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How to Convert ACFM to PPM

Parts per million expresses the quantity of one material within another one. For example one cubic centimeter of hydrogen gas in a liter of air has a density of 1 part per million, or 1 ppt. ACFM, or actual cubic feet per minute, describes the flow of a gas over a set time period so it cannot be directly converted to parts per million. However, if one gas is being added to another, it becomes possible to describe the concentration in the flow in terms of parts per million.

Instructions

- 1
  Multiply the flow expressed in ACFM by 28.3, the number of liters in one cubic foot. The result is the value expressed in cubic feet per minute converted into cubic liters per minute. For example, if 2,000 cubic feet of gas per minute is equivalent to 56,600 cubic liters per minute because 28.3 multiplied by 2,000 equals 56,600.
- 2
  Express the quantity of the second gas being added to the main flow in terms of milligrams per liter. A milligram (mg) is one-thousandth of a gram, or 1ppm. For example, if 100 g of the second gas are added to the flow every minute, then 100,000 mg are added every minute.
- 3
  Divide the mass of the second gas by the volume of the air flow. The result is the concentration of the second gas within the air flow, expressed in parts per million. For example, 100,000 mg of gas introduced to a flow of 56,000 liters per minutes produces a concentration of approximately 1.79ppm -- 100,000 divided by 56,000 equals 1.7857.

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