What Is a Vacuum Relief Valve?
There are two types of vacuum negative pressure safety valve: spring type and rod type. In addition, there are impulse-type safety valves, pilot-operated safety valves, safety switching valves, safety decompression valves, and deadweight safety valves. The spring-type safety valve mainly depends on the force of the spring to work. The spring-type safety valve is closed and non-closed. Generally, flammable, explosive or toxic media should be closed. Steam or inert gas can be closed. There are also wrenches and non-wrenches in spring-loaded safety valves. The function of the wrench is mainly to check the flexibility of the valve disc, and sometimes it can also be used for manual emergency pressure relief.
Vacuum negative pressure safety valve
There are two types of vacuum negative pressure safety valve: spring type and rod type. In addition, there are impulse-type safety valves, pilot-operated safety valves, safety switching valves, safety decompression valves, and deadweight safety valves. The spring-type safety valve mainly depends on the force of the spring to work. The spring-type safety valve is closed and non-closed. Generally, the flammable, explosive or toxic medium should be closed.
The main parameter of the vacuum negative pressure safety valve is the displacement. This displacement is determined by the diameter of the valve seat and the opening height of the valve disc. The opening height is different and it is divided into two types: slightly opened and fully opened. Micro-opening means that the opening height of the valve disc is 1/40 l / 20 of the throat diameter of the valve seat. Full open means that the opening height of the valve disc is 1/4 of the throat diameter of the valve seat. Today's mass-produced safety valves are spring-loaded and stem-type. In addition, there are impulse-type safety valves, pilot-operated safety valves, safety switching valves, safety decompression valves, and deadweight safety valves. The spring-type safety valve mainly depends on the force of the spring to work. The spring-type safety valve is closed and non-closed. Generally, flammable, explosive or toxic media should be closed. Steam or inert gas can be closed. There are also wrenches and non-wrenches in spring-loaded safety valves. The function of the wrench is mainly to check the flexibility of the valve disc, and sometimes it can also be used for manual emergency pressure relief. The lever type safety valve mainly relies on the force of the lever heavy hammer to work, but the volume of the lever type safety valve often limits the selection. Use a safety valve with a radiator when the temperature is high.
The operating pressure determines the nominal pressure of the safety valve, the operating temperature determines the operating temperature range of the safety valve, the constant pressure value of the calculated safety valve determines the constant pressure range of the spring or lever, and the material and Structure type, and then calculate the relief valve's throat diameter according to the relief valve relief. The following are general rules for selecting a safety valve.
(L) Hot-water boilers generally use a non-closed micro-opening safety valve with a wrench.
(2) For steam boilers or steam pipes, generally use non-closed full-open safety valves with wrenches.
(3) Liquid incompressible media such as water are generally used with closed micro-opening safety valves or safety relief valves.
(4) High-pressure feed water generally uses closed full-open safety valves, such as high-pressure feed water heaters and heat exchangers.
(5) Gas and other compressible media are generally closed full-open safety valves, such as gas storage tanks and gas pipelines.
(6) E-level steam boilers generally use deadweight safety valves.
(7) Pulse safety valves such as temperature reducing and pressure reducing devices and power station boilers are generally used in large-caliber, large-displacement and high-pressure systems, as shown in Figure 8.
(8) Train tank cars, car tank cars, storage tanks, etc. that transport liquefied gas are generally built-in safety valves, as shown in Figure 4.
(9) A hydraulic safety valve is generally used on the top of the oil tank, which needs to be used in conjunction with a breathing valve.
(10) Pilot-operated safety valves are generally used for underground drainage or natural gas pipelines, as shown in Figure 6.
(11) Generally used on the liquid return pipe of the tank pump outlet of the LPG station
The safety valve plays a safety role in the system. When the system pressure exceeds the specified value, the safety valve is opened, and a part of the gas in the system is vented to the atmosphere, so that the system pressure does not exceed the allowable value, thereby ensuring that the system does not have an accident due to excessive pressure. Safety valve is also called relief valve. The picture shows several typical structural forms of the safety valve. Figure a is a piston safety valve, the valve core is a flat plate. Air source pressure acts on piston A. When the pressure exceeds the safe value determined by the spring force, piston A is ejected, and a part of the compressed air is discharged into the atmosphere from the valve port; when the air source pressure is lower than the safe value, the spring drives The piston moves down and closes the valve port.
Figures b and c are ball valve and diaphragm safety valves, respectively, which work in exactly the same way as the piston type. These three types of safety valves are springs that provide control force. Adjusting the spring pretension force can change the safety value, so it is called a direct-acting safety valve.
Figure d is a pilot operated safety valve. A small direct-acting valve provides control pressure to act on the diaphragm. The hard core on the diaphragm is the valve core and is pressed against the valve seat. When the air source pressure A is greater than the safe pressure, the valve core opens, and the compressed air is discharged into the atmosphere from the left output hole. Diaphragm safety valve and pilot safety valve have good pressure characteristics and sensitive action; but the maximum opening force is relatively small, that is, the flow characteristics are poor. In practical applications, the type of safety valve should be selected according to actual needs, and its diameter should be selected according to the maximum displacement.
A72W-10P / R vacuum negative pressure safety
Urban construction, chemical, metallurgy, petroleum, pharmaceutical, food, beverage, environmental protection, vacuum devices.
Working temperature | 200 |
Suitable medium | HFA72W-10P is suitable for Nitric acid etc.medium |
HFA72W-10R is suitable for Acetic acid etc.medium | |
NO. | Name of part | HFA72W-P Materials | HFA72W-R Materials |
1 | Body | ZG1Cr18Ni9Ti | ZG1Cr18Ni12Mo2Ti |
2 | Valve seat Nozzle | 1Cr18Ni9Ti | ZG1Cr18Ni12Mo2Ti |
3 | Adjusting ring | 1Cr18Ni9Ti | 1Cr18Ni12Mo2Ti |
4 | Bonnet Bonnet | ZG1Cr18Ni9Ti | 1Cr18Ni9Ti |
5 | Stem | 1Cr18Ni9Ti | 1Cr18Ni12Mo2Ti |
6 | Spring | 50CrVA | 50CrVA Coated Teflon |
Nominal diameter DN (mm) Nominal diameter | Dimension (mm) | | | | | | |
D | D1 | D2 | Z-d | b | f1 | H | |
15 | 95 | 65 | 45 | 4-14 | 14 | 2 | 110 |
20 | 105 | 75 | 55 | 4-14 | 16 | 2 | 130 |
25 | 115 | 85 | 65 | 4-14 | 16 | 2 | 150 |
32 | 140 | 100 | 78 | 4-18 | 18 | 2 | 180 |
40 | 150 | 110 | 85 | 4-18 | 18 | 3 | 200 |
50 | 165 | 125 | 100 | 4-18 | 20 | 3 | 221 |
80 | 200 | 160 | 135 | 4-18 | twenty two | 3 | 245 |
100 | 220 | 180 | 155 | 8-18 | twenty two | 3 | 253 |
125 | 250 | 210 | 185 | 8-18 | twenty four | 3 | 280 |
150 | 285 | 240 | 210 | 8-23 | twenty four | 3 | 329 |
200 | 340 | 295 | 265 | 8-23 | 26 | 3 | 377 |
250 | 395 | 350 | 320 | 12-23 | 28 | 3 | 440 |
