CN213871265U - Pilot operated safety valve - Google Patents

Abstract

A pilot-operated safety valve includes a main valve, a pilot valve, a connection unit connected between the main valve and the pilot valve, and a residual medium draining unit. By controlling the opening and closing of the pilot valve, the main valve of the connecting pipeline is communicated or isolated from the outside world, and the residual medium row unit is connected to the connection unit and supplies auxiliary medium to the main valve and the pilot valve. Compared with the prior art, the pilot-operated safety valve of the present invention realizes the directional discharge of residual medium.

Description

Pilot operated safety valve

Technical Field

The utility model relates to a relief valve field especially relates to a guide's formula relief valve.

Background

Natural gas and liquefied petroleum gas are widely used in life. In order to ensure safe use and control the conveying pressure, a safety valve is often arranged on the conveying pipeline or equipment. The safety valve is in a state of being isolated from the outside under normal conditions, when the delivery pressure of the medium in the pipeline rises to exceed the rated pressure, partial medium is discharged outside the pipeline through the safety valve to release the pressure, and therefore the pressure value in the pipeline is maintained in the rated range. One of the safety valves is a pilot operated safety valve. The pilot operated safety valve has good sealing performance, and the action is basically not influenced by back pressure during discharge, so the pilot operated safety valve is widely installed on pipelines of natural gas distribution stations and storage tanks of liquefied petroleum gas filling stations in recent years and is special pressure-bearing equipment for protecting possible overpressure. The pilot operated safety valve mainly comprises a main valve, a pilot valve and a connecting pipeline connected between the main valve and the pilot valve. The opening and closing of the main valve are driven or controlled by the pilot valve. When the pressure in the pipe reaches the rated pressure, the pilot valve is opened and then triggers the main valve to open, the medium is rapidly discharged from the main valve to the outside, and the pressure in the pipe is reduced along with the discharge of the medium. When the pressure in the conduit drops below the nominal pressure, the pilot valve closes, which in turn triggers the main valve to close.

Specifically, referring to fig. 1, the patent application No. 201910035415.5 discloses a pilot operated safety valve including a main valve 10, a pilot valve 20, a first connection pipe 310, a second connection pipe 320, and a filter 330. A movable main valve spool 120, an upper chamber 111, a lower chamber 112 connected to a pipe (not shown), and a discharge chamber 113 communicating with the outside are provided in the main valve 10, and as the main valve spool 120 moves between the upper chamber 111 and the lower chamber 112, the lower chamber 112 communicates with or is separated from the discharge chamber 113. A movable pilot valve core 220 and an air inlet part 211 are arranged in the pilot valve 20, and the air inlet part 211 is communicated or separated with the outside along with the movement of the pilot valve core 220. The first connection pipe 310 communicates the air inlet part 211 with the upper chamber 111, the second connection pipe 320 communicates the air inlet part 211 with the lower chamber 112, and the filter 330 is disposed on the second connection pipe 320 and filters a medium flowing through the second connection pipe 320. When the pressure in the pipeline is lower than the rated pressure, the lower cavity 112 and the air inlet part 211 are both isolated from the outside. When the pressure in the pipeline increases and exceeds the rated pressure value, the pilot valve core 220 moves upwards, the air inlet part 211 is communicated with the outside, a small amount of medium flows out from the air inlet part 211, the medium outflow speed of the air inlet part 211 is greater than the medium inflow speed of the lower cavity 112 under the throttling action of the filter 330, the medium in the upper cavity 111 also flows to the air inlet part 211 along the first connecting pipe 310 under the action of pressure difference, the main valve core 120 moves in the direction away from the lower cavity 112, the lower cavity 112 is communicated with the discharge cavity 113, and a large amount of medium is discharged from the outside through the discharge cavity 113 so as to quickly release the pressure in the pipeline. When the pressure in the pipeline drops below the rated pressure, the pilot valve core 220 moves towards the air inlet part 211, the air inlet part 211 is isolated from the outside again, the pressure in the upper cavity 111 increases, the main valve core 4 moves towards the lower cavity 112 again, and the lower cavity 112 is isolated from the discharge cavity 113, namely, the pipeline is isolated from the outside, so that the process of regulating the pressure in the pipeline and sealing the pipeline again is completed.

