der bunkermann wrote:arthur, it dous not seem logical that there's also a VW filter above the HES?
the dustfilter on your picture is maybe a cheaper, easyer to produce variant than a VW?
gr, tim
Hi, The VW filter above the HES is for removing dust before the drawn air enters the gas filters.
The Staubfilter removes dust etc from the un-filtered air which is ducted directly into the HES from outside by bypassing the gas filters. During a gas attack the large shut-off valve to its right would be closed and the air would then be pulled through the VW filter and gas filters.
In the Channel Islands such a system is never seen
Instead the gas filters would be removed from the HES and a bakerlite tube would replace them so the air pump would pull in air directly from outside and in-comming air would only be filtered by the VW filter.
It is said by former soldiers that the HES would be run for 20 mins every hour to keep the air fresh inside bunkers and in some cases they were run constantly to try to keep humidity down.
Just realised that I know of 2 bunkers locally that have the large shut-off valve fitted but no connection pipe to the HES
Malcolm
