CPR Psychrometric Drying Principles 3

Question 1

A restorer raises the temperature inside a water-damaged structure from 65°F to 80°F without adding or removing moisture. What happens to the relative humidity?

Accepted Answer

It decreases because the air can now hold more moisture

Answer

Raising temperature increases the air's capacity to hold moisture, so the same amount of water vapor represents a lower percentage of saturation, reducing relative humidity.

Question 2

According to IICRC S500 guidelines, what is the target indoor relative humidity range for effective structural drying?

Accepted Answer

30–50%

Answer

IICRC S500 recommends maintaining indoor relative humidity between 30–50% to create conditions favorable for moisture migration out of wet building materials.

Question 3

What is the primary purpose of calculating the number of air changes per hour (ACH) during a drying project?

Accepted Answer

To ensure adequate airflow for moisture removal from structural cavities

Answer

ACH determines whether the air movers are circulating enough air volume to effectively move moisture from wet surfaces into the air stream for dehumidifier extraction.

Question 4

On a psychrometric chart, moving horizontally to the right along a constant dry bulb temperature line indicates:

Accepted Answer

An increase in humidity ratio (more moisture in the air)

Answer

Moving right along a constant dry bulb temperature line on a psychrometric chart means the humidity ratio increases — more moisture is present in the air.

Question 5

Equilibrium Moisture Content (EMC) in a building material is best defined as:

Accepted Answer

The moisture level at which the material neither gains nor loses moisture to the surrounding air

Answer

EMC is the stable moisture level a material reaches when it is in balance with the humidity of its surrounding environment.

(CPR) Certified Professional Restorer Practice Test

(CPR) Certified Professional Restorer Practice Test

CPR Psychrometric Drying Principles 3