GB/T 39841-2021Ultrasonic gas meters (English PDF)

5.2 Structure and materials

5.2.11 Resistance to solar radiation

After the gas meter is subjected to the solar radiation test, the appearance should not be changed, and the display content should be clear and easy to read.

5.2.12 Flame retardancy of outer surface

The materials of all external surfaces (including the observation window) of the gas meter should be flame-retardant. According to GB/T 11020-2005, these materials The flammability rating of the material should be V-0.

5.2.13 Storage temperature

Within the range of -20°C~60°C or the wider storage temperature declared by the manufacturer, the indication error of the gas meter should meet the requirements specified in Table 4. Initial MPE requirements.

5.2.14 Resistance to constant humidity and heat

After the gas meter is subjected to a constant damp and heat test without electricity, it should be restored to laboratory environmental conditions, and it should be able to work normally, and its appearance should be No rust.

5.2.15 Aging resistance

After the gas meter is subjected to the aging test, the error should meet the following requirements.

---1.0 level. The average error should meet the requirements of the initial MPE specified in Table 4; the average error deviation should not exceed the initial MPE specified in Table 4. Beginning one-third of MPE.

---1.5 level. The average error should meet the requirements of the durable MPE specified in Table 4; the average error deviation should not exceed ±2% (qt<=q<= qmax).

5.2.16 Resistance to external moisture

The gas meter shall meet the following requirements after being subjected to the external moisture resistance test.

a) There should be no obvious damage or information change;

b) The tightness still meets the requirements of 5.2.3;

c) The internal circuit should not have any signs of corrosion that may affect the functional characteristics of the gas meter, and there should be no change in the protective coating of the casing;

d) The error should meet the following requirements.

---1.0 level. The average error should meet the requirements of the initial MPE specified in Table 4; the average error deviation should not exceed the requirements of Table 4 1/3 of the initial MPE;

---1.5. The average error should meet the requirements of the durable MPE specified in Table 4; the average error deviation should not exceed ±2% (qt<= q<=qmax).

5.3 Explosion-proof performance

If the manufacturer declares that the gas meter is suitable for use in the hazardous area defined by GB 3836.14, the design, construction and marking of the gas meter shall be Meet the requirements of GB 3836.1 and GB 3836.4 or GB 3836.1 and GB 3836.8, and obtain the national authorized explosion-proof quality inspection Explosion-proof qualification certificate issued by the agency.

5.4 Seal

The mechanical seal of the gas meter should meet the following requirements.

---The structure of the gas meter should be such that any mechanical interference that can affect the metering performance of the gas meter is in the gas meter, the verification seal or the protection mark Permanent damage marks are left on the surface;

--- It should be able to effectively protect any device that adjusts the performance and characteristic parameters of the gas meter.

The electronic seal of the gas meter should meet the following requirements.

---You can only enter through a password or code that can be updated, or with a specific device;

---At least the last operation should be recorded in the memory, including the date and time of the operation and the special elements to confirm the operation;

---Operation records should be kept in the memory for at least 2 years.

5.5 Optional functions or features

5.5.5 Gas meter with built-in gas temperature or pressure, temperature conversion function See Appendix B for requirements.

5.5.1 Pressure tap

If the gas meter is equipped with a pressure tap, it should meet the following requirements.

a) The maximum aperture of the pressure tap is 1mm;

b) After undergoing the impact test, the tightness of the tested gas meter should meet the requirements of 5.2.3.

5.5.2 High temperature resistance

If the manufacturer declares that the gas meter is resistant to high temperatures of 650°C, when the high temperature test is carried out.

a) For gas meters with qmax not greater than 40m³/h, the shell leakage rate should not be greater than 150dm³/h;

b) For gas meters with qmax not less than 65m³/h, the leakage rate of the shell should not be greater than 450dm³/h. And should be marked in accordance with 5.12.1.

5.5.3 Thermal shut-off valve

The gas meter installed with the thermal shut-off valve should meet the following requirements.

--- When testing in accordance with 6.6.3a), the thermal shut-off valve should not be closed;

--- When testing in accordance with 6.6.3b), the thermal shut-off valve should be closed.

5.5.4 Anti-reverse flow device

If the gas meter is equipped with an anti-reverse flow device, the reverse flow through the gas meter should not be greater than 0.025qmax. For example, for qmax is For a 6m³/h gas meter, the reverse flow should not be greater than 0.15m³/h.

5.5.6 Additional devices

5.5.6.1 Control valve

5.5.6.1.1 Tightness

When the control valve is closed and the intake pressure is 4.5kPa~5kPa, the allowable internal leakage of the control valve should not be large At 0.55dm³/h.

5.5.6.1.2 Durability

The control valve can still be opened and closed normally after 4000 times of opening and closing, and the sealing performance should still meet the requirements of 5.5.6.1.1.

5.5.6.1.3 Corrosion resistance

If the manufacturer declares that the gas meter meets the requirements of 5.5.7 or 5.5.8, the control valve shall be sealed after being subjected to the test of 6.6.7 or 6.6.8 The performance should still meet the requirements of 5.5.6.1.1.

