PUMPS - TYPES & OPERATION - SINGLE ACTING RECIPROCATING PUMPS PDF Print E-mail
Written by Norrie   
Saturday, 27 March 2010 14:10
Article Index
PUMPS - TYPES & OPERATION
CENTRIFUGAL PUMPS
Centrifugal Pump: the rotor
Centrifugal Pump: the casing
Prime Movers
CHARACTERISTICS OF CENTRIFUGAL PUMPS
The Valves of a Centrifugal Pump
CENTRIFUGAL PUMP OPERATION
CENTRIFUGAL PUMPS - FLOW & PRESSURE
Cavitation
AIR BINDING IN A CENTRIFUGAL PUMP
POSITIVE DISPLACEMENT PUMPS
OTHER TYPES OF ROTARY PUMPS
RECIPROCATING (PISTON) PUMPS
SINGLE ACTING RECIPROCATING PUMPS
DOUBLE ACTING RECIPROCATING PUMPS
Advantages & Disadvantages of Piston Pumps
All Pages

SINGLE ACTING RECIPROCATING PUMPS

In industry, 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 :

1. 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.

2. 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 minimise 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.

Like the rotary pumps, because the action is positive displacement, a piston pump can generate very high pressure and therefore MUST NEVER be operated against a closed discharge system valve unless it is fitted with a safety relief system in order to prevent damage to the pump and/or the driver and/or other downstream equipment.

(See Figure: 30)

Figure: 30 -Single Acting Reciprocating Pump



Last Updated on Saturday, 27 March 2010 15:27