VSS 10-12
ABOUT DIAPHRAGM PUMPS
How the pump works
The diaphragm is what separates the pump oil from the spray solution. Each piston
down-stroke lowers the piston-attached diaphragm, drawing spray solution into the
pump head. As the piston passes below the cylinder sleeve side openings, oil is pulled
into the lower diaphragm cavity. During each piston up-stroke, the cushion of oil
between the piston and the diaphragm hydraulically pushes and cushions the
diaphragm as the piston tops out. This discharges the solution from the pump head.
The lower diaphragm cavity oil cushion also lubricates the diaphragm and pistons,
ensuring minimal mechanical wear.
Remember – low crankcase oil level causes excessive mechanical wear on
diaphragms and internal components. The transparent oil bowl makes checking the oil
easy. Keep the oil filled to the mark on the bowl.
Do not run the pump with a starved suction
The diaphragm pump will not suffer any damage if run dry due to an empty tank.
However, a starved suction due to a clogged suction strainer or a closed suction valve
will cause premature failure of the pump diaphragms.
Note – Only use filter screens that are between 16 and 20 mesh. Never use a fine filter
screen on a diaphragm pump.
Pulsation Dampeners
It is the nature of diaphragm pumps to have some pulsation. It is caused by the
sudden changes in the piston direction. The pulsation dampener reduces pulsation by
providing a cushion of air for the piston to bump against. The UDOR pulsation
dampener uses a rubber bladder to separate the air cushion from the solution being
pumped.
Pulsation Dampener Setting
The basic rule is to inflate the pulsation dampener to 20% of the systems’ working
pressure. For example, if the spraying pressure is set at 100 psi, the pulsation
dampener should be inflated to 20 psi.
Always shut down the pump before adding air to the pulsation dampener or checking
its pressure. Air pressure can be supplied from a compressor or a manual air pump.
The diaphragm dome contains a very small volume of air. Take care when checking
the air pressure that a minimum amount of air leaks out when the pressure gauge is
applied to the air valve. It is possible to lose 5–10 psi when checking the pulsation
dampener air pressure.
Note: Two-cylinder diaphragm pumps may require more air pressure than 20% of the
operating pressure. The minimum pulsation dampener air pressure is 20 psi.
DO NOT run two-cylinder pumps with less than 20 psi in the pulsation dampener.
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