UNIT 48 REVIEW QUESTIONS ANSWER KEY GO BACK TO INDEX
48-1) What standard covers ductboard and methods of connecting and sealing ductboard?
48-2) What standard covers flexible duct and methods of connecting and sealing flexible
duct?
48-3) What is the difference between class 0 duct and class 1 duct?
48-4) List the agencies that promote duct standards and briefly describe what they cover.
Underwriters Laboratories produces standards for manufactured duct and duct
connections
48-5) Explain the difference between a flexible duct and a flexible air connector.
48-6) List the materials commonly used to construct duct systems.
48-7) Describe how two pieces of round sheet metal pipe are joined.
One end of the duct is crimped, making it’s outside diameter slightly smaller than the
48-8) Describe how sheet metal ductwork is sealed.
48-9) Describe how to join fiberboard duct.
48-10) How far apart should hangers for metal duct be placed?
48-11) How far apart should hangers for fiber ductboard be placed?
48-12) Describe the proper method of hanging flexible duct.
48-13) List four methods of insulating metal ductwork.
Fiberglass outerwrap with vapor barrier
48-14) Using Table 48-2, what width should 2 inch fiberglass duct insulation be to wrap
an 8 inch diameter round duct?
48-15) Describe how ductboard is formed into ducts.
48-16) List three types of takeoff fittings available for sheet metal duct.
48-17) Describe how to install a dovetail takeoff fitting on a ductboard trunk.
Mark the hole on the trunk
48-18) What are some of the limitations on the use of flexible air connectors?
48-19) Describe how rectangular sheet metal ducts are joined.
Rectangular ducts are joined by S-locks and drives cleats. S locks are used on the
48-20) How do the staples that hold duct insulation together work?
48-21) What is the correct spacing for the mechanical fasteners used to hold duct liner in
place?
48-22) Discuss some of the major problems that cause leaky duct systems in older homes.
48-23) How does a duct blaster measure the amount of duct leakage?
48-24) What are the two main types of duct-cleaning equipment being used?
48-25) Why is a visual inspection necessary when cleaning ductwork?
48-26) What are the three methods used to quantify duct leakage?