CN221034142U - Emergency pressure vacuum relief valve for drainage - Google Patents

Abstract

The utility model relates to the technical field of storage tank safety valves, and provides a drainage type emergency pressure vacuum relief valve, which comprises: the positive pressure exhaust mechanism comprises a positive pressure valve seat and a positive pressure valve disc, and an air suction opening is formed in the positive pressure valve disc; the negative pressure air supplementing mechanism comprises a negative pressure valve seat and a negative pressure valve disc, the negative pressure valve seat is arranged on the positive pressure valve disc and aligned with the air suction opening, and the upper surface of the negative pressure valve disc is concave; the drainage system comprises a draining structure and a drainage pipe, the draining structure is formed on the negative pressure valve disc, the drainage pipe is arranged on the side wall of the positive pressure valve seat in a penetrating mode in a sealing mode, the liquid outlet end of the drainage pipe is located at the outer side of the positive pressure valve seat, and the liquid inlet end of the drainage pipe is communicated with the draining structure. The utility model can timely guide the moisture on the upper surface of the negative pressure valve disc to the outer side of the positive pressure valve seat, thereby ensuring that the materials in the storage tank are not polluted by rainwater.

Description

Emergency pressure vacuum relief valve for drainage

Technical Field

The utility model relates to the technical field of storage tank safety valves, in particular to a drainage type emergency pressure vacuum relief valve.

Background

The working principle of the emergency pressure vacuum relief valve is as follows: the emergency pressure vacuum relief valve is arranged at the top of the storage tank, and positive pressure and negative pressure are set for opening the emergency pressure vacuum relief valve according to the opening pressure requirement. When a fire disaster occurs outside the storage tank, the medium in the storage tank is heated, the volatile gas is greatly increased, and the gas phase space pressure in the storage tank is increased. When the pressure reaches the set positive pressure opening pressure of the emergency pressure vacuum relief valve, the positive pressure of the emergency pressure vacuum relief valve starts to open the valve disc, the gas in the storage tank is discharged, the positive pressure in the storage tank is controlled, and the positive pressure protection effect of protecting the storage tank is achieved. When the temperature of the storage tank is reduced or the discharge is carried out, the gas phase space in the storage tank is enlarged, so that the gas phase space of the storage tank is negative pressure, when the negative pressure reaches the set value of the negative pressure of the emergency pressure vacuum relief valve, the negative pressure valve disc is propped open by air, the gas phase space of the storage tank is supplemented with air, and the negative pressure in the storage tank is controlled to achieve the negative pressure protection effect on the storage tank. The conventional emergency pressure vacuum relief valve mainly has the following problems:

The first problem is: and a negative pressure valve seat is processed on the positive pressure valve disc, namely, the negative pressure valve seat and the positive pressure valve disc are of an integrated structure. Processing a negative pressure valve disc on the positive pressure valve disc, wherein when the positive pressure valve disc is thinner, the negative pressure valve seat is difficult to process, and the processing stress can cause the deformation of the positive pressure valve disc, so that the sealing effect of the positive pressure sealing pair and the negative pressure sealing pair is poor; the negative pressure valve seat and the positive pressure valve disc are integrated, when the negative pressure valve seat is damaged, the negative pressure valve seat and the positive pressure valve disc can be maintained or replaced together, and the maintenance and replacement cost is high.

A second problem: the negative pressure air inlet and the back surface of the positive pressure valve disc are a plane. When the rain falls into the weather, the rain water is splashed on the positive pressure valve disc from the side surface of the rain cover, the rain water on the positive pressure valve disc can be poured into a closed space formed by the negative pressure valve disc and the negative pressure valve seat from the negative pressure air inlet to form accumulated water, and when the negative pressure valve disc is opened, the accumulated water can enter the storage tank to pollute materials in the storage tank.

Disclosure of utility model

In view of the above-mentioned drawbacks of the prior art, the present utility model is to provide a drainage type emergency pressure vacuum relief valve, which can timely guide moisture on the upper surface of a negative pressure valve disc to the outer side of a positive pressure valve seat, so as to prevent the moisture on the upper surface of the negative pressure valve disc from flowing into the inner space of the positive pressure valve seat when the negative pressure valve disc is opened, and thus ensure that materials in a storage tank are not polluted by rainwater.

