JJG 1030-2007Ultrasonic Flowmeters (English PDF)

3.1 Ultrasonic Flowmeter

Ultrasonic flowmeter refers to a flowmeter which utilizes the transmission characteristic of ultrasonic wave in fluid to measure flow.

3.6 Acoustic Path

Acoustic path refers to the actual path of ultrasonic signal’s transmission among paired ultrasonic transducers.

3.7 Transmission Angle

Transmission angle refers to the included angle between acoustic path and pipeline’s axes.

3.8 Single-path Meter

Single-path meter refers to a flowmeter that merely has one pair of transducers.

3.9 Dual-paths Meter

Dual-paths meter refers to a flowmeter that has two pairs of transducers.

3.15 Signal Processing Unit

Signal processing unit is constituted of electronic components and microprocessor system. It is a part of flowmeter.

3.16 Transition Flowrate (qt)

Transition flowrate refers to a flow value between the maximum flow and the minimum flow. It segments the range of flow into two zones with different allowable errors, namely, “high zone” and “low zone”.

4.1 Operating Principle

Flowmeter takes the measurement of the relations between the time and the flow of acoustic wave’s transmission in flowing medium as the principle. Generally speaking, it is believed that acoustic wave’s actual transmission speed in fluid is constituted of acoustic wave’s transmission speed (cf) under the stationary state of the medium, and the component of fluid’s axial average flow rate (vm) in the direction of acoustic transmission.

4.2 Structural Form

4.2.1 Composition

Flowmeter is mainly constituted of meter body, ultrasonic transducer and its installation parts, signal processing unit, and (or) flow computer. In terms of on-site wetted ultrasonic meters and clamp-on ultrasonic meters, pipelines where transducer is installed may be used as meter body. The transducer of wetted ultrasonic meters directly contacts the fluid being measured, while the transducer of clamp-on ultrasonic meters is tightly installed on the external wall of pipelines.

4.2.2 Form

4.2.2.1 In accordance with the installation mode of transducer, flowmeter may be divided into two forms, namely, wetted and clamp-on.

5.1 Grade of Accuracy

Table 1 provides recommended accuracy grade series. If a grade of accuracy that is not listed in this table is adopted, the maximum allowable error needs to comply with corresponding principles in Table 1 and needs to be clearly indicated in flowmeter product instruction and flowmeter nameplate.

5.2 Repeatability

Repeatability of flowmeter shall not exceed 1/5 of the absolute value of the maximum allowable error stipulated by the corresponding grade of accuracy.

5.3 Flowmeter Factor Adjustment

If meter factor is changed during verification, then, the verification certificate shall clearly indicate the previous meter factor, the meter factor after the current adjustment and the amount of meter factor adjustment.

6.1 Product Documents

6.1.1 Flowmeter shall be accompanied by an instruction for use.

6.1.2 In terms of clamp-on ultrasonic meters, the instruction for use shall describes flowmeter’s installation methods and operating requirements in details.

6.2 Nameplate and Marking

6.2.1 Flowmeter shall have marking of flow direction.

6.2.3 Each pair of ultrasonic transducers shall have permanent uniqueness marking and installation marking in obvious positions.

6.2.4 When transducer’s signal cable needs to make one-to-one correspondence with

ultrasonic transducer, there shall be permanent uniqueness marking and installation marking in obvious positions.

6.3 Appearance

6.3.1 Newly manufactured flowmeter shall have satisfying surface treatment; there shall be no phenomena like burrs, scratches, cracks, corrosion, mildew stains or stripping of coating. The sealed surface shall be flat; there shall be no damages.

6.5 Air-tightness

Verify the medium under the maximum experimental pressure, maintain for 5 min, there shall be no leakage in the various ports of the flowmeter body.

7.1 Verification Conditions

7.1.1 Requirements of flow calibration device

7.1.1.5 When the pressure of fluid that flows through the flowmeter needs to be measured, directly take pressure from pressure ports on the flowmeter body. If there are no pressure ports on the flowmeter body, it shall, according to the requirements of the flowmeter, determine the measurement location of pressure.

7.1.2 Fluid for verification

7.1.2.1 Universal conditions

7.1.2.3 Gas used for verification

7.1.4 Installation conditions

7.1.4.1 The installation of flowmeter shall comply with the requirements in Appendix D.

7.1.4.2 During verification, in principle, all the components that constitute flowmeter

shall be submitted for verification.

7.1.5 Each measurement time shall be not less than the allowed shortest measurement time of the device and the flowmeter being verified.

7.1.6 When the pulse output of the flowmeter being verified is adopted for verification, the pulse count recorded in one verification shall not be less than 10 times of the reciprocal of the absolute value of the maximum allowed error.

7.1.7 All the electrical apparatus used for verification shall be grounded in the same point.

7.2 Verification Items and Verification Methods

7.2.1 Verification items

Verification items of the initial verification, subsequent verification and in-use inspection are listed in Table 2.

7.3 Processing of Verification Result

Flowmeters that are qualified in the verification shall receive a verification certificate.

The requirements of the content of the verification certificate are shown in Appendix E.

Flowmeters that are disqualified in the verification shall receive a verification result notification, which shall indicate the disqualified items. Flowmeters that receive in-use inspection shall receive an inspection report.

7.4 Verification Cycle

Generally speaking, verification cycle shall not exceed 2 years. In terms of plug-in flowmeter, if the flowmeter has self-diagnostic functions and can retain alarm records, verification may be conducted once in every 6 years and in-use inspection shall be conducted on the site every year.

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