Alternate pump: - If mechanical energy is converted into hydraulic energy by suctioning the liquid in a cylinder in which a piston is reciprocating, exerting the thrust on the liquid and increasing its hydraulic energy is known as an alternative pump. Positive plunger pump. It is often used when handling a relatively small amount of liquid and where the supply pressure is quite large. The alternating pump consists of the following parts.
1. A cylinder with a piston 5. Suction tube
2. piston rod 6. supply tube
3. connecting rod 7. suction valve
4. Hand-wheel 8. delivery valve
Single-acting alternative pump: -
An alternative, single-acting pump consisting of a piston that moves forward and backward in a closed cylinder. The movement of the piston is obtained by connecting the piston rod to the crank by means of a connecting rod. The crank is rotated by means of an electric motor. The suction and delivery lines with suction valve and discharge valve are connected to the cylinder. Suction and supply valves are unidirectional valves or check valves, which allow water to flow in one direction only. The suction valve allows the water from the suction pipe to the cylinder that the delivery valve allows the water from the cylinder to the supply pipe.
The rotation of the crank causes an outward and inward movement of the piston 'P' in the cylinder 'C'. During the suction stroke the piston moves to the right in the cylinder, this movement of the piston causes vacuum in the cylinder. The pressure of the atmosphere acting on the water surface of the sump forces the water upwards in the suction pipe 'S'. The forced water opens the suction valve V1 and the water enters the cylinder. The piston from its extreme right position begins to move to the left in the cylinder. Movement of the piston to the left increases the pressure of the liquid inside the cylinder rather than the atmospheric pressure. Therefore, the suction valve is closed and the delivery valve V2 is opened. The liquid is forced into the delivery tube and raised to a required height.
For a crank revolution, the amount of water raised in the supply pipe equals the stroke volume in the cylinder in the single acting pump and double this volume in the double acting pump.