Technical specifications of butterfly valves

DN - nominal diameter. The numerical designation of the internal diameter common to all components of a pipeline system except for those characterized by their external diameters. The nominal diameter is used to standardize the size of pipeline fittings, has no unit of measurement, and is approximately equal to the internal diameter of the connecting pipeline.

PN - nominal pressure. The maximum excess pressure of the working medium at a temperature of 20°C at which continuous operation is allowed and the calculated service life of the butterfly valve is provided.

Test pressure. The excess pressure at which a hydraulic test of the butterfly valve for strength and tightness with water should be carried out at a temperature of 5 to 70°C if no other test temperature is specified in the passport or normative documentation.

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

Kvs - flow coefficient. Numerically equal to the water flow rate, in m³/h at a temperature of 20°C, at which the pressure drop across the disk valve will be 1 bar. The value of the flow coefficient is used in hydraulic calculations to determine pressure losses on elements of the pipeline system.

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