Meanwhile, according to the stipulation of TSG ZF001-2006 safety technology supervision regulations for safety valves, the safety valves are generally checked at least once every year for tightness, the safety valves can be checked in an online checking mode of keeping the connection between the safety valves and pipelines or an offline checking mode of keeping the separation between the safety valves and the pipelines, and when a fault occurs or the performance is abnormal in the safety operation, the safety valves need to be detached for maintenance. However, as can be seen from the structure of the pilot operated safety valve, in the process of communicating with the outside and blocking the pilot operated safety valve, a part of the medium will remain in the pilot operated safety valve. In addition, the method for checking or disassembling in the current industry is usually to loosen a nut of a connecting pipeline, discharge a medium, and check or disassemble on line after the pressure in the valve is reduced to normal pressure. Although the pilot operated safety valve can be isolated from the pipeline before the check or removal, if the residual gas medium in the valve cannot be discharged, the medium in the valve is discharged to the outside in a non-directional manner during the check or removal. Furthermore, the piping associated with the safety valve is typically used to transport the combustible gaseous media, so the media remaining in the valve is typically combustible gas. The combustible medium is easy to generate strong friction with metal in the process of leakage, and is contacted with oxygen in the air, so that safety accidents are easily caused by fire, so that serious potential safety hazards exist in the process of using the existing pilot-operated safety valve, a plurality of persons are often required to be configured on a checking site for carrying out safety monitoring, the working efficiency is low, and the air can be polluted if the residual medium flows in a non-directional manner.

SUMMERY OF THE UTILITY MODEL

Based on this, the utility model aims at providing a pilot operated relief valve convenient to directional emission remains medium.

The utility model discloses a following scheme realizes:

a pilot operated safety valve includes

The main valve comprises a main valve body, a main valve spool and a main valve spring; an upper cavity, a lower cavity communicated with the outside and a discharge cavity which is positioned between the upper cavity and the lower cavity and is communicated with the outside are arranged in the main valve body; the main valve core slides in the discharge cavity and presses towards a communicating port of the lower cavity and the discharge cavity under the action of the elasticity of the main valve spring; in the sliding process of the valve core of the main valve, the upper cavity is always separated from the lower cavity and the discharge cavity, and the lower cavity is communicated with or separated from the discharge cavity;

the pilot valve comprises a pilot valve body, a pilot valve core and a pilot valve spring; the pilot valve body is provided with an air inlet part connected with the main valve and an air outlet part communicated with the outside; the pilot valve core slides in the air outlet part and is pressed to a communicating port of the air inlet part and the air outlet part under the elastic force action of the pilot valve spring; in the sliding process of the pilot valve core, the air inlet part is communicated or separated with the air outlet part;

the connecting unit comprises a first connecting pipe connected with the air inlet part and the lower cavity, a second connecting pipe connected with the air inlet part and the lower cavity, and a filter positioned on the first connecting pipe;

the residual medium discharging unit comprises a third connecting pipe and a first valve body; the third connecting pipe is connected with the upper cavity and the discharge cavity; the first valve body is positioned on the third connecting pipe and controls the upper cavity to be communicated or separated with the discharge cavity.

Compared with the prior art, the utility model discloses a residual medium unit of row is opened to pilot operated relief valve accessible for residual medium directional flow to with the emission intracavity of external intercommunication, realize the directional discharge of medium.

Further, the residual medium discharging unit further comprises a one-way valve; the one-way valve is communicated with the first connecting pipe; the one-way valve is located between the filter and the lower cavity. And a non-combustible auxiliary medium is introduced into the one-way valve to apply pressure, so that the discharge speed of the residual medium is improved, and the residual medium is rapidly discharged.

