JJG 162-2019Cold Potable Water Meters (English PDF)

3.1 Terms

3.1.1 Water meter

Under measurement conditions, an instrument used to continuously measure, record, and display the volume of water flowing through the measurement transducer.

3.1.2 Measurement transducer

The water meter component that converts the measured water flow or volume into a signal and transmits it to the calculator, including a sensor.

3.1.13 Permanent flow rate (Q3)

The maximum flow rate under rated working conditions. At this flow rate, the water meter shall work normally and meet the maximum allowable error requirements.

3.1.14 Overload flow rate (Q4)

The maximum flow rate that requires the water meter to meet the maximum allowable error requirements in a short period of time and then maintain the metering characteristics under rated working conditions.

4.1 Principle and structural composition

Cold portable water meter (hereinafter referred to as water meter) is a measuring instrument named after its use. It is used to measure the total volume of cold portable water flowing through a closed full pipe. It is widely used in the trade settlement measurement of the tap water delivery volume, as supplied by the tap water supply department to residents and industrial and commercial users.

4.2 Classification

According to the working principle and structural characteristics of the water meter, it can generally be divided into.

5.1 Flow characteristics of water meters

5.1.1 The flow characteristics of water meters shall be determined according to the values of Q1, Q2, Q3, Q4.

5.1.5 The ratio Q2/Q1 is 1.6.

5.1.6 The ratio Q4/Q3 is 1.25.

5.2 Accuracy level and maximum allowable error

5.2.1 The accuracy level of water meters is divided into level 1 and level 2.The maximum allowable error of water meters with different accuracy levels at different working temperatures shall comply with the provisions of Table 4.

5.2.2 If all indication errors of the water meter have the same sign, at least one of the indication errors shall not exceed 1/2 of the maximum allowable error.

6.1 Appearance, sign, seal

6.1.1 Appearance

6.1.2 Sign

6.1.2.1 Measurement legal sign

The water meter shall be marked with the type approval sign and number of the measuring instrument in a prominent position.

6.1.2.2 Marking of measuring instruments

The water meter shall clearly and permanently indicate the following information on the housing, the dial or nameplate of the indicating device, the inseparable cover, either centrally or dispersedly.

6.1.3 Seal

6.1.3.1 The water meter shall have a protective device with a seal or a closed structure, to ensure that before and after correct installation of water meter, it cannot disassemble or change the water meter and its adjustment device, correction device, related measuring instruments, without damaging the protective device or the seal of the protective device. The verification sign and protective seal of the water meter shall be applied to the part that can be seen without opening or disassembling the water meter.

6.2 Functions of electronic devices

6.2.1 For water meters with electronic devices, it shall explain various functions related to user use and operation in the instruction manual and other accompanying documents.

The modifiable parameters stored in the electronic device that affect the measurement results, such as sensor coefficient, instrument coefficient, signal equivalent, correction coefficient, etc., shall be available on the nameplate or accompanying documents of the water meter and related measuring instruments.

6.3 Tightness

6.3.1 Newly manufactured water meters shall be able to withstand a tightness test of

1.6 MAP for 1 min without seepage, leaking or damage.

6.3.2 Water meters in use shall not leak under working conditions.

7.1 Verification conditions

7.1.1 Measuring standards and supporting equipment

7.3 Verification method

7.3.1 Inspection of appearance, sign, seal

7.3.1.1 Carry out visual inspection for the appearance of the water meter; it shall comply with the provisions of 6.1.1.

7.3.1.2 Carry out visual inspection for the sign of the water meter; it shall comply with the provisions of 6.1.2.

7.3.1.3 Carry out visual inspection for the protective device and seal of the water meter.

7.3.4 Verification of indication error

7.3.4.1 Verification flow point

The verification flow points of the water meter are generally Q1, Q2, Q3, adding 1.1Qx2 for combination water meters. If the additional verification flow point is indicated in the accompanying documents of the water meter, this flow point shall also be added.

7.3.4.3 Verification signal

If the mechanical water meter contains a component that can be quickly verified, the verification function of the component can be used, to connect an external sensor to provide a verification signal.

7.5 Verification cycle

7.5.1 For water meters which have a nominal diameter of DN50 or less and Q3 not greater than 16 m3/h, only the first mandatory verification before installation is carried out; the meter is used within a limited period of time and replaced upon expiration. The service life is stipulated as follows.

7.5.2 The verification cycle of water meters, which have a nominal diameter exceeding

DN50 or a Q3 exceeding 16 m3/h, is generally 2 years.

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