Compressed air measurement in nm3/h and m3/h

Flow rate under standard conditions and operating conditions. Vortex flow meters with compensation can also display the flow rate under standard conditions

Conversion between operating conditions and standard conditions (cubic and standard cubic units). Keywords: operating conditions and standard conditions, cubic and standard cubic units, calculation software, how to perform conversions. Values: m3/h, working pressure in Mpa, working temperature in °C, actual atmospheric pressure in Kpa, flow rate under standard conditions in m3/h – 1.00, 0.60, 15.00, 101.325, 6.56. Flow rate under standard conditions in m3/h, working pressure in Mpa, working temperature in °C, actual atmospheric pressure in Kpa, flow rate under operating conditions in m3/h – 1.00, 0.60, 15.00, 101.325, 0.15. Note: The values in the blue areas of the table can be changed using the formulas provided, which will enable automatic conversion of the flow rates. Gas state equation: PV = nRT. Conversion between operating conditions and standard conditions (cubic and standard): P1×V1/T1 = P2×V2/T2. From this, it follows that: Flow rate under standard conditions = Flow rate under operating conditions × (Operating pressure in Mpa × 1000 + Actual atmospheric pressure in Kpa) × 273.15 / 101.325 × (Operating temperature in °C + 273.15). Flow rate under operating conditions = Flow rate under standard conditions × 101.325 × (Operating temperature in °C + 273.15) / ((Operating pressure in Mpa × 1000 + Actual atmospheric pressure in Kpa) × 273.15). P1: Pressure under standard conditions, in Kpa; the value is 101.325 Kpa based on standard atmospheric pressure. V1: Flow rate under standard conditions, in m3/h. T1: Temperature under standard conditions, in Kelvin; the value is 273.15 K (i.e., 0°C). P2: Pressure under operating conditions = (Gauge pressure in Mpa × 1000 + Current pressure) in Kpa. P_now: The actual atmospheric pressure at the site; it is approximated as the standard atmospheric pressure, i.e., 101.325 Kpa. V2: Flow rate under operating conditions. T2: Operating temperature = (actual temperature in °C + 273.15) K. Temperature conversion: K = °C + 273.15. Quick approximate conversion formula: Flow rate under standard conditions = Flow rate under operating conditions × (Operating pressure in kgf/cm2 + 1). This formula is most accurate when the operating temperature is -3°C and the actual atmospheric pressure is at standard level. There are three standard states for gases: 1. The standard state defined by the 10th General Conference on Weights and Measures (CGPM) in 1954 is a temperature of 273.15 K (0°C) and a pressure of 101.325 KPa. This standard state is widely adopted in the field of science and technology around the world. 2. International Standardization Organization and American **standards specify that a temperature of 288.15 K (15°C) and a pressure of 101.325 KPa constitute the standard conditions for measuring the volumetric flow rate of gases, applicable to rotameter-type gas flow meters, vortex flow meters, orifice plate gas flow meters, steam flow meters, air flow meters, and gas flow meters for air. 3. China’s \"Standard Orifice Plate Calculation Method for Natural Gas Flow Rate\" specifies that a temperature of 293.15 K (20°C) and a pressure of 101.325 KPa are to be used as the standard conditions for measuring the volumetric flow rate of gas. The formula for converting the volume of natural gas at standard conditions differs from that of ordinary gases, and it must comply with the standard SY/T6143-1996 issued by China National Petroleum Corporation. The gas equation of state (for gas flow meters): Qn = Zn/Zg • (Pg + Pa) / Pn • Tn / Tg • Qg. Where: Qn – volumetric flow rate under standard conditions (Nm3/h); Zn – compression coefficient under standard conditions; Zg – compression coefficient under operating conditions; Pg – gauge pressure (KPa); Pa – local atmospheric pressure (KPa); Pg + Pa – absolute pressure under operating conditions; Pn – standard atmospheric pressure (101.325 KPa); Tn – absolute temperature under standard conditions (20°C per national natural gas standards) (293.15 K); Tg – absolute temperature of the medium (273.15 + t) K; t – Celsius temperature of the medium being measured (°C); Qg – uncorrected volumetric flow rate (m3/h). The parameters marked with “n” refer to standard conditions, while those marked with “g” refer to operating conditions.

Does it need pressure and temperature compensation?

Does it need pressure and temperature compensation?

Does it need pressure and temperature compensation?

What’s the use of this one with temperature and pressure compensation?

As long as temperature and pressure signals are acquired, the instrument can convert them into standard condition data on its own.

Gas flow meters all require temperature and pressure compensation, as the density of gas changes significantly

Theoretically, if one wants to measure the flow rate of a gas under standard conditions, temperature and pressure compensation is necessary; using the equation PV=NRT, one can perform the necessary conversions, with NR remaining constant

1. Thermal mass flow meters directly measure the flow rate under standard conditions in Nm3/h, whereas vortex flow meters directly measure the flow rate under actual operating conditions in m3/h. Only after applying temperature and pressure corrections can this value be converted to Nm3/h; hence, thermal flow meters have higher accuracy than vortex flow meters. 2. Without considering the compression factor, the formula for converting the gas flow rate under standard conditions to that under actual operating conditions is: Standard condition flow rate = Operating condition flow rate * [(Gauge pressure + 0.1)/0.1] * [273.15/(273.15 + Operating condition temperature)]. Therefore, a simple calculation gives: (0.68 + 0.1)/0.1 = 7.8； 1060/7.8=136m3/h