1 Application scope and instruction
1.0.1 This specification is applicable to separate calculation of the pressure loss at inlet and outlet nozzles of equipment. The resistance of the nozzles is a part of system pressure drop, which is called local resistance. It is caused by the sudden change of fluid velocity or direction when the liquid passes through the inlet or outlet of the equipment, resulting in vortex, which increases the relative motion of fluid particles and internal friction.
1.0.2 There are three ways to express the pressure loss at inlet and outlet nozzles of equipment:
1.0.2.1 It is expressed by fluid velocity head in pipe and local resistance coefficient.
1.0.2.2 It is expressed by pressure drop.
1.0.2.3 In this method, equivalent length is adopted, and the pressure loss is expressed by converting the local resistance generated by a fluid to the resistance generated by the fluid flowing through a pipe of the same diameter and equivalent length.
1.0.3 The local resistance coefficient, which expresses the resistance at inlet and outlet of the pipe together with the fluid velocity head, is related to the pipe connecting form of the equipment (see Figure 7.0.1). Generally, the pressure loss at the inlet and outlet of equipment may be conservatively estimated according to the sharp-edged inlet and outlet nozzles (velocity head loss).
1.0.4 Unless otherwise specified in this specification, the pressures are absolute pressures.
1 Application scope and instruction
2 Expression of pressure loss at inlet and outlet nozzles of equipment
3 Precautions in calculation
4 Calculation of pressure loss at equipment inlet
5 Calculation of pressure loss at equipment outlet
6 Calculation examples
7 Attached figures and tables
