Air Passes Through Exhaust Without Diaphragm / Shaft Movement (Stalling)

What happens: The pump receives air but the diaphragm or shaft does not move. Air simply passes through the exhaust without any pumping action.

Cause: This stalling is mainly due to damaged shaft or piston O-rings. There might also be insufficient lubrication on the air side of the pump.

Chemical / Material Leakage from the Air Side or Exhaust

What happens: Fluid or chemical is visible leaking from the air exhaust port — a serious safety concern, especially with hazardous chemicals.

Cause: Damaged diaphragms are the main reason. A torn or worn diaphragm allows the chemical to enter the air side of the pump.

AODD Pump is Running but No Suction or Very Low Suction

What happens: The pump cycles normally but does not draw any liquid, or the flow is much lower than expected.

There are two main causes:

1. Air gap in the suction line — There might be an air gap either in the suction line or at the liquid contact parts of the pump. Check and tighten all nuts and fittings to resolve the issue.
2. Suction line too long — If the suction line is more than a couple of meters, it becomes difficult for the AODD pump to create adequate suction. Try reducing the suction height by positioning the pump closer to the chemical source.

Insufficient Flow Rate or Output Pressure

What happens: The pump runs but delivers less flow or pressure than required for the application.

Causes:

• Low air supply pressure at the pump inlet
• Delivery line is too long with many bends — leading to frictional and gravitational losses
• Wrong AODD pump size selected for the application

AODD Pump Stops Intermittently During Operation

What happens: The pump starts, runs for a while, then stops or stalls — and then starts again intermittently.

Causes: Back pressure from the liquid line causing the pump to stall, or insufficient air pressure or air volume being supplied.

The required air pressure is generally 2–6 kg/cm². Air volume requirements by pump size:

Choking or Blockage in the Pump

What happens: The pump stops flowing or becomes restricted due to material hardening or solidifying inside the pump.

Cause: This is generally observed with viscous chemicals (cream, paste, etc.) or chemicals that dry or solidify over time — such as glue, fevicol, paint, or resins.

Why is my AODD pump stalling with air passing through the exhaust?

This is caused by damaged shaft or piston O-rings, or insufficient lubrication on the air side. Fix: add a couple of spoons of oil at the air inlet and start the pump at low pressure, gradually increasing until the pump begins to stroke normally.

Why is there chemical leakage from the air side or exhaust?

Chemical leakage from the exhaust indicates damaged diaphragms allowing fluid to enter the air side. Stop the pump immediately, open the liquid side, replace the diaphragm, clean and inspect the piston and spool, replace O-rings if needed, and reassemble.

Why is my AODD pump running but not creating suction?

No suction is usually caused by an air gap in the suction line — check and tighten all fittings. It can also be caused by a suction line that is too long — reduce the suction height by placing the pump closer to the fluid source.

Why does my AODD pump stop intermittently?

Intermittent stopping is caused by back pressure or insufficient air pressure/volume. Required air: 2–6 kg/cm². Check your compressor SCFM output against your pump size requirements and install an FRL unit to regulate pressure consistently.