In order to solve the above technical problems, the present utility model provides a drainage type emergency pressure vacuum relief valve, comprising:

The positive pressure exhaust mechanism comprises a positive pressure valve seat and a positive pressure valve disc, the positive pressure valve disc is in resetting fit with the positive pressure valve seat in an opening and closing manner, and an air suction opening is formed in the positive pressure valve disc;

The negative pressure air supplementing mechanism comprises a negative pressure valve seat and a negative pressure valve disc, the negative pressure valve seat is arranged on the positive pressure valve disc and aligned with the air suction opening, the negative pressure valve disc is in resetting fit with the negative pressure valve seat in an opening and closing manner, and the upper surface of the negative pressure valve disc is concave so that moisture on the upper surface of the negative pressure valve disc is completely converged to the center of the negative pressure valve disc under the action of self gravity;

The rain shielding structure comprises a rain shielding cover, and the rain shielding cover is arranged above the positive pressure valve seat;

The drainage system comprises a draining structure and a drainage pipe, the draining structure is arranged in the center of the negative pressure valve disc, the drainage pipe is arranged on the side wall of the positive pressure valve seat in a penetrating mode in a sealing mode, the liquid outlet end of the drainage pipe is arranged on the outer side of the positive pressure valve seat, and the liquid inlet end of the drainage pipe is communicated with the draining structure;

The setting position of the draining structure is always higher than the penetrating position of the drain pipe on the positive pressure valve seat, and the drain pipe is always inclined downwards from inside to outside.

Preferably, the rain shield structure further comprises a shield support, and the rain shield is connected to the positive pressure valve seat through the shield support.

Preferably, the liquid inlet end of the drain pipe is communicated with the draining structure through a pagoda joint.

Preferably, the negative pressure valve seat is detachably and sealingly arranged on the positive pressure valve disc.

Preferably, the drain pipe comprises a hard drain section and a flexible drain section which are mutually communicated, the hard drain section is sealed to penetrate through the side wall of the positive pressure valve seat, and the flexible drain section is communicated with the draining structure.

Preferably, the negative pressure air supplementing mechanism further comprises a negative pressure guiding assembly, wherein the negative pressure guiding assembly comprises a negative pressure bracket arranged on the positive pressure valve disc, a negative pressure valve rod arranged on the negative pressure bracket in an up-down sliding mode and a negative pressure resetting assembly for driving the negative pressure valve rod to reset, and the lower end of the negative pressure valve rod is in sealing connection with the negative pressure valve disc.

Preferably, the negative pressure reset assembly comprises a negative pressure spring and a negative pressure regulating piece, the negative pressure spring is sleeved on the negative pressure valve rod, and two ends of the negative pressure spring are respectively abutted to the negative pressure bracket and the negative pressure regulating piece so that the negative pressure spring is in a compressed state.

Preferably, the negative pressure support comprises a water retaining ring and a guide pipe, wherein the water retaining ring is connected with the guide pipe through spokes, the negative pressure valve rod is arranged in a pipe cavity of the guide pipe in a penetrating mode, and the water retaining ring is arranged on the upper surface of the positive pressure valve disc in a sealing mode and is aligned with the air suction opening.

Preferably, the draining structure is formed at the lower end of the negative pressure valve rod.

Preferably, the draining structure comprises a radial draining part and a vertical draining part which are mutually communicated, the radial draining part is positioned at the lowest part of the upper surface of the negative pressure valve disc, and the vertical draining part is communicated with the liquid inlet end of the drain pipe.

