To convert grain depression to PPD, which formula is used?

To convert grain depression to pounds per pint (PPD), the formula involves multiplying the cubic feet per minute (CFM) of the dehumidifier by the grain depression, and then dividing by a constant value, which is 71. This specific formula is derived from the relationship that connects grain depression to moisture removal capability in a controlled environment.

Using the CFM of the dehumidifier indicates the volume of air being processed, while the grain depression reflects the difference in moisture content between the air inside the structure and the air outside. By multiplying these two values, you calculate the total moisture that the dehumidifier can extract in a given timeframe. Dividing by 71 standardizes the outcome to user-friendly units for moisture content measurement, specifically converting it to PPD.

By contrasting this with the other options, one can see that they do not accurately represent the necessary steps for calculating PPD from grain depression. They either misplace the operation order or use incorrect constants which would yield inaccurate results. Thus, the chosen formula represents the correct method for making this conversion effectively.