RIA Psychrometrics & Structural Drying Principles 1 — Questions and Answers
Question 1: What does psychrometrics refer to in the context of restoration?
- The study of water pressure in pipe systems
- The science of measuring and controlling air-moisture properties (Correct answer)
- The process of extracting standing water from a structure
- The chemical treatment of contaminated building materials
Correct answer: The science of measuring and controlling air-moisture properties
Psychrometrics is the science that studies the properties of air-water vapor mixtures, which is foundational to structural drying in restoration.
Question 2: How is relative humidity (RH) best defined?
- The total weight of water vapor contained in one cubic foot of air
- The temperature at which air reaches full saturation
- The ratio of actual water vapor in air to the maximum possible at that temperature, expressed as a percentage (Correct answer)
- The amount of moisture a structural material can absorb before saturation
Correct answer: The ratio of actual water vapor in air to the maximum possible at that temperature, expressed as a percentage
Relative humidity expresses actual moisture content as a percentage of the maximum moisture air can hold at a given temperature.
Question 3: What is the dew point temperature?
- The temperature at which air becomes saturated and condensation begins to form (Correct answer)
- The minimum safe operating temperature for a refrigerant dehumidifier
- The moisture content of a wood subfloor when it reaches equilibrium
- The relative humidity level at which mold growth becomes likely
Correct answer: The temperature at which air becomes saturated and condensation begins to form
The dew point is the temperature at which air must be cooled, at constant pressure, to reach saturation and begin condensing moisture onto surfaces.
Question 4: In psychrometrics, what is a 'grain' of moisture?
- A standard unit of moisture equal to 1/7,000 of a pound (Correct answer)
- A unit used to measure air pressure differentials
- The visible mineral deposit left behind by evaporating water
- The smallest detectable increment of relative humidity change
Correct answer: A standard unit of moisture equal to 1/7,000 of a pound
A grain is a unit of weight for water; there are 7,000 grains per pound, used to express airborne moisture content in grains per pound (GPP) of dry air.
Question 5: What does the abbreviation GPP stand for in structural drying?
- General Psychrometric Parameters
- Gallons Per Process
- Grains Per Pound of dry air (Correct answer)
- Ground Pressure Protocol
Correct answer: Grains Per Pound of dry air
GPP (Grains Per Pound) measures the actual water vapor content of air by weight and is used to assess how much moisture the air is carrying at any given time.
Question 6: How is wet bulb temperature measured?
- By placing a thermometer directly on the surface of standing water
- By measuring the surface temperature of wet building materials
- By reading the temperature inside a dehumidifier's evaporator coil
- By reading a thermometer whose bulb is wrapped in a moistened wick exposed to moving air (Correct answer)
Correct answer: By reading a thermometer whose bulb is wrapped in a moistened wick exposed to moving air
Wet bulb temperature is measured with a thermometer wrapped in a wet wick; evaporative cooling from the wick lowers the reading, indicating the air's moisture content.
Question 7: Which standard provides the primary psychrometric and structural drying guidance used by restoration professionals?
- NFPA 70 (National Electrical Code)
- IICRC S500 Standard for Professional Water Damage Restoration (Correct answer)
- EPA 402-K-02-003 Mold Remediation in Schools and Commercial Buildings
- OSHA 1910.134 Respiratory Protection Standard
Correct answer: IICRC S500 Standard for Professional Water Damage Restoration
The IICRC S500 is the principal standard governing water damage restoration, including the psychrometric principles that guide structural drying decisions.
RIA Psychrometrics & Structural Drying Principles 1
What does psychrometrics refer to in the context of restoration?