Heavy electric pneumatic control valve of the closed pressure relief devices and what type?

Heavy electric pneumatic control valve of the closed pressure relief devices and what type? After a action to keep open the pressure relief devices of a blasting device > a device by the static pressure difference of import and export driven not closed pressure relief devices, its function is through the pressure of the blasting and implementation. B > a broken pin device driven by imported static pressure of closed pressure relief devices, the functions of system through the pressure parts supporting pin bearing cross section of broken and implementation. c) A bent pin device electric pneumatic - valve driven by imported open pressure of closed pressure relief devices, the functions of system through the pressure parts supporting pin bearing cross-section bending and implementation. d) A shear pin device driven by imported static pressure not closed pressure relief devices, its function is through the pressure of a pin bearing section shear and implementation. e) Fusible plug device is a kind of closed pressure relief devices, electric pneumatic control valve is its function by a plug made appropriate melting point of materials to yield or melting and implementation.