What is the difference between vacuum pneumatic valve and the overflow pneumatic valve

the overflow pneumatic valve is to prevent system overload, ensure safety.
the reduced pressure pneumatic valve is on the premise of guarantee system but load, reduce the system pressure.
say the overflow pneumatic valve is passive, and reduced pressure pneumatic valve is active work.
, reduced pressure pneumatic valve to maintain constant pressure at the exit, and the overflow pneumatic valve inlet pressure unchanged;
when not working, the reduced pressure pneumatic valve import and export, pneumatic valve import and export can overflow;
and non-working state, the reduced pressure of the pneumatic valve pneumatic valve is wide open mouth, the overflow of the pneumatic valve is normally closed overflow pneumatic valve, pneumatic pressure control valve is mainly to control the system pressure, also ACTS as unloading: reduced pressure pneumatic valve is a kind of pneumatic valve outlet pressure below the pressure of the inlet pressure pneumatic valve adjustment.
and pressure pneumatic valve is mainly used to reduce the pressure of hydraulic system of a branch circuit, make the branch pressure is low and stable than the main oil path, in the range of setting pressure, reduced pressure pneumatic valve also like overflow pneumatic valve is closed. But with the increase of system pressure when reach vacuum pneumatic valve setting pressure, reduced pressure pneumatic valve open, part of the oil tank after his return ( At this time there are certain pressure of oil tank, oil tank of the oil temperature rise) , a branch of the oil pressure is not increased. This branch of decompression and regulated effect it! The overflow pneumatic valve is different, it will ensure the overall system on the pump outlet pressure stable and overpressure. So he has the effect such as safety, voltage regulator, voltage regulator.
, the overflow pneumatic valve general parallel branch of the system voltage regulator, voltage regulator and relief role, and reduced pressure pneumatic valve series in a general way plays a role of decompression and the holding of this branch!
the overflow of the pneumatic valve is normally closed, only when the system overpressure actions; Decompression is Chang Tong pneumatic valve, decompression through the narrow passage.
the overflow the pneumatic valve regulated, overflow, overload protection. Reduced pressure pneumatic valve is reduced pressure, pressure in one part of the hydraulic system. Is not the same as the purpose. So can't replace.
the overflow of pneumatic control valve inlet pressure, reduced pressure pneumatic valve control oil outlet pressure.