The high-efficiency zone of a pump refers to the operating range in which the pump is running under its design conditions—specifically, when the pump’s suction lift, head, supply voltage, motor speed, and the characteristics of the liquid being pumped all conform to the design parameters specified by the pump manufacturer, or fall within the manufacturer’s design limits. Under these conditions, the pump is operating in its high-efficiency zone. Therefore, The following points should be observed during pump installation: ：

1) The installation location of the pump shall meet the requirements for the allowable net positive suction head; the foundation must be level and stable, and the rotation direction of the prime mover must be consistent with that of the pump.
2) When the pump and the prime mover are connected via a shaft coupling, the shaft centers must be aligned on the same straight line to prevent vibration and uneven bearing wear during operation.
3) If belt drive is used, the shafts must be parallel and the pulleys aligned.
4) If multiple units are installed in the same equipment room, a clearance of at least 800 mm shall be maintained between units and between each unit and the wall.
5) The pump suction pipe must be tightly sealed, with as few bends and gate valves as possible. During priming, all air must be completely purged; during operation, no air should accumulate inside the pipe. The suction pipe should be slightly inclined upward and connected to the pump inlet at an angle, with the inlet submerged to a specified depth.
6) The reserved holes on the pump foundation shall be cast in accordance with the dimensions of the pump.

Centrifugal pump

Cavitation in Centrifugal Pumps and Installation Height
I. Cavitation in Centrifugal Pumps
Cavitation in centrifugal pumps occurs when the liquid being conveyed partially vaporizes because its saturation vapor pressure at the operating temperature equals or falls below the pressure at the pump inlet—typically at the impeller inlet—resulting in noise and vibration. In severe cases, cavitation leads to a significant decline in pump flow rate, head, and efficiency. Clearly, cavitation is an undesirable condition that must be avoided during normal operation of centrifugal pumps. The key to preventing cavitation is ensuring proper pump installation elevation, particularly when handling high-temperature, highly volatile liquids.
II. Installation Height Hg of Centrifugal Pumps
The allowable suction vacuum height, Hs, refers to the maximum degree of vacuum that can be achieved at the pump inlet pressure, p1. However, the actual value of Hs is not calculated using the formula; rather, it is determined experimentally by the pump manufacturer and is provided in the centrifugal pump catalog for users’ reference. It should be noted that the Hs value listed in the pump catalog is based on clear water as the working fluid, under operating conditions of 20°C and a pressure of 1.013 × 10^5 Pa. When the operating conditions or the working fluid differ, appropriate corrections must be made.
(1) The centrifugal pump is used to convey clear water, but the operating conditions differ from the experimental conditions; therefore, Hs1 can be calculated using the following equation: Hs1 = Hs + (Ha − 10.33) − (Hυ − 0.24).
(2) Conveying other liquids: When both the liquid to be conveyed and the operating conditions differ from the test conditions, a two-step conversion is required: first, use the above equation to convert the Hs1 value obtained from the pump catalog; second, use the following equation to convert Hs1 into H?s.
2 Cavitation margin Δh of centrifugal pump
For oil pumps, the installation height is calculated using the net positive suction head (NPSH) margin Δh, which is obtained from the pump manufacturer’s data sheet and is also determined using 20°C clear water. If other liquids are being conveyed, corrections must be made; refer to relevant technical literature for detailed guidance.
From a safety standpoint, the actual installation height of the pump should be less than the calculated value. Furthermore, when the calculated Hg is negative, it indicates that the pump’s suction inlet must be located below the liquid level in the storage tank. Example 2-3: A centrifugal pump is specified in the catalog as having an allowable net positive suction head (NPSH) of 5.7 m. The total head loss in the suction piping is 1.5 mH₂O, the local atmospheric pressure is 9.81 × 10⁴ Pa, and the dynamic head in the suction piping can be neglected.
Submersible pump
Submersible pump for drainage systems
Submersible pumps are suitable for drainage systems under a wide range of environments and operating conditions, with specific applications including: wastewater discharge in industrial enterprises; effluent discharge systems at municipal sewage treatment plants; drainage stations in subways, basements, and civil defense facilities; sewage discharge from hospitals, hotels, and high-rise buildings; sewage pumping stations in residential areas; slurry discharge in municipal engineering projects and construction sites; water supply systems at water treatment plants; sewage discharge from livestock farms and irrigation of rural farmland; support for mining exploration and water treatment equipment; and replacing manual labor such as shoulder-carrying or hand-pumping to suction and convey river sediment.

Features of Submersible Pumps ：

The unique single- or double-vane impeller design significantly enhances the pump’s ability to pass debris, allowing it to effectively handle fibrous materials up to five times the pump’s nominal diameter and solid particles with diameters of approximately 50% of the pump’s nominal diameter.
The mechanical seal of the submersible pump is made from a new, hard, corrosion-resistant tungsten carbide material, and the seal design has been upgraded to a double-end-face configuration. This allows the seal to operate continuously in the oil chamber, enabling the pump to run safely and reliably for more than 8,000 hours.
Submersible pumps feature a compact overall structure, small footprint, low noise, and significant energy-saving performance. They are easy to maintain, eliminate the need for a pump house, and can operate simply by being submerged in water, thereby substantially reducing project costs.
The submersible pump features a sealed oil chamber equipped with a high-precision, interference-resistant leak detection sensor, as well as thermally sensitive elements embedded in the stator windings, providing absolute protection for the pump motor.
Submersible pumps can be equipped, as per customer requirements, with a fully automatic safety protection control cabinet that provides comprehensive protection against pump leakage, electrical leakage, overload, and overheating, thereby enhancing the product’s safety and reliability.
The float switch can automatically start and stop the pump in response to changes in the liquid level, eliminating the need for dedicated supervision and making operation extremely convenient.
Submersible pumps can be equipped with a dual-rail automatic coupling installation system as per customer requirements, which greatly simplifies installation and maintenance by eliminating the need for personnel to enter the sewage pit.
Submersible pumps can be operated across the entire head range while ensuring that the motor is not overloaded. There are two distinct installation methods: a fixed, automatic coupling system and a mobile, free-standing system.