Apparently the monoamonum phosphate in ABC powder units is heat reactive ( it forms a skin over burning combustible materials )
so if the unit gets hot especially in a car in summer there's a risk of it caking,
years ago I did a full day [back when they used real fire be it wood or petrol in trays (none of this modern risk averse "safe fire" gas burner which as Long as you sweep from side to side the man turns the gas off making you think you put the fire out] fire course and was told to invert the extinguisher and shake it before discharge larger units drop it on its side .... To break up small clumps that can clog the "pick up tube" resulting in a blast of nitrogen and very little powder.......
Recent amendments to the bsi installation of extinguisher regs make powder forbidden indoors in most industrial settings exclusions apply to filling stations or fuel stores where rappid knock down is needed and they won't freeze .. you'll know first hand the mess they make...
Talking to my friend in home insurance it won't affect a domestic policy they'd rather pay a cleaning firm to clean up or replace soft furnishings from dry powder residue than rebuild a house due to fire damage
https://www.fireprotectiononline.co.uk/ ... rd-change/
If your roughing it, Your doing it wrong
Lack of planning on your part doesn't make it an emergency on mine