QUOTE (Yorts @ Tue, 27 Apr 2004 23:06:24 +0000)
How did one decide that his filling was ineffective? Was it just a case of waiting until the gas got to you, or was their a proscribed time that a filter should be used for before being disposed of? How quickly could the cartridge be changed under battle conditions, and how many spares did one carry?
The filter became clogged and breathing became most difficult, if not impossible (usually between 2 and 6 hours of use, though in extremely heavy concentrations, "lifespan" could be cut down to as little as half an hour - these lifespans are still valid today with the S10 filters).
I'm unsure of the amount of spares carried, but , before the onset of the gasmask tin, the masks were carried in a tubular canvas case with 1 spare filter. Spare filters can also be encountered in their own individual cases being carried on the gasmask tin straps.
It should be possible to change a filter in less than 2 seconds (and is!). The proceedure being that the wearer closes his eyes, takes a deep breath and holds it, unscrews the filter, screws the new one in place, blows out (hard!), tentatively takes a breath, opens eyes and continues. If it's been cross threaded or incorrectly fitted, or leaks, then tough luck!