The introduction of outside air to the air conditioning system is 90°F with a relative humidity of 60%. The air has been conditioned to 70°F with a relative humidity of 80%. Using the psychrometric chart, shown in the illustration, determine the quantity of moisture removed from one pound of the conditioned air. See Illustration GS-RA-22

Illustration GS-RA-22: the U.S. Coast Guard has not released this illustration.

Question

The introduction of outside air to the air conditioning system is 90°F with a relative humidity of 60%. The air has been conditioned to 70°F with a relative humidity of 80%. Using the psychrometric chart, shown in the illustration, determine the quantity of moisture removed from one pound of the conditioned air. See Illustration GS-RA-22

Illustration GS-RA-22: the U.S. Coast Guard has not released this illustration.

Accepted Answer

Option A: 40 grains. Psychrometric chart analysis tracks specific humidity values before and after conditioning. Subtracting the moisture content of the conditioned air from the entering outside air yields a net reduction of approximately 40 grains of moisture per pound of dry air.