12-08-2013, 03:41 PM
A Working Model of Single Acting Reciprocating Pump
Working Model of Single.docx (Size: 155.22 KB / Downloads: 50)
OBJECTIVE:
To prepare a working model of single acting reciprocating pump, can be used for laboratory experiments.
SCOPE:
A working model can be useful to give the proper understanding of how reciprocating pumps work to the coming students. This will also be helpful to them to perform practical of Turbo Machines Lab. and clear their basics about working of such pumps.
A reciprocating pump is a positive plunger pump. It is often used where relatively small quantity of liquid is to be handled and where delivery pressure is quite large.
Reciprocating pumps can be classified based on:
1. Sides in contact with water
a) Single acting Reciprocating pump
b) Double acting reciprocating pump
2. Numbers of cylinder used
a) Single cylinder pump
b) Two cylinder pumps
c) Multi-cylinder pumps
SINGLE ACTING RECIPROCATING PUMPS
In industries, reciprocating pumps are of many sizes and designs. Their operation is similar to the bicycle pump described above. An industrial reciprocating pump is constructed of metal and has the following main parts:
THE CYLINDER:
This is a metal tube-shaped casing (or body), which is generally fitted with a metal lining called a 'cylinder liner'. The liner is replaceable when it becomes worn and inefficient. The cylinder is also fitted with suction and discharge ports which contain special spring loaded valves to allow liquid to flow in one direction only-similar to check valves.
THE PISTON:
The piston consists of a metal drive rod connected to the piston head which is located inside the cylinder. The piston head is fitted with piston rings to give a seal against the cylinder lining and minimize internal leakage. The other end of the drive rod extends to the outside of the cylinder and is connected to the driver. (In the old days of piston pumps, the driver used to be (and still is in some cases), high pressure steam which was fed to a drive cylinder by a system of valves in a steam chest.
Modern industries generally use high power electric motors, linkages and gearing to convert rotating motion into a reciprocating action. In a single acting pump, the backward stroke of the piston causes a suction which pulls in liquid through the inlet valve. (The same suction action keeps the discharge valve closed).
On the forward stroke, the increase in pressure generated by the piston, closes the inlet valve and opens the discharge valve. The liquid is displaced into the discharge system. The flow from a reciprocating pump is uneven or pulsating. This can be undesirable in some applications. Flow can be smoothed out, but we will discuss this a little later.