AWP check valves open autonomously by the pressure that is exerted by the working medium upon the valve disc. They start to open at a differential pressure of 0.14 psi to 0.72 psi and are fully open between 1.45 psi and 2.9 psi. As soon as the flow is interrupted or the flow direction is reversed, the valve closes automatically. Additionally, RVA stop check valves may also be closed manually with a handwheel or a ratchet attached to the lifting stem. Rotating the stem clockwise will keep the valve disc down on the valve seat and therefore keeps the valve closed, counter-clockwise rotation will enable the valve disc to be opened by the pressure of the medium. The built-in damping device makes this type of valve especially suitable in cases where the power requirement / flow rate fluctuates. AWP stop check valves are designed for installation in industrial heating and refrigeration systems. They are installed on either the pressure or suction side of compressors or in pipes in which only one direction of flow is intended. The stem sealing is provided by a threaded bush with spring-elastic PTFE ring.