The acceptance criteria and methods for turbine flow meters mainly follow standards such as JJG 1037-2008 “Verification Procedure for Turbine Flow Meters”. Through technical document review, visual inspection, installation condition verification and performance testing, the accuracy, stability and applicability of the flow meter are ensured to meet the usage requirements.
I. Acceptance Basis
1. Main Standards and Specifications
The core standard is the National Verification Regulation: JJG 1037-2008 “Verification Regulation for Turbine Flow Meters,” which specifies the environmental conditions, equipment requirements, and methods for verifying turbine flow meters. This regulation applies to type evaluation, initial verification, and subsequent verification of gas and liquid turbine flow meters.
National Standards:
GB/T 18940-2003 “Measurement of Gas Flow Rate in Closed Pipelines – Turbine Flow Meters”
GB/T 21391-2008 “Measurement of Natural Gas Flow Rate Using Gas Turbine Flow Meters”
GB/T 18603-2014 “Technical Requirements for Natural Gas Metering Systems”
International Standard: ISO 9951:1993 “Measurement of Gas Flow Rate in Closed Pipelines – Turbine Flow Meters”
Industry Standard: Q/SY 1447-2011 “Technical Requirements for Natural Gas Metering Systems”
2. Acceptance Technical Documents
Design Documents: Confirm whether the flow meter design meets the requirements of standards such as GB/T 18940-2003.
Manufacturing Qualifications: Check whether the manufacturer possesses relevant qualification certificates.
Factory Inspection Report: Verify whether the factory inspection data meets the standard requirements.
Calibration Certificate: Confirm the qualifications of the calibration institution and the validity of the calibration results.
II. Acceptance Methods
1. Technical Document Review
Selection Matching: Verify whether the selected flow meter matches the site conditions, including media characteristics (temperature, pressure, viscosity, corrosiveness), flow range, and pipeline parameters.
Technical Parameter Confirmation: Check basic parameters such as pipe diameter, flow unit, and pulse coefficient.
Special Requirements Check: Check whether explosion-proof rating (ExdⅡBT4, etc.) and protection rating (IP65, etc.) meet site requirements.
2. Visual Inspection
Equipment Integrity: Check the flow meter casing for cracks, deformation, or corrosion, ensuring sealing.
Connection Parts: Confirm that the inlet and outlet flanges and threaded connections are intact, without looseness or damage.
Display and Indicator Lights: Check whether the display screen is normal and whether the indicator lights are functioning correctly.
Nameplate Information: Verify that the model, specifications, manufacturer, calibration date, and other information are clear and complete.
3. Installation Condition Verification
Straight Pipe Section Requirements: The installation of the gas turbine flow meter should comply with GB/T According to 21391, the upstream straight pipe section generally requires ≥10D and the downstream straight pipe section ≥5D.
Installation Location: Check if it is installed in the lower half of a horizontal pipe (to avoid air bubbles at the top or impurities at the bottom).
Coaxiality Check: Confirm that the upstream and downstream pipes are coaxial with the flow meter flange (deviation ≤0.5mm).
Sealing Check: The sealing gasket must not protrude into the pipe to avoid interfering with the fluid flow.
4. Performance Testing
Flow range test: Perform multi-point tests within 10%-100% of the flow metering range to verify linearity.
Accuracy test: Compare with a standard flow meter and calculate the indication error. The accuracy class of gas turbine flow meters is typically 1.0 (±1.0%).
Repeatability Test: Perform multiple measurements at the same flow point and calculate the repeatability error (should be ≤0.33%).
Zero-point Calibration: Confirm the instrument output is zero under no-flow conditions.
Dynamic Response Test: Observe the instrument’s response speed and accuracy to flow changes.
5. Functional Checks
Signal Output Check: Verify that the pulse signal or 4-20mA analog signal output is normal.
Temperature and Pressure Compensation: If temperature/pressure compensation is required, check that the compensation function is working properly.
Alarm Function: Test low battery, fault, and other alarm functions.
Data Storage: Verify that the data storage function is normal.
III. Acceptance Criteria
1. Accuracy Requirements
Gas turbine flow meters: Within the range qt≤qv≤qmax, the accuracy class 1.0 requires an error ≤±1.0%; within the range qmin≤qv＜qt, the error ≤±2.0%.
Liquid turbine flow meters: Typically require an error ≤±0.5% (low viscosity liquids) or ≤±1.0% (high viscosity liquids).
2. Repeatability Requirements
Class 1.0 flow meter: Repeatability should be ≤0.33%
Class 0.5 flow meter: Repeatability should be ≤0.17%
3. Installation Requirements
Straight Pipe Section: Standard installation requirements: upstream ≥10D, downstream ≥5D; Short Pipe Installation (with built-in flow adjuster): total length ≥6D
Pipe Inner Diameter Deviation: Should be ≤±1%
Temperature Sensor Insertion Depth: Should be ≤1/3 pipe diameter
IV. Acceptance Considerations
Influence of Media Characteristics: Turbine flow meters have strict requirements for the measured medium. The medium should be a low-viscosity single-phase fluid. Gas viscosity is typically ≤5×10⁻⁶ m²/s, and liquid viscosity is ≤5×10⁻⁶ m²/s.
Fluid State Requirements: The measured medium should be in a turbulent state to avoid laminar flow affecting measurement accuracy.
Cleanliness Requirements: The fluid should be clean and free of impurities. If necessary, a filter (usually 40-100 mesh) should be installed upstream of the flow meter.
Environmental conditions: The calibration environment temperature should be (5～45)℃, relative humidity generally 15%～95%, and atmospheric pressure generally (70～106)kPa.
Special media handling: For high-viscosity liquids (>5×10⁻⁶m²/s), viscosity correction or a special calibration method is required.
Acceptance timing: The flow meter should be operated for at least 5 minutes within 70%～100% of the achievable MAX calibration flow rate. Formal calibration can only be performed after the fluid temperature, pressure, and flow rate have stabilized.
A qualified turbine flow meter should accurately reflect the flow characteristics of the measured fluid and meet process requirements and metrological standards. For flow meters used in trade settlements, the acceptance process is particularly important and should be strictly carried out in accordance with relevant standards to ensure the accuracy and reliability of the measurement results. After acceptance, a complete acceptance report should be prepared, including the acceptance process, test data, result analysis, and conclusions, serving as an important basis for subsequent use and maintenance.
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