SIST-TP CEN/TR 16061:2010

SLOVENSKI STANDARD
01-december-2010
Plinomeri - Pametni plinomeri
Gas meters - Smart Gas Meters
Gaszähler - Intelligente Gaszähler (Smart Gas Meters)
Compteurs de gaz - Compteurs de gaz intelligents
Ta slovenski standard je istoveten z: CEN/TR 16061:2010
ICS:
91.140.40 Sistemi za oskrbo s plinom Gas supply systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
CEN/TR 16061
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
October 2010
ICS 91.140.40
English Version
Gas meters - Smart Gas Meters
Compteurs de gaz - Compteurs de gaz intelligents Gaszähler - Intelligente Gaszähler (Smart Gas Meters)

This Technical Report was approved by CEN on 19 July 2010. It has been drawn up by the Technical Committee CEN/TC 237.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2010 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 16061:2010: E
worldwide for CEN national Members.

Contents Page
Foreword .4
1 Scope .5
2 Definitions, glossary .5
2.1 Glossary .5
2.2 Numerical list of standards .6
3 What is a Smart Meter? .8
3.1 General .8
3.2 Basic meter .9
3.3 Basic meter with output of pulses or data .9
3.3.1 General .9
3.3.2 Pulse output .9
3.3.3 Data output .9
3.4 AMR meter . 10
3.5 Prepayment meter. 10
3.6 Smart meters . 10
4 Smart metering system – The smart meter in its context. 11
5 Basic recommendations – Apply to all Smart Gas Meters . 12
5.1 General . 12
5.2 Metrology . 12
5.3 Safety recommendations . 12
5.3.1 Gas containment . 12
5.3.2 Pressure absorption . 12
5.3.3 Explosive atmospheres and electrical considerations . 12
5.4 Environmental recommendations, EMC, vibration, temperature and humidity . 13
5.5 Battery management . 13
5.5.1 General . 13
5.5.2 Single battery . 13
5.5.3 Multiple batteries . 13
5.5.4 Implications of add-on devices (e.g. for communications) for batteries installed in meters . 14
5.5.5 Battery compartment . 14
5.6 Battery powered electronic indexes . 14
5.6.1 General . 14
5.6.2 Recommendations . 15
6 Additional Functions . 17
6.1 General . 17
6.2 Pulse output . 17
6.3 Data recommendations . 18
6.3.1 General . 18
6.3.2 Volume/mass . 18
6.3.3 Time . 19
6.3.4 Temperature . 21
6.3.5 Pressure . 21
6.3.6 Compressibility factor, Z . 21
6.3.7 Calorific Value . 21
6.3.8 Logging . 21
6.4 Firmware upgrade . 22
6.5 Energy calculation within the meter . 22
6.5.1 General . 22
6.5.2 Calculation of energy as an approximation for the invoice . 22
6.5.3 Calculation of energy as part of the invoicing process . 23
6.5.4 Meters that record in volume units . 23
6.5.5 Meters that record in mass units . 23
6.6 Tariff Operations . 23
6.7 Display/human interface . 24
6.8 Communications . 24
6.8.1 To devices in home . 24
6.8.2 To host systems . 25
6.9 Valve . 25
6.9.1 General . 25
6.9.2 Valve design recommendations . 25
6.10 Fraud prevention . 26
Annex A (informative) Regulatory & Legislative framework . 27
A.1 European Directives . 27
A.2 Measuring Instruments Directive, 2004/22/EC ("MID") . 27
A.3 Energy End-Use Efficiency and Energy Services Directive, 2006/32/EC ("ESCO") . 28
A.4 "AtEx" Directives . 28
A.5 Battery Directive . 29
A.6 National projects across Europe . 29
Annex B (informative) Further Work . 30
B.1 Further work in this document . 30
B.2 Actions that other organisations may wish to consider . 30
Annex C (informative) Tests – Recommended type test plan . 31
C.1 List of tests . 31
C.2 Endurance test . 31
C.3 Environmental Tests . 32
C.4 Toluene/iso-octane test . 32
C.4.1 General . 32
C.4.2 Test 1 . 32
C.4.3 Test 2 . 32
C.4.4 Example of a typical apparatus . 32
C.4.5 Procedure . 33
C.4.6 Preparation of a 3 % by volume of a 30 % toluene/70 % iso-octane mixture with nitrogen . 33
C.4.7 Calculation . 33
C.5 Water vapour test . 34
C.6 Ageing test . 36
C.7 Basic performance test procedure . 36
Bibliography . 38

Foreword
