It is an alloy made from 96%-98% iron, 2%-4% carbon, and small amounts of silicone. It has impressive temperature tolerance, with some cast iron capable of handling temperatures over 2100F (1150C). When it comes to pressure, cast iron's strength depends on its pressure class.

What is non-return valve used for?

A non-return valve allows a medium to flow in only one direction and is fitted to ensure that the medium flows through a pipe in the right direction, where pressure conditions may otherwise cause reversed flow.

What is the difference between check valve and non-return valve?

A non-return valve lets the fluid flow in one direction. When fluid in the line reverses direction, a check valve prevents backflow by allowing flow in one direction. The check valves are usually designed for a particular pressure.