Nitrogen Generator Troubleshooting: Causes & Fixes

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Problems on this page:

Nitrogen purity too low Not enough flow or pressure Oil or water reaching the generator Switching valve faults Oxygen analyser drifting Sieve dust in the nitrogen Pressure swings at the users Generator not starting Purity low after a stop or at shift start High air use for the nitrogen produced

Nitrogen purity too low

Hits OEE: Quality

Symptoms: The analyser shows more oxygen than the product needs.

Demand above the generator rating

Check the flow against the rating and reduce or add capacity.

Sieve contaminated by oil or water

Fix the air treatment and have the sieve checked.

Switching valve fault

Check each valve opens and closes on time.

Cycle settings changed

Check the cycle timing with the maker settings.

Prevention: Purity logged and alarmed at the point of use.

Not enough flow or pressure

Hits OEE: Availability

Symptoms: Machines using nitrogen alarm on low pressure.

Compressed air supply low

Check the air pressure and flow to the generator.

Demand grown since installation

Measure the demand and compare it with the rating.

Leaks in the nitrogen pipework

Find and repair leaks.

Prevention: Nitrogen demand reviewed when new users are added.

Oil or water reaching the generator

Hits OEE: Quality

Symptoms: Filters ahead of the generator are wet or oily.

Air dryer not working

Check the dryer dew point.

Filter elements overdue

Replace the elements at the maker interval.

Drains blocked

Check the automatic drains.

Prevention: Dew point and filter differential pressure checked weekly.

Switching valve faults

Hits OEE: Availability

Symptoms: The generator alarms on a valve or cycle fault.

Valve sticking

Service or replace the valve.

Solenoid coil failed

Replace the coil.

Pilot air supply low

Check the pilot air.

Prevention: Valve service kits fitted at the maker interval.

Oxygen analyser drifting

Hits OEE: Quality

Symptoms: Purity readings move without a real change in the gas.

Analyser not calibrated

Calibrate with a certified reference gas.

Sensor at end of life

Replace the sensor.

Sample line leak

Check the sample line and fittings.

Prevention: Analyser calibration on a fixed schedule.

Sieve dust in the nitrogen

Hits OEE: Quality

Symptoms: Fine black dust is found in filters or at the users.

Sieve bed not compacted

Have the bed compaction checked.

Flow through the beds too high

Keep the flow within the rating.

Outlet dust filter missing or damaged

Fit and maintain the outlet filter.

Prevention: Outlet filters inspected at each service.

Pressure swings at the users

Hits OEE: Quality

Symptoms: Nitrogen pressure rises and falls with the generator cycle.

Buffer vessel too small

Add or enlarge the nitrogen receiver.

Pressure regulator faulty

Service the regulator.

Peak demand above the generator output

Spread the demand or add storage.

Prevention: Pressure at the main users trended.

Generator not starting

Hits OEE: Availability

Symptoms: The generator stays off or shows a start fault.

No air supply or low pressure

Check the compressor and the air line valves.

Controller fault or alarm latched

Read the alarm list and reset after fixing the cause.

Power supply problem

Check the power and fuses.

Prevention: Generator alarms sent to the maintenance team.

Purity low after a stop or at shift start

Hits OEE: Quality

Symptoms: Users get gas with too much oxygen for the first minutes after the generator restarts.

Off-specification vent not working

Check the valve that vents gas to atmosphere until purity is reached, and its control signal.

Users drawing gas before purity is reached

Interlock the outlet valve to the purity signal so no gas reaches users too early.

Nitrogen receiver drained during the stop

Keep the receiver isolated and pressurised during short stops.

Sieve beds picking up moisture during long stops

Run the generator to purity before opening the outlet after a long stop.

Prevention: Start-up purity logged so slow recovery after stops is noticed.

High air use for the nitrogen produced

Hits OEE: Performance

Symptoms: The compressors run harder than before for the same nitrogen flow.

Purity set higher than the product needs

Set the purity to the level the process actually requires, since higher purity takes much more air.

Leaks in the nitrogen network

Find and fix leaks, which waste both nitrogen and the air used to make it.

Economy or demand mode switched off

Use the mode that slows the cycle when demand is low.

Sieve performance declining with age

Have the sieve condition checked at the service.

Prevention: Air use per unit of nitrogen reviewed monthly.

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

Stop the same fault coming back

Recurring nitrogen generator 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