An `in-line´`check´ or `non-return´valve, with a parallel, male, gas, pipe-thread union at each extreme. The 3/4" version is also available with a 1" female gas pipe-thread union at the input. This is aimed at ease of installation on existing systems. These valves are specifically designed to prevent backflow once the central heating pump is switched off. Whilst the stainless steel spring is very `light-weight´ and provides very little resistance in the forward condition, it is sufficient to pervent `thermo-circulation´ in the forward direction due to residual heat.
   This short, compact valve has been specifically desiged for ease of installation in general applications, and specially for flow meters and hot water boilers.

Ultra low water absorption; conforming to ISO-62.Conforms to DIN-5346; ISO-75 1st and 2nd part. O-ring Spec: Temperature range -55ºC to +150ºC. This valve has zero leakage in the closed condition. For pressure drop across the valve in the open condition, see the flow/pressure drop graphs.