Hand-pulling type pressure relief valve

Abstract

The utility model provides a hand-pull type pressure relief valve, which relates to the technical field of pressure relief valves and comprises a connecting flange, a valve seat, a conical surface, a combined mandrel, a permeable plate, a reset spring and a locking device. A device body is a valve seat, a combined mandrel is coaxially inserted into the inner ring face of the valve seat in a clearance sliding mode, the lower end of the combined mandrel is attached to the conical face of the lower end of the inner ring face of the valve seat in a sealed mode, the upper end of the inner ring face of the valve seat is in threaded connection with a permeable plate, the permeable plate is sleeved with the upper end of the combined mandrel in a clearance sliding mode, and a reset spring is sleeved with an annular groove in the upper end of the combined mandrel. When pressure inside and outside the transformer box needs to be manually uniformized, the locking device connected in a clamped mode is detached, the upper end of the combined mandrel is pulled to rise, the reset spring is compressed, the lower end of the combined mandrel is separated from the conical face, attached to the inner ring face of the valve seat in a sealed mode, of the inner ring face of the valve seat, and then the pressure inside and outside the transformer box needs to be manually uniformized. And gas is discharged from the permeable plate along the valve seat to finish pressure relief.

Description

Technical Field

[0001] This utility model relates to the field of pressure relief valve technology, and in particular to a hand-operated pressure relief valve. Background Technology

[0002] With the rapid development of new energy photovoltaic power stations, onshore wind power, and offshore wind power, new energy transformers are being transported to the vast Gobi Desert, the thin-air plateau, or exported to all parts of the world by sea. Due to the swaying and bumping of sea and land routes, the difference in altitude, and the change in temperature, the pressure difference between the inside and outside of the transformer tank can easily increase, which will test the pressure bearing capacity of the transformer tank and increase the risk of oil leakage during transportation.

[0003] Traditional oil-immersed power transformers have pressure relief valves installed on the outside of the tank. However, these valves are locked during transportation, preventing them from functioning properly. Even when not locked, it is difficult to manually equalize the pressure inside and outside the transformer. The locking device can only be removed when the transformer is energized. During transportation, it is impossible to manually equalize the pressure inside and outside the transformer tank. Utility Model Content

[0004] The purpose of this utility model is to provide a hand-operated pressure relief valve, which has the advantage of manually equalizing the internal and external pressure of the transformer tank. It solves the technical problem that traditional oil-immersed power transformer tanks have pressure relief valves installed on the outside, but these pressure relief valves are in a locked state during transportation, and the pressure relief function is locked and cannot be used. Even if they are not in a locked state, it is very difficult to manually operate them to equalize the internal and external pressure of the transformer.

[0005] This utility model provides a hand-operated pressure relief valve, comprising:

[0006] The connecting flange has a valve seat screwed onto its upper end for sealing.

[0007] The valve seat has a valve cavity at its axis, and a tapered surface is provided at the lower end of the inner annular surface of the valve seat.

[0008] The combined mandrel is slidably inserted into the inner annular surface of the valve seat with a coaxial clearance, and the lower end of the combined mandrel is sealed and fitted with the tapered surface at the lower end of the inner annular surface of the valve seat;

[0009] A vent plate is screwed onto the upper end of the inner ring surface of the valve seat, and the vent plate is slidably sleeved onto the upper end of the combined spindle with gaps. Vent holes are provided on the vent plate.

[0010] The upper end of the outer wall of the combined mandrel is provided with an annular groove, and a return spring is sleeved in the annular groove at the upper end of the combined mandrel.

[0011] The two ends of the reset spring abut against the bottom surface of the vent plate and the bottom surface of the annular groove, respectively.

[0012] A locking device is engaged at the upper end of the outer wall of the valve seat, and the upper end of the locking device abuts against the top of the combined spindle.

[0013] As a further optimization, in order to relieve pressure by lifting the combined mandrel-center shaft when the transformer pressure is too high, the combined mandrel includes:

[0014] The combined spindle-center spindle has a combined spindle-valve core limiting plate connected to its lower outer wall via a thread;

[0015] The threaded connection between the combined mandrel-valve core limiting plate and the combined mandrel-center shaft is coated with thread-locking adhesive.

