main safety valve

I. Product Overview:

The A49H main safety valve is mainly used in power station boilers, pressure vessels, and temperature and pressure reduction devices to prevent pressure from exceeding the maximum allowable pressure value and ensure the safe operation of equipment. When the medium pressure rises to the set pressure, the pilot safety valve opens, and the medium enters the piston chamber of the main safety valve from the pilot pipe, pushing the piston down to automatically open the valve. When the pilot valve closes, the valve disc automatically closes again. The sealing surface is surfaced with cobalt-based chromium-nickel stainless steel, and the valve disc undergoes heat treatment to improve wear resistance and erosion resistance.

II. Selection Rules for Safety Valves:

(1) Hot water boilers generally use non-sealed spring-loaded low-lift safety valves with a lever.

(2) Steam boilers or steam pipelines generally use non-sealed full-lift safety valves with a lever.

(3) For incompressible media such as water, sealed low-lift safety valves or safety relief valves are generally used.

(4) For high-pressure feed water, sealed full-lift safety valves are generally used, such as high-pressure feed water heaters, heat exchangers, etc.

(5) For compressible media such as gas, sealed full-lift safety valves are generally used, such as gas storage tanks, gas pipelines, etc.

(6) Class E steam boilers generally use dead-weight safety valves.

(7) For large-diameter, large-displacement and high-pressure systems, pilot-operated safety valves are generally used, such as temperature and pressure reduction devices, power station boilers, etc., as shown in Figure 8.

(8) For railway tank cars, road tank cars, storage tanks, etc. transporting liquefied gas, internal safety valves are generally used, as shown in Figure 4.

(9) Hydraulic safety valves are generally used at the top of oil tanks and need to be used in conjunction with breathing valves.

(10) Pilot-operated safety valves are generally used for downhole drainage or natural gas pipelines, as shown in Figure 6.

(11) Safety return valves are generally used on the liquid-phase return pipelines at the outlet of tank pumps in liquefied petroleum gas stations.

(12) Vacuum negative pressure safety valves are generally used for systems with negative pressure or systems that may generate negative pressure during operation.

(13) Bellows safety valves are generally used for containers or pipeline systems with large backpressure fluctuations and toxic and flammable media.

(14) For systems with media with low solidification points, heat-insulated jacket-type safety valves are generally selected.

III. Installation Instructions:

1. The valve must be installed vertically at the highest position of the equipment.
2. The main safety valve is fastened on the support, which bears the reaction force generated when the main safety valve discharges steam.
3. The exhaust pipe shall have special hangers. The weight of the exhaust pipe shall not be borne by the main safety valve, and any additional prestress shall be eliminated at the connection flange between the main safety valve and the exhaust pipe.
4. The lowest point of the exhaust pipe shall be designed for drainage to avoid water hammer during steam discharge.

IV. Main External Dimensions and Connection Sizes: