Flood Restoration Psychrometrics and Humidity Control 2

Question 1

Which type of dehumidifier performs best in low-temperature environments below 50°F?

Accepted Answer

Desiccant dehumidifier

Answer

Desiccant dehumidifiers use a moisture-absorbing rotor and regeneration heat rather than refrigerant coils, so they are not degraded by cold temperatures that would ice a refrigerant unit.

Question 2

Vapor pressure differential in the context of structural drying refers to:

Accepted Answer

The difference in moisture vapor pressure between wet building materials and the surrounding air

Answer

Moisture migrates from areas of higher vapor pressure (wet materials) toward areas of lower vapor pressure (drier air), making this differential the driving force behind evaporation.

Question 3

In psychrometrics, 'humidity ratio' (specific humidity) is expressed as:

Accepted Answer

Pounds of water vapor per pound of dry air

Answer

Humidity ratio is the mass of water vapor relative to the mass of dry air, commonly expressed in grains per pound (gr/lb) in restoration work.

Question 4

During the evaporation phase of structural drying, what happens to the relative humidity of the air in the drying space?

Accepted Answer

It increases as water evaporates from wet surfaces into the air

Answer

As wet building materials release moisture through evaporation, that water vapor enters the air and raises the relative humidity of the drying space.

Question 5

The primary function of air movers (axial fans) in a structural drying system is to:

Accepted Answer

Create high-velocity airflow across wet surfaces to accelerate evaporation

Answer

Air movers sweep away the saturated boundary layer of air clinging to wet surfaces, replacing it with drier air and dramatically increasing the rate of evaporation.

Flood Restoration Practice Test

Flood Restoration Practice Test

Flood Restoration Psychrometrics and Humidity Control 2