The United States the CCS 611GE 611GEM series of explosion-proof pressure switch 

 611GE (set up) 
 Port size of 1/4 " 
 Interface material aluminum alloy 
 Membrane material poly Buna 

 Pressure Switch Model 
 The maximum allowable pressure (MPa) pressure range (MPa) SPDT DPDT 
 1.724 0.010 ~ 0.078 0.010 ~ 0.078 611GE8001 611GEM8001 
 3.448 0.083 ~ 0.193 0.083 ~ 0.193 611GE8003 611GEM8003 
 3.448 0.208 ~ 0.462 0.208 ~ 0.462 611GE8005 611GEM8005 
 3.448 0.483 ~ 1.193 0.483 ~ 1.193 611GE8007 611GEM8007