How To Select A Clean Water Pump

Aug 13, 2025

A pump is a machine that converts the mechanical energy of a prime mover into energy for pumping liquid. Pumps are used to increase the potential energy, pressure energy, and kinetic energy of liquids. The prime mover drives the impeller to rotate through the pump shaft, doing work on the liquid and increasing its energy, thereby delivering the required amount of liquid through the suction and flow components of the pump to the required height or pressure. A water pump is a machine that converts mechanical energy into liquid water energy, and is a commonly used supply and return water pump. It is called a water pump because it is different from other special water quality applications such as sewage pumps and anti-corrosion pumps.

Working principle

The prime mover of the clean water pump drives the impeller to rotate through the pump shaft, doing work on the clean water inside the pump, increasing its energy, and thus delivering the required amount of clean water from the suction and through the pump's flow components to the required height or pressure.

Basic Composition
Shell:

The shell is used to collect liquid from the impeller, convert some of the fluid's kinetic energy into pressure energy, and finally guide the fluid evenly to the discharge outlet. The casing of a single suction single-stage clean water pump is mostly spiral volute, and some even have fixed guide vanes inside the casing.
Impeller:

It is the main component of the pump. It is divided into open impellers, semi open impellers (with only the rear plate), and closed impellers (with front and rear plates). Open impellers are often used to transport liquids containing impurities, such as sewage pumps. Clear water pumps all use closed impellers, and most of them are backward impellers.
Sealing ring:

In order to reduce the amount of liquid leaking from the high-pressure area to the low-pressure area inside the casing, sealing rings (also known as leakage reduction devices) are usually installed separately on the pump body and impeller. Due to the small gap between the moving ring and the fixed ring of the sealing ring, it is prone to wear and tear, which reduces the efficiency of the pump. Therefore, it should be checked or replaced regularly.
Suction chamber:

The function of the suction chamber of the pump is to minimize the flow loss of liquid entering the pump body. The structural shape of the suction chamber has a significant impact on the suction performance of the wall mounted pump, and the commonly used suction chamber forms include conical tube and circular ring. Cone tube type is commonly used, with a taper of about 70-180 degrees.
Shaft seal:

At the point where the pump shaft extends out of the pump body, a shaft seal is installed between the rotating pump shaft and the fixed pump body to reduce the leakage of high-pressure fluid from the pump to the outside of the pump body and prevent air from entering the pump. Commonly used shaft seals include packing shaft seals, skeleton rubber shaft seals, mechanical shaft seals, and floating ring shaft seals.
Axial force balancing device:

The blade shafts of single suction single-stage pumps and some multi-stage pumps have axial thrust. The main cause is the imbalance of fluid pressure acting on the ears on both sides of the impeller. If no measures are taken to eliminate it, it will cause the pump shaft and impeller to move, and damage the components due to mutual friction caused by force. Generally, a balance pipe is installed or a balance hole is opened on the rear plate, and a thrust bearing is used to balance the remaining pressure.

In addition to the main components mentioned above, the water pump also includes pump shaft, bracket, coupling, bearings, etc.

Selection Guide

1. The selection of a clean water pump mainly depends on the parameters of flow rate and head;

2. Centrifugal pumps are suitable for places with high flow rates and high head;

3. The flow range of pipeline pumps is not large, suitable for places with low head;

4. Horizontal pumps are commonly chosen, while vertical pumps are selected when there is a local installation;

5. When a single-stage pump cannot meet the requirements, choose a two-stage pump;

6. When the temperature t>65 ℃, choose a hot water pump; When t ≤ 65 ℃, choose a cold water pump.

classification

Divided by different media: cold water pump and hot water pump.

According to different working principles, it can be divided into centrifugal pumps and pipeline pumps.

According to the position of the pump shaft, it can be divided into horizontal pumps and vertical pumps.

According to the number of impeller stages, it can be divided into single-stage pumps and multi-stage pumps.