9
0
10
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3 4
5 6
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9
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Hydraulic End Structure for
Double Diaphragm Dosing Pump
0
10
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3 4
5 6
7
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9
Bar
0
10
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Figure 4 Hydraulic end structure for double diaphragm metering pump
2.2.2Working principal
：
Diaphragm separates the medium and hydraulic oil. The piston takes use of the power of crosshead in driving
end to conduct
reciprocating motion
in hydraulic cylinder. When the piston is in suction stroke,
oil in the
hydraulic chamber enters into displacement space of the
piston
with
piston
displacement. Pressure
drops in the liquid chamber, then diaphragm makes flexure displacement with the change of
hydraulic oil. After the flexure displacement exceeds the median, it pushes the limit valve to turn on
the oil supplementary channel. When there’s 80% vacuum inside the liquid chamber, oil
supplementary valve turns on timely to automatically supplement the insufficiency. Meanwhile, with
the flexure displacement of diaphragm in medium chamber, the pressure in the chamber drops to be
different from differential pressure of the outside world. Then outside pressure presses the medium
into medium chamber.
At the moment when the piston suction stroke terminates and discharge stroke starts, the pressure in
liquid chamber surges. The deflation valve is turned on to let out gas-liquid mixture accumulated in
the top of liquid chamber, then shut down soon. The piston continues the displacement. Hydraulic oil
pushes the diaphragm, and diaphragm conducts reverse deflection displacement to expel the medium
to be discharged from outlet valve, and then flow into process pipeline. When the discharge stroke
terminates, the piston turns to suction stroke. Then, the next cycle begins. It’s to transport the
medium from a low position to a higher position.
