Water damage course 46-75 Flashcards
In an area that measures 15,000 cubic feet, what is the initial recommended AHAM requirement (PPD) for a Class 2 loss, using LGR (refrigerant) dehumidifiers?
300
A Class 3 loss that measures 15’ x 35’ and has a ceiling height of 9’, how many 100-pint LGRs are needed?
2
A warehouse that measures 35’ x 40’ x 10’ has a class 4 loss, using a desiccant dehumidifier. How many CFM are required?
700 cfm
To help control particles in the air you could install
An air filtration device (AFD)
Generally, to dry the wood subfloor under a resilient floor (e.g., sheet vinyl, VCT, LVT, LVP), what should a restorer do?
Remove vinyl to access and dry the subfloor
If you decrease GPP what happens to the vapor pressure?
Decreases
A hardwood floor primarily absorbing moisture from the bottom and the sides of the boards are higher than the center. This is referred to as
Cupping
When arriving on a water loss that has an elevated humidity; if the outside conditions are right, what could be done to reduce the humidity?
Open the windows to ventilate the structure
What happens when air reaches saturation?
Condensation because the air can’t hold more water vapor
When could a closed drying system be utilized?
When the Humidity Ratio outside is higher than the GPP indoors
What happens when the vapor pressure of wet materials is increased?
Moisture evaporates if the ambient air has a lower vapor pressure
To determine the amount of dehumidification necessary, the following information is needed:
Cubic footage, class of loss and type of dehumidifier
Why should air movers not be installed when microbial growth is found or suspected?
It can contaminate other areas
What is evaporation?
Changing liquid to a vapor
What is vapor pressure?
The force from water vapor on materials
What results as the air becomes warmer (temperature increases)?
Relative humidity decreases
When drying a hardwood floor, typically we will need to?
Allow for acclimation and refinishing after the floor is dry
If insulation is affected by water, what would be the typical response?
Remove the insulation to access and dry structural materials
What is the primary function of a dehumidifier?
Reduce the water vapor in the air
Why are desiccant dehumidifiers often used in Class 4 losses?
it creates the lowest vapor pressure of any type of dehumidifier
How often should a job site be monitored?
every day
If thermal energy is added to affected materials
Evaporation increases
If humidity remains high, what can happen to hygroscopic materials?
Secondary damage can occur
If plywood is affected by water damage
It can typically be dried and restored
In a drying chamber with the conditions of 75°F and 65%RH, at what temperature could condensation form on materials?
62°F
Which of the following is a vapor barrier/retarding material?
Vinyl flooring
Why are low grain refrigerants (LGR) generally more efficient than a conventional refrigerant?
They create lower vapor pressure
A material that is very weakened when wet but, if dried properly, retains its original strength is
Gypsum (drywall, wallboard)
What is permeance
The rating of vapor passing through a material
If attempting to dry tile over a wood subfloor
Increase heat or thermal energy
