VERIFICATION OF WATER METERS

A water meter, also known as a flow meter or water flow meter, is a device used to continuously measure, record, and display the volume of water passing through the measuring converter under measurement conditions.

Currently, based on structure and operating principles, water flow meters are divided into two types: Mechanical cold water meters and electronic cold water meters.

Water meters are classified as Group 2 measuring devices that are mandatory for verification according to the regulations issued by the Directorate for Standards, Metrology and Quality of Vietnam, and are under the state management of the Ministry of Science and Technology. Therefore, water meters must be verified before it is put into operation.

Verification of water meters is an essential task. This process is crucial to ensure their optimal performance, accuracy, and integrity. Verification mitigates potential risks encountered by water meters and enhances their operational lifespan.

After verification, water meters are sealed with a lead wire, labeled with a verification label, and accompanied by a verification certificate.

• Maintain the water meter's stability
• Promptly identify any damages to prevent operational incidents
• Ensure its accuracy within permissible error ranges, in accordance with standards and measurement requirements.
• Comply and adhere to the regulations of the law.. (Circular 07/2019/TT-BKHCN)​

• Water meter verification before usage and post-repair.
• If the meter's seal is broken, it indicates potential external interference compromising its integrity.
• Any signs of abnormal operation, inaccuracies, or suspected water leakage warrant immediate attention.​

• Initial verification is the process of water meter verification for the first time upon installation and put into operation
• Periodic verification involves verifying the meters regularly, such as annually or monthly, after the meter has been in operation, to ensure the meter's accuracy throughout its operation. 
• Post-repair verification is necessary for water meters that have been repaired due to not meeting measurement requirements or operational quality standards. 
• In case of any operational irregularities detected by the user that deviate from the technical measurement standards, a re-verification is required to confirm the meter's operational efficiency and quality.

Verification requires adherence to several conditions:

• Mechanical cold water meters and electronic cold water meters must have a decision on type approval of measurement instruments
• The meter must be installed in the verification system according to the manufacturer's instructions.
• Gaskets must not encroach on the inner part of the pipe.
• The straight pipe section in front and behind the meter must have a length not less than the values specified in the manufacturer's instructions and have the same nominal diameter as the meter.
• Verification requires impurity-free water, sourced from an overhead tank, pumped from a pipeline, or a verification system source tank.
• Cold water meters are verified under environmental conditions with a maximum water temperature of 40ºC. Hot water meters, on the other hand, are verified using untreated water, ensuring the temperature does not exceed the manufacturer's specified limit. The water temperature is directly measured at either the inlet or outlet of the meter-installed pipe section.
• During measurements, ensure that the pressure behind the meter is not less than the atmospheric pressure.
• The system’s maximum pressure should not exceed the meter’s maximum working pressure.

Before the verification process, it’s important to operate the system to ensure there are no leaks of the verification liquid and that the water source is stable.

The verification of water meters must be carried out by ĐLVN 17: 2017, which encompasses the following steps:

Visual assessment to determine if the meter meets the stipulated requirements:

• Size and shape, dimensions, dial - pointer, brand label, and coating. The meter should be in good condition with no cracks on the body, casing, or indicator components.
• Symbol, Q_n or Q₃.
• The meter’s lead seal clamp mechanism.
• The indicator on a water meter must provide a clear and accurate reading to ensure precise measurement of water usage.
• There should be a decision from the measurement management agency on the type approval of water meters. This applies to both mechanical cold water meters and electronic cold water meters. 

The technical check must be carried out according to the following requirements:

• Detailed examination of the meter’s seal integrity upon its integration into the overall system.
• Check the stability of the meter readings when the water flow inside the system has completely stopped.

The measurement check of the water meter should be conducted following the sequence, method, and requirements below:

• Identify the flow rate points.
• Determine the relative error at each flow rate point. The meter's error at each measurement should not exceed the Maximum Permissible Error (MPE) value stipulated in ĐLVN 96: 2002 

Step 4: Processing the Results 

• After the verification process, water meters that fulfill the requirements of the procedure are granted a verification certificate and marked with a verification stamp or sticker. 
• Water meters that fail to meet one of the specified requirements are not issued a certificate, and any pre-existing verification marks are removed.

​The verification cycle of water meters is 60 months for mechanical cold water meters and 36 months for electronic cold water meters.

Customers in need of water meter verification services can easily find such facilities in Ho Chi Minh City or any other province across Vietnam. For bulk verification requirements, customers are encouraged to contact specialized verification centers or organizations. Alternatively, they can request their water meter provider to undertake the water meter verification. The associated with this service costs will be determined according to a provided quotation. It's noteworthy that certain water meter retailers are also authorized to conduct verification under the supervision of Vietnam's General Department of Metrology.

Dong Tam Measurement and Technical Trading Service Co., Ltd has been designated by the General Department of Standards, Metrology, and Quality to be allowed to initially inspect, periodically, after repairing various types of mechanical cold water meters and cold water meters with electronic mechanisms with diameters from DN15mm to DN300mm.

• Our laboratory, accredited under the ISO/IEC 17025:2017 standard, maintains stable temperature and humidity conditions to meet strict verification requirements.
• Our team of skilled, highly specialized, and experienced technicians is equipped to handle any unexpected issues during the verification process.
• Offer flexible verification costs suitable for all customers
• Provide fast, accurate, and effective service.
• Support delivery and pickup services for meters upon customer request.
• Verification certificates are securely archived in our system and can be quickly retrieved via a QR code or through The Certificate Information Lookup Portal on our website.

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To consult and request for quote on our water meter verification services, please kindly contact us via the following information:

LABORATORY: DONG TAM MEASUREMENT AND TECHNICAL TRADING SERVICE CO., LTD

ADDRESS : No.57-59 Street 11, Binh Hung Residential Area, Binh Hung Commune, Binh Chanh District, Ho Chi Minh City

TEL: 028 375 83 869 - Hotline: 0909 347 891 (Mr. Lâm)

Email: info@dongtam-mes.vn