1. Calibration basis (reference) : J JG10 33 -20 07

2. Calibration location: Liquid laboratory

3. Standard Instruments

Static mass method water flow standard device U = 0.065% ( k = 2).

The static mass method water flow standard device mainly consists of a controller and a water reservoir. The water reservoir is connected to a water pump via a pipeline, the water pump is connected to a measuring pipe via a pipeline, and the measuring pipe is connected to a weighing system via a pipeline. The weighing system includes multiple commutators. The commutator includes a housing, which is provided with a water inlet, a first water outlet, and a second water outlet. The inner wall of the housing is provided with two grooves that are symmetrical about the plane and the axis of the housing. The first water outlet and the second water outlet are respectively located on one side of the two grooves. The housing is provided with end caps at both ends. The end caps are rotatably connected to the rotors, which are connected to the rotating cylinders provided on the caps. As shown in Figure 1.

Figure 1 Static mass method water flow standard device

1 Calibration method

a. Preparation before calibration

Start the device calibration system software, enter the calibration task interface, determine the calibration items according to user requirements, fill in the basic information of the calibrated flow meter, and set relevant parameters. Check whether the environmental conditions are met: the ambient temperature is generally (5~35)℃; the relative humidity is generally 15%~85%; the atmospheric pressure is generally (86 ~ 106) kPa. The temperature range of the calibration liquid should be (4 ~ 35) °C. During each calibration process at each flow point, the liquid temperature should not vary by more than ±0.5 °C.

b. Appearance inspection

Random documents: The flow meter should have an instruction manual.

Markings and nameplates: The flow meter body should have a clear flow direction marking. The flow meter should also have a nameplate. The nameplate should generally indicate the product and manufacturer name, product specifications and model, factory serial number, maximum operating pressure, applicable operating temperature range, caliber, flow range, flow meter characteristic coefficient, explosion-proof rating, protection level, manufacturing date, and other technical requirements.

Appearance: Newly manufactured flow meters should have good surface treatment and should be free of burrs, scratches, cracks, rust, mildew, and the coating should not be peeling or flaking.

The welding of the connecting parts of the flow meter body should be smooth and clean, without any cold welding or desoldering.

The sealing surface should be flat and free of damage.

The numbers displayed on the flow meter should be eye-catching and neat, and the text symbols and logos indicating functions should be complete, clear and correct.

The flowmeter's markings are correct; the protective glass covering the flowmeter's display should be transparent and free of defects that could distort the reading or interfere with the display. The flowmeter's buttons should not be sticky.

c. Install the flowmeter into the pipeline according to the regulations. Check the connection between the flowmeter and the test pipe for leaks. Open the rear air valve to allow air in to check for leaks. Ensure that the gasket at the connection does not protrude into the fluid. Fill the flowmeter with fluid and check for leaks. After confirming that the flowmeter to be calibrated meets the installation requirements, connect the output signal of the flowmeter to the flow calibration system and turn on the flowmeter power. Check the flowmeter parameters according to the methods specified in the flowmeter manual.

d. Run the flowmeter at 70% to 100% of the maximum flow rate for 5 minutes until the fluid temperature, pressure, and flow rate are stable, then reduce the flow rate to 0, close the valves before and after the flowmeter, and perform flow zero point calibration on the instrument.

e. Basic error - cumulative flow calibration

On the calibration interface of the calibration system, adjust the flow rate to the specified calibration flow rate point. After the pressure, temperature, and flow rate stabilize, click Start Verification to measure the flow rate of the flow meter being tested. After the set measurement time, the device displays the standard cumulative flow rate, measurement time, and the cumulative number of pulses of the flow meter being tested. The flow error of the calibrated flow meter is calculated, completing a measurement for each flow point. Repeat the above steps until all set flow points are calibrated.

Calibration interface

2 Calibration records

a. Save calibration records in file format

After the calibration is completed, the software system automatically generates and displays the calibration record. As shown in the following figure:

Click "Save" in the above picture, the following screen will appear, confirm the file name, and click "Save" to save the calibration record.

b. Data query

In the calibration interface, you can query and delete the calibration records saved in the database.

Calibration record query interface and calibration record search condition input interface

4. Data Processing -Error Calculation

E _{Q )} calculated according to formula (1) should meet the requirements for flow meter error limits in Table 1 of J JG10 29-2007.

E _Q = ×100% (1)

Where: ——The cumulative volume flow rate indicated by the flowmeter, L, =N/K (N--the cumulative number of pulses, K--the flowmeter pulse equivalent, 1/L);

      ——The cumulative volume flow of the device is converted to the flow meter status value, L.

5. Uncertainty Assessment

1. Measurement basis

JJG 1033-2007 “Electromagnetic Flowmeter”.

2. Measurement data

3 Uncertainty analysis

The sources of uncertainty of the indication error E of the measured electromagnetic flowmeter mainly include: the relative uncertainty introduced by the standard device; the relative uncertainty introduced by the measurement repeatability.

(1) Relative uncertainty introduced by the standard device

According to the calibration certificate, the expanded uncertainty of the standard device is U _rel = 0.065% ( k = 2), and the Class B standard uncertainty of the device is obtained as 0.065%/2 = 0.0325%.

(2) Uncertainty introduced by measurement repeatability

qmax in the original record of the electromagnetic flowmeter. The repeatability was s=0.164%.

Therefore the mean test standard deviation is:

 (5) Combined standard uncertainty 0.10%

3. Expanded uncertainty

Take k = 2, = k • = 0.20%

4 Reporting and expression of measurement uncertainty

The relative uncertainty of the electromagnetic flowmeter at the flow point 0.5Qmax is: U rel ≈0.20%, k =2.

5. Evaluation of measurement uncertainty of mass flowmeters using mass flow standard devices as standard instruments

Within the flowmeter range, calibration is performed at five flow points: Q max, 0.75Q max, 0.5Q max, 0.25Q max, and Q min. The measurement uncertainty is shown in Table 2.

Table 2 Measurement uncertainty

5. Calibration results:  

Calibrator : Year Month Day

Verification personnel: Year Month Day