Internally, at the top, is a small container of 'something' which when tipped upside down, spills into the main container which holds 'something else' - the resultant chemical reaction creates a foam which is discharged via the hose thingo.
PS That exhausts my technical knowledge of those things. So I guess that violent vehicle movements might see some accidental discharges.
Edit: It's coming back, I think. The small container near the top I think was somewhat bottle shaped (perhaps even made of glass??), with a lead stopper to prevent accidental spillage, so needed to be tipped upside down to displace the stopper. Wikipedia probably has a story on them.
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Allan Layton
Last edited by Allan L; 23-10-18 at 11:35.
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