Technical specifications of gate valves

DN - nominal diameter. The numerical designation of the internal diameter, common to all components of the pipeline system, except for components that are characterized by external diameters. The DN value is used to standardize the sizes of pipeline fittings, it has no unit of measurement and is approximately equal to the internal diameter of the connected pipeline.

PN - nominal pressure. The maximum excess pressure of the working medium at a temperature of 20°C, at which continuous operation is permissible and the specified service life of the valve is ensured.

Test pressure. The excess pressure at which the valve must be hydraulically tested for strength and tightness with water at a temperature from 5 to 70°C, if the passport or regulatory documentation does not specify a different test temperature.

Working pressure - this is the maximum excess pressure at which the specified operating mode of the valve is ensured, taking into account the actual temperature of the working medium. The value of the working pressure is usually less than the value of the nominal pressure, so operation at maximum working temperature and nominal pressure of the medium is not allowed.

Kvs - flow coefficient. Corresponds to the water flow rate, in m³/h at a temperature of 20°C, at which the pressure loss on the valve will be 1 bar. The value of the flow coefficient is used in hydraulic calculations to determine the pressure loss on the valve.

Sealing class - determines the maximum allowable leakage through the closed valve of the valve at atmospheric pressure on one side and water pressure at 1.1*PN on the other. The water temperature during testing should be in the range of 5 to 40°C.