JONLOO is an industrial check valves manufacturer & supplier in China for more than 20 years. Check valve is also called Non-return valve. JONLOO offers wide range check valves in various materials like cast steel, stainless steel, forged steel and alloy steel etc. There are mainly four types of JONLOO check valves--swing type, lift type, dual plate type and stop check type. The only function of a Non-return valve is to prevent backflow. It shall be choosen when you cannot supplement it with another valve.