Further, the residual medium discharge unit further comprises a joint; the check valve is communicated with the first connecting pipe through a joint. The connection of the non-return valve with the first connecting pipe is stabilized by means of a joint.

Further, the device also comprises a sampling unit; the sampling unit comprises a fourth connecting pipe and a second valve body, wherein one end of the fourth connecting pipe is connected with the third connecting pipe, and the second valve body is positioned on the fourth connecting pipe and controls the fourth connecting pipe to be switched on or switched off. The medium components in the pilot operated safety valve are sampled and analyzed through the sampling unit, and the medium components can be detected or disassembled under the qualified condition, so that the construction safety is improved.

Further, the pilot valve also comprises a spring seat which is arranged in the air outlet part and has adjustable distance to the communicating port of the air inlet part and the air outlet part; the pilot valve spring is positioned between the spring seat and the pilot valve spool. The distance from the spring seat to the communication port of the air inlet part and the air outlet part is adjusted to adjust the compression amount of the pilot valve spring, so that the opening pressure of the pilot valve is controlled, the pilot safety valve is used in pipelines with different rated pressures, and the applicability is improved.

Furthermore, the pilot valve also comprises an adjusting bolt with one end in threaded connection with the valve body of the pilot valve, and the adjusting bolt is connected between the valve body of the pilot valve and the spring seat. The adjusting bolt is convenient for the adjustment of the distance from the spring seat to the communicating opening of the air inlet part and the air outlet part.

Furthermore, the pilot valve also comprises a pilot valve guide sleeve fixed in the pilot valve body, and the pilot valve core slides in the pilot valve guide sleeve. The guide sleeve guides the sliding of the guide valve body.

Furthermore, the main valve also comprises a main valve guide sleeve fixed in the main valve body, and the main valve body slides in the main valve guide sleeve. The main valve guide sleeve guides the sliding of the main valve body.

Furthermore, the pilot valve also comprises a valve cap which is covered on the adjusting bolt and is positioned on the outer side of the valve body of the pilot valve. The valve cap improves the sealing performance of the pilot operated safety valve.

Further, the first valve body and the second valve body are ball valves.

For a better understanding and an implementation, the present invention is described in detail below with reference to the accompanying drawings.

Drawings

FIG. 1 is a prior art pilot operated safety valve;

fig. 2 is a schematic view of the overall structure of the pilot operated safety valve of the present invention;

FIG. 3 is a schematic view of a main valve according to the present invention;

FIG. 4 is a schematic structural view of the pilot valve of the present invention;

fig. 5 is a schematic structural diagram of the connection unit of the present invention.

Detailed Description

Specifically, referring to fig. 2, the pilot operated safety valve of the present invention includes a main valve 10, a pilot valve 20, a connection unit 30 connected between the main valve 10 and the pilot valve 20, and a residual medium discharging unit 40. The main valve 10 of the connecting pipeline is communicated or isolated with the outside by controlling the on-off of the pilot valve 20, and the residual medium discharging unit 40 is connected with the connecting unit 30 and supplies auxiliary medium to the main valve 10 and the pilot valve 20.

Referring to fig. 3, the main valve 10 includes a main valve body 110, a main valve spool 120, and a main valve spring 130. The inner space of the main valve body 110 is provided with an upper cavity 111, a lower cavity 112 and a discharge cavity 113 located between the upper cavity 111 and the lower cavity 112, the main valve spool 120 slides in the discharge cavity 113, and the main valve spool 120 always separates the upper cavity 111 from the lower cavity 112 and the discharge cavity 113 in the sliding process, and the medium in the cavity 111 can only flow to the lower cavity 112 or the discharge cavity 113 through the connecting unit 30 and the residual medium discharging unit 40. The main valve spool 120 covers the gas inlet 114 at the connection of the lower chamber 112 and the discharge chamber 113. The main valve spring 130 is disposed in the upper chamber 111 and compressed by the main valve spool 120 to generate a spring force toward the gas inlet 114. When the main valve spool 120 covers the gas inlet 114, the lower chamber 112 is blocked from the discharge chamber 113; when the main valve spool 120 is pressed away from the gas inlet 114, the lower chamber 112 communicates with the drain chamber 113. The lower chamber 112 communicates with the duct 1. The discharge chamber 113 communicates with a discharge pipe 8 connected to the outside. Preferably, the main valve 10 further includes a main valve guiding sleeve 140 fixedly installed on an inner wall of the main valve body 110, the main valve guiding sleeve 140 has a gap with the gas inlet 114, and the main valve spool 120 slides within the main valve guiding sleeve 140. Further, the compression amount of the main valve spring 130 in the upper cavity 111 is adjusted by adjusting the height of the main valve spool 120 to adjust the magnitude of the elastic force of the main valve spring 130 pressing against the main valve spool 120.

