8 dredge pump works

pumps

Pumps

By :Aly Adel Aly El-shabrawy Mohammad Magdy EL-ghayesh

Outlines

Why do we need pumps ? Types of Pumps. Positive displacement Pumps. Centrifugal Pumps. Volute casing Pumps. Advantages and disadvantages.

Why do we need Pumps?

Pump is a mechanical device generally used for raising liquids from lower level to a higher one. This is achieved by creating a low pressure at the inlet& high pressure at the outlet of the pump, the outlet discharge can be stored or supplied. Work done in pumps by a prime mover to enable it to impart mechanical energy to the liquid which ultimately converts into pressure energy.

Centrifugal Pumps.

A centrifugal pump is a roto-dynamic pump that uses a rotating impeller to create flow by the addition of energy to a fluid. Centrifugal pumps are commonly used to move liquids through piping. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radiailly outward into a diffuser or volute chamber (casing), from where it exits into the downstream piping. Centrifugal pumps are used for large discharge through smaller heads.

Volute casing pump

The centrifugal pump creates an increase in pressure by transferring mechanical energy from the motor to the fluid through the rotating impeller. The fluid flows from the inlet to the impeller centre and out along its blades. The centrifugal force hereby increases the fluid velocity and consequently also the kinetic energy is transformed to pressure.

Components of centrifugal pump

Impeller (rotor). Pump casing. Suction pipe. Delivery pipe (discharge outlet). Prime mover(shaft). Wear rings.

Impeller

Opened Semi-opened Closed

Advantages of centrifugal pumps

steady flow Uniform torque High efficiency for low head pumps High speed (directly coupled with motor) Handles all types of fluids Low initial cost Low maintenance cost Compact design, require less floor space Gross weight is less Instillation is easy Simplified construction Less noise.

Disadvantages of centrifugal pumps

Single stage pump will not develop a high pressure. Centrifugal pumps not always a self-priming pumps. Cannot handle high viscosity liquids. If a non-return valve is not incorporated at suction, the liquid will return back into suction tank and pump stops.