[0016] The combined spindle-valve core limiting plate has ten through holes evenly distributed on it, and the outer diameter of the combined spindle-valve core limiting plate is larger than the inner diameter of the upper end of the tapered surface at the lower end of the inner ring surface of the valve seat.

[0017] The lower end of the combined mandrel-center shaft is sealed and fitted with the tapered surface at the lower end of the inner ring surface of the valve seat, and the sealing and fitting point is located below the combined mandrel-valve core limiting plate.

[0018] As a further optimization, in order to prevent the combined mandrel seal ring from being damaged by excessive pressure when the combined mandrel is pressed down, a limiting plane is formed on the upper side of the tapered surface at the lower end of the inner ring of the valve seat, and the bottom surface of the combined mandrel-valve core limiting plate abuts against the limiting plane.

[0019] As a further optimization, in order to tighten the pressure relief valve during the transformer sealing test to ensure the normal conduct of the transformer sealing test, and to facilitate manual pressure relief by easy removal of the pressure relief valve when needed, the locking device includes:

[0020] The lower clamping plate of the locking device has a U-shaped groove in the middle of its side wall;

[0021] The lower clamping plate of the locking device has hexagonal through holes on both the left and right sides, and the flange nuts of the locking device are inserted into them with an interference fit.

[0022] The locking device flange face nut is screwed with a locking device clamping screw.

[0023] The upper pressure plate of the locking device is slidably sleeved on the upper end of the outer wall of the clamping screw of the locking device on both sides, and it abuts against the top of the combined mandrel;

[0024] The U-shaped groove of the lower clamping plate of the locking device is sleeved on the upper end of the outer wall of the valve seat.

[0025] The upper end of the outer wall of the valve seat is integrally formed with a boss, and the lower clamping plate of the locking device abuts against the bottom surface of the boss.

[0026] As a further optimization, in order to facilitate manual lifting of the upper end of the combined mandrel for pressure release, a side hole is provided on the side wall of the upper end of the combined mandrel, and a manual venting pull ring is sleeved in the side hole.

[0027] As a further optimization, in order to provide a dustproof function, when the vent plate exhausts gas, the gas pushes the dust cover upwards and is discharged. The dust cover is slidably sleeved on the outer wall of the upper end of the combined spindle, and it fits against the upper end of the valve seat.

[0028] As a further optimization, in order to ensure the sealing between the connecting flange and the valve seat, a first annular sealing groove is provided on the inner wall of the connecting flange;

[0029] The valve seat and connecting flange sealing ring are glued and fixed to the lower end of the outer wall of the valve seat, and are inserted into the first annular sealing groove.

[0030] As a further optimization, in order to ensure the sealing between the valve seat and the combined spindle, a second annular sealing groove is provided on the conical surface of the inner annular surface of the valve seat;

[0031] A combined mandrel sealing ring is attached and fixed to the lower end of the outer wall of the combined mandrel, which is inserted into the second annular sealing groove.

[0032] As a further optimization, to facilitate the connection of the device to the transformer tank cover or side wall, the connecting flange is fixedly connected to the transformer tank cover or side wall.

[0033] As a further optimization, in order to prevent the vent plate from loosening and affecting the opening pressure value of the pressure relief valve after the vent plate screw connection position is adjusted, the threads of the valve seat that mate with the vent plate are coated with threadlocker.

[0034] This utility model provides a hand-operated pressure relief valve with the following improvements and advantages compared with the prior art:

[0035] The main body of the device is a valve seat. The combined mandrel is slidably inserted into the inner ring surface of the valve seat with a gap, and the lower end of the combined mandrel is sealed and fitted with the tapered surface of the lower end of the inner ring surface of the valve seat. A vent plate is screwed to the upper end of the inner ring surface of the valve seat. The vent plate is slidably fitted to the upper end of the combined mandrel with a gap. An annular groove is opened on the upper end of the outer wall of the combined mandrel. A return spring is fitted in the annular groove at the upper end of the combined mandrel. The two ends of the return spring abut against the bottom surface of the vent plate and the bottom surface of the annular groove, respectively. When it is necessary to manually equalize the internal and external pressure of the transformer tank, the locking device is disassembled, the upper end of the combined mandrel is pulled up, the return spring is compressed, the lower end of the combined mandrel is disengaged from the sealed tapered surface of the inner ring surface of the valve seat, and the gas is discharged from the vent plate along the valve seat to complete the pressure relief. Attached Figure Description

