Arizona ROC C-45 Sheet Metal Examination

According to SMACNA HVAC Duct Construction Standards, what is the minimum sheet metal thickness (gauge) required for a 36-inch wide rectangular galvanized steel duct operating at a positive static pressure of 2.0 inches water gauge (in. w.g.) without intermediate transverse reinforcement?

• A24 gauge (0.028 inches)
• B26 gauge (0.022 inches)
• C22 gauge (0.034 inches)
• D20 gauge (0.040 inches)

In rectangular sheet metal duct fabrication, which type of transverse joint connection consists of a flat strip with folded edges slipped over the turned-up flanges of adjacent duct sections on top and bottom, combined with drive cleats on the sides?

• ACompanion angle flange joint
• BFlat S-cleat joint
• CStanding S-cleat joint
• DPocket lock joint

What is the maximum allowable horizontal spacing for hangers supporting 24-gauge rectangular sheet metal ductwork installed in commercial HVAC systems per SMACNA and the International Mechanical Code (IMC)?

• A6 feet
• B8 feet
• C10 feet
• D12 feet

A technician is replacing a 24-inch wide by 12-inch deep rectangular duct with an equivalent round duct. Using the standard equivalent-diameter formula De = 1.30 x (a x b)^0.625 / (a + b)^0.25, what is the approximate equivalent round duct diameter?

• A14 inches
• B16 inches
• C18 inches
• D19 inches

When installing flexible air ducts, what is the maximum allowable sag permitted per foot of distance between support hangers according to SMACNA and IMC guidelines?

• A1/2 inch per foot
• B1 inch per foot
• C1/4 inch per foot
• D2 inches per foot

According to the International Mechanical Code (IMC Section 603.6), what is the maximum permitted length of a flexible air connector used in branch supply runs?

• A8 feet
• B14 feet
• C20 feet
• D6 feet

External duct insulation installed on supply air ducts carrying chilled air through an unconditioned attic must feature a vapor retarder jacket with a maximum water vapor permeance rating of:

• A0.50 perms
• B0.10 perms
• C0.05 perms
• D1.00 perm

Which SMACNA duct sealing class requires sealing ALL transverse joints, longitudinal seams, and duct wall penetrations regardless of static pressure class?

• ASeal Class C
• BSeal Class B
• CSeal Class D
• DSeal Class A

Which type of longitudinal lock seam is continuously machine-formed along the helical length of round spiral ductwork?

• ARL-1 continuous spiral lock seam
• BGrooved lock seam (piping seam)
• CSnap-lock seam (button lock)
• DStanding seam lock

An air handling unit delivers 2,400 CFM through a 24-inch by 12-inch main supply trunk duct. What is the average air velocity inside the duct in feet per minute (FPM)?

• A1,000 FPM
• B1,200 FPM
• C1,400 FPM
• D1,600 FPM

Per SMACNA duct support tables, what is the minimum steel threaded rod diameter required for hangers supporting a rectangular duct with a cross-sectional area between 4.1 and 10.0 square feet?

• A1/4 inch
• B5/16 inch
• C3/8 inch
• D1/2 inch

To avoid airflow restrictions and excessive friction loss, flexible duct turns must maintain a minimum centerline bend radius equal to how many duct diameters?

• A0.5 duct diameters
• B2.0 duct diameters
• C1.5 duct diameters
• D1.0 duct diameter

Which static pressure rating class applies to standard residential and light commercial HVAC duct systems operating up to positive 2.0 inches water gauge?

• ALow pressure class
• BMedium pressure class
• CHigh pressure class
• DUltra-high pressure class

When laying out a Pittsburgh lock seam on 24-gauge galvanized sheet metal, what total material allowance must be added to the sheet pattern for the pocket side of the joint?

• A1/4 inch
• B1 inch
• C1/2 inch
• D1-1/2 inches

Sheet metal screws used to assemble metal branch duct connections must NOT penetrate into the air stream when connecting flexible duct liners because:

• AThey cause galvanic corrosion between metal and fiberglass.
• BThey create air leakage pathways through the metal wall.
• CProtruding sharp screws catch airborne debris and tear flexible duct cores during install…
• DCode requires all joints to be welded.