As described above, the drainage type emergency pressure vacuum relief valve of the present utility model has the following beneficial effects: the drainage system can avoid rainwater from forming ponding in a groove space defined by the negative pressure valve disc and the negative pressure valve seat, and timely drain water on the upper surface of the negative pressure valve disc out of the positive pressure valve seat. When the emergency pressure vacuum relief valve is used, a worker needs to fixedly install the lower port of the positive pressure valve seat on the peripheral wall of a storage tank, and when the pressure in the storage tank does not reach the set pressure of the emergency pressure vacuum relief valve, the emergency pressure vacuum relief valve is in a state as shown in the figure. When encountering weather, rainwater is driven into the space right below the rain shield from the area between the rain shield and the positive pressure valve seat, falls on the upper surface of the positive pressure valve disc, and possibly flows into the groove space defined by the negative pressure valve disc and the negative pressure valve seat. Because the upper surface of negative pressure valve disc is concave, can make the moisture that is located negative pressure valve disc upper surface all converge to the waterlogging caused by oneself gravity effect like this. Because the liquid outlet end of the drain pipe is positioned at the outer side of the positive pressure valve seat, the liquid inlet end of the drain pipe is communicated with the draining structure, and water in the draining structure flows into the drain pipe. More important is: the setting position of waterlogging caused by excessive rainfall structure is higher than the wearing position of drain pipe on the malleation disk seat, and the drain pipe is by interior outside slope down all the time, and the moisture that is arranged in the drain pipe like this can flow to the outside department of malleation disk seat along the extending direction of drain pipe to avoid the moisture of negative pressure valve disk upper surface to flow into the inner space of malleation disk seat when the negative pressure valve disk is opened, avoid the material in the storage tank to receive the pollution.

Therefore, the drainage type emergency pressure vacuum relief valve can timely guide moisture on the upper surface of the negative pressure valve disc to the outer side of the positive pressure valve seat, so that the moisture on the upper surface of the negative pressure valve disc is prevented from flowing into the inner space of the positive pressure valve seat when the negative pressure valve disc is opened, and the materials in the storage tank are prevented from being polluted by rainwater.

Drawings

FIG. 1 is a schematic diagram illustrating a closed state of an embodiment of a drain type emergency pressure vacuum relief valve according to the present utility model;

FIG. 2 shows an enlarged view of portion A of FIG. 1;

FIG. 3 is a diagram illustrating an exhaust state of an embodiment of the drain emergency pressure vacuum relief valve of the present utility model;

FIG. 4 is a schematic diagram of a state of charge of an embodiment of the drain emergency pressure vacuum relief valve of the present utility model;

Fig. 5 shows a bottom view of the negative pressure bracket.

Description of element reference numerals

1. Positive pressure exhaust mechanism

11. Positive pressure valve seat

12. Positive pressure valve disc

121. Suction opening

13. Positive pressure guide assembly

131. Positive pressure valve rod

132. Positive pressure regulating piece

133. Positive pressure spring

2. Negative pressure air supplementing mechanism

21. Negative pressure valve seat

22. Negative pressure valve disc

23. Negative pressure sealing gasket

24. Negative pressure guide assembly

241. Negative pressure bracket

241A water retaining ring

241B guiding tube

241C spoke

242. Negative pressure valve rod

243. Negative pressure reset assembly

243A negative pressure spring

243B negative pressure regulating member

3. Rain shielding structure

31. Rain-proof cover

32. Cover body support

4. Drainage system

41. Draining structure

411. Radial liquid discharge part

412. Vertical liquid discharge part

42. Drain pipe

421. Hard drainage section

422. Flexible drainage section

43. Pagoda joint

Detailed Description

Further advantages and effects of the present utility model will become apparent to those skilled in the art from the disclosure of the present utility model, which is described by the following specific examples.

It should be understood that the structures, proportions, sizes, etc. shown in the drawings are for the purpose of understanding and reading the disclosure, and are not intended to limit the scope of the utility model, which is defined by the appended claims, but rather by the claims, unless otherwise indicated, and unless otherwise indicated, all changes in structure, proportions, or otherwise, used by those skilled in the art, are included in the spirit and scope of the utility model. Also, the terms such as "upper," "lower," "left," "right," "middle," and "a" and the like recited in the present specification are merely for descriptive purposes and are not intended to limit the scope of the utility model, but are intended to provide relative positional changes or modifications without materially altering the technical context in which the utility model may be practiced.

