Water pump is a machine that transports or pressurizes a liquid. It transmits the mechanical energy of the prime mover or other external energy to the liquid to increase the energy of the liquid. It is mainly used to transport liquids including water, oil, acid and alkali, emulsions, suspoemulsions and liquid metals, etc., and can also transport liquid and gas mixtures. and liquids containing suspended solids. The basis for water pump selection should be based on the process flow, water supply and drainage requirements, and be considered from five aspects, namely liquid delivery volume, device lift, liquid properties, pipeline layout, and operating conditions.
1. The flow rate is one of the important performance data of the water pump, which is directly related to the production capacity and delivery capacity of the whole device. For example, in the process design of the design institute, the three flow rates of normal, small and large pumps can be calculated. When selecting a pump, the maximum flow is taken as the basis and the normal flow is taken into consideration. When there is no large flow, usually 1.1 times the normal flow can be taken as the maximum flow.
2. The head required by the installation system is another important performance data for pump selection. Generally, the head needs to be enlarged by 5-10 to select the model.
3. Liquid properties, including the name of the liquid medium, physical properties, chemical properties and other properties. Physical properties include temperature c density d, viscosity u, solid particle diameter and gas content in the medium, etc., which involve the head of the system, effective gas Calculation of corrosion residue and suitable pump type: Chemical properties mainly refer to the chemical corrosion and toxicity of the liquid medium, which is an important basis for selecting the pump material and the type of shaft seal.
4. The pipeline layout conditions of the device system refer to the liquid delivery height, the delivery distance, the delivery direction, some data such as low liquid level on the suction side, high liquid level on the discharge side, and pipeline specifications and their length, material, pipe fitting specifications, and quantity etc., in order to carry out the calculation of the comb head and the check of NPSH.
5. There are many operating conditions, such as liquid operation T saturated steam force P, suction side pressure PS, discharge side container pressure PZ, altitude, ambient temperature, whether the operation is intermittent or continuous, whether the pump position is fixed or adjustable moved.