In HVAC rectangular duct design, what is the maximum recommended aspect ratio (width to height ratio) to avoid excessive friction loss, pressure drop, and material cost?

• A2:1
• B3:1
• C5:1
• D4:1

According to the SMACNA HVAC Air Duct Leakage Test Manual, allowable duct leakage F, in CFM per 100 square feet of duct surface, is calculated as F = C x P^0.65. What does the variable C represent?

• ADuct Leakage Class coefficient
• BDuct cross-sectional area coefficient
• CFan capacity rating
• DAir density correction factor

When fabricating rigid fiberglass duct board systems, transverse joint closures must be sealed using heat-activated tape or pressure-sensitive aluminum foil tape. How must staples be spaced along the closure flap prior to taping?

• A1 inch on center
• B2 inches on center
• C4 inches on center
• D6 inches on center

In rectangular 90-degree square elbow supply ducts, turning vanes are installed primarily to:

• AFilter large airborne dust particles.
• BIncrease static pressure inside the elbow.
• CReduce turbulent air resistance and pressure drop through the turn.
• DPrevent fire propagation through duct bends.

A 24-inch by 12-inch fire damper is installed in a 2-hour fire-resistance-rated masonry wall. Per UL 555 and SMACNA standards, what is the minimum required steel sleeve thickness for this fire damper?

• A22 gauge steel
• B20 gauge steel
• C18 gauge steel
• D16 gauge steel

When joining two sections of round rigid metal ductwork with a male-to-female slip joint, what is the minimum insertion depth and fastening requirement?

• A2 inches overlap fastened with at least 3 sheet metal screws spaced equally around the pe…
• B1 inch overlap fastened with pop rivets only
• C4 inches overlap fastened with duct tape only
• D3 inches overlap fastened with 1 screw

Galvanized sheet metal designated as G90 in sheet metal specifications refers to:

• AA 90-gauge steel thickness measurement.
• BA total zinc coating weight of 0.90 ounces per square foot on both sides combined.
• CA maximum operating temperature limit of 90 degrees Celsius.
• DA yield strength rating of 90,000 PSI.

To minimize dynamic pressure losses in rectangular supply duct fittings, what is the maximum recommended slope angle for expanding duct transitions (increasers)?

• A30 degrees
• B45 degrees
• C15 degrees
• D60 degrees

What is the SMACNA standard minimum gauge for a 14-inch diameter round single-wall galvanized steel supply duct operating at positive 2.0 in. w.g. static pressure?

• A22 gauge
• B24 gauge
• C28 gauge
• D26 gauge

When installing acoustic internal duct liner with adhesive and mechanical fasteners, SMACNA standards require mechanical fasteners to be installed within what maximum distance from all leading edges of the liner?

• A3 inches
• B6 inches
• C12 inches
• D18 inches

The equal friction method of sizing HVAC ductwork is based on designing the entire duct distribution system so that:

• AAir velocity remains constant throughout all supply branches.
• BFriction loss per unit length of duct (e.g., 0.10 in. w.g. per 100 ft) remains constant.
• CStatic pressure increases uniformly toward terminal diffusers.
• DDuct cross-sectional area stays identical from fan to end runs.

Support straps used to hang flexible ductwork must have a minimum material width of how many inches to prevent crimping and restricting the internal airflow core?

• A1.0 inch
• B2.0 inches
• C1.5 inches
• D3.0 inches

Per the International Fuel Gas Code (IFGC) and NFPA 54, what is the minimum required clearance to combustible materials for double-wall Type B gas vents?

• A2 inches
• B6 inches
• C9 inches
• D1 inch

Under NFPA 54 and IMC termination rules, a masonry chimney or gas vent penetrating a pitched roof surface must extend at least how many feet above the highest point where it passes through the roof, and how many feet higher than any portion of the building within 10 feet horizontally?

• A3 feet above roof penetration; 2 feet higher than building within 10 feet
• B2 feet above roof penetration; 3 feet higher than building within 10 feet
• C4 feet above roof penetration; 2 feet higher than building within 10 feet
• D3 feet above roof penetration; 3 feet higher than building within 10 feet

Which NFPA 54 appliance category classification describes a gas heater that operates with non-positive vent static pressure and with a vent gas temperature high enough to avoid excessive condensate production in the vent?