This document (CEN/TR 16061:2010) has been prepared by Technical Committee CEN/TC 237 "Gas
meters", the secretariat of which is held by BSI.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document is intended to be a precursor to a formal standard for Gas Meters that provide some additional
functions beyond that required under the Measuring Instruments Directive (MID). It is noted that other CEN
and CENELEC Technical Committees are active in the areas of metering communications – most relevant
being CEN/TC 294 "Communication systems for meters and remote reading of meters", which covers
automatic reading of Gas Meters in great detail. The functions described are mainly for use on Residential
Utility meters, but may be equally applicable to meters used for commercial and industrial applications. A
number of the requirements may be applicable to "add-on" devices to Gas Meters. However, it is outside the
scope of the TC to standardise beyond Gas Metering devices.

1 Scope
This Technical Report outlines recommendations for "smart gas meters", specifies recommendations where
there is clear consensus, and identifies areas where there are barriers to standardisation. It indicates how
functions may be implemented in a harmonized way if they are selected. It does not seek to select which
functions are to be implemented in a smart meter. The report covers simple to complex implementations of
smart metering.
st nd rd
This Technical Report is applicable to 1 , 2 and 3 family gases according to EN 437.
2 Definitions, glossary
2.1 Glossary
MID Measuring Instruments Directive, 2004/22/EC
AtEx "Atmospheres Explosibles". A pair of EU Directives governing hazardous areas, 99/92/EC; and
the equipment that can be used within hazardous areas, 94/9/EC
CEN European Committee for Standardization: European standards body for non-electrical
equipment
CENELEC European Committee for Electrotechnical Standardisation: European standards body for
electrical equipment
BSI British Standards Institution
DLMS UA The Device Language Message Specification User Association
Harmonised European Standard adopted by a European standardisation body, made available to the public
standard and that has been recognised as a method to demonstrate conformity to Essential
Requirements of a European Directive
PED Pressure Equipment Directive, 97/23/EC
WELMEC Western European Legal Metrology Cooperation: an organisation of legal metrologists
ESCO Energy End-Use Efficiency and Energy Services Directive, 2006/32/EC
Basic Meter a meter that is safe and provides no function beyond that required by the MID
IT System Information Technology System
AMR Automatic Meter Reading. A technology that allows a meter to be read that does not require
direct observation of the meter
AMM Advanced Meter Management
AMI Advanced Meter Infrastructure
Connector a mechanical device, or pair of devices, that makes a semi-permanent circuit between the
meter and a cable
Normative a document containing technical specifications adopted by the Organisation Internationale de
document Métrologie Légale (OIML), subject to the procedure stipulated in Article 16(1) of the MID
Standard a technical specification approved by a recognised standardisation body for repeated or
continuous application, with which compliance is not compulsory and which is one of the
following:
 International Standard: a standard adopted by an international standardisation organisation
and made available to the public;
 European Standard: a standard adopted by a European standardisation body and made
available to the public;
 national standard: a standard adopted by a national standardisation body and made
available to the public
1)
Base
specific conditions to which the measured quantity of gas is converted
Condition
EXAMPLES Temperature of 273,15 K and absolute pressure of 1,013 25 bar or temperature of
288,15 K and absolute pressure 1,013 25 bar.
