A21F-16C  A21H-16C  A21H-40  A21H-64  A21Y-100  A21H-160  A21W-16P  A21W-40P  A21F-40P  A21W-64P  A21W-100P  A21W-160P  KA21Y-16C  KA21Y-16P  A21Y-16R  A21Y-40R  A21Y-64R  A21Y-100R  A21Y-160R
A21F、A21H-C型适用于工作温度≤200℃的空气、氨、石油气……等介质的设备或管路上。A21W-P、R型适用于温度≤200℃有腐蚀性的气体或液体的设备或管路上，作为超压保护装置。KA21Y型适用于温度≤100℃的液化石油气等。
A21F, A21H-C type are used for the equipment and pipeline of the air,  ammonia, petroleum gas, etc. medium what the wor-king temperature are less than 200 . A21W-P, R type are used for the equipment and pipeline of the quality with corr ode gas and liquid medium shat the wor-king temperature are less than 200 . Take for  extrapressure protection devices. KA21Y type are used for liquefied petroleum gas what the working temperature are less  than 100