Referring to FIG. 4, the pilot valve 20 includes a pilot valve body 210, a pilot valve spool 220, and a pilot valve spring 230. The pilot valve body 210 has an inlet 211 connected to the main valve 10, an outlet 212 communicating with a medium collector (not shown), and an outlet 213 provided at the connection of the inlet 211 and the outlet 212. The media collector may be a sealed container that stores media or a conduit that transports media to a secure location. The pilot valve spool 220 slides within the outlet 212 and covers the outlet 213. The pilot valve spring 230 is installed in the gas outlet portion 212 and generates an elastic force toward the gas outlet port 213 under compression of the pilot valve spool 220. When the pilot valve core 220 is covered on the exhaust port 213, the air inlet part 211 is separated from the air outlet part 212; when the pilot valve spool 220 moves away from the exhaust port 213, the inlet 211 communicates with the outlet 212. Further, the pilot valve 20 further includes a pilot valve guiding sleeve 240 fixed on the inner wall of the pilot valve body 210, the pilot valve guiding sleeve 240 has a gap with the exhaust port 213, and the pilot valve core 220 slides in the pilot valve guiding sleeve 240. Further, the pilot valve 20 further includes an adjusting bolt 250 in threaded connection with the pilot valve body 210 and a spring seat 260 fixed on the adjusting bolt 250, the pilot valve spring 230 is sleeved on the adjusting bolt 250 and located between the spring seat 260 and the pilot valve core 220, and the adjusting bolt 250 is rotated to adjust the distance between the spring seat 260 and the exhaust port 213, so as to adjust the compression amount of the pilot valve spring 230. Preferably, a bonnet 270 covers the adjusting bolt 250 outside the pilot valve body 210 to ensure sealing.

The connection unit 30 further includes a first connection pipe 310 connected between the air inlet part 211 and the lower chamber 112, a second connection pipe 320 connected between the air inlet part 211 and the upper chamber 111, and a filter 330 disposed on the first connection pipe 310. The filter 330 filters the medium flowing through the first connection pipe 310.

The residual medium discharging unit 40 includes a joint 410, a check valve 420, a third connection pipe 430, and a first valve body 440. One end of the joint 410 is in communication with the first connection pipe 310 between the filter 330 and the lower chamber 112. The other end of the joint 410 is connected to an auxiliary medium reservoir (not shown) for supplying an auxiliary medium through the check valve 420, and when the auxiliary medium reservoir is opened, the auxiliary medium flows into the joint 420 through the check valve 420 in a single direction and into the first connection pipe 310. The third connection pipe 430 connects the upper chamber 111 and the discharge chamber 113. The first valve body 440 is provided on the third communication pipe 430 and controls the on/off thereof. In this embodiment, the joint 410 is a T-joint, and the first valve body 440 is a ball valve.

Further, for sampling detection, the pilot operated safety valve further includes a sampling unit 50. The sampling unit 50 includes a fourth connection pipe 510 connected to the third connection pipe 430, and a second valve body 520 disposed on the fourth connection pipe 510 and controlling on/off of the same. One end of the fourth connection pipe 510 is communicated with the third connection pipe 430, and the other end is connected with an analyzer (not shown). The second valve body 520 controls the connection and disconnection between the fourth connection pipe 510 and the analyzer. In this embodiment, the second valve body 520 is a ball valve, and the fourth connection pipe 510 is communicated with the third connection pipe 430 through a T-joint.

