AOD pump maintenance: a ten-minute monthly checklist

Air operated diaphragm pumps are among the most forgiving pumps made, which is exactly why they are often neglected until they stop. Most failures give weeks of warning if anyone is looking.

Check the air supply first. A clogged filter-regulator or a drooping supply pressure shows up as a pump that seems to have lost capacity, and it is the single most common false alarm we are called out to.

Second, listen at the exhaust. Air escaping continuously means a diaphragm has failed or the shaft seals are passing; both are inexpensive to fix and expensive to ignore, because product can migrate into the air chamber.

Third, look at the ball or flap valves for wear and for debris trapped under a seat — that produces the classic symptom of a pump that runs but will not hold head.

Fourth, check the torque on the diaphragm plates and chamber bolts at the interval the manual specifies; vibration loosens them. Fifth, confirm the pump is not run dry for long periods against a closed discharge, which overheats the diaphragms.

Ten minutes a month, logged, will usually double the interval between unplanned rebuilds.