These valves use a bellow displacement system. In most bellow valve systems used for prevention of leakage, contraction (sometimes compression or extension) may take place in a cartridge that is affixed to the valve stem causing it to open and drain. In the case of the 20406303, the "bellows {are} in normal position at 15ºC (+4ºC, -2ºC) and {they are} contracting inward at 4(+4, -2)ºC with a stroke of more than 5mm"
Replied on March 17, 2022 by Ori from Industrial Stores