Based on the structure of the pilot operated safety valve, the working process thereof is specifically described as follows:

first, the lower chamber 112 is connected to the pipe 1, the discharge chamber 113 is connected to the discharge pipe 2, and the gas outlet 212 is connected to the medium collector. And the first valve body 440 and the second valve body 530 are closed, the auxiliary medium reservoir is closed.

When the pipeline 1 conveys a medium and the conveying pressure is less than or equal to the rated pressure, the medium flows into the lower cavity 112, and enters the upper cavity 111 along the first connecting pipe 310 through the air inlet 211 and the second connecting pipe 320 in sequence. Due to the action of the medium pressure, a pressure F1 acting on the main valve spool 120 and directed toward the upper chamber 111 and a pressure F2 directed toward the lower chamber 112 are generated, and F1 is equal to F2 in the equilibrium state. The height of the main valve spool 120 is adjusted to adjust the compression amount of the main valve spring 130 and obtain the elastic force F3 acting on the main valve spool 120 and toward the lower chamber 112. Since F2+ F3> F1, the main valve spool 120 is pressed against the gas inlet 114 so that the lower chamber 112 is blocked from the discharge chamber 113, and the medium cannot be discharged from the discharge pipe 2. Meanwhile, in the pilot valve 20, the pilot valve core 220 is subjected to an elastic force F4 generated by the pilot valve spring 230 and pressing the pilot valve core against the exhaust port 213 and F5 generated by medium in a direction opposite to the direction of F4, the adjusting bolt 250 is rotated to adjust the compression amount of the pilot valve spring 230 so that F4 becomes F5, the pilot valve core 220 is covered on the exhaust port 213, and the air inlet portion 211 and the air outlet portion 212 are also in a blocking state.

When the pipe 1 delivers a medium and the delivery pressure increases to more than the rated pressure, F5 increases at this time, and since the amount of compression of the pilot valve spring 230 remains unchanged, F5> F4, the pilot valve spool 220 is pushed away from the exhaust port 213, the inlet portion 211 communicates with the outlet portion 212, and a small amount of gas is discharged from the outlet portion 212 to the medium collector. Since the upper chamber 111 communicates with the air inlet 211 through the second connection pipe 320, a part of the medium in the upper chamber 111 is discharged to the medium trap, and the medium is discharged to the medium trap, F1 and F2 become smaller at the same time, and the medium outflow speed in the upper chamber 111 is greater than the medium outflow speed in the lower chamber 112 by the throttling action of the filter 330, so that the rate of decrease of F2 is greater than F1. When F2+ F3< F1, the main valve spool 120 moves away from the prime gas inlet 114, the lower chamber 112 communicates with the exhaust chamber 113, a large amount of medium flows from the pipe 1 through the gas inlet 114 and into the exhaust chamber 113, and then flows out to the exhaust pipe 2 to release the pressure, until the delivery pressure in the pipe 1 decreases to F5< F4, the pilot valve spool 220 is re-covered on the exhaust port 213, the inlet portion 211 is blocked from the outlet portion 212 again, the medium continues to flow into the upper chamber 111 until F2+ F3> F1, the main valve spool 120 is re-covered on the gas inlet 114, and the lower chamber 112 is blocked from the exhaust chamber 113.

