Non-return, or block, or unidirectional valves are commonly used in most hydraulic applications, both in the mobile and industrial sectors. The VUR-NPTF non-return valves are parts-in body valves, suitable for in-line installation. Inside the valve body a conical poppet guarantees the locking of the flow from port 1 to port 2. The passage of the whole flow is free from port 2 to port 1, at the pressure corresponding to the chosen spring. For VUR-NPTF unidirectional valves the standard opening pressure of the shutter is fixed at 1 bar; different opening pressures are available on request. Depending on the size chosen, the VUR-BSPP block valves can be used in systems with flow rates up to 430 lpm (113,5 gpm) and maximum working pressures up to 400 bar (5800 PSI). The valve body has NPTF female threads, available in sizes from NPTF 1/8 to NPTF 2 and is made of high-strength steel and protected externally from corrosion with a galvanizing surface treatment. The zinc/nickel treatment is available on request for applications exposed to corrosive agents, such as environmental factors, particularly aggressive.