The Use of Pilot Type Safety Valve
Pilot type safety valve converts the direct effect of the spring into the indirect effect of the guide valve, which improves the action’s sensitivity. And the main valve is sleeve piston type. Double sealing sanitary valve seat structure ensures high action precision, good repeatability, quick seat returning, no leakage, the ability to discharge with high back pressure, long service life, stability and reliability. It can also be adjusted on-site. After repeated start and discharge, it can still return to the seat automatically. Tight closing ensures convenient operation and maintenance.
Pilot-type safety valve is widely used in natural gas, LPG and chemical pressure vessel equipment and industrial pipelines. It has obvious advantages such as fire-proof and explosion-proof, static-electricity-proof, reliable sealing, quick opening and closing, large amount of discharge.
Pilot-type safety valve consists of main valve, pilot valve, relief valve, fittings and conduits. Under normal working conditions, the medium pressure of the system is both applied to the lower part of the main valve flap and upper part of the main valve flap. As the medium effect area at the upper chamber of the main valve flap is greater than that of the lower chamber, under the effect of the pressure difference, the main valve is in a closed state. With the rise in medium pressure of the pipelines, the sealing pressure obtained by the sealing pair will also rise accordingly. This is the opposite of spring direct loading type safety valve, namely, that the higher the medium pressure, the more reliable the sealing. When the medium pressure of the pipeline is abnormal, reaches or exceeds the set pressure, the upper valve flap of the pilot valve quickly opens. The medium inside the upper chamber of the main valve flap is quickly discharged through the exhaust fitting of the pilot valve. Under the strong effect of the lower medium pressure, main valve flap instantly opens, quickly discharging medium in large quantity from the outlet of the main valve, so that the medium pressure in the pipeline is restored to the normal working pressure, which ensures the safety of the system. When the medium pressure in the pipeline drops to around 90% of the set pressure of the system, the upper valve flap of the pilot valve closes, and the medium in the pipeline enters the upper chamber of the main valve flap through pilot valve. Under the effect of the pressure difference, the main valve closes, ensuring the normal operation of the system.