The classification of the safety valve

According to the principle classification, can be divided into direct acting safety valve and the direct acting API 6A gate valve.
Direct acting safety valve is opened under the direct effect of working medium, which rely on the role of the working medium pressure load mechanism to overcome the mechanical load on the disc, the valve opens. The safety valve has simple structure, quick, good reliability, etc. But because depend on the structure of the load, the load size is restricted, cannot be used for high pressure, large caliber.The direct acting safety valve, this class can be divided into the guide type safety valve, relief valve driving force auxiliary device of the relief valve.
Pilot operated relief valve is depend on medium from a pilot valve to drive or control. The pilot valve itself is a direct acting safety valve, sometimes also adopt other forms of the valve. Pilot operated relief valve is suitable for high pressure, large diameter of the occasion. Pilot operated relief valve of the main valve can also be designed to rely on the working medium to seal form, or can be on the disc is much bigger than direct acting safety valve mechanical load, thus has good sealing performance. At the same time, its action is rarely influenced by back pressure. The choke valve of the reliability of the drawback is that it related to the main valve and pilot valve, action is better than direct acting safety valve as rapidly, reliable, and the structure is complicated.
Driving force auxiliary device of the relief valve is by using a power aided device, in the case of below the normal opening pressure forced the relief valve opens. This valve is suitable for the opening pressure is very close to the working pressure, or need to open the relief valve on a regular basis to check or remove adhesive, freezing medium. At the same time, also provide a means of forced open the relief valve in an emergency.
According to pressure regulating classification, according to pressure can adjust classification, can be divided into fixed an adjustable adjustable relief valve and safety valve. Fixed an adjustable relief valve pressure value, the factory has set good, can't change, when used in cb are commonly used in central air conditioning air conditioning, boilers, solar system, such as S10 safety valve series. Adjustable pressure relief valve jump is along with the different needs of users in a certain range can be arbitrarily set, often used in system protection pressure to change often, such as S10 valve series, but the price is generally high.
Steam boiler safety valve, generally choose open all rev. Spring safety valve, 0490 series; Liquid medium with safety valve, generally choose micro rev. Spring safety valve, 0485 series; Air or other gas medium with safety valve, general choose closed all rev type spring safety valve; Liquefied petroleum gas (LPG) in rail tanker car tank lorry or liquefied petroleum gas (LPG) with safety valve, generally choose the rev type globe valve is installed inside; Failure of export with safety valve, pilot operated relief valve is generally selected; Steam generating equipment of high pressure bypass valve, general selection has a dual function of safety and control pilot operated relief valve.
If you want to do when you start the test on a regular basis, should be chosen with ascension wrench of the relief valve. When the medium pressure reaches more than 75% of the opening pressure, can improve wrench lift the disc from the seat a bit, in order to check the safety valve opening flexibility; If the medium temperature is higher, in order to lower the temperature of the spring chamber, generally when the temperature of the safety valve in closed more than 300 ℃, and open the relief valve using temperature exceeds 350 ℃, should choose safety valve with radiator; Back pressure is changing if the valve outlet, and its variation by more than 10% of the opening pressure, should choose bellows valve; If corrosive medium, should choose bellows valve, prevent important parts due to failure by corrosion medium.