The micro open closed spring safety valve is different from the general full open safety valve. It can close automatically after pressure relief without manual reset. The maximum opening height is 1 / 4 of the inner diameter.

According to the supervision regulation on safety technology of steam boiler issued by the boiler and pressure vessel Supervision Bureau of the State Administration of quality supervision, the safety valve of boiler in use shall be calibrated at least once a year, and the supervision regulation on boiler and pressure vessel of electric power industry (dl612-1996) 9.1.13, the safety regulation of boiler installation and overhaul and the safety regulation of micro opening and closing spring type After the valve is overhauled, the starting pressure of the micro opening and closing spring safety valve shall be verified (and the "supervision scope of regulations: F) pressure vessel of thermal system: high and low pressure heater, deaerator, various expansion vessels, etc.); the" 25 key requirements for preventing major accidents in electric power production "issued by state power company stipulates:" micro opening and closing shells of various pressure vessels The spring safety valve shall be regularly calibrated and tested for discharge ". These Regulations are very clear on the power plant micro open closed spring safety valve regular calibration work.