Conversion between cubic meters at 0 degrees Celsius and 20 degrees Celsius
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Our company purchases natural gas from the three major oil companies, and the measurement is based on cubic meters at 20 degrees Celsius. However, the design specifications use cubic meters at 0 degrees Celsius as the standard. There are disputes regarding how to carry out this conversion; some believe that a correction factor derived from flow meters should be used, resulting in a value of 1.036, while others think that equation of state methods should be employed, yielding a value of 1.073. Which of those results is correct? What is the reason?
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. The International Organization for Standardization and U.S. **standards specify 288.15 K (15°C) as temperature and 101.325 KPa as pressure to serve as the standard conditions for measuring the volumetric flow rate of gases. 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. 4. The standard state for gases in high school physics is 1 atm at 0°C. From Baidu Baike! I’m not sure which one to go by.
In my opinion, if the flow meter is to be adjusted to measure in cubic units at 0 degrees Celsius, the method of using flow meter correction coefficients should be employed to calculate the conversion factor. The mathematical models and programming configurations used in flowmeters vary; the use of state equations leads to different coefficients, which affects the accuracy of the measurement results.
There are two standards; one is under standard conditions: a temperature of 273.15 K (0°C) and a pressure of 101.325 KPa. One is the normal condition: temperature of 293.15 K (20°C) and pressure of 101.325 KPa. The measurement of natural gas sales is crucial; the differences in coefficients are small, but over time these differences can have a significant impact on the final measurement results. Given this, it is advisable for both the buyer and the seller to agree on a unified standard to be used. We generally adopt the standard conditions set by the design institute.
My understanding is that you believe the two conversions should be carried out using the equation of state, rather than with a flow correction coefficient equation; in other words, the coefficient should be 1.073, not 1.036
Yes, different flowmeters have different correction coefficients; it is feasible and reasonable to perform conversions using the equation of state and to adopt unified international standards
It seems that using equation formulas for conversion is more reliable