[0036] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0037] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0038] Figure 2 This is a schematic diagram of the left-side structure of this utility model;

[0039] Figure 3 This utility model Figure 2 Schematic cross-sectional view of the structure at point AA;

[0040] Figure 4 This is a schematic diagram of the combined mandrel structure of this utility model;

[0041] Figure 5 This is a schematic cross-sectional view of the combined mandrel structure of this utility model;

[0042] Figure 6 This is a schematic diagram of the locking device structure of this utility model;

[0043] Figure 7 This is a schematic front view of the locking device structure of this utility model.

[0044] Explanation of reference numerals in the attached figures:

[0045] 1-Connecting flange, 2-Valve seat, 3-Combined mandrel, 3.1-Combined mandrel-center shaft, 3.2-Combined mandrel-valve core limiting plate, 4-Ventilator plate, 5-Dust cover, 6-Locking device, 6.1-Locking device upper pressure plate, 6.2-Locking device lower clamping plate, 6.3-Locking device flange face nut, 6.4-Locking device clamping screw, 7-Reset spring, 8-Combined mandrel sealing ring, 9-Valve seat and connecting flange sealing ring, 10-Manual venting pull ring, 11-Transformer box cover or side wall. Detailed Implementation

[0046] The technical solution of this utility model will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0047] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0048] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0049] Please see Figure 1-7 This utility model provides a technical solution: a hand-operated pressure relief valve, comprising:

[0050] The connecting flange 1 has a valve seat 2 sealed and screwed to its upper end. The connecting flange 1 is made of 304 or 316 stainless steel, and the valve seat 2 is made of high-quality brass with a nickel-plated surface. Both materials are profiles with high strength and no defects caused by casting. The valve seat 2 is made of hexagonal brass rods, and the lower end of the valve seat 2 is machined with external threads for connection with the connecting flange 1.

[0051] A valve cavity is provided at the center of the valve seat 2, and a tapered surface is provided at the lower end of the inner annular surface of the valve seat 2;

[0052] The combined spindle 3 is slidably inserted into the inner annular surface of the valve seat 2 with a coaxial clearance, and the lower end of the combined spindle 3 is sealed and fitted with the tapered surface at the lower end of the inner annular surface of the valve seat 2;

[0053] A breather plate 4 is screwed onto the upper end of the inner ring surface of the valve seat 2. The breather plate 4 is slidably sleeved onto the upper end of the combined spindle 3 with a gap, and a breather hole is provided on the breather plate 4.

[0054] The opening pressure of the pressure relief valve is adjusted by rotating the vent plate 4 to compress the return spring 7.

[0055] An annular groove is provided on the upper end of the outer wall of the combined mandrel 3, and a return spring 7 is sleeved in the annular groove at the upper end of the combined mandrel 3.

[0056] The outer diameter of the uppermost section of the combined spindle 3 is small, while the diameter of the middle section is large. When the combined spindle 3 of the pressure relief valve is manually pulled and moved upward, the large-diameter middle section forms a limiting relationship with the lower end face of the vent plate 4, thereby protecting the reset spring 7 from damage.

[0057] The two ends of the return spring 7 abut against the bottom surface of the vent plate 4 and the bottom surface of the annular groove, respectively.

[0058] A locking device 6 is engaged with the upper end of the outer wall of the valve seat 2, and the upper end of the locking device 6 abuts against the top of the combined spindle 3.

