Pneumatic System Troubleshooting: Causes & Fixes

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Problems on this page:

Low pressure at the machine Air leaks across the system Valves sticking or slow to switch Water in the air lines Too much oil or the wrong lubrication Actuators moving at uneven speed Silencers blocked or missing Pressure drops when several machines run Filters and dryers causing pressure loss Machines stopping on low pressure at start-up

Low pressure at the machine

Hits OEE: Performance

Symptoms: Actuators are slow or weak although the compressor shows normal pressure.

Regulator set low or failing

Check and set the regulator.

Hoses or piping too small for the flow

Check sizes against the flow the machine needs.

Clogged filter

Replace the filter element.

Leaks between the header and the machine

Find and fix the leaks.

Prevention: Pressure checked at the machine, not only at the compressor.

Air leaks across the system

Hits OEE: Performance

Symptoms: Hissing on a quiet line, compressors running when nothing is moving.

Worn fittings and quick couplings

Replace them.

Aged or damaged hoses

Replace the hoses.

Worn valve seals

Repair or replace the valves.

No regular leak checks

Run a leak survey with an ultrasonic detector or soapy water, tag and fix.

Prevention: Leak surveys on a schedule, with tags until fixed.

Valves sticking or slow to switch

Hits OEE: Availability

Symptoms: Valves hesitate or stick, actuators move late.

Dirt in the air

Check the filters upstream.

Water or oil in the valves

Check the dryer and the lubricator.

Pilot pressure too low

Check the pilot supply.

Worn seals

Service the valve.

Prevention: Air treatment checked on the route.

Water in the air lines

Hits OEE: Quality

Symptoms: Water at the exhausts, rust in fittings, sluggish valves.

Dryer not working

Check the dryer.

Drains blocked

Clear the drains.

No drop legs on the branch lines

Take branch lines off the top of the header and fit drop legs.

Lines running through cold areas

Insulate or reroute the lines.

Prevention: Drains tested on the route.

Too much oil or the wrong lubrication

Hits OEE: Quality

Symptoms: Oil mist at exhausts, oil on products or in clean areas.

Lubricator set too high

Set it to the lowest rate needed.

Lubricated and lubrication-free parts on one line

Follow each component maker's guidance on lubrication.

Oil carried over from the compressor

Check the compressor and fit coalescing filters.

Prevention: Lubricator settings recorded per line.

Actuators moving at uneven speed

Hits OEE: Performance

Symptoms: The same move takes different times, or speed changes during the stroke.

Flow controls misadjusted

Set the flow controls.

Supply pressure fluctuating

Check the regulator and the supply.

Varying load

Check the load and the guides.

Sticking seals

Service the actuator.

Prevention: Cycle times monitored per station.

Silencers blocked or missing

Hits OEE: Performance

Symptoms: Slow exhaust, slow actuators, or loud exhaust noise.

Silencer clogged with oil and dirt

Replace the silencer.

Silencer removed

Refit a silencer suited to the flow.

Silencer too small for the valve

Use the size the valve maker gives.

Prevention: Silencers on the cleaning route.

Pressure drops when several machines run

Hits OEE: Performance

Symptoms: Machines work alone but slow down when the whole line runs.

Header or manifold too small

Review the pipe sizes for the combined demand.

Long supply runs

Loop the main or shorten the runs.

No local air receiver

Fit a receiver near the large users.

Compressor capacity

Check the compressor output against peak demand.

Prevention: Pressure logged at the line during peak production.

Filters and dryers causing pressure loss

Hits OEE: Performance

Symptoms: Pressure falls between the compressor and the machines even without leaks.

Filter elements blocked

Replace elements on their differential pressure reading.

Dryer too small for the flow

Check the dryer rating against the demand.

Pipework too small for the flow

Check pipe sizes on the main runs.

Too many fittings and quick couplings

Simplify the supply to large users.

Prevention: Pressure measured at the compressor and at the far end of the network each month.

Machines stopping on low pressure at start-up

Hits OEE: Availability

Symptoms: Machines alarm on low air pressure in the first minutes of the shift.

Receiver drained by leaks overnight

Fix leaks or isolate the network when the plant is idle.

Compressor starts too late

Start the compressor before the machines.

Isolation valves left closed

Check valves on the start-up round.

Too many machines starting at once

Stagger the start-up of large air users.

Prevention: Compressor start time included in the shift start routine.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Related equipment guides: pneumatic cylinder · solenoid valve · compressed air system · air compressor · compressed air dryer · clipping machine

Stop the same fault coming back

Recurring pneumatic system stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

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Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover