he selection conditions of the pump

The selection conditions of the pump

1. Physical and chemical properties of the conveying medium

The physical and chemical properties of the conveying medium directly affect the performance, material and structure of the pump.Physical and chemical properties of the medium include: medium name, medium characteristics (such as corrosion, abrasive, toxicity, etc.), solid particle content and particle size, density, viscosity, vaporization pressure, etc., indicating whether the medium is easy to crystallize.

2. Process parameters

Process parameters are the most important basis for pump selection.

(1) Flow Q flow refers to the medium quality of the pump transport required in the production of the process unit, and the process personnel should generally give the normal, minimum and maximum flow.

Only normal and rated flow rates are often given on the pump data sheet.When selecting a pump, the rated flow rate is required to be no less than the maximum flow rate of the device, or 1.1 to 1.15 times the normal flow rate.

(2) Head H refers to the head value required by the process device, also known as the calculated head.Generally, the rated lift of the pump is 1.05 to 1.1 times the lift required by the device.

(3) Inlet pressure Ps and outlet pressure Pd Inlet and outlet pressure refers to the pressure of the pump in and out of the nozzle flange, and the size of the inlet and outlet pressure affects the pressure resistance of the shell and the requirements of the shaft seal.

(4) Temperature T refers to the temperature of the inlet medium of the pump, and the normal, minimum and maximum temperature of the inlet medium of the pump should generally be given during the process.

(5) Device cavitation allowance NPSHa is also known as effective cavitation allowance.

(6) Operation state Operation state is divided into two kinds of continuous operation and intermittent operation.

3. Site conditions

Site conditions include the installation location of the pump (indoor and outdoor), ambient temperature, relative humidity, atmospheric pressure, atmospheric corrosion status and classification of dangerous areas.