Low compressed air pressure — gates close late and batches go over
Symptom
Main pressure is low all the time or drops during a batch, one machine group is weak, the compressor runs loaded all the time, or gates and the mixer door close slowly.
Likely causes
- Leaks, which often waste 20–30 % of the compressor's output.
- Compressor too small, blocked intake filter, or compressor fault.
- Receiver too small, or long small-bore pipes to the users.
- A blocked FRL filter or a regulator set too low at one group.
Most likely and cheapest to check first.
Checks
- Watch the main gauge during discharge of a full batch.
- Walk the plant when it is quiet and listen for leaks; use soapy water on fittings.
- With no air used, note how fast receiver pressure falls with the compressor stopped.
- Check the FRL elements and regulator settings at each group.
Fix
- Tag and repair every leak; repeat the survey regularly.
- Replace the intake filter; service the compressor.
- Add a receiver near the users; fit larger FRLs or pipes.
- Test the low-pressure switch that stops batching before gates lose force.
Parts you may need
One gauge tells you a lot
Plant air systems typically run at about 6–8 bar. If the main gauge falls close to the low-pressure setting while a full batch discharges, the system is too small or leaking. Low pressure makes gates close late, so batches go over target.
DANGERNever put any part of your body under a gate, door or load held only by air. Block it mechanically. Air receivers are pressure vessels and must be examined as your law requires.
⚠ Every check inside a machine starts with full lockout. Safety disclaimer