It is stated without a unit quantity. Its numerical value states the permissible working gauge pressure in bar at a temperature of 20°C (68°F) to which a component or specified material may be subjected. In the field of pump technology, it is common to use pressure ratings according to DIN 2401 for the range from PN 1.6 to PN 200.
Preferential designation for pressure ratings are 1.6; 2.5; 4; 6; 10; 16; 25; 40….
The vapour pressure of the pumped fluid greatly influences Cavitation Behaviour and thus the System NPSHavailable.
The vapour pressure is one of the important liquid properties for pump selection and depends on the fluid temperature.
The maximum and minimum temperatures of the pumped medium are of particular importance for the design of the pump. They are taken into account in the selection of materials and seals and, if necessary, in a media-material resistance test.
The fluid properties (density, viscosity) change with the temperature. The power requirement of the pump is directly proportional to the density. Therefore, the temperature must be taken into account from the operating range with the maximum density. Furthermore, for viscous media (ν > 10 mm²/s), the shape of the pump performance curve must be converted.
