Flame arrester
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Could it be that the original question really meant "heat diffusers" as used to reduce the chances of getting a SAM up the jetpipe? Remember Air Rhodesia using such devices on their Viscounts in the late 70's - early 80's.
That's the beauty of the technical section of Pprune. A guy comes in and asks a simple technical question using some jargon which they heard someplace. Us technocrats know that there is an answer someplace among us if we guess at the meaning behind the question. So we have a go at it
The winner is not the best answer it's the best guess at what the question really was
Now what's the chances that the guy who asked the question will actually come back and tell us whence the question and in what context?
Meanwhile the casual readers hopefully have learned something new from the myriad of answers.