[0059] The main body of the device is a valve seat 2. A combined spindle 3 is slidably inserted into the inner ring surface of the valve seat 2 with a gap. The lower end of the combined spindle 3 is sealed and fitted with the tapered surface at the lower end of the inner ring surface of the valve seat 2. A vent plate 4 is screwed to the upper end of the inner ring surface of the valve seat 2. The vent plate 4 is slidably fitted to the upper end of the combined spindle 3 with a gap. An annular groove is opened on the upper end of the outer wall of the combined spindle 3. A return spring 7 is fitted in the annular groove at the upper end of the combined spindle 3. The two ends of the return spring 7 abut against the bottom surface of the vent plate 4 and the bottom surface of the annular groove, respectively. When it is necessary to manually equalize the internal and external pressure of the transformer tank, the locking device 6 is disassembled, the upper end of the combined spindle 3 is pulled up, the return spring 7 is compressed, and the lower end of the combined spindle 3 is disengaged from the tapered surface of the inner ring surface of the valve seat 2. The gas is discharged from the vent plate 4 along the valve seat 2 to complete the pressure relief.

[0060] In some embodiments, in order to relieve pressure by lifting the combined mandrel-center shaft 3.1 when the transformer pressure is too high, the combined mandrel 3 includes:

[0061] The combined mandrel-center shaft 3.1 has a combined mandrel-valve core limiting plate 3.2 connected to its lower outer wall via a thread. Both the combined mandrel-center shaft 3.1 and the combined mandrel-valve core limiting plate 3.2 are made of high-quality brass and are nickel-plated after machining.

[0062] The threaded connection between the combined mandrel-valve core limiting plate 3.2 and the combined mandrel-center shaft 3.1 is coated with thread-locking adhesive. After assembly, the outer circle of the combined mandrel-valve core limiting plate 3.2 needs to be machined to a surface finish of Ra1.6. The advantage of making the center shaft into a combined component is to save raw materials and reduce costs. After assembly, the outer circle of the combined mandrel-valve core limiting plate 3.2 is machined to ensure the concentricity of the axis of the combined mandrel-center shaft 3.1 and the outer circle of the combined mandrel-valve core limiting plate 3.2 after assembly.

[0063] The combined spindle-valve core limiting plate 3.2 has ten through holes evenly distributed on it, and the outer diameter of the combined spindle-valve core limiting plate 3.2 is larger than the inner diameter of the upper inner diameter of the tapered surface at the lower end of the inner ring surface of the valve seat 2. The tapered surface limits the sliding of the combined spindle-valve core limiting plate 3.2.

[0064] The lower end of the combined mandrel-center shaft 3.1 is sealed and fitted with the tapered surface at the lower end of the inner ring surface of the valve seat 2, and the sealing and fitting point is located below the combined mandrel-valve core limiting piece 3.2.

[0065] The inner circular surface of the valve seat 2 and the outer circular surface of the machined combined mandrel-valve core limiting piece 3.2 form a clearance fit. This fit is the key structure to ensure that the central axis of the tapered surface and the central axis of the combined mandrel sealing ring 8 can coincide.

[0066] In some embodiments, in order to improve the limiting effect, when the combined spindle 3 is pressed down, to prevent the combined spindle sealing ring 8 from being damaged by excessive pressure, a limiting plane is formed on the upper side of the tapered surface at the lower end of the inner ring surface of the valve seat 2, and the bottom surface of the combined spindle-valve core limiting piece 3.2 abuts against the limiting plane.

[0067] In some embodiments, in order to tighten the pressure relief valve during the transformer sealing test to ensure the normal conduct of the transformer sealing test, and to facilitate manual pressure relief by removing the pressure relief valve when necessary, the locking device 6 includes:

[0068] The lower clamping plate 6.2 of the locking device has a U-shaped groove in the middle of its side wall;

[0069] The lower clamping plate 6.2 of the locking device has hexagonal through holes on both the left and right sides, and the locking device flange nut 6.3 is inserted into the hole with an interference fit. This eliminates the need to machine threads on the stainless steel plate, which is difficult to machine, thus simplifying the process and reducing costs.

[0070] The locking device flange face nut 6.3 is internally threaded with a locking device clamping screw 6.4;

[0071] The upper end of the outer wall of the locking device clamping screws 6.4 on both sides is slidably sleeved with the upper pressure plate 6.1 of the locking device, which abuts against the top of the combined spindle 3;

[0072] The U-shaped groove of the lower clamping plate 6.2 of the locking device is sleeved on the upper end of the outer wall of the valve seat 2;

[0073] The upper part of the outer wall of the valve seat 2 is integrally formed with a boss, and the lower clamping plate 6.2 of the locking device abuts against the bottom surface of the boss.

