Characteristics of Centrifugal Pumps

Pumps are generally grouped into two broad categories—positive displacement pumps and dynamic (centrifugal) pumps. Positive displacement pumps use a mechanical means to vary the size of (or move) the fluid chamber to cause the fluid to flow. On the other hand, centrifugal pumps impart momentum to the fluid by rotating impellers that are immersed in the fluid. The momentum produces an increase in pressure or flow at the pump outlet.In Newtonian (true) fluids (non-viscous liquids, such as water or gasoline), the term head is the measurement of the kinetic energy that a centrifugal pump creates. Imagine a pipe shooting a jet of water straight into the air. The height that the water reaches is the head. Head measures the height of a liquid column, which the pump could create resulting from the kinetic energy the centrifugal pump gives to the liquid. The main reason for using head instead of pressure to measure a centrifugal pump’s energy is that the pressure from a pump will change if the specific gravity (weight) of the liquid changes, but the head will not change. End users can always describe a pump’s performance on any Newtonian fluid, whether it is heavy (sulfuric acid) or light (gasoline), by using head. Head is related to the velocity that the liquid gains when going through the pump.

1. Introduction

A gear pump uses two meshing, toothed cogs to force water from the inlet of the pump through to the outlet. Figure No. 1 shows a simplified drawing of an external teeth gear pump on the left along with the alternate arrangement of internally pointing teeth.The design of a gear pump lends itself to use with clean liquids. Insure they draw liquid from well above the bottom of the supply tank in clear liquid space. Both low and high viscosity liquids can be pumped. If food grade products sensitive to shear (i.e. where the churning action of the pump breaks cells and fibres) are to be pumped the size of the pump will need to be increased and the speed reduced.

When using a gear pump a pressure relief valve must be fitted to protect the pump if deadheaded against a closed valve or blockage. The PRV can be piped back to the suction side of the pump or into the supply tank.A ball valve is a shut off valve that controls the flow of a liquid or gas by means of a rotary ball having a bore. By rotating the ball a quarter turn (90 degrees) around its axis, the medium can flow through or is blocked. They are characterized by a long service life and provide a reliable sealing over the life spanThere is a wide range of applications for when Butterfly valves are ideal for use as a fluid flow control valve. They can be used for capacity lines on shops and perform well within slurry and water applications with high volume.

Some of the applications, where the different types of Butterfly valves that BM Engineering stock, can be used include:
Cooling water, air, gases and fire protection

Slurry