Dynamic stability of the safety valve

When the protected system pressure increases, resulting in an additional force elements acting on feelings, so that the element moves to open a gap in the valve passage, the medium is discharged through the gap.
Its part of the life of the discharge capacity of the safety valve, safety valve and dynamic stability in work on. Channel cross-sectional area and the discharge capacity of the Gas Heater Control Valve of the shock would reduce the safety valve, and the valve seat and the same opening height limit collision bits will damage the valve sealing surfaces and other parts. two acting safety valve most likely to produce valve shocks.
Dynamic safety valve instability is mainly caused by the following reasons: Pilot operated safety valve discharge capacity is more than a safety valve into the media flow, spring just had big, big back pressure valve and the outside world in the chamber when the valve is opened Dynamic interference.

Classification of the safety valve

Valve structure are two major categories: spring-loaded and leveraged. Spring means sealing valve and valve seat by spring force. Leveraged rely on leverage and weight forces. With the large capacity needs, harboring a pulse valve, also known as the patio heater control valve, the main valve and the auxiliary valve. When the pipeline medium pressure exceeds a predetermined pressure value, the auxiliary valve to open, the media along the catheter into the main gas stove safety valve and the main valve is opened to reduce the media pressure increased. Emissions safety valve depends on the caliber of the valve seat and valve opening height, it can be divided into two types: Weiqi opening height is the seat diameter (1/20) - (1/40), the entire Kai It is (1/3) - (1/4).
In addition, with different requirements, there are enclosed and non-enclosed. Enclosed discharge medium that is not compromised, the entire exhaust outlet along a predetermined, generally used for toxic and corrosive media. Enclosed is generally not used for toxic or corrosive media.

In the form of structural safety valve lever hammer

Simple lever hammer safety valve structure, adjust easily and more accurately, the applied load will not increase the valve flap and a larger increase for higher temperature of the occasion, it was more commonly used in the past, especially It is used in high temperature boiler and pressure vessel. But hammer lever Water Heater Gas Valves structure is relatively bulky, easy loading mechanism vibration, and often due to vibration leakage; lower its back seat pressure, not easy to close after opening and holding tight.

Safety valve selection principles are analyzed as follows:

1. steam boiler safety valve, generally used to open the entire Kai spring safety valve;
2. The liquid medium with a safety valve, generally used Weiqi safety valve spring;
3. The air or other gas media safety valve, generally used in the entire Kai spring safety valve closed;
4. LPG tankers or liquefied petroleum gas tanker railroad safety valve, generally used all Kai built-in Propane Control Valve;
5. outlet safety valve production wells, generally used in the pilot valve;
6. The high-pressure bypass valve steam generating equipment, generally used in a safe and controlled dual function of the pilot valve
7. If the requirements of the safety valve for regular open test should be used to enhance the wrench with a safety valve. When the pressure reaches more than 75% of the opening pressure of the medium can be used to enhance the wrench slightly lifted from the valve seat to check the safety valve opens flexibility;
8. If the medium temperature is higher, in order to reduce the temperature of the spring chamber, usually enclosed safety valve when the temperature exceeds 300 ℃ and open valve temperature than 350 ℃ and should be used in safety valve with radiator;
9. If the valve outlet back pressure is changing, the change amount exceeds 10% of the opening pressure should be used bellows safety valve;
10. If a corrosive medium should be used bellows safety valve, preventing the important parts due to media corrosion and failure.

Direct-acting valve working medium

Direct acting valve is opened under the direct action of the working medium, which rely on the role of the working medium pressure against the biasing mechanism is applied to the Gas Heater Control Valve flap mechanical load, the valve open. This safety valve has a simple structure, quick action, good reliability advantages. But because relying on the structure of load, the load size is limited and can not be used for high-pressure, large diameter occasions.

Safety valve should note the following:

(1) there is gas in the container when liquid two-phase material safety valve should be installed in the gas phase portion.
(2) Aluminum safety gas valve for venting flammable liquid outlet valve of the tank should be connected to the accident. When the discharge of the material is a high temperature fuel, its receiving container should have the appropriate protective equipment.
(3) general safety valve may be vented, the vent should be above the fire site operator 1 meter (m) or more and not toward 15 meters (m) or less, emitting sparks and high temperature equipment location. Indoor equipment, safety containers should lead roof vent and the roof above two meters (m) or more.
(4) When the inlet oven non safety valves has cut off valve, cut off valve should be in a normally open state, and to be seals, to avoid mistakes.