Category: Advance Concept Mechanical Eng

There are many variants of screw type positive displacement, rotary pump. The various designs depend on the number of intermeshing screws involved, the pitch of the screws and the direction of fluid flow. Two common designs are the two-screw, low-pitch, double-flow pump and the three-screw, high-pitch, double-flow pump.

This is also used to pump oils. The schematic diagram of a lobe pump is shown in Figure 9.27. This is a three-lobed pump. Two-lobed pump is also used. Two lobes are arranged in a casing. As the rotor rotates, oil is trapped in the space between the lobe and the casing and is carried to the…

In a vane pump, a rotor is coupled to the drive shaft and rotates inside a cam ring. Vanes are fitted to the rotor slots and follow the inner surface of the ring as the rotor turns (Figure 9.26). Centrifugal force and pressure under the vanes keep them pressed against the ring. Pumping chambers are…

A gear pump maintains the flow of fluid by carrying the fluid between the teeth of two meshed gears. One gear is connected to drive shaft and other is meshed with the first gear. The pumping chambers formed between the gear teeth are enclosed by the pump housing and the side plates. A low pressure…

Air vessel is a closed chamber containing compressed air in the top space and liquid at the bottom of the chamber. At the base of the chamber, there is an opening through which the liquid (water) may flow into or out from the vessel. When liquid enters the air vessel, air gets compressed and when…

In centrifugal pump, transformation of energy from mechanical to hydraulic form is done by rotating action of impeller, but in reciprocating pump this energy transformation is done by reciprocating action of piston. In reciprocating pump, the rotary motion of crank shaft is converted into reciprocating motion of pump by means of a connecting rod. Pressure…

Example 9.13: A centrifugal pump running at 1,500 rpm has internal and external impeller diameter of 200 and 300 mm, respectively. The vane angles of impeller at inlet and outlet are 25° and 30°, respectively. If water enters the impeller radially and velocity of flow remains constant, determine the work done by the impeller per unit…

Suction Head (hs): It is height of centre (eye) of pump from water level. Delivery Head (hd): It is height of the tank from centre of the pump. Static Head (Hs): It is sum of suction and delivery heads, i.e., Hs = hs + hd. Manometric Head (Hm): It is the head against which a centrifugal pump has to work. where subscript o is used for…

Velocity triangle for centrifugal pump is shown in Figure 9.18. Figure 9.18 Velocity Triangle for Centrifugal Pump Here,

The main components of a centrifugal pump are impeller, casing, suction pipe, foot valve, strainer, delivery pipe, and are discussed below. Impeller: Impeller is a backward curved vane. It is mounted on the shaft coupled to electric motor. Thus, it is a rotating part of centrifugal pump. Casing: It is air tight passage surrounding the pump. Its…