Burst Data this may be generated at the pulse outputs of electronic indexes and volume converters. To
save power, electronic devices will only wish to switch on output circuits infrequently.
Therefore, rather than emit a pulse as soon as one should be generated, the output circuit will
only be switched on infrequently, and then a burst of pulses is transmitted
Gas for billing purposes, the "day" may not start at 00:00: it may start at some other time. This start
Metering time may also be subject to daylight savings time changes, leading to "days" with lengths other
Day than 24 h
UTC Coordinated Universal Time. This is a "world time", without daylight savings
Electronic the register, electronics, and battery
Index
Assembly
Index an enclosure to contain the index assembly, where the index assembly is not contained in the
Housing body of the meter
Register the display element + data store

2.2 Numerical list of standards
NOTE Other documents are listed in the Bibliography.
Body Reference Title Note
CEN EN 12261 Gas meters ― Turbine gas meters Standard for Turbine Meters,
Harmonised with MID.
1) The calorific values of gas are expressed usually in megajoules per cubic metre (MJ/m³). The amount of gas in the
determined volume, however, will depend on temperature and pressure. Therefore a nominated base condition is used.
Volume conversion takes the volume of gas measured, then converts this to a volume of gas at the equivalent base
condition. See EN 12480:2002, 3.1.9, and EN 12405-1.
Body Reference Title Note
CEN EN 12405-1 Gas meters ― Conversion devices ― Standard for Volume
Part 1: Volume conversion Converters. Harmonised with
MID.
CEN EN 12480:2002 Gas meters ― Rotary displacement gas Standard for Rotary Piston
meters meters. Harmonised with
MID.
CEN EN 1359:1998 Gas meters ― Diaphragm gas meters Standard for diaphragm
meters, Harmonised with
MID.
CEN EN 13757 Communication systems for and remote Multi-part document detailing
reading of meters communications formats
CEN EN 13757-1 Communication system for and remote OBIS-COSEM Application
reading of meters ― Part 1: Data layer for Gas, etc. meters.
exchange
CEN EN 13757-2 Communication systems for and remote
reading of meters ― Part 2: Physical and
link layer
CEN EN 13757-3 Communication systems for and remote M-Bus Wired specification
reading of meters ― Part 3: Dedicated
application layer
CEN EN 13757-4 Communication systems for and remote M-Bus Radio specification
reading of meters ― Part 4: Wireless
meter readout (Radio meter reading for
operation in the 868 MHz to 870 MHz
SRD band)
CEN EN 14236:2007 Ultrasonic domestic gas meters Standard for Ultrasonic
meters. Harmonised with
MID.
CEN EN 13463 (In a number of parts) Non-electrical
equipment for use in potentially explosive
atmospheres
CENELEC/IEC EN 60079-10; Electrical apparatus for explosive gas
IEC 60079-10 atmospheres ― Part 10: Classification of
hazardous areas
CENELEC/IEC EN 60079; (In a number of parts) Electrical apparatus
IEC 60079 for explosive gas atmospheres
Body Reference Title Note
CENELEC EN 62056-61 Electricity metering ― Data exchange for For information. Sister
meter reading, tariff and load control ― document to EN13757-1
Part 61: Object identification system
(OBIS) (IEC 62056-61:2006)
CENELEC EN 62056-21 Electricity metering ― Data exchange for For information. Electricity
meter reading, tariff and load control ― standard for opto-electrical
Part 21: Direct local data exchange ("flag") interface.
(IEC 62056- 21:2002)
CENELEC/IEC EN 60529:1991 Degrees of protection provided by
enclosures (IP Code) (IEC 60529:1989)
3 What is a Smart Meter?
3.1 General
A Smart Meter is one that is compatible with the MID and ESCO directives, and has communications
capabilities.
The following sections detail the variations of functional complexity that are likely to make up smart meters or
may form part of a smart metering system. The table below details some of the possible aims and methods
that may form part of a smart meter.
