www.saVRee.com Diaphragm Pumps pg. 3
Single and Double Acting Pumps
Diaphragm Pump Operation
Compressed air (typically 6-7 bar/87-101psi pressure) is connected to a double diaphragm
pump via hoses or piping. A pneumatic piston (air distributor) delivers compressed air to
the space behind one of the diaphragms whilst air is simultaneously exhausted from the
other; this is made possible because both diaphragms are mounted on a common shaft i.e.
when one moves, so does the other. Exhausted air is usually discharged through a muffler
to make the pump operate quieter and to eliminate a high pressure jet of air being
intermittently discharged from the pump.
If air is being exhausted, the affected diaphragm contracts and obtains a concave shape. If
air is being supplied, the affected diaphragm expands and obtains a convex shape. As the
diaphragm changes shape, a positive pressure (convex shape), or negative pressure
(concave shape) is created within the pumping chamber. Fluid is sucked into, or discharged
from, the pump, due to the pressure differences created within the pumping chambers.
Non-return valves are used to ensure that flow through the pump only occurs in one
direction.