5.5.6.2 Remote transmission device

5.5.6.2.1 Data Transmission

The remote transmission device should have the function of active data reporting or passive wake-up, so as to realize the transmission of gas meter data and management system. transfer method It can be wired or wireless, and the transmit power used for wireless transmission should comply with relevant national regulations.

5.5.6.2.2 Remote valve control

For a gas meter with a control valve function, the remote transmission device shall have the function of controlling the opening and closing of the valve. Among them, the remote valve should be opened by sending the remote valve Instruction, the valve can be opened after manual intervention on site. After the switch operation is implemented, the gas meter should return a prompt indicating whether the operation is successful, and Make sure to return to the state of the control valve.

5.5.6.3 Prepaid control device

5.5.6.3.1 Control function

The prepaid control device shall have the following control functions.

a) The pre-purchased gas volume value should be correctly read, and the control valve should be opened;

b) It should have the gas volume accumulation function. After entering the new gas volume, the remaining gas volume in the prepaid control device should be the original remaining gas volume and the newly purchased gas volume. Sum of air;

c) When the remaining air volume in the prepaid control device drops to the set valve-closing air volume value, the control valve should be able to be closed.

5.5.6.3.2 Information feedback function

When the prepaid control device establishes gas purchase communication, the prepaid control device should automatically install the current gas volume transaction information and prepaid control equipment.

The status information, etc. are fed back to the prepaid management system for easy query.

5.5.6.3.3 Prompt function

5.5.6.3.3.1 Insufficient remaining gas prompt

When the remaining gas volume drops to the alarm gas volume value, the prepaid control device should have clear text, symbols or alarms and other prompts.

5.5.6.3.3.2 Misoperation prompt

If the additional device uses a gas card to realize the prepaid function, when the gas card that is not the prepaid control device is used, the prepaid The control device should have clear indications of misoperation or sound and light alarms.

5.5.6.3.3.3 Prompt for transaction completion

After the prepayment control device establishes the gas purchase communication, there should be corresponding prompts after the reading and writing are completed.

5.5.6.3.4 Durability of gas-purchased cards and card readers

If the additional device uses a gas card to realize the prepaid function, after the gas card and the card reader have read and write a total of 5000 times, the gas The card and card reader should still work normally.

5.5.6.4 Tiered billing control device

5.5.6.4.1 Synchronizing meter clock

The ladder billing control device should have the function of synchronizing the gas meter clock as a standard clock, and should have a prompt to return whether the operation is successful.

5.5.6.4.2 Tiered billing price

The ladder billing control device should have the function of setting or receiving the ladder price information that the gas meter needs to execute in real time.

5.5.6.4.3 Tiered price adjustment

The tiered billing control device should have the function of setting or receiving tiered price information to be executed by the gas meter.

5.5.7 Toluene/iso-octane resistance

If the manufacturer declares that the gas meter is resistant to toluene/iso-octane, the error of indication measured during the toluene/iso-octane test and before the test The value change should not be greater than 3%; after the toluene/iso-octane test, the indication error should still meet the requirements of the initial MPE specified in Table 4.

5.5.8 Water vapor resistance

If the manufacturer declares that the gas meter is resistant to water vapor, when it is subjected to a 7d (168h) low humidity test, the indication error should meet the initial value specified in Table 4.

Start MPE requirements; during the high humidity test of up to 42d (1008h), compared with the measured error value of the display before the test, it will change The change should not be greater than 3%; after the water vapor resistance test, the indication error should still meet the requirements of the initial MPE specified in Table 4.

5.6 Display information

5.6.1 Recording and storage

The cumulative volume recorded by the gas meter should be displayed on the display, and the storage time on the non-volatile memory should not be less than that of the gas meter For life, the manufacturer should state the memory retention time.

5.6.2 Display

The display letter logo characters should not be confused with numbers, and the number showing the cubic meter should be clearly distinguished from other numbers, and there should be a clear The displayed decimal point symbol separates the two numbers, and there should be enough digits to ensure that the gas meter runs at qmax for 8000h.

The gas volume will not reset the display. The digital display should meet the following requirements.

a) The resolution of the standard mode should meet the following requirements.

---qmax<=10m³/h, should be displayed to at least 1dm³;

---10m³/h \u003cqmax<=65m³/h,10dm³;

---qmax >65m³/h, should be displayed to at least 100dm³.

b) The resolution of the test mode should be displayed to at least 0.1dm³.

The display should be easy to read, the minimum height of important characters displayed is 5mm, and the measurement unit should be clearly displayed in cubic meters (m3).

5.6.3 Self-check display

The self-inspection display should first display all fields, and then all fields are not displayed. After the self-inspection display is terminated, the monitor should automatically restore the display Real-time volumetric volume.

5.6.4 Non-volatile memory

The non-volatile memory should be refreshed at least every 6h and should meet the following requirements.

