The working principle of a double suction pump


Published:

Aug 19,2022

The basic components of a double-suction pump are a high-speed rotating impeller and a fixed worm-shaped pump casing. The impeller with multiple (usually 4 to 12) back-bending vanes is fixed on the pump shaft and driven by an electric motor

The working principle of a double suction pump

Double-suction pumps are used in a wide range of applications, generally in factories, cities, mines, farmland, water conservancy projects and other fields.

The working principle of a double suction pump is as follows.  

The basic components of a double-suction pump are a high-speed rotating impeller and a fixed worm-shaped pump casing. The impeller with multiple (usually 4 to 12) back-bending vanes is fixed on the pump shaft and driven by an electric motor, rotating at high speed together with the pump shaft. The impeller is the component that acts directly on the liquid in the pump and is the energy supply unit for the pump. The suction port in the centre of the pump casing is connected to the suction pipe, which is fitted with a one-way foot valve at the bottom of the suction pipe. The discharge outlet near the side of the pump casing is connected to the discharge pipe fitted with a regulating valve.

When a double suction pump is started, the pump shaft drives the impeller together to execute a high speed rotational motion, forcing the liquid pre-filled between the vanes to rotate and flowing from the centre of the impeller to the outer circumference under inertial centrifugal force. The energy gained by the liquid flowing through the impeller increases the hydrostatic energy and flow rate. As the liquid leaves the impeller and enters the pump casing, the flow path in the casing gradually expands and decelerates. Part of the kinetic energy is converted into hydrostatic energy and flows in a tangential direction into the discharge pipe. The double suction pump casing is therefore not only the part that collects the liquid flowing from the impeller, but is also the energy transfer device. As the liquid is thrown from the centre of the impeller to the outer circumference, a low pressure area is formed in the centre of the impeller. The liquid is drawn into the centre of the impeller by the overall effect between the level of the storage tank and the centre of the impeller. Depending on the continuous operation of the impeller, the liquid is continuously drawn in and discharged. The mechanical energy gained by the liquid in a double suction pump is represented by an increase in static pressure.

double suction pump

The double suction pump shaft is supported by two single row radial ball bearings. The bearings are mounted in bearing bodies at both ends of the pump body and lubricated with grease. A double suction sealing ring is used to reduce the leakage of water from the pressurised water chamber of the pump to the suction chamber. The water pump is driven directly by the electric motor via a coupling. The shaft seal is a soft packing seal. To cool and lubricate the seal chamber and to prevent air leakage into the pump, there is a water seal ring between the packings. When the pump is operating, a small amount of high-pressure water flows through the water seal tube into the filling chamber and acts as a water seal. The main components of this type of pump are: pump body, pump cover, impeller, shaft, double suction seal, sleeve, bearings etc. Most of them are made of the following materials: cast iron, except for the shaft, which is made of high-quality carbon steel. The pump body and pump cover form the impeller's working chamber. Pipe threaded holes for mounting vacuum and pressure gauges are formed in the inlet and outlet flanges, and pipe threaded holes for drainage are provided below the inlet and outlet flanges. The impeller is statically balanced and has a bushing and bushing nut fixed on both sides. Its axial position can be adjusted by means of the bushing nut. The axial force of the impeller is balanced by the symmetrical arrangement of its blades, and there may be some residual. The remaining axial force is carried by the bearings at the coaxial end.  

The above is a brief analysis of the working principle of the double suction pump by Long March Pump Valve. 

Keyword:

double suction pump