How is the Fuel Moisture Content (FMC) percentage calculated?

How is the Fuel Moisture Content (FMC) percentage calculated?

• A. (Wet Weight - Dry Weight) / Dry Weight × 100
• B. (Dry Weight - Wet Weight) / Dry Weight × 100
• C. (Wet Weight + Dry Weight) / Dry Weight × 100
• D. Wet Weight / Dry Weight × 100

Answer: (A)

Fuel Moisture Content is the amount of water in the fuel expressed as a percentage of its dry weight. To get it, you compare how heavy the fuel is when it’s wet (Ww) to when it’s completely dry (Wd). The water portion is Ww − Wd, and dividing that by the dry weight (Wd) and multiplying by 100 converts it to a percent: FMC = (Ww − Wd) / Wd × 100. For example, if the wet weight is 4.0 g and the dry weight is 3.0 g, the water is 1.0 g and FMC = 1.0 / 3.0 × 100 = 33.3%. The other forms either don’t represent water relative to dry mass, add weights, or omit the reference to dry weight, so they don’t yield the correct FMC.

Fuel Moisture Content is the amount of water in the fuel expressed as a percentage of its dry weight. To get it, you compare how heavy the fuel is when it’s wet (Ww) to when it’s completely dry (Wd). The water portion is Ww − Wd, and dividing that by the dry weight (Wd) and multiplying by 100 converts it to a percent: FMC = (Ww − Wd) / Wd × 100. For example, if the wet weight is 4.0 g and the dry weight is 3.0 g, the water is 1.0 g and FMC = 1.0 / 3.0 × 100 = 33.3%. The other forms either don’t represent water relative to dry mass, add weights, or omit the reference to dry weight, so they don’t yield the correct FMC.