TL;DR
An Armstrong 800 inverted-bucket trap at full condensate load will discharge nearly continuously. Distinguish normal operation from a fault by checking with an ultrasonic tester: continuous high-frequency noise means steam loss; intermittent modulated noise at high rate is normal condensate discharge.
What you might see
- trap discharging continuously with no off cycle
- outlet piping warm to the touch at all times
- higher than expected condensate return flow
- difficulty distinguishing from a failed-open trap
Likely causes
High condensate load at the trap rated capacity, which appears continuous but is not steam loss
Oversized trap for the application: a larger trap than needed discharges in long open periods
Worn bucket or valve allowing partial steam pass-through combined with condensate discharge
Loss of prime in the bucket due to a water hammer event, causing the bucket to fail to float
Required tools
- Ultrasonic steam trap tester
- IR thermometer
- Armstrong 800 capacity table (from the Armstrong technical data sheet)
- LOTO kit and isolation valves
- Heat-resistant gloves
Safety first
- Wear heat-resistant gloves and face shield when opening any steam trap.
- Isolate and depressurize before opening the trap cover to re-prime the bucket.
Procedure
- 1
Test the trap with an ultrasonic detector. A truly continuous discharge from live steam shows a constant high-frequency signal. A high condensate flow shows a modulated signal with slight rhythmic variation.[1]
- 2
Use an IR thermometer to compare inlet and outlet temperatures. Both at saturation temperature for the system pressure indicates steam blowthrough. Outlet temperature well below inlet temperature indicates mostly condensate discharge.
- 3
Check the trap sizing. Compare the condensate load at the drip leg or heat exchanger to the Armstrong 800 capacity table for the operating differential pressure. An oversized trap is a design correction, not a repair.[1]
- 4
If steam loss is confirmed by ultrasonic test, follow the steam-loss-failed-open procedure on this machine.
- 5
If the trap has lost bucket prime from a water hammer event, isolate the trap, remove the cover, and manually fill the bucket chamber with condensate before reassembling. This re-primes the bucket.[1]
- 6
Retest after re-priming. Confirm cyclic operation returns within 5 minutes.
Sources
Armstrong 800 Series Inverted Bucket Steam Trap Installation and Maintenance, Armstrong International
Armstrong International 800 Series Steam Trap Installation and Maintenance Instructions, capacity and diagnosis of continuous discharge (general)
View source
More guides for Armstrong International 800 Series
How to diagnose a cold Armstrong 800 steam trap
A cold trap means no steam is reaching it. Check the upstream isolation valve first, then the inlet strainer. A cold trap with upstream steam and no isolation valve closed is a failed-closed trap or a plugged strainer.
How to fix steam loss from a failed-open Armstrong 800 steam trap
A failed-open trap is blowing live steam continuously. Confirm with an ultrasonic tester, then isolate and replace the trap internals (the Armstrong 800 has a replaceable bucket module). Leaving a blown trap in service wastes significant energy.
How to fix waterlogging from a failed-closed Armstrong 800 steam trap
A failed-closed trap does not discharge condensate, causing waterlogging upstream. Test with an IR thermometer: the trap inlet will be cold. Isolate, clear the strainer, and replace the trap internals if the strainer is clean.
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