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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. The influence of temperature on orifice flow meters
The influence of temperature on orifice flow meters is mainly reflected in measurement accuracy, which can cause the actual flow reading to deviate from the true value, and temperature compensation correction must be carried out.
. 1. The principle of temperature influence: Changes in fluid temperature directly affect the density and viscosity of the medium. The flow calculation formula of an orifice flowmeter is based on a constant fluid density design. An increase in temperature will cause gas expansion and a decrease in density. Under the same differential pressure value, the actual flow rate is greater than the displayed value. For liquids, temperature changes can also affect their viscosity and density, thereby changing the Reynolds number and flow coefficient of the fluid2. Specific ways of influence • Gas medium: For every 10 ℃ increase in temperature, the indication error can reach 2% -5% (depending on the gas type) • Steam medium: Saturated steam temperature changes by 1 ℃, density changes by about 0.5% • Liquid medium: Temperature changes affect viscosity, th
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