The Case of the Howling Burner


One of ACES’ aerospace customers had an atmosphere oven which they used for heat treating parts. It was down for an overhaul, and they asked ACES to remove the eight burners and burner tubes and clean and inspect them. When the ACES Control Systems Inspector (CSI) fired up the machine to tune it, one of the burners started to make a loud howling like a ship’s horn, or — as the CSI put it — “like Shamu stepping on a lego.”


The operators said the burner had actually been wailing ever since another company had serviced the oven several years earlier. Any time that burner was running at temperature they had to endure the ear-splitting commotion.

The CSI disassembled the burner and tube and began investigating. He observed that the burner tube had been installed incorrectly by the previous company so there was both an old-style burner tube and a newer burner tube with varying thicknesses of spacing adapters layered between them to maintain distance between the tubes.


Somebody had taken these spacing adapters apart and put them back together again, mixing both old and new adapters of varying thicknesses. This haphazard variation was what was causing the ear-splitting noise.

“A lot of the equipment we work on,” says the CSI, “you’ve got 30 years of somebody who didn’t know what they were doing poking at it and making booby traps.”


The CSI sorted out the spacing adapters and reordered them with uniform thicknesses, and the horn noise was silenced.


Now another burner was set to howling, affected by the change in pressure from the first burner. This time the CSI reasoned that sound is made of vibration, and he thought through the flame, temperature and airflow causing the loud noise. He knew that an increase or decrease in pressure could send a burner into a high-frequency resonance.


To resolve the vibration, the CSI increased the back pressure slightly to that particular burner by blocking off the airflow a tiny bit at various points. This allowed for more steady pressure and eliminated the high-speed build-and-release resonance.

Now the customer has a unit that ramps up to temperature correctly, and all the burners and burner tubes are in great shape, clean and ready to go for several more years. All eight are humming along instead of howling, much to the relief of the operators.

If you have chattering, squealing, squawking equipment — or any other puzzling issue — let ACES’ crack troubleshooters resolve the problem and get it running smoothly. Give us a shout today for a free estimate and enjoy the sweet silence.