Wilden PX4 series, Engineering, Operation & Maintenance

WIL-12310-E-04

3 

WILDEN PUMP & ENGINEERING, LLC

The Wilden diaphragm pump is an air-operated, positive displacement, self-priming pump. These drawings show fl ow  pattern 
through the pump upon its initial stroke. It is assumed the pump has no fl uid in it prior to its initial stroke.

FIGURE 1

  The air valve directs pressurized 

air to the back side of diaphragm A. The 
compressed air is applied directly to the 
liquid column separated by elastomeric 
diaphragms. The diaphragm acts as 
a separation membrane between the 
compressed air and liquid, balancing the 
load and removing mechanical stress 
from the diaphragm. The compressed 
air moves the diaphragm away from 
the center of the pump. The opposite 
diaphragm is pulled in by the shaft 
connected to the pressurized diaphragm. 
Diaphragm B is on its suction stroke; air 
behind the diaphragm has been forced 
out to atmosphere through the exhaust 
port of the pump. The movement of 
diaphragm B toward the center of the 
pump creates a vacuum within chamber B. 
Atmospheric pressure forces fl uid  into 
the inlet manifold forcing the inlet valve 
ball off its seat. Liquid is free to move 
past the inlet valve ball and fi ll the liquid 
chamber (see shaded area).

FIGURE 2

 When the pressurized diaphragm, 

diaphragm A, reaches the limit of its discharge 
stroke, the air valve redirects pressurized 
air to the back side of diaphragm B. The 
pressurized air forces diaphragm B away 
from the center while pulling diaphragm A 
to the center. Diaphragm B is now on its 
discharge stroke. Diaphragm B forces the 
inlet valve ball onto its seat due to the 
hydraulic forces developed in the liquid 
chamber and manifold of the pump. These 
same hydraulic forces lift the discharge 
valve ball off its seat, while the opposite 
discharge valve ball is forced onto its seat, 
forcing fl uid to fl ow through the pump 
discharge. The movement of diaphragm A 
toward the center  of the pump creates a 
vacuum  within  liquid  chamber  A.  Atmos-
pheric pressure forces fl uid into the inlet 
manifold of the pump. The inlet valve ball 
is forced off its seat allowing the fl uid being 
pumped to fi ll the liquid chamber.

FIGURE 3

    At  completion  of  the  stroke, 

the air valve again redirects air to the 
back side of diaphragm A, which starts 
diaphragm B on its exhaust stroke. As 
the pump reaches its original starting 
point, each diaphragm has gone through 
one exhaust and one discharge stroke. 
This constitutes one complete pumping 
cycle. The pump may take several cycles 
to completely prime depending on the 
conditions of the application.

OUTLET

CLOSED

CLOSED

OPEN

OPEN

INLET

B

A

OUTLET

OPEN

OPEN

CLOSED

CLOSED

INLET

B

A

OUTLET

CLOSED

CLOSED

OPEN

OPEN

INLET

B

A

S e c t i o n   3

H O W   I T   W O R K S — P U M P