When the residual medium is discharged by detection or disassembly, the lower chamber 112 and the pipe 1 are cut off, the first valve body 440 is opened, and the medium remaining in the upper chamber 111 flows into the discharge chamber 113 along the third connection pipe 430, and then flows into the discharge pipe 2 to be discharged. Since the gas in the upper chamber 111 flows out, the pressure of the lower chamber 112 is greater than the pressure of the upper chamber 111, and the medium flows from the lower chamber 112 through the first connection pipe 310, the filter 330, the gas inlet 211, and the second connection pipe 320 in sequence and enters the upper chamber 111. The F2 caused by the media is reduced simultaneously with F1, but the rate of reduction of F2 is greater than F1 under the restriction of the filter 330. When F2+ F3< F1, the main valve spool 120 moves toward the upper chamber 111, the lower chamber 112 communicates with the discharge chamber 113, the medium in the lower chamber 112 is directly discharged from the discharge chamber 113, and F1 rapidly decreases. When F2+ F3> F1, the main valve spool 120 is re-seated on the exhaust port 213 until there is no pressure difference between the lower chamber 112 and the upper chamber 111, and the medium stops flowing between the lower chamber 112 and the upper chamber 111. In the process, the air inlet part 211 and the air outlet part 212 are always in a blocking state, and the medium remained in the pilot operated safety valve is only discharged to the discharge pipe 2, so that the directional discharge of most of the remained medium is realized.

Further, in order to accelerate the flow of the medium, quickly discharge the residual medium, open the auxiliary medium reservoir, and make the non-combustible auxiliary medium inflow pressure less than F4, in this embodiment, the auxiliary medium in the auxiliary medium reservoir is nitrogen. The auxiliary medium enters the first connection pipe 310 through the joint 410 and simultaneously flows toward the lower chamber 112 and the upper chamber 111 through the gas inlet 211. The medium remaining in the upper chamber 111 flows into the discharge chamber 113 through the third connection pipe 350 and flows out to the discharge pipe 2 under the pressure of the auxiliary medium, the pressures in the upper chamber 111 and the lower chamber 112 are simultaneously increased, and the pressure increase rate of the lower chamber 112 is greater than the pressure increase rate of the upper chamber 111 under the throttling action of the filter 330. When F2+ F3< F1, the main valve spool 120 leaves the exhaust port 213, the lower chamber 112 communicates with the discharge chamber 113, and the medium remaining in the lower chamber 112 and the upper chamber 111 is discharged to the discharge pipe 2 through the discharge chamber 113 by the urging of the auxiliary medium. The auxiliary medium reservoir is closed and the pressure in the pilot operated safety valve decreases as the medium is discharged to the discharge pipe 2. When F2+ F3> F1, the main valve spool 120 is re-seated to the exhaust port 213, and the pressure is balanced between the lower chamber 112 and the upper chamber 111. Preferably, the auxiliary medium reservoir is switched on and off 2 to 3 times repeatedly until the pilot operated safety valve is filled with the auxiliary medium and the residual medium is completely discharged. At this time, because the combustible medium does not exist in the pilot operated safety valve, the external atmosphere is not polluted even if the pilot operated safety valve is directly opened or disassembled, and the safety is improved.

Further, the first valve body 440 is closed, the second valve body 520 is opened, and the fourth connection pipe 510 is connected to the analyzer. The auxiliary medium reservoir is opened, so that the mixture of the combustible medium and the non-combustible auxiliary medium reservoir in the pilot operated safety valve flows from the upper chamber 111 into the fourth connecting pipe 510 through the second valve body 520, and then enters the analyzer for sampling and analysis. By analyzing the content of the residual combustible medium, when the result detected by the analyzer is qualified, the operation of opening or disassembling can be carried out to improve the safety of construction.

When the reliability of the pilot operated safety valve is detected, the first valve body 440 and the second valve body 520 are closed at the same time, the auxiliary medium reservoir is opened, and an auxiliary medium is introduced; preferably, when the auxiliary medium is introduced, the inflow pressure of the auxiliary medium is slowly increased, so as to ensure that the pressure in the upper chamber 111, the lower chamber 112 and the air inlet 211 keeps increasing steadily. When the pilot valve body 210 moves away from the exhaust port 213 when the inflow pressure of the auxiliary medium is equal to F4, the pressure between the exhaust portion 212 and the medium trap is detected and set to a standard pressure. Reducing the inflow pressure of the auxiliary medium to 90% of the standard pressure, covering the pilot valve body 210 on the exhaust port 213, covering the main valve body 110 on the gas inlet 114, closing the auxiliary medium reservoir, detecting whether the pressure at the connection part of the discharge chamber 113 and the discharge pipe 2 is reduced, if yes, judging that the pilot safety valve has poor air tightness and has unqualified reliability.