[0074] In actual use, the combined spindle 3 can be pulled up without disassembling the locking device 6. The corresponding pre-operation is to evenly and alternately loosen the locking device clamping screws 6.4 on both sides, so that the upper pressure plate 6.1 of the locking device no longer presses on the top of the combined spindle 3.

[0075] When it is necessary to re-enter the locked state, tighten the locking screws 6.4 of both locking devices evenly and alternately. The middle of the upper pressure plate 6.1 of the locking device presses against the top of the combined spindle 3. After the locking screws 6.4 of both locking devices are tightened, the pressure relief valve enters the locked state.

[0076] In some embodiments, in order to facilitate manual lifting of the upper end of the combined mandrel 3 for pressure release, a side hole is provided on the upper side wall of the combined mandrel 3, and a manual venting pull ring 10 is sleeved in the side hole.

[0077] In some embodiments, in order to provide a dustproof function, when the vent plate 4 exhausts gas, the gas pushes the dust cover 5 upwards and is discharged, without affecting the pressure relief of the device. The dust cover 5 is slidably sleeved on the outer wall of the upper end of the combined spindle 3, and it fits against the upper end of the valve seat 2.

[0078] In some embodiments, in order to ensure the sealing between the connecting flange 1 and the valve seat 2, a first annular sealing groove is provided on the inner wall of the connecting flange 1;

[0079] A valve seat and connecting flange sealing ring 9 is attached and fixed to the lower end of the outer wall of valve seat 2, which is inserted into the first annular sealing groove.

[0080] In some embodiments, in order to ensure the sealing between the valve seat 2 and the combined spindle 3, a second annular sealing groove is provided on the conical surface of the inner annular surface of the valve seat 2;

[0081] A combined mandrel sealing ring 8 is attached and fixed to the lower end of the outer wall of the combined mandrel 3, which is inserted into the second annular sealing groove.

[0082] In some embodiments, in order to facilitate the connection of the device to the transformer tank cover or side wall 11, the connecting flange 1 is fixedly connected to the transformer tank cover or side wall 11.

[0083] In some embodiments, in order to prevent the vent plate 4 from loosening and affecting the opening pressure value of the pressure relief valve after the vent plate 4 is adjusted in the screw position, thread sealant is applied to the threads of the valve seat 2 that mate with the vent plate 4.

[0084] Working principle:

[0085] The main body of the device is a valve seat 2. A combined spindle 3 is slidably inserted into the inner ring surface of the valve seat 2 with a gap. The lower end of the combined spindle 3 is sealed and fitted with the tapered surface at the lower end of the inner ring surface of the valve seat 2. A vent plate 4 is screwed to the upper end of the inner ring surface of the valve seat 2. The vent plate 4 is slidably fitted to the upper end of the combined spindle 3 with a gap. An annular groove is opened on the upper end of the outer wall of the combined spindle 3. A return spring 7 is fitted in the annular groove at the upper end of the combined spindle 3. The two ends of the return spring 7 abut against the bottom surface of the vent plate 4 and the bottom surface of the annular groove, respectively. When it is necessary to manually equalize the internal and external pressure of the transformer tank, the locking device 6 is disassembled, the upper end of the combined spindle 3 is pulled up, the return spring 7 is compressed, and the lower end of the combined spindle 3 is disengaged from the tapered surface of the inner ring surface of the valve seat 2. The gas is discharged from the vent plate 4 along the valve seat 2 to complete the pressure relief.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A hand-operated pressure relief valve, characterized in that, include: A connecting flange (1) has a valve seat (2) screwed onto its upper end; The valve seat (2) has a valve cavity at its axial center, and a tapered surface is provided at the lower end of the inner annular surface of the valve seat (2); The combined spindle (3) is slidably inserted into the inner ring surface of the valve seat (2) with a coaxial clearance, and the lower end of the combined spindle (3) is sealed and fitted with the tapered surface at the lower end of the inner ring surface of the valve seat (2); The valve seat (2) has a vent plate (4) screwed onto the upper end of its inner ring surface. The vent plate (4) is slidably sleeved onto the upper end of the combined spindle (3) with a gap. Vent holes are provided on the vent plate (4). The upper end of the outer wall of the combined mandrel (3) is provided with an annular groove, and a return spring (7) is sleeved in the annular groove at the upper end of the combined mandrel (3); The two ends of the return spring (7) abut against the bottom surface of the vent plate (4) and the bottom surface of the annular groove, respectively; The upper end of the outer wall of the valve seat (2) is fitted with a locking device (6), and the upper end of the locking device (6) abuts against the top of the combined spindle (3).