As shown in fig. 1, 2, 4 and 4, the present utility model provides a drainage type emergency pressure vacuum relief valve, comprising:

The positive pressure exhaust mechanism 1, the positive pressure exhaust mechanism 1 comprises a positive pressure valve seat 11 and a positive pressure valve disc 12, the positive pressure valve disc 12 is in open-close fit with the positive pressure valve seat 11 in a resettable manner, and an air suction opening 121 is formed in the positive pressure valve disc 12;

The negative pressure air supplementing mechanism 2 comprises a negative pressure valve seat 21 and a negative pressure valve disc 22, wherein the negative pressure valve seat 21 is arranged on the positive pressure valve disc 12 and aligned with the air suction opening 121, the negative pressure valve disc 22 is in open-close fit with the negative pressure valve seat 21 in a resetting manner, and the upper surface of the negative pressure valve disc 22 is concave so that moisture on the upper surface of the negative pressure valve disc 22 is completely converged to the center of the negative pressure valve disc 22 under the action of self gravity;

the rain shielding structure 3, the rain shielding structure 3 comprises a rain shield 31, and the rain shield 31 is arranged above the positive pressure valve seat 11;

The drainage system 4 comprises a draining structure 41 and a drainage pipe 42, wherein the draining structure 41 is arranged at the center of the negative pressure valve disc 22, the drainage pipe 42 is hermetically penetrated through the side wall of the positive pressure valve seat 11, the liquid outlet end of the drainage pipe 42 is arranged at the outer side of the positive pressure valve seat 11, and the liquid inlet end of the drainage pipe 42 is communicated with the draining structure 41;

The draining structure 41 is always higher than the penetrating position of the drain pipe 42 on the positive pressure valve seat 11, and the drain pipe is always inclined downwards from inside to outside.

Compared with the traditional emergency pressure vacuum relief valve, the utility model has the main innovation points that: the drainage system 3 can avoid rainwater from forming ponding in a groove space defined by the negative pressure valve disc and the negative pressure valve seat together, and drain water on the upper surface of the negative pressure valve disc out of the positive pressure valve seat 11 in time. When in use, a worker needs to fixedly install the lower port of the positive pressure valve seat 11 on the outer peripheral wall of a storage tank, and when the pressure in the storage tank does not reach the set pressure of the emergency pressure vacuum relief valve, the emergency pressure vacuum relief valve is in a state as shown in fig. 1. When it encounters weather, rainwater is caught from the area between the rain cover 31 and the positive pressure valve seat 11, and falls directly under the rain cover 31 on the upper surface of the positive pressure valve disc 12, and may enter the recessed space defined by the negative pressure valve disc and the negative pressure valve seat together. Since the upper surface of the negative pressure valve disc 22 is concave, the water on the upper surface of the negative pressure valve disc 22 can be completely collected to the draining structure 41 under the action of self gravity. Because the liquid outlet end of the drain pipe 42 is located at the outer side of the positive pressure valve seat 11, the liquid inlet end of the drain pipe 42 is communicated with the draining structure 41, so that water in the draining structure 41 flows into the drain pipe 42. More important is: the setting position of the draining structure 41 is higher than the penetrating position of the drain pipe 42 on the positive pressure valve seat 11, so that the water in the drain pipe 42 can flow to the outer side of the positive pressure valve seat 11 along the extending direction of the drain pipe 42, thereby avoiding that the water on the upper surface of the negative pressure valve disc 22 flows into the inner space of the positive pressure valve seat 11 when the negative pressure valve disc 22 is opened, and avoiding that the materials in the storage tank are polluted.

When the pressure in the storage tank is higher than the positive pressure opening pressure set by the emergency pressure vacuum relief valve, the positive pressure valve disc 12 is pushed up by the high pressure in the tank, the high pressure gas of the storage tank is released, and when the pressure of the storage tank is released to reach the back seat pressure, the positive pressure valve disc 12 returns to the positive pressure valve seat 11 to realize positive pressure sealing as shown in a state shown in fig. 3; when the vacuum pressure in the storage tank is lower than the negative pressure opening pressure set by the emergency pressure vacuum relief valve, the negative pressure valve disc 22 is pressed downwards by air, the negative pressure valve disc is separated from the negative pressure valve seat, the air sequentially flows through the air suction opening 121, the inside of the negative pressure valve seat 21 and the inside of the positive pressure valve seat 11, and finally is supplemented into the storage tank, the pressure in the storage tank is gradually increased, and when the pressure in the storage tank is increased to the negative pressure returning pressure, the negative pressure valve disc 22 is pulled back until the negative pressure valve seat 21 is closed.

