Orifice flowmeter | When measuring flow with an orifice plate flowmeter, what should be used to select the orifice size and range of the differential pressure gauge? _Baidu Knowledge ..

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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. Why cant orifice flow meters measure small-diameter flow? The orifice flowmeter cannot measure small-diameter flow mainly due to its design limitations and physical characteristics. Orifice flowmeter is a differential pressure flowmeter, which works based on the pressure difference generated when the fluid flows through the orifice plate to measure the flow rate. Although orifice flow meters have the advantages of simple structure, firmness, stable and reliable performance, long service life, and low price, and can be put into use without actual flow calibration, there are limitations in their application in small-diameter working conditions. Specifically, the disadvantages of orifice flow meters include: 1. Low measurement accuracy: This means that orifice flow meters may not provide sufficiently accurate measurement results in small-diameter measurements. 2. Narrow range: Due to the square relationship between differential pressure signals and flow rates, the general range of orifice flow meters is only 3:1~4:1, which is known to be a limitation when accurate measurement of small flow rates is needed. The adjusted components increase

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