Characteristics of ball valves

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

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

Most ball valves have leakage class A.

DN - nominal diameter - is used to designate the sizes of pipeline valves, it has no dimensions, and the numerical value of DN is approximately equal to the internal diameter of the connected pipeline in millimeters. The nominal diameter is applied to all elements of pipeline systems, except for pipes and components that are characterized by the external diameter.

PN - nominal pressure - is the maximum excess pressure of the working medium at a temperature of 20°C, under which the continuous operation of the ball valve is allowed.

Test pressure - is the excess pressure at which the hydraulic test for strength and tightness with water at a temperature of 5 to 70°C should be carried out, unless otherwise specified in the ball valve's manual or normative documentation.

Working pressure - is the maximum excess pressure under which the specified operating mode of the shut-off valve is ensured, taking into account the temperature of the working medium. The value of the working pressure is generally lower than the value of the nominal pressure, so simultaneous operation at maximum working temperature and nominal pressure is not allowed.

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

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