『Calculation of orifice flow rate』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)
1. Calculation of Orifice Flow Meter
The core calculation formula of an orifice flow meter 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=0.62 × 1 × 0.00196 × √ (2 × 5000/998
2. Allowable range for calculating pressure difference of flow orifice plate
The allowable range for calculating pressure difference of flow orifice plate is usually 20-50 kPa, but it needs to be determined comprehensively according to the fluid type, orifice plate parameters and international standards, as follows:
1. Pressure difference range classified by fluid properties Gas: The pressure drop is usually designed to be 10-30 kPa.
. Gas has low density and strong compressibility, and excessive pressure drop may lead to increased measurement errors. Therefore, it is necessary to control the pressure difference within a lower range. Liquid: The allowable pressure drop range is 30-80 kPa, but cavitation should be avoided. For example, when the water temperature exceeds 60 ℃, the pressure drop needs to be lower than 40 kPa, otherwise local vaporization of the liquid will disrupt the measurement stability and linearity. Steam: The design pressure difference range is 0-60 kPa, and the maximum allowable pressure difference is 100 kPa. The density and flow rate of steam vary greatly, and the pressure difference needs to be adjus
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