RECIPROCATING PUMP TEST RIG

Introduction

In general, a pump may be defined as mechanical device when connected in a pipe line, can convert the mechanical energy into hydraulic energy, thus resulting in the flow of liquid from lower potential to higher potential.

Pumps are of major concern to most engineers and technicians. The types of pumps vary in principle and design. The selection of the pump for any particular application is to be done by understanding their characteristics. The most commonly used pumps for domestic, agricultural and industrial are Centrifugal, reciprocating, axial flow (stage pumps), air jet, diaphragm and turbine pumps. Most of these pumps fall mainly into a class namely rotodynamic, reciprocating (positive displacement) and fluid operated pumps.

Reciprocating pump is based purely on mechanical concepts, since the liquid is displaced by a piston (plunger) moving in a cylinder. They discharge a definite quantity of liquid irrespective of the head on the pump i.e., positive displacement. However, in a single acting pump, water is sucked into the cylinder in the suction stroke and delivered out of the cylinder in the delivery

stroke that is the discharge only on alternate strokes, where as in double acting pump there is suction and delivery in each stroke, that is the discharge is continuous.

General Description

The Reciprocating Pump Test Rig mainly consists of

A Reciprocating Pump

A Single phase 2.0 HP 1440 RPM AC Motor

Piping system & Collecting tank

Input power Measuring arrangement and

SS Sump tank

Constructional Specification

Reciprocating Pump: 

The Reciprocating pump is of single acting type. The suction & delivery size are 1″ x 3/2″ respectively.

Bore: 38 mm, Stroke: 48 mm.

Motor: 

The Motor supplied is of 2 HP 1440 RPM. It can be operated on AC 50 cycles 220 / 230 V, through mains. A smaller HP motor can be used for normal working conditions, a higher power motor is selected to test the pump at higher speed, high pressure combinations, without over loading it.

Piping System: 

Suitable piping system with pipes, bends valves etc. Arrangement with cocks is , also provided for connecting pressure and vacuum gauges to the delivery and suction

pipes.

A simple strainer valve is provided on the suction side to prevent any foreign matter from entering into the pump. The gate valve is provided on the delivery side to control the Head of the pump. Note that the delivery valve should never be closed when the pump is working.

While starting the motor always keep the valve in open position. Otherwise the pump parts will be damaged. Collecting Tank: A Collecting tank is provided to measure the discharge water through pizeo meter arrangement.

Input Power Measurement: 

A Kilowatt-hour meter is provided to measure the power input to the motor. The energy meter constant (The Number of Revolutions per minute of the energy meter Disc) is stamped on the meter. From this the input power can be easily calculated.

Sump: 

A Sump is provided compactly within the (Floor space of the main unit to store adequate water for circulation through the unit for experimentation)

Before Commissioning

Check whether all the joints are leak proof and watertight.

Check the gauge glass and meter scale assembly of the measuring tank and see that it is fixed water tight and vertically.

Check whether all the electric connection are correct.

See that the gauges are mounted on the correct position and their cocks closed.

Delivery valve should be in fully open condition.

Starting

Pour the lubricating oil SAE 40 in the crankcase of the reciprocating pump to the required level once in a year. This will require about 250 cc of oil prime the pump before starting see that the V belt are in proper tension. Start the Motor keeping the delivery valve in fully open position. Open the gauge cocks, and see the pressure developed by the pump. Delivery control valve may be closed up to about 30 meters of the water head on the delivery side. Under any circumstances the valve should not be closed beyond 40 meters head on the delivery side. If the pressure exceeds this valve (40 Kg/sq.cm) the cylinder head gasket joints, piston, pressure gauge etc. would be damaged. To stop the pump set, first close the gauge cocks. Do not close the delivery valve on the other hand it may open fully. Then switch off the motor.

Experiments

Start the pump and run it at a constant speed and the hand head may be tried, say from 10 meters to 30 meters. The discharge will be more or less thank same depending upon the leakage past the piston, which is dependent this on the total on the pump 6 to 8 readings can be taken within this head range. The above procedure can be repeated and the pump tested the different heads.

Maintenance

As these units are built very sturdily, they do not require any routine or regular maintenance; however we recommend the following to be checked then and there to increase the life of the elements.

Lubricate all the working parts where provision for lubrication is made Grease cups are provided for lubricating ball bearings. Remove the grease drain plugs where fitted, and inject fresh grease through grease cups until waste grease along with a portion of fresh grease is ejected out through the grease drain hole.

Then run the machine for a few minutes to eject the excess grease in the bearing housings.

Then fix the grease drain plug. Over greasing results in excessive heat due to a pumping action of the bearings, and it is as harmful as under greasing. Suitable grease should contain no mineral acid, free alkali or foreign matter. Suitability is of the at most importance and the grease should show no tendency to run, thin out or separate into its constituents on standing or in of such substances as graphite, talcum etc., even in an extremely finely divided state will give rise to lapping of the bearing parts. For normal condition of operation soda soap grease of softer consistency for working temperature up to 75 ° C having a melting point of about 150° / 175°C shall be used.

Never run the pump without water in it, as this would cause damage to stuffing box, bush bearings etc. Never try to throttle the suction side of the pump to control discharge, as it would seriously affect the performance of the pump.