Technical specifications of check valves

DN - nominal diameter - a conventional designation of the size of pipeline fittings. The nominal diameter has no unit of measurement and approximately corresponds to the inner diameter of the opening in the connecting flanges of the check valve, measured in millimeters. Nominal diameters are adopted to standardize the sizes of pipeline fittings and elements of pipeline systems.

PN - nominal pressure - this is the maximum allowable water pressure at a temperature of 20°C, at which long-term operation of the check valve is permitted.

Ppr - test pressure - this is the water pressure at a temperature from 5 to 70°C, at which the check valve should be tested for strength and tightness.

Opening pressure of the check valve - the difference in pressures between the inlet and outlet nozzles of the valve at which the disc begins to open the passage. The full opening pressure corresponds to the required pressure difference for the full opening of the disc.

Рр - working pressure - this is the maximum excess pressure for each temperature of the working medium, at which long-term operation of the check valve is permitted.

For most types of pipeline fittings, operation at nominal pressure with the maximum allowable temperature is not permitted. Therefore, as the pressure increases to nominal, the maximum working temperature decreases.

Kvs - flow capacity coefficient - its value corresponds to the water flow in m³/h at a temperature of 20°C, at which the pressure loss on a fully open check valve will be 1 bar. The flow capacity of the check valve is used when selecting them and in the hydraulic calculations of pipeline systems.

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