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『Standard plate orifice flowmeter』Related information(clamp on meter|electromagnetic meter|venturi meterrotameter|orifice meter|ultrasonic flow meter|mass flow meter|coriolis mass flow meter|coriolis flow meter|magnetic flow meter|magmeter flow meter|magflow flow meter|mag meter flow meter|electromagnetic flow meter|vortex flow meter|turbine flow meter|thermal mass flow meter|thermal flow meter|rotameter flow meter)
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2. Calculation of orifice flowmeter
The core calculation formula of orifice flowmeter is qv=C × ε× A0 × √ (2 Δ p/ρ), and the calculation result directly reflects the flow rate.
1. Basic Parameter Analysis 1 Outflow coefficient C: It is related to the geometry of the orifice plate and the pressure measurement method, and needs to be obtained through experiments or by referring to standard charts. two The coefficient of expansion ε: for liquids, it is set to 1, while for gases, it needs to be corrected through charts based on pressure difference and temperature. three Opening area A0: calculated as A0=π d ²/4, where d is the measured inner diameter of the orifice plate. four Differential pressure Δ p: directly measured by a pressure sensor or U-tube, in Pa. 5. Density ρ: The density of the liquid is less affected by temperature, and the gas needs to be converted according to the working pressure and temperature.
2. Decomposition of Calculation Steps 1 Determine the fluid nature of the Mingshi field: distinguish between liquids or gases, and select the corresponding ε value. two Parameter measurement and acquisition: - Measure the diameter d of the orifice plate opening and calculate A0. - Record the reading Δ p of the pressure differential exciter. -Check the table or conduct experiments to determine C and ε. 3. Substitute into the formula for calculation: evaluate step by step according to qv=C ε A0 √ (2 Δ p/ρ).
III. Example Calculation of Water Flow Measurement in a Pump Pipeline: • Known Conditions: d=0.05m, Δ p=5000Pa, ρ=998kg/m ³ (20 ℃ water), C=0.62，ε=1。 • Calculation process: 1 A0=π× (0.05) ²/4 ≈ 0.00196m ². two Substitute into the formula: qv=0.
3. The reason for the gradual decrease in flow rate of an orifice flowmeter
The gradual decrease in flow rate of an orifice flowmeter is usually caused by blockage of the throttling device, changes in fluid properties, or measurement system failures.
. The accumulation of impurities or crystals in the pipe routing at the front end of the orifice plate can alter the cross-section of the flow channel, causing the actual flow coefficient to deviate from the design value. A certain chemical plant once formed an oil film on the surface of the orifice plate due to the presence of condensate oil in natural gas, resulting in a measurement deviation of up to 15%. In low temperature environments during winter, water containing media are prone to freezing at the throttling element, causing a decrease in the flow area. This seasonal fluctuation requires special attention. 1. Changes in fluid parameters such as viscosity, density, or temperature of the medium can affect measurement accuracy. In steam flow measurement, a pressure fluctuation of 0.1 MPa can cause a density change of about 3%, which can cause a