QBY Diaphragm Pump – Troubleshooting Common Problems

Problem 1: Pump Runs But No Liquid
Check for vapor lock. The pump may be running too fast for the liquid to enter the chamber. Slow down the air supply. Also check if the suction line is blocked or if the inlet ball valve is stuck.
Problem 2: Low Flow
Possible causes include worn diaphragms, clogged ball valves, or low air pressure. Inspect the diaphragms for cracks. Clean or replace the ball valves. Verify air pressure is at least 2 Bar.
Problem 3: Air Valve Freezing
This happens when compressed air contains too much moisture. Install an air dryer or moisture separator. Drain the air receiver tank regularly.
Problem 4: Bubbles in Discharge
Air bubbles usually mean a ruptured diaphragm. Stop the pump and inspect both diaphragms. Replace if damaged. Also check that all clamps are tight.
Problem 5: Liquid Leaking from Air Exhaust
This is another sign of diaphragm failure. The liquid is crossing through the torn diaphragm into the air chamber. Replace the diaphragm immediately.

Quick Fix Reference

Applications Summary:​
maintenance troubleshooting, pump repair, industrial fluid handling, chemical transfer, wastewater
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