GB/T 778.1-2018Meters for cold potable water and hot water -- Part 1: Metrological requirements and technical requirements (English PDF)

Foreword

GB/T 778, Meters for cold potable water and hot water, consists of 5 parts.

— Part 1.Metrological and technical requirements;

— Part 2.Test methods;

— Part 3.Test report format;

— Part 4.Non-metrological requirements not covered in GB/T 778.1;

— Part 5.Installation requirements.

This Part is Part 1 of GB/T 778.

This Part was drafted in accordance with the rules given in GB/T 1.1-2009.

This Part replaces GB/T 778.1-2007, Measurement of water flow in fully charged

closed conduits - Meters for cold potable water and hot water - Part 1.Specifications.

Compared with GB/T 778.1-2007, its major technical changes are as follows.

— it changes the standard name;

— it extends the applicable scope of the standard, without specifying maximum

admissible working pressure (see Clause 1; Clause 1 of 2007 edition);

— it adjusts the structure of the standard;

— it adds the terms, including "water meter", "tariff control device", "pre-setting

device", "meter for two constant partners", "cartridge meter", "cartridge meter

connection interface", "meter with exchangeable metrological module",

"exchangeable metrological module", "connection interface for meters with

exchangeable metrological modules", "error", "durability", "metering conditions",

"resolution of a displaying device", "combination meter changeover flow rate",

"durability test", "temperature stability", "preconditioning", "conditioning",

"recovery", "type evaluation" and "type approval" (see 3.1.1, 3.1.9, 3.1.10, 3.1.12,

3.1.20, 3.1.21, 3.1.22, 3.1.23, 3.1.24, 3.2.4, 3.2.10, 3.2.11, 3.2.14, 3.3.6, 3.4.7,

3.4.8, 3.4.9, 3.4.10, 3.4.11, 3.4.12, 3.4.13);

— it modifies the terms including "flow sensor", "correction device", "initial intrinsic

error", "working temperature", "influence factor", "rated operating condition",

"type P automatic checking facility" (see 3.1.3, 3.1.7, 3.2.7, 3.3.10, 3.4.2, 3.4.4

and 3.5.6; 3.26, 3.32, 3.49, 3.17, 3.50, 3.5 and 3.40 of 2007 edition);

— it deletes the definitions of the terms including "minimum admissible working

pressure", "limiting conditions" and "power supply device" (see 3.15, 3.6 and 3.43

of 2007 edition);

— it modifies the selection of the value of Q3/Q1 (see 4.1.4; 5.1.2 of 2007 edition);

— it deletes the determination of reference flow (see 5.1.5 of 2007 edition);

— it adds the classification of water meter accuracy classes and adds the maximum

permissible error requirements for class 1 meters (see 4.2.2);

— it deletes the column of reference conditions in the table of "temperature classes"

(see 5.4.1 of 2007 edition);

— it adds different requirements for permanent flow and measuring range in two

directions of reverse flow water meters (see 4.2.7);

— it adds the requirement that water meters are capable of withstanding static

pressure without damage or leakage (see 4.2.10);

— it adds the requirement that for a replaceable battery, a low battery or exhausted

battery indicator or a meter replacement date shall be indicated on the meter

(see 5.2.3.2);

— it adds the requirement that, for a replaceable battery, if the register display gives

an indication of "low battery", there shall be a minimum useful life for the register

display from the time "low battery" indication is displayed to end of life (5.2.4.2);

— it adds the requirement that Replacement of the battery shall be carried out in a

way that does not necessitate breaking the seal required for statutory

metrological inspections (5.2.4.4);

— it adds the requirement that a water meter shall be of such design, composition,

and construction that it does not facilitate the perpetration of fraud and that it

does not exploit the MPE or favour any party (see 6.1.7 and 6.1.9);

— it adds the requirement that the adjustment of the meter may not exploit the MPE

or systematically favour any party (see 6.2.1);

— it adds the requirements for meter installation conditions (see 6.3);

— it adds the requirements for accuracy classes and pressure loss classes on the

nameplate (see 6.6.2);

— it deletes the requirements for the types of output signals provided for auxiliary

devices on the nameplate (see 6.8 of 2007 edition);

— it is modified that it requires provision of environmental classes and

electromagnetic compatibility only on the nameplate of water meters with

electronic devices (see 6.6.2; 2007 edition);

— it adds the display requirements for electronic indication devices (see 6.7.2.2);

— it adds the requirements for resolution of the indicating device of class 1 water

meters (see 6.7.3.2.3);

— it adds the requirements for the indicating device of combination water meters

(see 6.7.3.3);

— it deletes the requirements for additional verification elements (see 6.6.3.3 of

2007 edition);

— it adds the requirements for metrological controls, including type test and initial

verification (see Clause 7);

— it deletes Annexes A and B to 2007 edition;

— it adds the annex "Performance tests for water meters with electronic devices"

(see Annex A);

— it adds the annex "Permissible errors in service and subsequent verification" (see

Annex C).