Therefore, the drainage type emergency pressure vacuum relief valve can timely guide the moisture on the upper surface of the negative pressure valve disc 22 to the outer side of the positive pressure valve seat 11, so that the moisture on the upper surface of the negative pressure valve disc 22 is prevented from flowing into the inner space of the positive pressure valve seat 11 when the negative pressure valve disc 22 is opened, and the materials in the storage tank are prevented from being polluted by rainwater.

In order to ensure smooth exhaust or air supply of the drainage type emergency pressure vacuum relief valve, the rain shield structure 3 further includes a cover bracket 32, and the rain shield 31 is connected to the positive pressure valve seat 11 through the cover bracket 32. Specifically, the cover body support 32 includes a plurality of support rods uniformly distributed in the circumferential direction, and each support rod is fixedly connected with the rain cover 31 and the positive pressure valve seat 11.

The negative pressure valve seat 21 may be a separate machined part, and the negative pressure valve seat 21 may be detachably and sealingly provided to the positive pressure valve disc 12. The negative pressure valve seat and the positive pressure valve disc are mounted together through bolts.

The utility model can realize the rapid maintenance and low-cost replacement of the negative pressure valve seat by using the negative pressure valve seat which is formed independently. In some preferred embodiments, a negative pressure sealing gasket 23 is provided between the negative pressure valve seat 21 and the positive pressure valve disk 12. This further facilitates the above-mentioned airtight connection between the negative pressure valve seat 21 and the positive pressure valve disc 12.

As shown in fig. 3, for quick-assembly and butt joint of the pipeline, the liquid inlet end of the drain pipe 42 is connected to the draining structure 41 through a pagoda joint 43. In order to improve the flow guiding smoothness of the drain pipe 42, the drain pipe 42 is made of different materials, the drain pipe 42 includes a hard drain section 421 and a flexible drain section 422 which are mutually communicated, the hard drain section 421 is sealed to penetrate through the side wall of the positive pressure valve seat 11, and the flexible drain section 422 is communicated with the draining structure 41. The rigid drain section 421 and the flexible drain section 422 may also be docked using the pagoda fitting 43. In some embodiments, the extending track of the hard water draining section 421 is L-shaped, the long pipe portion of the hard water draining section 421 is obliquely sealed and penetrated through the side wall of the positive pressure valve seat 11, and the short pipe portion of the hard water draining section 421 is vertically arranged. The flexible drainage section 422 is obliquely hung at the lower end of the negative pressure valve rod and can move up and down along with the positive pressure valve disc 12 or the negative pressure valve disc 22, but the inner height and the outer height are always kept.

As shown in fig. 1, in order to ensure the up-and-down movement of the positive pressure valve disc 12, the positive pressure exhaust mechanism 1 further includes a positive pressure guide assembly 13, the positive pressure guide assembly 13 includes a positive pressure valve rod 131 vertically arranged and slidably penetrating the positive pressure valve disc 12, the bottom end of the positive pressure valve rod 131 is provided with a positive pressure valve seat 11, the top end of the positive pressure valve rod 131 is provided with a positive pressure adjusting member 132 (e.g. an adjusting nut), the positive pressure guide assembly 13 further includes a positive pressure spring 133, and the positive pressure spring 133 is respectively abutted against the positive pressure adjusting member 132 and the positive pressure valve disc 12. In some preferred schemes, positive pressure valve rods are uniformly arranged on the positive pressure valve seat 11 through threaded connection, the positive pressure valve rods are slidably arranged in valve rod holes of the positive pressure valve discs in a penetrating mode, and the positive pressure valve discs are mutually abutted with the positive pressure valve bodies through self gravity and elasticity of the positive pressure springs 133 to form positive pressure sealing pairs; the different positive pressure opening pressures of the emergency pressure vacuum relief valve are achieved by adjusting the weight of the positive pressure valve disc or the compression amount of the positive pressure spring 133.

