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Figure 5 Diaphragm Rupture Warning Device Schematic Diagram
2.2.3
“
Three valves
”
of hydraulic system:
The most outstanding feature of hydraulic diaphragm metering pump is the continuous process in which
diaphragm separates medium and hydraulic oil, the plunger drives hydraulic oil, the oil drives
diaphragm, and
diaphragm absorbs and discharges media. The measuring accuracy of hydraulic diaphragm metering
pump totally depends on hydraulic system, while the reliability of the hydraulic system shall be
guaranteed by 3 valves (Oil refilling valve, deflation valve and safety valve).
2.2.3.1 Limit-refilling device
The hydraulic pressure diaphragm metering pump adopts limiting-refilling system, which makes a
new leap to the technical level of hydraulic pressure diaphragm metering pump. The limit valve
restricts the position for oil filling. Once the piston passes the mid-point conductor in suctioning
stroke, diaphragm will push the limit valve to exit the oil filling passage. Then if the vacuum degree
in the liquid chamber reaches 80%, the refilling valve will refill oil to the liquid chamber
automatically to guarantee the fullness of the liquid chamber and avoid excessive oil refilling and
protect diaphragm. When there’s a negative pressure in the inlet, it also has a function of
self-absorption. It both improves volume efficiency of the pump, and measurement accuracy.
1) Limit valve
The limit valve comprises the valve sleeve and valve spool which are well matched. A limit body is arranged at
the right end of the valve spool, and a limit spring is placed between the limit body and the valve sleeve; a limit
