4.1　General Requirements

4.1.1　Pump types shall be determined based on operating parameters and medium characteristics，and may be determined based on the proven successful experience in similar cases.

4.1.2　When selecting pumps，centrifugal pumps should be preferably selected.When the medium viscosity is larger than or equals to 100MPa·s，displacement type pump should be selected.

4.1.3　When the operating parameters are low flow and high head，pumps should be selected in the following order:

1　High-speed centrifugal pump，pitot tube pump；

2　Rotary pump，reciprocating pump；

3　Multi-stage centrifugal pump；

4　Vortex pump may be selected with lower cavitations tendency.

4.1.4　If metering is required，metering pump shall be selected.

4.1.5　Centrifugal pump and rotary pump shall be equipped with cartridge mechanical seals.The seals and sealing systems shall be selected according to SH/T 3156 Engineering Specification of Pumpshaft Seal Systems of Centrifugal and Rotary Pumps for Petrochemical Industry.