LJQF-7800-DN10-300 Critical Flow Venturi Sonic Nozzle Type Gas Flow

Short Description:

The “Critical Flow Venturi Sonic Nozzle Gas Flow Standard Device” is a standard for the unification and transfer of flow unit values, and is a standard measurement device for the value traceability, value transfer and detection of gas flow detection equipment. This set of devices uses the critical flow Venturi nozzle as a standard table and air as a test medium to perform metrological verification, calibration and inspection of various gas flow meters .

The absolute pressure transmitter and temperature transmitter configured in this device measure the airflow pressure and temperature before and after the nozzle and the flowmeter being tested, as well as the nozzle back pressure. The control system synchronously collects and processes various parameters in real-time during the calibration process. The lower computer judges and averages the data uploaded by the transmitter and stores it. During this period, the data distorted by the transmitter itself is eliminated. After receiving the average data from the lower computer, the upper computer stores it in the transmitter verification result database, and at the same time performs a secondary judgment and screening on the stored data to ensure that the data involved in the calculation is accurate and reliable, and the correction is truly realized.

In the computer system of the device, the operation of establishing or modifying the basic data of the system is set. In addition to the transmitter verification result database, a nozzle basic database is also built to store the parameters such as the serial number and outflow coefficient of each nozzle equipped with the device. If the nozzle verification data changes or a new nozzle is replaced, the user only needs to modify the basic data.

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Product Detail

Product Tags

Calibration medium: clean air.
Calibration method: negative pressure method .
Flow range: (0.5～7800)m³/h (with reserved interface for expansion to 16000m³/h).
Device expanded uncertainty: U = 0.33% ( k = 2). Provide the verification certificate issued by the national legal metrology verification department.
Sonic nozzle accuracy level: 0.2 . Provide the verification certificate issued by the national statutory metrology verification department, and the manufacturing material is 304 stainless steel.
Device flow stability: ≤0.1%.
Stagnation vessel: The influence of pressure and temperature fluctuations on the calibration data is controlled within 1/5 of the measurement uncertainty of the entire device.
Verification flow point control: <3min. The timer resolution is better than 0.001s, with a crystal output port and can be disassembled, the timer frequency measurement expanded uncertainty U = 3×10-6 ⁽k = 2) , and a certificate issued by a provincial or higher statutory metrology verification department is provided.
Inspection caliber: DN10, DN15, DN20, DN25, DN32, DN40, DN50, DN65, DN80, DN100, DN125, DN150, DN200 , DN250, DN300, a total of 15 calibers.
Basic inspection pipeline: There are 7 inspection pipelines with diameters of DN50 (compatible with DN40/32/25/15/10), DN80 (compatible with 65), DN100, DN150 (compatible with 125), DN200, DN250, and DN300. The upstream of each inspection pipeline is a pneumatic clamp, which drives the displacement and clamping of the upstream straight pipe section. The wall thickness of the pipeline is based on the national standard, made of 304 stainless steel material, equipped with a muffler, and an automatic lifting inspection table.
Meter inspection pipeline: working conditions are slightly negative pressure, air; leakage level: 6-level sealing, zero leakage; pneumatic ball valves are used as pipeline on-off valves for DN150 and below, and pneumatic butterfly valves are used as pipeline on-off valves for DN200 and above.
Types of flowmeters inspected: turbine flowmeter, vortex flowmeter, swirl flowmeter, ultrasonic flowmeter, differential pressure flowmeter, positive displacement flowmeter, Coriolis mass flowmeter, thermal gas mass flowmeter.
Absolute pressure transmitter: accuracy level is 0.075, response time: ≤1ms, measurement range is (0～110)kPa. Set up 7 meter inspection pipelines to share 1, 1 large stagnation container to uniformly sample 3 points, 1 small stagnation container, a total of 3, and provide certificates issued by provincial and above statutory metrology verification departments. Set up 1 large and 1 small vacuum back pressure container, each with an accuracy level of 0.5.
Temperature transmitter: The maximum allowable error is ±0.2℃, the graduation value is 0.1℃, and the measuring range is (0～50)℃. Set one for each meter inspection pipeline , two large stagnation vessels, and one small stagnation vessel, a total of 10, and provide a certificate issued by the statutory metrology verification department at the provincial level or above.
Humidity transmitter: Maximum allowable error ±2%RH, measuring range is (0～100)%RH. Set up 1 large stagnation container and 1 small stagnation container, a total of 2, and provide a certificate issued by the statutory metrology verification department at the provincial level or above.
Sealing: The device maintains pressure for 5 minutes, and the rate of change of the ratio of absolute pressure to absolute temperature in the stagnation container does not exceed 0.1%.
Valve: The nozzle position uses two upper and lower ball valves, both of which use pneumatic ball valves, leakage level: 6 level sealing, zero leakage.
Critical flow back pressure ratio: When the whole device is operating at full load ( 7800 m³ /h), the critical back pressure ratio of the device is not greater than 0.8 ; when the flow rate is ≤ 64 m³ /h, the critical back pressure ratio of the device is not greater than 0.5.
Device power supply: AC 3×380V～50Hz; total distribution power is not less than 250kW.
Signals of the meter under test: pulse (frequency) signal, analog signal (4-20) mA, direct reading meter without transmitter (multimedia), etc.
Device material: The device body and metering part are made of 304 stainless steel, and the pump room equipment and pipeline supports are made of carbon steel spray-painted for corrosion protection.
Control method: Except for manual clamping of the tested instrument, all other calibrations can be automatically completed on the computer (simply input the relevant information and parameters of the tested instrument), or manually completed.