Psychrometrics and Humidity Control Flashcards
7 cards from real Flood Restoration practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Psychrometrics and Humidity Control flashcards as text
Which type of dehumidifier performs best in low-temperature environments below 50°F?
Answer: Desiccant dehumidifier
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.
Vapor pressure differential in the context of structural drying refers to:
Answer: The difference in moisture vapor pressure between wet building materials and the surrounding air
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.
In psychrometrics, 'humidity ratio' (specific humidity) is expressed as:
Answer: Pounds of water vapor per pound of dry air
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.
During the evaporation phase of structural drying, what happens to the relative humidity of the air in the drying space?
Answer: It increases as water evaporates from wet surfaces into the air
As wet building materials release moisture through evaporation, that water vapor enters the air and raises the relative humidity of the drying space.
The primary function of air movers (axial fans) in a structural drying system is to:
Answer: Create high-velocity airflow across wet surfaces to accelerate evaporation
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.
Desiccant dehumidifiers have an advantage over refrigerant units specifically when:
Answer: Temperatures are very low or extremely low humidity levels must be achieved
Desiccant units use hygroscopic material to absorb moisture and are unaffected by cold temperatures that cause refrigerant coil icing and loss of performance.
The IICRC S500 standard reference drying conditions used as a psychrometric baseline are approximately:
Answer: 70°F and 50% RH
IICRC S500 defines standard conditions as approximately 70°F (21°C) at 50% RH for baseline psychrometric calculations and equipment performance comparisons.