According to the ratio of the maximum disc lifting height and valve orifice, the safety valve or relief valve can be divided into spring low lift safety valve or relief valve and spring full lift safety valve or relief valve.
1. Spring low lift safety valve or relief valve
The disc lift of spring low lift safety valve or relief valve is smaller than 1/4 of valve nozzle, normally 1/40 ~ 1/20 of the valve nozzle. The acting of spring low lift safety valve or relief valve is proportion type, so spring low lift safety valve or relief valve is mainly applied to liquids, although sometimes to little gas discharge.
2. Spring full lift safety valve or relief valve
The disc lift of spring full lift safety valve or relief valve is equal or greater than 1/4 of valve nozzle, normally 1/40 ~ 1/20 of the valve nozzle. The discharge area of the spring full lift safety valve or relief valve is just the minimum cross-sectional area of valve orifice. The acting of spring full lift safety valve or relief valve is two section acting, which must depend on one lifting device to achieve in full lifting. Spring full lift safety valve or relief valve is mainly applied to gas.