve outlet of the pressure relief valve assembly by sitting on or lifting off the main valve seat of the pressure relief valve assembly. A flow channel that extends through the main valve component; as well as An intermediate valve, arranged along the flow channel, is used to control the flow from the upstream side of the main valve to the dome of the pressure relief valve assembly.

12. The valve internals according to claim 11, further comprising: A piston assembly configured to move the main valve member to seat or lift it from the main valve seat according to the pressure in the dome of the pressure relief valve assembly. The flow channel further extends through the piston assembly to provide a flow path through the main valve and the piston assembly between the upstream side of the main valve and the rounded top of the piston assembly.

13. The valve assembly of claim 11, wherein, The intermediate valve includes a seal that is movable upward along the flow channel to sit on the dome-side valve seat of the intermediate valve and prevent flow toward the dome.

14. A method for operating a pilot-operated pressure relief valve, the method comprising: A pilot valve is used to provide a pilot flow path between the monitored pressure and the dome of the pilot-operated pressure relief valve; as well as Between the monitored pressure and the dome, a valve internal flow path parallel to the pilot flow path is provided along the flow passage of the valve internals through the pilot-operated pressure relief valve; Specifically, when the pilot valve is closed to maintain the pressure within the dome at the monitored pressure, if the monitored pressure rises below the set pressure of the pilot-controlled pressure relief valve, the intermediate valve along the valve internals flow path allows fluid to flow from the monitored pressure to the dome via the valve internals flow path; and Specifically, when the pilot valve is in the open state to discharge pressure from the dome, the intermediate valve prevents fluid from flowing from the monitored pressure through the valve internals to the dome.

15. The method of claim 14, further comprising: Adjust the setting screw inside the dome to regulate the flow rate into the dome through the intermediate valve.

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