---It should be readable within the extreme ambient temperature range declared by the manufacturer;

---In the storage temperature range declared by the manufacturer, the data can be maintained without power supply.

5.6.5 Display reset

The cumulative gas volume of the gas meter should not be reset during use.

5.7 Battery

5.7.1 General

If the battery is a replaceable battery, the battery box should be able to be operated without removing the gas meter, and the battery should be replaced without opening any Metering seal.

The battery should meet the requirements of GB/T 8897.1, and the lithium battery should meet the requirements of GB 8897.4.

The gas meter should be designed so that the structural parts of the gas meter will not be affected when the battery leaks.

If a non-replaceable battery is used for power supply, the rated working life of the battery should not be less than the specified service life of the gas meter.

5.7.2 Voltage interruption

After the voltage interruption test, the average error deviation should not exceed one third of the initial MPE specified in Table 4.

5.7.3 Minimum operating voltage

When the battery voltage drops to the minimum operating voltage specified by the manufacturer, the gas meter should have clear text, symbols, sound, light, etc.

Or multiple ways to indicate that the current is low voltage state, the indication error should meet the requirements of the initial MPE specified in Table 4.

5.8 Software protection

5.8.1 Misuse protection

The software design of the gas meter should minimize the possibility of unintentional, accidental or even intentional misoperation, and the display of measurement results should be accurate Unmistakable.

Note: Software-controlled gas meters are often complicated in function, and users need a detailed operation manual in order to use them correctly and get the correct measurement results. Example:

The user operates according to the menu. The related functions of legal measurement are integrated under a certain level of menu. If the measured value may be lost due to an operation, the user should be warned, And you can perform another operation before executing this function.

5.8.2 Fraud protection

5.8.2.1 Seal

Based on the use of mechanical sealing technology, necessary technical skills can be adopted for gas meters with operating systems or software loading options. The paragraph comes to seal.

When the software is stored in a write-protected memory (such as ROM), the requirements for technical means can be simplified accordingly.

5.8.2.2 User interface protection

The interface design should avoid the purpose of deceptive use by users.

The inspector decides whether the commands in all documents are acceptable.

5.8.2.3 Protection of legal measurement related parameters

Determine the relevant characteristics of the gas meter legal system and the parameters solidified in it should be protected by a seal to prevent unauthorized permission. modify.

If the verification process is necessary, the currently set parameters should be able to be displayed or printed.

Only in the special operating mode of the gas meter, can the device-specific parameters be adjusted or selected. They can be divided into two categories. one is curing The other type is accessible (adjustable parameters), which is adjusted by authorized gas meter users. Type-specific parameters are the same All parameters of a model have the same value and are determined by the approved model.

5.8.2.4 Software protection measures

Software protection measures include the use of mechanical, electronic and/or data encryption sealing measures to prevent unauthorized interference and leave interference evidence of.

If you want to modify the parameters and configuration, you should switch the switch and break the seal.

5.9 Electromagnetic compatibility

5.9.1 General

The design and manufacture of gas meters should minimize the influence of magnetic field, electrostatic discharge and other electromagnetic interference, and meet the requirements of 5.9.2 to 5.9.6;

If it is AC power supply, it should also meet the requirements of 5.9.7 and 5.9.8.

5.9.2 Electrostatic discharge immunity

The gas meter should be able to work normally after being subjected to the electrostatic discharge test of contact discharge 6kV and air discharge 8kV, and the indication error should meet

5.9.3 Radio frequency electromagnetic field radiation immunity

The gas meter should be able to work normally after being subjected to the radio frequency electromagnetic field radiation immunity test with a test field strength of 10V/m (80MHz~1GHz).

The indication error should meet the requirements of the initial MPE specified in Table 4.

5.9.4 Power frequency magnetic field immunity

The gas meter should be able to work normally after being subjected to a power frequency magnetic field immunity test with a magnetic field strength of 30A/m and a duration of 15 minutes.

Meet the requirements of the initial MPE specified in Table 4.

5.9.5 Pulse magnetic field immunity

The gas meter should be able to work normally after being subjected to a pulsed magnetic field immunity test with a magnetic field strength of 100A/m and a duration of 15 minutes, and the indication error It shall meet the requirements of the initial MPE specified in Table 4.

5.9.6 Radiation disturbance

Under zero flow conditions, the electromagnetic radiation generated by the gas meter should not exceed the B-level radiation disturbance limit specified in GB/T 9254-2008.

5.9.7 Electrical fast transient pulse group immunity

For AC-powered gas meters, when a test voltage of 2kV (5/50ns, 5kHz) with a peak voltage of 2kV (5/50ns, 5kHz) is applied to the power input port, the gas meter should Can work normally.

5.9.8 Surge (impact) immunity

For AC-powered gas meters, when a surge test voltage of 1kV line-to-line and 2kV line-to-ground is applied to the power input port, the gas meter should It can work normally. After the surge (impact) immunity test, check the gas meter again and it should be able to work normally.