2. A hand-operated pressure relief valve according to claim 1, characterized in that, The combined mandrel (3) includes: The combined spindle-center shaft (3.1) has a combined spindle-valve core limiting plate (3.2) connected to its lower outer wall by a thread; The threaded connection between the combined spindle-valve core limiting piece (3.2) and the combined spindle-center shaft (3.1) is coated with thread-locking adhesive; The combined spindle-valve core limiting plate (3.2) has ten through holes evenly distributed on it, and the outer diameter of the combined spindle-valve core limiting plate (3.2) is larger than the inner diameter of the upper end of the tapered surface at the lower end of the inner ring surface of the valve seat (2); The lower end of the combined mandrel-center shaft (3.1) is sealed and fitted with the tapered surface at the lower end of the inner ring surface of the valve seat (2), and the sealed and fitted part is located below the combined mandrel-valve core limiting piece (3.2).

3. A hand-operated pressure relief valve according to claim 2, characterized in that, A limiting plane is formed on the upper side of the tapered surface at the lower end of the inner annular surface of the valve seat (2), and the bottom surface of the combined spindle-valve core limiting piece (3.2) abuts against the limiting plane.

4. A hand-operated pressure relief valve according to claim 1, characterized in that, The locking device (6) includes: The lower clamping plate (6.2) of the locking device has a U-shaped groove in the middle of its side wall; The lower clamping plate (6.2) of the locking device has hexagonal through holes on both the left and right sides, and the flange nut (6.3) of the locking device is inserted into the hole with an interference fit. The locking device flange face nut (6.3) is internally screwed with a locking device clamping screw (6.4); The upper end of the outer wall of the locking device clamping screw (6.4) on both sides is slidably sleeved with the upper pressure plate (6.1) of the locking device, which abuts against the top of the combined mandrel (3); The U-shaped groove of the lower clamping plate (6.2) of the locking device is sleeved on the upper end of the outer wall of the valve seat (2); The upper end of the outer wall of the valve seat (2) is integrally formed with a boss, and the lower clamping plate (6.2) of the locking device abuts against the bottom surface of the boss.

5. A hand-operated pressure relief valve according to claim 1, characterized in that, The upper side wall of the combined mandrel (3) is provided with a side hole, and a manual venting pull ring (10) is sleeved in the side hole.

6. A hand-operated pressure relief valve according to claim 1, characterized in that, The upper outer wall of the combined spindle (3) is slidably fitted with a dust cover (5), which is attached to the upper end of the valve seat (2).

7. A hand-operated pressure relief valve according to claim 1, characterized in that, The inner wall of the connecting flange (1) is provided with a first annular sealing groove; The valve seat (2) has a valve seat and connecting flange sealing ring (9) attached and fixed to the lower end of its outer wall, which is inserted into the first annular sealing groove.

8. A hand-operated pressure relief valve according to claim 1, characterized in that, A second annular sealing groove is provided on the conical surface of the inner annular surface of the valve seat (2); The lower end of the outer wall of the combined mandrel (3) is fixed with a combined mandrel sealing ring (8), which is inserted into the second annular sealing groove.

9. A hand-operated pressure relief valve according to claim 1, characterized in that, The connecting flange (1) is fixedly connected to the transformer box cover or side wall (11).

10. A hand-operated pressure relief valve according to claim 1, characterized in that, The threads of the valve seat (2) that mate with the vent plate (4) are coated with threadlocker.

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