1. Background and Major Changes
The new edition of JJG 1033-202X for electromagnetic flowmeters has been officially released, replacing the old JJG 1033-2007. Significant adjustments have been made in metrological performance requirements, verification conditions, test items, and data processing to enhance consistency and reliability.
2. Key Clause Interpretation
2.1 Accuracy Classes and Maximum Permissible Error
The new regulation divides accuracy into classes 0.2, 0.5, 1.0, 1.5, and 2.5, similar to the old version, but adds a stricter repeatability requirement: repeatability shall not exceed one-third of the absolute value of the maximum permissible error for the corresponding accuracy class (previously one-half). For example, a class 0.5 flowmeter must have repeatability ≤ 0.17%.
2.2 Verification Conditions
- Environmental conditions: Ambient temperature changed from 5~35°C to 15~35°C; relative humidity relaxed from 45%~75% to 30%~80%, but condensation must be avoided.
- Power supply: Voltage fluctuation ≤ ±5% of rated value, frequency fluctuation ≤ ±1%.
- Warm-up time: At least 30 minutes before testing.
2.3 Verification Items and Methods
- New items: Added insulation resistance (≥20 MΩ) and dielectric strength tests (500V or 1000V depending on working voltage) for new or repaired meters.
- Flow points: Increased from 3 to at least 5, including normal flow, minimum flow, and maximum flow.
- Number of tests: Each flow point tested 6 times (previously 3), and the arithmetic mean is taken as the error.
2.4 Data Processing and Judgment
Adopts an "error limit" approach: each flow point must be within the maximum permissible error, and repeatability must pass. The old version allowed some points to exceed limits as long as the average error was acceptable. Additionally, optional stability data over the verification interval is required.
3. Impact on the Industrial Instrumentation Industry
3.1 Instrument Selection and Procurement
Stricter repeatability and insulation requirements drive buyers to prioritize long-term stability and insulation design. For instance, a large chemical company now requires type evaluation reports and repeatability test data in bids, eliminating low-end products.
3.2 On-Site Verification and Maintenance
Environmental conditions (e.g., 15~35°C) challenge field verification. A municipal water company reported needing sunshades and air conditioning for outdoor meters during summer, increasing costs. The increase to 5 flow points extends verification time per meter by about 40%.
3.3 Compliance and Costs
Enterprises must recalibrate existing standard devices to meet new accuracy requirements (uncertainty ≤ 1/3 of MPE). Small and medium-sized enterprises may face upgrade costs of 50,000 to 150,000 RMB per device.
4. Recommendations
- Plan ahead: Study the new regulation, update internal procedures, and revise work instructions.
- Upgrade equipment: Replace or upgrade standard devices that do not meet new requirements, preferably with automatic temperature control and programmable flow points.
- Data management: Implement electronic verification records to handle multiple flow points and repeated tests.
- Collaborate with suppliers: Request type evaluation certificates and factory test data, especially repeatability.
5. Conclusion
The new JJG 1033 represents progress in electromagnetic flowmeter metrology. Although it increases short-term costs and workload, it will improve the accuracy and reliability of flow measurement data, benefiting process optimization and fair trade. Users should adapt proactively to ensure compliance.