• ACategory II
• BCategory I
• CCategory III
• DCategory IV

High-efficiency condensing gas furnaces classified as Category IV appliances require vent piping that is rated for positive static pressure and corrosive liquid condensate. Which material is code-approved for Category IV venting?

• ASingle-wall galvanized steel pipe
• BType B double-wall aluminum/galvanized vent
• CUL 1738 listed Special Gas Vent (such as AL29-4C stainless steel or approved PVC/CPVC sch…
• DMasonry chimney with unlined clay tile

What is the minimum required upward pitch (slope) for horizontal runs of vent connectors leading from a gas appliance to a vertical chimney or vent per IFGC 503.10.8?

• A1/8 inch per foot of horizontal run
• B1/2 inch per foot of horizontal run
• C1 inch per foot of horizontal run
• D1/4 inch per foot of horizontal run

Per the International Mechanical Code, unlisted single-wall metal vent pipe passing through a room to connect a residential gas appliance to a chimney must maintain what minimum clearance to combustible construction?

• A6 inches
• B1 inch
• C3 inches
• D12 inches

Factory-built Type L low-temperature venting systems (used for oil-burning and gas appliances) require what standard clearance to combustible construction unless otherwise listed?

• A1 inch
• B2 inches
• C6 inches
• D9 inches

What is the primary function of a factory-installed draft hood on a Category I natural draft gas appliance?

• ATo mix ambient air with flue gas to increase draft velocity.
• BTo prevent gas leaks into the room during burner shutdown.
• CTo neutralize downdrafts, prevent chimney draft fluctuations from affecting burner combus…
• DTo isolate burner flames from main gas valve electrical signals.

A barometric draft regulator (draft control damper) installed on an oil-fired furnace vent pipe functions by opening automatically when chimney draft becomes excessive. Where should this regulator be located?

• AInside the chimney flue lining near the roof termination cap
• BOn the fresh air intake duct supplying outdoor combustion air
• CDirectly inside the burner combustion chamber
• DIn the same room as the appliance, on the vent connector between the appliance flue colla…

According to NFPA 54 / IFGC standards, a mechanical draft venting system termination located adjacent to a building window or door must be installed at least how far away horizontally or below the opening?

• A4 feet
• B12 inches
• C2 feet
• D10 feet

Connecting a small Category I gas water heater into a massive, unlined exterior masonry chimney often causes severe chimney damage primarily because:

• AThe flue pipe velocity becomes too high and cracks tiles.
• BFlue gases cool below their dew point before reaching the top, causing acidic water conde…
• CFlue gases expand too rapidly and blow out the cleanout door.
• DThe water heater creates excessive positive pressure inside the chimney.

When two or more gas appliance vent connectors enter a common vertical chimney or vent manifold, how must the connections be made relative to the direction of flue gas flow?

• AAt a 90-degree perpendicular tee connection
• BAt a 45-degree angle pointing opposite to flue flow
• CThrough a single 180-degree return bend
• DAt a 45-degree angle pointing in the direction of flue gas flow (using a 45-degree wye fi…

When calculating indoor combustion air for gas appliances installed in an unconfined space using the standard method (IFGC 304.5), what is the minimum required room volume per total appliance input rating?

• A100 cubic feet per 1,000 BTU/hr total input
• B25 cubic feet per 1,000 BTU/hr total input
• C10 cubic feet per 1,000 BTU/hr total input
• D50 cubic feet per 1,000 BTU/hr total input

Per NFPA 211 standards, clay tile flue liners in masonry chimneys must be laid with refractory cement joints not exceeding what thickness, smooth on the inside?

• A1/16 to 1/8 inch
• B1/2 inch
• C3/4 inch
• D1 inch

Spark arrestors installed on chimney caps serving solid-fuel or gas equipment must feature woven wire mesh screen openings with dimensions within what range per NFPA 211?

• A1/16 inch minimum to 1/4 inch maximum
• B3/8 inch minimum to 1/2 inch maximum
• C1 inch minimum to 2 inches maximum
• D3/4 inch minimum to 1-1/2 inches maximum

The outdoor wall termination cap of a direct-vent wall furnace must be installed with its bottom at least how far above finished ground grade level?

• A6 inches
• B18 inches
• C12 inches
• D24 inches