The well labeled "Sicherheitstank" is a separate tank with either water - or more likely class A foam mix - for the self-protection system. The plumbing for this is enclosed within the yellow roll cage. Rather than relying on the main water tank, this separate system and extinguishing agent supply usually holds enough to give the crew time to "get out of Dodge", without the risk of the supply drying up too quickly. Similar separate self-protection systems are often fitted to units which respond to tunnel fires these days, as well as brush pumpers and tankers.
The earliest systems were sourced from the main tank, but this proved to be a problem if the truck crew only decided to relocate after their main tank ran dry, which was not uncommon....
The earliest systems were sourced from the main tank, but this proved to be a problem if the truck crew only decided to relocate after their main tank ran dry, which was not uncommon....
Added by on 15 November 2022.