Table 1 — Aims and methods for smart meters
Aim Means Possible methods
Reduction of costs for meter Remote meter reading Minimum one way communication
reading (in case frequent meter from meter
reading is obliged)
Reduction of complaints – Remote meter reading Minimum one way communication
improved quality of meter from meter
reading
Reduction of payment arrears Prepayment, or shutting off Remotely operated valve in meter;
customer supply Two-way communication
Regular billing based on real Remote meter reading Minimum one way communication
consumption from meter
Providing customer consumption Info on meter display (or home Two-way Communication;
information display unit) Electronic Display
Advertising Info on meter display (or home Two-way Communication;
display unit) Electronic Display
Aim Means Possible methods
Limitation of production capacity Peak shaving by differential Two way communication;
tariffs Electronic Display;
Interval data
Stop supply during shortage Switching off customers Remotely operated valve in meter;
Two way communication
Safeguard for excess flow Switch off customers when there Local control of valve in meter
sensed at the meter is a customer installation
problem (e.g. caused by a leak)
Safeguard for network issues Control signal for an area Remotely operated valve in meter;
Two way communication
3.2 Basic meter
It may be helpful, as a starting point, to observe that a "Basic" meter is one that is safe and provides no
2)
function beyond that required by the MID . It is worth noting the quotations from MID Annex 1, "Essential
Requirements" that are contained in Annex A of this document.
It can be argued that prepayment meters that provide data back to the suppliers IT systems via a token are
Smart. To try to clarify the different types of meter that are available, different categories are defined below.
3.3 Basic meter with output of pulses or data
3.3.1 General
A basic meter with output can be part of a smart (AMR) system. It may be possible for this system to meet the
recommendations of ESCO.
3.3.2 Pulse output
The basic meter may have an integrated or a remotely equipped pulse output or a data output.
The pulse is widely used as a method of providing data from a meter. The meter emits a pulse each time a
fixed volume is measured.
The pulse value outputs are marked as 1 imp ≙ … m³ (or dm³) or 1 m³ (or dm³) ≙ … imp.
The most widely used method for pulse output is to use a magnet in one of the least significant wheels in the
index. A reed switch is commonly used to detect the passage of the magnet.
3.3.3 Data output
Data outputs can be provided through serial interfaces. Data outputs should provide information on meter
readings, meter identification and meter status. The index value (as read on the meter) is provided by the data
output. Data outputs can be built-in or provided by add-on to an existing meter. Depending on the interface
used, data encryption and access control has to be considered. Guidance on data outputs is detailed in
WELMEC Software Guides 7.1 and 7.2.

2) Please note that meters with pre-MID approvals will also usually meet this recommendation.
3.4 AMR meter
An Automatic Meter Reading (AMR) meter can form part of a smart metering system. An AMR-equipped
meter can provide data to an IT system. In its simplest form, it provides a current meter read without physical
access to the meter. A number of technologies exist that can be used to collect and transfer the data – from
inductive pad, where a meter reader needs to physically connect a reading device to a component connected
to the meter, through walk-by and drive-by systems, to fixed wired or wireless networks with star or mesh
topologies.
An AMR system can be built based on a basic meter with pulse or data output.
3)
An AMR meter may or may not log data, and provide information about events and its status when it
transmits data.
While it is possible for an AMR Meter to be truly one way, broadcasting data either continuously or at pre-set
intervals, most systems are at least 1,5 way (which report when stimulated), and many are two way, and give
answers to specific questions.
3.5 Prepayment meter
4)
Prepayment, or "pay as you go", meters allow customers to make advanced payment for energy . In their
simplest form, a mechanical token (or coin) is used to allow the valve within the meter to be opened until a
measured quantity of gas has been consumed. State of the art prepayment meters use electronic tokens or
SMS to add credit to the meter, set tariffs on the meter and provide data on consumption and events to the IT
system. The latest meters can remotely manage the repayment of debts, and perform the calculations to
consume the credit applied to the meter based on tariff and energy conversion data. They can manage
change of retailer in a competitive retail market for energy, and some can even be switched to a mode where
they function as a credit meter.