Compared with the prior art, the utility model discloses a pilot operated relief valve can dismantle or inspect before directional, discharge remaining medium fast, improve the security of construction and reduce atmospheric pollution. And the device is firmly connected with the device for providing the auxiliary medium, and the applicability is wide. In addition, the sealing performance of the sealing device can be detected regularly, and the sealing device is safe and reliable.

The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention.

Claims (10)

1. A pilot-operated safety valve, characterized in that: comprising: The main valve includes a main valve body, a main valve core and a main valve spring; the main valve body is provided with an upper cavity, a lower cavity communicating with the outside world, and a main valve body located in the upper cavity and the lower cavity A discharge cavity between and communicated with the outside world; the main valve spool slides in the discharge cavity and is pressed to the communication port between the lower cavity and the discharge cavity under the elastic force of the main valve spring ; During the sliding process of the main valve spool, the upper cavity is always isolated from the lower cavity and the discharge cavity, and the lower cavity and the discharge cavity are communicated or isolated; A pilot valve includes a pilot valve body, a pilot valve spool and a pilot valve spring; the pilot valve body is provided with an air inlet part connected to the main valve and an air outlet part communicated with the outside world; the pilot valve spool Sliding in the air outlet and pressed to the communication port between the air inlet and the air outlet under the elastic force of the pilot valve spring; during the sliding process of the pilot valve spool, the air intake The part is communicated or cut off with the air outlet; The connecting unit includes a first connecting pipe connected between the air inlet and the lower cavity, a second connecting pipe connecting the air inlet and the lower cavity, and a connecting pipe located on the first connecting pipe. filter; The residual medium discharge unit includes a third connecting pipe and a first valve body; the third connecting pipe connects the upper cavity and the discharge cavity; the first valve body is located on the third connecting pipe and controls The upper cavity is communicated with or isolated from the discharge cavity. 2 . The pilot-operated safety valve according to claim 1 , wherein: the residual medium discharging unit further comprises a check valve; the check valve is communicated with the first connecting pipe; the check valve is located in the between the filter and the lower cavity. 3 . The pilot-operated safety valve according to claim 2 , wherein the residual medium discharging unit further comprises a joint; the one-way valve communicates with the first connecting pipe through the joint. 4 . 4 . The pilot-operated safety valve according to claim 2 , further comprising a sampling unit; the sampling unit includes a fourth connecting pipe connected to the third connecting pipe at one end, and a fourth connecting pipe located in the fourth connecting pipe. 5 . On and control the second valve body on and off. 5 . The pilot-operated safety valve according to claim 4 , wherein the pilot valve further comprises a spring arranged in the air outlet and having an adjustable distance from the communication port between the air inlet and the air outlet. 6 . seat; the pilot valve spring is located between the spring seat and the pilot valve core. 6 . The pilot-operated safety valve according to claim 5 , wherein the pilot valve further comprises an adjustment bolt, one end of which is threadedly connected to the pilot valve body, and the adjustment bolt is connected to the pilot valve body. 7 . and the spring seat. 7 . The pilot safety valve according to claim 6 , wherein the pilot valve further comprises a pilot valve guide sleeve fixed in the pilot valve body, and the pilot valve core is guided in the pilot valve. 8 . Slip inside the sleeve. 8 . The pilot-operated safety valve according to claim 7 , wherein the main valve further comprises a main valve guide sleeve fixed in the main valve body, and the main valve body is guided in the main valve. 9 . Slip inside the sleeve. 9 . The pilot-operated safety valve according to claim 8 , wherein the pilot valve further comprises a bonnet covering the adjusting bolt and located outside the pilot valve body. 10 . 10 . The pilot-operated safety valve according to claim 9 , wherein the first valve body and the second valve body are both ball valves. 11 .

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