ASCS ASCS Equipment and Tools 1 — Questions and Answers
Question 1: What is the primary function of a negative air machine used during duct cleaning?
- To create negative pressure inside the duct system so contaminants are captured rather than released (Correct answer)
- To pressurize the ducts for leak testing
- To measure airflow velocity
- To sanitize duct surfaces with UV light
Correct answer: To create negative pressure inside the duct system so contaminants are captured rather than released
A negative air machine draws air through the duct system under controlled negative pressure, ensuring dislodged contaminants flow into a HEPA filtration unit rather than into occupied spaces.
Question 2: What type of filter should a negative air machine use to capture fine particulates during duct cleaning?
- HEPA filter rated to capture 99.97% of particles at 0.3 microns (Correct answer)
- Standard fiberglass panel filter
- Electrostatic filter
- Carbon activated filter only
Correct answer: HEPA filter rated to capture 99.97% of particles at 0.3 microns
HEPA filters capture 99.97% of particles at 0.3 microns, ensuring that fine dust, mold spores, and other contaminants do not escape back into the building.
Question 3: Which type of brush is most commonly used for mechanical agitation of debris inside rectangular sheet metal ducts?
- Rotary or spinning brush attached to a flexible rod or drill (Correct answer)
- Wire wheel brush
- Horsehair paintbrush
- Stiff-bristle hand scrub brush
Correct answer: Rotary or spinning brush attached to a flexible rod or drill
Rotary brushes attached to flexible extension rods allow technicians to agitate debris along the full length of rectangular ductwork from a single access point.
Question 4: What is the purpose of an air whip or skipper ball tool in duct cleaning?
- To use compressed air to propel the tool through ducts and dislodge debris with air jets (Correct answer)
- To seal access holes after cleaning
- To measure dust accumulation thickness
- To apply chemical coatings inside ducts
Correct answer: To use compressed air to propel the tool through ducts and dislodge debris with air jets
Air whips and skipper balls use compressed air jets to propel themselves through ductwork while simultaneously blasting debris loose toward the collection point.
Question 5: What is the minimum CFM (cubic feet per minute) capacity typically recommended for a negative air machine used in commercial duct cleaning?
- At least 1,000 CFM to maintain adequate negative pressure in larger systems (Correct answer)
- 100 CFM is sufficient for all systems
- CFM does not matter as long as HEPA is present
- 500 CFM maximum to avoid duct damage
Correct answer: At least 1,000 CFM to maintain adequate negative pressure in larger systems
A minimum of 1,000 CFM is typically required for commercial systems to maintain sufficient negative pressure and capture dislodged debris effectively.
Question 6: How should duct cleaning equipment be maintained to prevent cross-contamination between job sites?
- Thoroughly cleaned and HEPA-vacuumed after each job before transporting to the next site (Correct answer)
- Rinsed with water between jobs only
- Stored in an open truck bed to air out
- Used until visibly dirty then replaced
Correct answer: Thoroughly cleaned and HEPA-vacuumed after each job before transporting to the next site
Equipment must be cleaned and HEPA-vacuumed after each job to prevent transferring contaminants from one site to another, which could expose new clients to foreign debris or pathogens.
ASCS ASCS Equipment and Tools 1
What is the primary function of a negative air machine used during duct cleaning?