3.6 Smart meters
There are a number of terms, such as "AMI", "Smart", "AMM", where there is no commonly agreed definition.
5)
A smart meter will have communications operating within acceptable timeframes and at least one additional
function from the following list:
 Built-in Customer Display of time of use information (see 6.7);
 Local provision of time of use information (see 6.8);
 Shut-off Valve (see 6.9);
 Home Automation interface (see 6.8.1);
 Prepayment functionality (see 6.5, 6.6, 6.7 and 6.9);
6)
 Remote update of configuration data (see 6.3);

3) The term "event" covers changes of status within the meter. Changes of status can occur when a meter senses
something out of the ordinary (perhaps flow beyond the Q of the meter, or battery level falling to a pre-set level), when
max
there is a tamper or fraud attempt, or if there is an error.
4) Energy Cost and transportation costs are accrued when the supplier collects money from the customer.
Transportation charges may, in some cases, require meter reading data to be provided.
5) Communications in this context can be either wired or wireless.
6) Note that metrological parameters may not be updated under MID rules.
 Datalogging functionality (see 6.3).
Fraud and Tamper detection will be a feature of most smart meters. The levels of protection from fraud and
tamper will be related to the complexity of the meter. Meters that include a valve will require high levels of
protection and detection of fraud and tamper attempts. This is discussed further in 6.10.
The above is not intended to be an exhaustive list, and it is likely that there will be updates to this document
on an ongoing basis as further additional functions become defined.
Firmware upgrade may be required in some situations. This is discussed in 6.4 of this Technical Report and
the WELMEC Software Guide.
4 Smart metering system – The smart meter in its context
Meters form part of a system. The huge majority of gas meters are used simply as part of a chain that
provides an invoice for energy to the energy customer.
In the simplest system, basic meters communicate via a "visual read" to a meter reader, who transmits the
data into a meter read system, where the data is validated, and then passed through to the billing system,
where volume conversion and energy calculation is performed.
A smart metering system performs the same functions with the meter reader eliminated. Basic AMR will
eliminate the "eyeball" element of the read, and AMR into a fixed network will remove the need for the meter
reader to visit site and thus provide the Wide Area Network (WAN) functionality. A meter with more
functionality (or, in the case of industrial gas use, a Volume Conversion system) may be able to perform the
volume conversion and the energy consumption calculation by applying values supplied by the IT system.
The tariff and energy conversion technology in prepayment meters can be applied to a smart meter which will
lead to an ability to estimate energy usage and cost for the customer. In theory, this could be extended to the
point where the bill is calculated on the meter, and the billing amount provided to the energy supplier via a
communications channel, though provision of calorific value (CV), pressure and temperature is a significant
issue in taking this approach. While there are technologies that can register energy directly, none have come
to market in a way that delivers cost effective real-time energy calculation, except on large industrial
applications. This adds a complexity to the accurate provision of energy consumption on the meter; either
 calorific value, pressure and temperature would have to be available in "real time"; or
 the meter would have to be capable of retrospectively recalculating the energy based on information
when validated data becomes available.
It should be noted that the auditing of software capable of retrospective recalculation would be a very difficult
task. It should also be noted that a gas meter that estimates the energy usage and the cost for the customer
will, inevitably, provide information that differs from the invoice, and therefore some customers will query the
difference. This difference is similar to that noted when electricity customers have "clip on" electricity monitors
that estimate energy consumption.
A method that may be adopted to manage the difference between real time energy estimates and billed
energy is to set the calorific value used for real time estimates a little higher than expected. This will mean that
meters give a slightly high estimate of energy consumption, and it is expected that most energy customers will
be unlikely to contact their energy supplier on this basis.
It should be noted that the end-to-end process of invoice generation is not changed by the application of smart
meters, but smart meters will automate the data collection, and may push the energy and tariff calculation
from the central system to the meter.
