BY G R O U P A 1 (E H 1 1 0 4 A ) :FAT H I N N O R FA R I D A H B I N T I M O H A M E D N AW I (2 0 1 3 4 8 5 4 0 8 )

FAT I N N A B I L A B I N T I M O H D A R I P I N ( 2 0 1 3 4 0 2 1 0 2 )

N U R I L H A M B I N T I Z A I N U D D I N( 2 0 1 3 4 3 4 9 5 6 )

N U R U L A F I FA H B I N T I M O H D Y U S O F F(2 0 1 3 2 7 5 4 6 4 )

PROCESS CONTROL & EQUIPMENT

Lecturer’s Name : Sir Azmi Mahmood

ASSIGNMENT 2

METERING PUMP

WHAT IS METERING PUMP

A type of pump which is used on ship to pump a precise volume of liquid.

Metering pump can be adjusted to provide different flow rates.

They are generally used when the precision of volume to be delivered is very important.

The metering pump is connected to the system in which the chemicals are injected with the help of valve in the pipeline. The pressure produced by this pump should be higher than the pressure in the pipeline, or else there will not be any dosing and the level of chemicals in the dosing tank will be the same.

A metering pump moves a precise volume of liquid in a

specified time period providing an accurate flowrate.

Delivery of fluids in precise adjustable flow rates is

sometimes called metering.

Many metering pumps are rated to be able to pump into a

high discharge pressure.

They are typically made to meter at flow rates which are

practically constant (when averaged over time) within a

wide range of discharge (outlet) pressure.

Manufacturers provide each of their models of metering

pumps with a maximum discharge pressure rating against

which each model is guaranteed to be able to pump against.

An engineer, designer, or user should ensure that the

pressure and temperature ratings and wetted pump

materials are compatible for the application and the type of

liquid being pumped.

Most metering pumps have a pump head and a motor. The liquid

being pumped goes through the pump head, entering through

an inlet line and leaving through an outlet line. The motor is

commonly an electric motor which drives the pump head.

The marine is in the form of application of metering pump

chemical dosing pumps, which is used to transfer precise

amount of dosing chemicals, especially in boilers. They are also

used for dosing chemical additives to protect corrosion in the

cooling water system. It is to note that the amount of dosing has

to be precise. Over dosing or under dosing may cause corrosion

and other damages inside the boiler, which may end up in heavy

repairs.

 Metering pumps are used in almost every segment of an industry to meter, inject, transfer, dispense, sample, or proportion fluids.

Metering pumps and dispensers are used in a variety of applications, including chemical process industries (CPI), laboratory, OEM analytical instrumentation, and automated medical diagnostic equipment.

With such an array of applications it can be difficult for customers to know which pump is best for their industry. These important considerations can help you get started on selecting the perfect pump.

The metering pumps consist of a small

motor which moves the plunger, in and

out of the barrel, to provide pressure in

the system. The check valves are provided

in the suction and discharge side of the

pump. Since the pump is of the plunger

type, metering pump is a positive

displacement pump.

Generally metering pumps are connected

to the dosing pumps and the whole unit is

known as the dosing unit. The relief valve

is connected to the dosing pump, which

releases the excess pressure back to the

dosing tank.

Working of Metering Pump

As the plunger moves away from the suction valve, a vacuum is created inside the pump because of which makes liquid flow inside the pump. This closes the check valve closes and the plunger again starts moving towards the valves. The discharge valve then opens and supplies the liquid to the system.

Cross-section of piston metering pump head towards end of suction and discharge strokes. Blue arrow shows direction of flow allowed through check valves.

The seal arrangement is provided at the end of the plunger i.e. towards the

motor side so that no leak should take place.

The volume of the liquid supplied can be altered by altering the movement of

the plunger inside the barrel. This is generally done by a small knob provided

on the pump and which thus allows adjusting the percentage of liquid supplied.

When the knob is turned to increase or decrease the flow rate, it alters the

movement of the plunger, which means that it moves less in the plunger rather

than along the full length of the plunger. Because of this the liquid enters the

chamber and changes the plunger position along with the flow rate.

5 criteria to select the perfect metering pump

1) Flow Rate or Dispense Volume – The first parameter to consider when selecting a metering pump is the required pump capacity. Looking at a manufacturer’s flow capabilities will immediately narrow the choices of the metering pumps that meet the flow criteria.

2) Fluid Characteristics – Assuming you now have several metering pump options that meet your flow rate requirements, it is important to examine the physical and chemical characteristics of the specific fluid being pumped.

3) Pressure – When considering pressure, it’s important to know both the differential pressure (difference between the inlet and outlet), as well as the overall system pressure. Not only does the pump need to have the ability to pump against the outlet pressure, but also be rated to withstand the overall system pressure plus a margin for safety.

4) Temperature – Fluid temperature is an important factor in determining pump compatibility. As mentioned above, fluid temperature can affect the corrosive chemical properties. But, additionally, fluid temperature will affect the mechanical components and integrity of the pump. This is especially true of pumps that use elastomers and fluorocarbons (PVDF, Teflon®) which lose structural integrity as temperatures increase.

5) Accuracy and Precision – Inaccurate pumps can generate waste and incur extra costs. Fluid Metering pumps accuracy is held from microliters to the full flow range and output does not change more than ± 1% of set value.

Advantages of ChemIndustrial pumped venturi metering pumps VS piston and diaphragm pumps

CSI pumped venturi metering pumps

Most piston and diaphragm metering pumps

Simple flow rate adjustment:No need to stop the metering pump. Adjust the metering valve and immediately see the effect of the adjustment on the built-in flowmeter.

Complex flow rate adjustment:Stop the metering pump. Change stroke length. Calibrate. Repeat the procedure until you get it right.

Foolproof calibration:Built-in flowmeter provides continuous flow rate information.

Tiresome calibration procedure:The only way to check flow rate is by timing the emptying of a calibrated cylinder with a stopwatch.

Excellent accuracy and repeatability:Pumped venturi injects at constant rate over its whole operating pressure range.

Flow varies with line pressure:Flow rate fluctuates when pipeline pressure changes, due to diaphragm flexing and/or ball-check seating.

CSI pumped venturi metering pumps

Most piston and diaphragm metering pumps

Smooth flow:Venturi draws injected fluid into the water stream smoothly, continuously.

Pulsing flow:Flow starts and stops with each stroke of the pump.

No bleed valve:Venturi systems are inherently self-priming -- even when the injection lines are dead-dry.

Bleed valve needed:Most reciprocating metering pumps require bleed valves and manual priming from a dry condition.

No backpressure valve needed:All required flow devices are included with the metering pump.

Backpressure valve adds cost:Injection quill backpressure valve adds to initial cost and adds another component that needs maintenance.

Variable Speed Drives

Variable-speed drive (VSD) describes equipment used to control the speed of machinery.

Many industrial processes such as assembly lines must operate at different speeds for different products. Where process conditions demand adjustment of flow from a pump or fan, varying the speed of the drive may save energy compared with other techniques for flow control.

Where speeds may be selected from several different pre-set ranges, usually the drive is said to be adjustable speed. If the output speed can be changed without steps over a range, the drive is usually referred to as variable speed.

Adjustable and variable speed drives may be purely mechanical (termed variators), electromechanical, hydraulic, or electronic.

Applications of Metering Pump

 Metering pumps are used in almost every segment of an industry to meter, inject, transfer, dispense, sample, or proportion fluids.

Metering pumps and dispensers are used in a variety of applications, including chemical process industries (CPI), laboratory, OEM analytical instrumentation, and automated medical diagnostic equipment.