This Part identically adopts ISO 4064-1.2014, Water meters for cold potable water and

hot water - Part 1.Metrological and technical requirements, using the translation

method.

The following editorial modifications are made in this Standard.

— the standard name is modified.

This Part was proposed by the China Machinery Industry Federation.

This Part shall be under the jurisdiction of National Technical Committee 124 on

Industrial Process Measurement, Control and Automation of Standardization

Administration of China (SAC/TC 124).

The drafting organizations of this Part. Shanghai Institute of Process Automation and

Instrumentation Co., Ltd., Ningbo Water Meter Co., Ltd., Sanchuan Wisdom

Technology Co., Ltd., Ningbo Donghai Instruments and Water channels Co., Ltd.,

Suzhou Water Meter Co., Ltd., Zhejiang Institute of Metrology, Henan Institute of

Metrology, Ningbo Institute of Measurement and Testing, Nanjing Tap Water General

Company Water Meter Factory, Chongqing Intelligent Water Meter Co., Ltd., Wuxi

Water Meter Co., Ltd., Shanghai Water Meter Co., Ltd., Shanghai Inspection and

Testing Institute of Instruments and Automation Systems, Hangzhou Water Meter Co.,

Ltd., Shenzhen Jiexian Digital Technology Co., Ltd., Huizhong Instrumentation Co.,

Ltd., Fuzhou Kerong Instrument Co., Ltd., Yangzhou Hengxin Instrument Co., Ltd.,

Beijing Waterworks Group Jingzhao Water Meter Co., Ltd., Jinan Richens Electronic

Co., Ltd., Hangzhou Jingda Electronic Co., Ltd., Jiangyin Lixin Intelligent Device Co.,

Ltd., Hunan Changde Water Meter Manufacture Co., Ltd., Ningbo Jingcheng

Technology Co., Ltd., Hunan Weiming Energy Technology Co., Ltd., Qingdao IESLab

Electronic Co., Ltd., Tianjing New Sun Energy Technology Co., Ltd.

1 Scope

This Part of GB/T 778 specifies the metrological and technical requirements for water

meters for cold potable water and hot water flowing through a fully charged, closed

conduit. These water meters incorporate devices which indicate the integrated volume.

2 Normative references

The following referenced documents are indispensable for the application of this

document. For dated references, only the edition dated applies to this document. For

undated references, the latest edition of the referenced documents (including all

amendments) applies to this document.

3 Terms and definitions

For the purposes of this document, the following definitions apply.

part of the meter that transforms the flow rate or volume of water to be measured into

signals which are passed to the calculator and includes the sensor

4 Metrological requirements

A water meter shall be designed and manufactured such that its errors (of indication)

do not exceed the maximum permissible errors (MPEs) as defined in 4.2.2 or 4.2.3

under rated operating conditions.

The meters fall under water temperature classes corresponding to the various ranges,

chosen by the manufacturer from the values given in Table 1.

5 Water meters equipped with electronic devices

All water meters equipped with checking facilities shall prevent or detect reverse flow,

as specified in 4.2.7.

Replacement of the battery shall be carried out in a way that does not

necessitate breaking the seal required for statutory metrological inspections.

6 Technical requirements

Under specific installation conditions, a strainer or filter, fitted at the inlet of a

meter or in the upstream pipeline, may be required.

The colour black should be used to indicate the cubic metre and its multiples.

The colour red should be used to indicate sub-multiples of a cubic metre.

7 Metrological controls

Before undergoing type evaluation tests, each type of water meter submitted shall be

examined externally to ensure that it complies with the provisions of the relevant

preceding clauses of GB/T 778.1.

Annex A

(Normative)

Performance tests for water meters with electronic devices

This annex defines the programme of performance tests intended to verify that water

meters with electronic devices can perform and function as intended in a specified

environment and under specified conditions. Each test indicates, where appropriate,

the reference conditions for determining the intrinsic error.

......