Specifiche tecniche delle valvole a globo

DN - nominal diameter - a numerical designation of the size of pipeline fittings that approximately equals the internal diameter of the passage section (in millimeters) in the valve's connecting nozzles. The actual diameter of the passage section may differ from the DN value.

PN - nominal pressure - is the maximum excess pressure of the working medium at a temperature of 20°C, at which long-term operation is allowed and the declared service life of the valve is maintained. The value of PN is usually indicated in bars (bar).

Test pressure - is the maximum excess water pressure at which hydraulic tests of the valve for strength must be carried out. The water temperature during hydraulic testing should be in the range of 5 to 70°C, unless otherwise specified in the valve's operating instructions.

Working pressure - is the maximum excess pressure at which the valve is allowed to operate, taking into account the temperature of the working medium. At high temperatures of the working medium, the value of the working pressure is usually lower than the nominal pressure.

Kvs - flow coefficient - is a numerical value equal to the volume flow rate of water at a temperature of 20°C through a fully open valve in m³/hour, at which the pressure drop across the valve is 1 bar. The Kvs value is used in hydraulic calculations to determine the pressure drop across the valve.

Sealing class - is a characteristic of shut-off valves that determines the maximum allowable leakage through the closed 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.

• Class A - no leakage
• Class B - no more than 0.0006*DN(mm) cm³/s
• Class C - no more than 0.0018*DN(mm) cm³/s
• Class D - no more than 0.006*DN(mm) cm³/s

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