When a compressor stops in the middle of a shift, the first task is to make the site safe and preserve the evidence that will shorten the diagnosis. It is not to strip the machine or keep resetting a trip.
Design Air, Atlas Copco authorised distributor in Scotland, asks operators to isolate correctly, record what the controller reported and describe what changed before the fault. Those checks help our dipCAM-qualified engineers distinguish a supply fault from a demand-side problem without asking site staff to enter a guarded, live or pressurised area.
Make the Compressor Safe Before You Investigate
Compressed air stores energy. Electrical panels, hot oil and moving drive components add separate hazards. Use your site’s isolation procedure and do not treat a check valve, a stopped motor or a controller message as proof that the system is safe.
Before any external inspection:
- Stop the machine using its normal controls.
- Isolate the electrical supply at the local isolator and apply the site lock-off procedure.
- Depressurise only the section your written procedure identifies as safe to vent.
- Allow hot discharge pipework and oil-circuit surfaces to cool.
- Keep guards in place and do not open electrical or pressure-containing components.
The Pressure Systems Safety Regulations 2000 cover compressed air above 0.5 bar. A Written Scheme of Examination is required before a qualifying pressure system is operated. PSSR guidance (hse.gov.uk) explains the duty and the role of the competent person. Routine servicing is not a substitute for a statutory examination.
Record the Evidence Before It Disappears
Most useful fault evidence is already visible on the controller or can be observed without dismantling anything. Take photographs of alarm codes and note the time, load state and production demand when the fault occurred. A reset can clear the exact clue the engineer needs.
Record:
- Controller alarm code and any alarm history.
- Receiver pressure, load and unload settings, if shown.
- Running temperature and ambient temperature in the compressor room.
- Operating hours and the time since the last service.
- Whether the fault occurred on start-up, under load, at unload or after a production change.
- Any new sound, vibration, smell, leak or visible contamination.
If your site has SMARTLINK or another monitoring platform, export the trend around the event rather than only sending the current screen. Pressure, temperature and motor-load history can show whether the failure was sudden or developing across several shifts.
Check What Operators Can Safely See
The first ten minutes should focus on observations, not repair. The checks below are safe only where they are accessible outside guards and covered by the site’s operating procedure.
Low receiver pressure can indicate a compressor output issue or demand that now exceeds supply. If the nominated operator can close the main service valve under the site procedure, note whether pressure then recovers normally. A rapid recovery points to a demand-side problem such as a large leak, an open valve or a new user. Failure to recover still points to the compressor package and its controls.
High running temperature often starts with the room. Check that ventilation openings are unobstructed and that externally accessible intake filters are not visibly blocked. Do not remove panels to chase a cooling fault.
Wet downstream air calls for a check of the visible receiver drain status and dryer alarm. A blocked drain, a failed dryer or cold downstream pipework can all create water at the point of use. Do not open a drain manually unless the equipment instructions and site procedure specifically permit it.
Oil at a tool or process connection is a stop-and-report condition. Note the separator service history and the oil level shown on the approved sight glass, if one is externally visible. Do not assume that topping up oil will correct carryover.
Stop and Wait for an Engineer When These Signs Appear
Some findings are not diagnostic tasks for an operator. Isolate the equipment, keep people clear and report the condition if you see any of the following:
- Repeated safety-relief-valve lifting or signs that a valve has been tampered with.
- Damage to a receiver, separator or pipework, including corrosion, bulging or impact damage.
- An electrical smell, smoke, scorching or repeated electrical trips.
- Failed guards, interlocks, emergency stops or isolation points.
- Severe or rapidly worsening vibration.
- Visible oil carryover in process air where product quality or clean-air controls apply.
The Provision and Use of Work Equipment Regulations require work equipment to be maintained and used safely. PUWER guidance (hse.gov.uk) is the right reference point when guarding or safety controls are involved.
Give the Engineer a Useful Handover
An emergency call is resolved faster when the engineer receives a short, ordered handover instead of a list of possible causes. State what happened first, what the controller recorded, what production was doing and what has already been isolated.
For example: “GA 55 tripped on high temperature at 14:20 while Line 2 was on its cleaning cycle. The room was warm, the intake looked dusty and the receiver was at 5.8 bar. The machine is electrically isolated, guards remain in place and no restart has been attempted.”
That gives the engineer a starting condition, a load context and a safety boundary. It also prevents repeated resets from turning an intermittent fault into a larger repair.
Use the Repair to Improve the Next Response
After the repair, retain the alarm history, failed component, service findings and operating conditions in the asset record. If the same fault returns, the pattern matters more than the individual callout. Repeated high temperature, low pressure or moisture alarms usually point to a condition in the room, treatment system or production demand that a component replacement alone will not remove.
Design Air provides emergency compressor diagnosis and repair across Scotland. If a compressor fault is affecting production, isolate the equipment safely, capture the evidence above and contact our Airdrie engineering team with the alarm code, pressure and operating condition.