d4 customer meter management

8/6/2019 D4 Customer Meter Management

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Integrated customer meter management - Module 2/2: Meter Selection 1

The views expressed in this paper/presentation are the views of the author anddo not necessarily reflect the views or policies of the Asian Development Bank

(ADB), or its Board of Governors, or the governments they represent. ADB doesnot guarantee the accuracy of the data included in this paper and accepts no

responsibility for any consequence of their use. Terminology used may notnecessarily be consistent with ADB official terms.



Integrated customer metermanagement

Module 2:Meter selection and specifications Version 1.0 27/05/08




General considerations

The cost of the meter should be in accordance to thewater selling price

The acquisition cost it is often a minor part of the totalcosts of the meter

The long term metrological performance is, with nodoubt, the most important parameter to be observed

A serious effort for buying robust meters should always

be made Incorrect sizing of large customer meters is often a

source of large financial losses




Selecting an appropriate domesticwater meter




Positive displacement or

velocity meters?

Cost

Low flow sensitivity

Resistance to particles

Long term durability

Installation position

Performance with air

Sensibility to upstream flowdistortions

Metrology: back and forwardflow

Cost

Low flow sensitivity

Resistance to particles

Long term durability

Installation position

Performance with air

Sensibility to upstream flowdistortions

Metrology: back and forwardflow

Velocity Positive displacement


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Mechanical or magnetictransmission?



Mechanical transmission

Always associated with wet

totalizers

Mechanical transmissionsneed some of the gears ofthe totalizer to be in contactwith water

Suspended particles mayblock the totalizer

The gear on the turbine issubject to wear



Mechanical transmission

Incrustations may grow on the turbine gear stopping themeter

Turbine has less inertia and weight

Mechanical transmission allows for lower friction

Many Class C velocity meters use mechanicaltransmission



Magnetic transmission

The magnetic transmission is not as strong as themechanical transmission

Robustness of the transmission should always be checkedat high flows or with sudden changes on flow

Poorer low flow sensibility More chances for fraud

The inclusion of a magnetic

shield is advisable



Wet or dry totalizer?



Wet totalizers

A number of gears are in

contact with water Water quality affects the

metrology and long termperformance of the meter

Calcium incrustations maygrow inside the totalizer

Suspended particles mayblock the totalizer



Wet totalizers

The lubrication of water allows for better low flowsensibility

Some dirt may appear inside the totalizer making readingdifficult




Dry totalizers

The gears of the totalizer are not in contact with water

Water meters are more robust with respect water quality

Lower flow sensibility. The magnet adds weight andinertia to the turbine

The magnetic transmission should always be checked forrobustness

An external magnetic field may block the totalizer

movement




Magnetic transmission

Condensation may appear in the totalizer

Some of them include a wiping device




Class B or C meters?




Class B or Class C meters?

Class C meters are more expensive than Class B meters

Class C meters have better low flow sensibility

Low flow sensibility is attained by reducing the friction inmoving parts

Depending on the design this low friction can be lostrapidly

Some Class C meters are less robust than the equivalent

Class B meter Special care should be taken studying how a better

metrological Class is achieved




Example of a velocity Class C meter

construction - 1

A plastic shaft is used to reduced friction

Long term performance islimited due to the durabilityof this element




Example of a velocity Class C meter

construction - 2

A wet totalizer is used to reduce

friction

Low water quality may block thetotalizer




How can I estimate the long term

performance of the meter?

Two strategies can be followed

Laboratory testingo Endurance tests

o Mechanical tests at high flows, high pressures

Field testingo Installing meters in a sample of users for 1-2 years




Laboratory testing

Only takes into account the mechanical robustness of the

meter

The effect of variables like water quality are difficult toreproduce in laboratory

ISO 4064 defines endurance tests for domestic and largemeters

Tests can be carried out in 3-6 months




How much should I spend on a

meter?

What is the average tariff?

Are the meters installed in a difficult environment?

Need for protection against theft/tampering

Frequent pipe breaks

Intermittent supply (air passing through the meter)

Frequent high or low flows

Any legal requirement about the replacement frequency

or metrological Class? As a rule of thumb, a meter and its installation, should

not cost more than 70% of the annual revenues itgenerates




Type of pulse emitters

There are three types of pulse emitters:

Mechanical pulse emitters (REED)

Optical pulse emitters

Inductive pulse emitters

Meters with an electronic totalizer can also be read usinga digital protocol




Mechanical pulse emitters

Resistance51 Ohm

Varistor

Gear

Magnet




Mechanical pulse emitters

Low cost

Low working frequency (max. 1 Hz.)

The volume associated to each pulse will always be large

Possibility of false pulses to occur due to rebounds of

the pulse plates

Low reliability

Voltage free signal is very sensible to electromagnetic

interferences Often it is not possible to know the direction of flow

In some cases it affects the metrology at low flows




Optical pulse emitters

Reflectingwheel

Opticalsensor





1 pulse every 0.1 litres





1 pulse every 1 litre





Medium cost

High working frequency

The volume associated to each pulse can be small

High reliability

No power supply needed (Internal lithium battery)

It is possible to know the direction of flow

Output signal not so easily influenced by electromagnetic

interferences

Available for all sizes of meters




Meters with an electronic totalizer




Meters with an electronic totalizer

High cost

High reliability in the communications

No mechanical parts in the totalizer (however, the sensorpart is usually mechanical)

No power supply needed (Internal lithium battery)

It is possible to know the direction of flow and thevolumes totalized in both directions

Output signal not so easily influenced by electromagneticinterferences

Available for all sizes of meters



General considerations on meters

remote reading

Even with a remote reading system it is important to

assure on the long term the metrology of the meters

Remote reading systems have to be reliable. Readingfrom the totalizer should always match remote reading

Remote reading needs additional infrastructure (Handheld, radio repeaters, bus concentrators, etc.)

Implementing a remote reading system takes long time

and resources Therefore, remote reading is not applicable to all users

in large users is a serious option

In domestic users should be considered carefully

d4 customer meter management

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