Plug with shut-off valve for diagnostic quick coupling, with external NPT thread, used for pressure measurement in hydraulic power systems. Manufactured according to ISO 15171-1 and SAE J1502 standards, interchangeable with couplings from other manufacturers. Quick coupling plugs made of hardened steel are typically permanently installed in the hydraulic system, while the quick coupling sockets remain connected via a hose to the pressure gauge. The connection of the socket to the plug should only occur when the system is not operating, with no pressure or very low pressure of a few bars. The working pressure for the disconnected plug is 400 bar, and the minimum burst pressure is 1600 bar. The working pressure for the connected socket and plug is also 400 bar, while the minimum burst pressure is 1300 bar. The socket and plug are equipped with valves that ensure leak-free connection and disconnection as well as sealing. Their flat surfaces minimize residual oil leakage and air inclusion into the system (leakage approx. 0.1 ml during disconnection, air inclusion approx. 0.02 ml during connection). For proper operation, it is essential to maintain the cleanliness of the valve surfaces. Working pressure: 400 bar. Burst pressure: 1300 bar. Vacuum: up to 0.9 bar. Hydraulic oil flow at Δp = 3 bar: 4.2 [l/min]. Material: galvanized steel. Sealing: NBR. Operating temperature: from -40°C to +120°C.