5 Basic recommendations – Apply to all Smart Gas Meters
5.1 General
Many of the recommendations below are applied to new meters being supplied today. Some
recommendations are new, and need to be considered in detail when new meters are being developed.
5.2 Metrology
New meter designs have to be accurate. Several European Standards, EN 1359, EN 12405, EN 12261,
EN 12480 and EN 14236 are applicable to Gas Meters and should be applied as they are "harmonised"
standards. OIML recommendation R137-1 is identified as a normative document.
NOTE Current approvals continue until their natural expiry, or until October 2016. It is not therefore necessary that a
"smart" meter is an "MID Approved" meter.
5.3 Safety recommendations
5.3.1 Gas containment
EN 1359 and EN 14236 include testing for pressure containing parts. At the time of writing, EN 12261 and
EN 12480 are in the process of being harmonised to the PED, which will also validate pressure containing
parts. EN 1359 and EN 14236 have optional recommendations for pressure containing parts for meters that
must remain safe at high ambient temperatures.
5.3.2 Pressure absorption
EN 1359 and EN 14236 have requirements for the pressure absorption of the meter. Pressure at the
appliance is very important to safe use of gas, especially where older appliances which may lack flame failure
detection, or where flame failure detection sensors and/or valves may fail. Correct operation of valves and
their impact on pressure absorption are discussed further in 6.9.2.
NOTE 1 There may be national or international standards that set recommendations for the pressure absorption of
meter installations.
NOTE 2 Any valve incorporated within the meter should not cause the pressure absorption to be greater than that
required by the appropriate standard while it is open.
5.3.3 Explosive atmospheres and electrical considerations
5.3.3.1 The environment around the meter
If there is a failure of the meter installation, it is possible for there to be an escape of gas. In rare
circumstances this can lead to the presence of an explosive atmosphere. Guidance on the risks of explosive
atmospheres can be found in EN 60079-10.
Because of this small risk, meters should be designed to minimise the risk of ignition. A level of protection
against ignition with respect to the risk should be considered in the design process.
Electrical protection is covered by the EN 60079 series of standards. Protection for non-electrical aspects is
covered by the EN 13463 series of standards.
5.3.3.2 The environment within the meter
There has been some discussion about the hazardous area zone that may exist within the meter. While it is
being commissioned or decommissioned, explosive mixtures of gas may be present within a meter. The time
that these explosive mixtures may be present is very small, in that it typically takes 5 min to purge a meter
installation, and in most cases the meter will then stay in situ for many years. Further work is required to
establish the level of risk and make further recommendations in this area. In the meantime, meter designers
should attempt to minimise the energy and temperatures generated within the gas containing parts of the
meter.
5.4 Environmental recommendations, EMC, vibration, temperature and humidity
Meters may be installed in a wide range of environments, and the underlying standard for the basic meter will
have requirements for the environments likely to be faced.
Generally, meters with additional functions should meet the requirements for the underlying standard, and
should be tested for EMC requirements in accordance with Clause 13 of EN 14236:2007, or 8.5 and 8.6 of
EN 12405-1:2005.
NOTE If a field installable add-on unit is only connected by a single electrical multi-core cable, then the
environmental requirements in EN 12405 should be considered.
5.5 Battery management
5.5.1 General
The Welmec Software Guide to the MID, 7.2 is one method of compliance with MID with respect to battery
management.
Protection of the metrology part may be achieved using single or multiple batteries.
NOTE The life of the battery depends on the environmental conditions, flow rate, and number of operations of
external communications devices. It is not therefore possible to determine battery life unambiguously. It is advisable for
the meter designer to make a spreadsheet model of battery life for internal use.
5.5.2 Single battery
The battery should support all functions for more than five years.
NOTE Many purchasers will require battery life in excess of ten years.
It should be noted that some functions, for example communications circuits and valves may require an
estimate of the use likely to be made, as exact figures are not obtainable. In this situation, the manufacturer
should make clear these estimates, and determine measures put in place to protect the metrology in the event
that more energy than estimated is used by these extra functions.