As shown in fig. 3, in order to ensure the up-and-down movement of the negative pressure valve disc 22, the negative pressure air supply mechanism 2 further includes a negative pressure guide assembly 24, wherein the negative pressure guide assembly 24 includes a negative pressure bracket 241 provided on the positive pressure valve disc 12, a negative pressure valve rod 242 provided on the negative pressure bracket 241 in a manner of sliding up and down, and a negative pressure resetting assembly 243 for driving the negative pressure valve rod 242 to reset, and a lower end of the negative pressure valve rod 242 is connected to the negative pressure valve disc 22.

As shown in fig. 4, the negative pressure resetting assembly 243 further includes a negative pressure spring 243a and a negative pressure adjusting member 243b, wherein the negative pressure spring 243a is sleeved on the negative pressure valve rod 242, and two ends of the negative pressure spring 243a are respectively abutted against the negative pressure bracket 241 and the negative pressure adjusting member 243b so as to make the negative pressure spring 243a in a compressed state. The negative pressure adjusting member 243b may be a compression nut, and the compressed negative pressure spring will react the elastic force to the negative pressure valve disc, and the acting force will press the negative pressure valve disc and the negative pressure valve seat together to form a negative pressure sealing pair; the compression amount of the negative pressure spring is adjusted through the compression nut, so that different negative pressure opening pressures of the emergency pressure vacuum relief valve are realized.

As shown in fig. 4 and 5, the negative pressure support 241 includes a water blocking ring 241a and a guide tube 241b, where the water blocking ring 241a and the guide tube 241b are connected by spokes 241c, the lumen of the guide tube 241b is perforated with the negative pressure valve rod 242, and the water blocking ring 241a is sealingly disposed on the upper surface of the positive pressure valve disc 12 and aligned with the air suction opening 121. So configured, when the water blocking ring 241a is horizontally sealingly disposed on the upper surface of the positive pressure valve disk 12, the water blocking ring 241a can block the water located at the outside of the upper surface of the positive pressure valve disk 12 from flowing to the negative pressure valve disk 22 because the water blocking ring 241a has a certain thickness. Only when the wind and rain are large, a small amount of rainwater may fall into the water blocking ring 241 a. Further, in order to increase the water blocking performance, a water blocking sealing gasket is provided between the water blocking ring 241a and the positive pressure valve disc 12.

As shown in fig. 2, the draining structure 41 is formed at the lower end of the negative pressure valve stem 242 in order to avoid breaking the overall balance structure of the negative pressure valve disc 22. To further drain the moisture on the upper surface of the suction valve disc 22 to the drain pipe 42 in time. The draining structure 41 includes a radial draining portion 411 and a vertical draining portion 412, wherein the radial draining portion 411 is located at the lowest position of the upper surface of the negative pressure valve disc 22, and the vertical draining portion 412 is connected to the liquid inlet end of the drain pipe 42.

In summary, the drainage type emergency pressure vacuum relief valve can timely guide moisture on the upper surface of the negative pressure valve disc to the outer side of the positive pressure valve seat, so that the moisture on the upper surface of the negative pressure valve disc is prevented from flowing into the inner space of the positive pressure valve seat when the negative pressure valve disc is opened, and the materials in the storage tank are prevented from being polluted by rainwater. Therefore, the utility model effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles of the present utility model and its effectiveness, and are not intended to limit the utility model. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the utility model. Accordingly, it is intended that all equivalent modifications and variations of the utility model be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims (10)

1. A drain type emergency pressure vacuum relief valve, comprising:

The positive pressure exhaust mechanism (1), the positive pressure exhaust mechanism (1) comprises a positive pressure valve seat (11) and a positive pressure valve disc (12), the positive pressure valve disc (12) is in resetting fit with the positive pressure valve seat (11) in an opening and closing way, and an air suction opening (121) is formed in the positive pressure valve disc (12);

The negative pressure air supplementing mechanism (2), the negative pressure air supplementing mechanism (2) comprises a negative pressure valve seat (21) and a negative pressure valve disc (22), the negative pressure valve seat (21) is arranged on the positive pressure valve disc (12) and aligned to the air suction opening (121), the negative pressure valve disc (22) is in resetting fit with the negative pressure valve seat (21) in an opening and closing manner, the upper surface of the negative pressure valve disc (22) is concave so that moisture on the upper surface of the negative pressure valve disc (22) is completely converged to the center of the negative pressure valve disc (22) under the action of self gravity;

The rain shielding structure (3), the rain shielding structure (3) comprises a rain shielding cover (31), and the rain shielding cover (31) is erected above the positive pressure valve seat (11);

The drainage system (4), the drainage system (4) comprises a draining structure (41) and a drain pipe (42), the draining structure (41) is arranged at the center of the negative pressure valve disc (22), the drain pipe (42) is hermetically penetrated through the side wall of the positive pressure valve seat (11), the liquid outlet end of the drain pipe (42) is positioned at the outer side of the positive pressure valve seat (11), and the liquid inlet end of the drain pipe (42) is communicated with the draining structure (41);

Wherein, the setting position of the draining structure (41) is always higher than the penetrating position of the drain pipe (42) on the positive pressure valve seat (11); the drain pipe (42) is always inclined downwards from inside to outside.

2. The drain emergency pressure vacuum relief valve of claim 1, wherein: the rain shielding structure (3) further comprises a cover body support (32), and the rain shielding cover (31) is connected to the positive pressure valve seat (11) through the cover body support (32).

3. The drain emergency pressure vacuum relief valve of claim 1, wherein: the liquid inlet end of the drain pipe (42) is communicated with the draining structure (41) through a pagoda joint (43).

4. The drain emergency pressure vacuum relief valve of claim 1, wherein: the negative pressure valve seat (21) is detachably arranged on the positive pressure valve disc (12) in a sealing mode.

5. The drain emergency pressure vacuum relief valve of claim 1, wherein: the drain pipe (42) comprises a hard drain section (421) and a flexible drain section (422) which are mutually communicated, the hard drain section (421) is hermetically penetrated through the side wall of the positive pressure valve seat (11), and the flexible drain section (422) is communicated with the draining structure (41).

6. The drain emergency pressure vacuum relief valve of claim 1, wherein: the negative pressure air supplementing mechanism (2) further comprises a negative pressure guide assembly (24), the negative pressure guide assembly (24) comprises a negative pressure support (241) arranged on the positive pressure valve disc (12), a negative pressure valve rod (242) arranged on the negative pressure support (241) in an up-down sliding mode and a negative pressure reset assembly (243) for driving the negative pressure valve rod (242) to reset, and the lower end of the negative pressure valve rod (242) is in sealing connection with the negative pressure valve disc (22).

7. The drain emergency pressure vacuum relief valve of claim 6, wherein: the negative pressure reset assembly (243) comprises a negative pressure spring (243 a) and a negative pressure adjusting piece (243 b), the negative pressure spring (243 a) is sleeved on the negative pressure valve rod (242), and two ends of the negative pressure spring (243 a) are respectively abutted against the negative pressure bracket (241) and the negative pressure adjusting piece (243 b) so that the negative pressure spring (243 a) is in a compressed state.

8. The drain emergency pressure vacuum relief valve of claim 6, wherein: the negative pressure support (241) comprises a water retaining ring (241 a) and a guide pipe (241 b), wherein the water retaining ring (241 a) is connected with the guide pipe (241 b) through spokes (241 c), the negative pressure valve rod (242) is arranged in the pipe cavity of the guide pipe (241 b) in a penetrating mode, and the water retaining ring (241 a) is arranged on the upper surface of the positive pressure valve disc (12) in a sealing mode and is aligned with the air suction opening (121).

9. The drain emergency pressure vacuum relief valve of claim 6, wherein: the draining structure (41) is formed at the lower end of the negative pressure valve rod (242).

10. The drain emergency pressure vacuum relief valve of claim 9, wherein: the draining structure (41) comprises a radial draining part (411) and a vertical draining part (412) which are communicated with each other, the radial draining part (411) is positioned at the lowest part of the upper surface of the negative pressure valve disc (22), and the vertical draining part (412) is communicated with the liquid inlet end of the drain pipe (42).