After 90 % of battery lifetime, the meter should provide information to the IT system of its condition.
The meter should show an indication that 90 % of the battery lifetime has been used.
Where a battery is intended for replacement in the field, then the meter should be resistant to unauthorised
access of the battery. Where the battery is intended to operate for the full life of the meter, then there should
be no access to the battery except by disassembly of the meter.
5.5.3 Multiple batteries
Where multiple batteries are used, the battery supporting the metrology should meet the recommendations in
5.5.2.
Any non-metrological batteries ideally also meet the recommendations in 5.5.2. However, in certain
circumstances it may be advisable for the energy customer to change the non-metrological battery, and in this
situation the access to this battery should be without specialist tools.
5.5.4 Implications of add-on devices (e.g. for communications) for batteries installed in meters
Battery management design in the device should be aware of the power demands that may be placed on the
battery for external communications. It is recommended that power be prioritised as the battery nears end of
life such that integrity is maintained in the following order of priority:
a) Safety;
b) Metrology;
c) Local datalogging and calculations;
d) Communications and valve operations.
NOTE The priorities here may differ slightly from those in the Welmec Software Guide, 7.2. This is because there is a
possibility that a valve may present a hazard should the processor fail or power fail during the operation. Therefore safety
is the highest priority.
5.5.5 Battery compartment
The battery should be integral with the meter.
The battery compartment(s) should be designed such that the battery is chemically isolated from the meter
case.
If it is intended that the battery can be changed, then:
 the battery compartment, or compartments should be separate from any of the index circuitry, except
for the wiring from the battery to the electronic index;
 the time to change the battery should be less than 5 min;
 the battery compartment(s) should be so designed that the battery can be replaced by authorized
personnel without having to remove the meter from standard installations with access only to the
aspect of the meter with the display visible;
 the battery compartment(s) should be capable of being sealed such that unauthorized interference is
detectable, and such that the metrological authority seal should not be broken when replacing the
battery;
 the battery compartment(s) should be fitted with a socket having a polarizing slot, or should be
clearly marked to show the correct battery polarity (or polarities) for replacement purposes.
5.6 Battery powered electronic indexes
5.6.1 General
There are three possible scenarios for electronic displays on gas meters:

 electronic index with all functionality;
 mechanical index with electronic secondary display;
 electronic index with secondary display.

The recommendations below focus on a single electronic index giving both metrological and non-metrological
information. The recommendations below may be appropriate for metrological only and non-metrological only
displays but should be considered in the context of their use.
5.6.2 Recommendations
5.6.2.1 General
This section specifies recommendations and tests for meters provided with an electronic index assembly as
the official indication of the volume or mass of gas passed by the meter. This display may also present
additional information – defined as "preliminary energy consumption and time of use information".
5.6.2.2 Mechanical construction of the Electronic Index Assembly
5.6.2.2.1 Protection against penetration of dust and water
The meter should be tested using the method in EN 60529:1991 for IP54. During and after exposure to the
IP54 test, the electronics should continue to function normally. The meter should not be subject to flow of gas
during the test.
Procedure:
a) cap the gas inlet and outlet of the meter to prevent flow and ingress, and record the metrological register
value(s);
b) expose meter to the EN 60529:1991 test. Inspect the register value(s) once during the test;
c) after the test is complete, inspect the register value(s);
d) after 24 h and one week at normal lab conditions, inspect the register value(s).
The test is passed if there is no change in the metrological value(s) on the display and within the electronic
memory.
NOTE The EN 60529 test requires no ingress. This report does not recommend no ingress, it just states that the
meter continue to function during the test and in the medium term.
5.6.2.2.2 Relative humidity
In the case of an ultrasonic meter, no further test is required other than that in 6.8.2 of EN 14236:2007.
For other meter types:
a) test the meter in accordance with EN 135
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