Exam Cheat Sheet · Quick Reference
Kansas Journeyman Mechanical Exam (ICC KGG, 2018 IMC/IFGC)
Kansas · Pearson Vue
Kansas State Portion 50 questions
Key Distinctions
Where a general requirement conflicts with a requirement written specifically for the appliance being installed, the specific requirement governs; the separate 'most restrictive governs' rule applies only where different sections specify different materials, methods or other requirements.
IMC 2018 Section 102.1The longest length method sizes every section from the longest length of piping from the point of delivery to the most remote outlet, while the branch length method sizes each branch using that branch's own length from the meter (e.g., a 120 cfh branch at its own 50 ft needs 3/4 inch, whereas the longest length 90-ft row would call for 1 inch).
IFGC 2018 Section 402.4.1The one-permanent-opening method requires 1 square inch per 3,000 Btu/h of total input (and not less than the sum of the areas of all vent connectors), while each opening of the two-opening horizontal-duct method requires 1 square inch per 2,000 Btu/h of total input; 1 in² per 4,000 Btu/h reflects the vertical two-opening method.
IFGC 2018 Section 304.6.2 — One-permanent-opening methodPer IFGC 304.10, when design and free area are not known, wood louvers are assumed to have 25-percent free area and metal louvers and grilles 75-percent free area, so the same 100 in² net free area needs 400 in² gross with wood versus 133 in² with metal.
IFGC 2018 Section 304.10 — Louvers and grillesPer IMC 607.3.3.1 Item 1, the non-smoke-control damper's actuation device operates at approximately 50°F above normal duct temperature but not less than 160°F; the 350°F figure is the maximum operating temperature permitted under Item 2 for dampers in a smoke control system.
IMC 2018 Chapter 6 — Section 607.3.3.1 Fire damper actuation devicePer IFGC 406.7.1, piping systems with a design operating gas pressure greater than 2 psig must be purged outdoors; indoor purging (such as through an appliance burner) is allowed only for systems at 2 psig or less that also do not meet the size and length criteria of Table 406.7.1.1.
IFGC 2018 Section 406.7.1Per IMC 1105.6.3.2, halocarbon machinery room emergency exhaust on detector actuation is Q = 100 × √G (G = design refrigerant mass of the largest system with parts in the room), while the 30 air-changes-per-hour rate applies only to ammonia systems.
IMC 2018 Chapter 11 — Section 1105.6.3.2, BookPer IFGC 403.4.1 steel pipe, copper tubing and CSST are permitted when meeting their respective standards, but cast-iron pipe shall not be used for gas piping.
IFGC 2018 Section 403.4.1CSST lacking an arc-resistant jacket requires a bonding jumper not smaller than 6 AWG copper wire or equivalent (IFGC 310.2.2), while each above-ground portion of a gas piping system other than CSST that is likely to become energized must be electrically continuous and bonded to an effective ground-fault current path (IFGC 310.1).
IFGC 2018 Section 310.2.2IFGC 305.5 requires appliances in private garages to be installed with a minimum clearance of 6 feet above the floor (exception where protected from vehicle impact with ignition source elevated per 305.3), while IMC 304.6 requires not less than 8 feet above the floor in public/repair garages and, where vehicles can pass under the appliance, not less than 1 foot higher than the tallest vehicle garage door opening.
IFGC 2018 Section 305.5Per IMC 507.1.1, where one or more temperature or radiant energy sensors are used instead of a direct interlock, the fan must activate not more than 15 minutes after the first appliance served by that hood is turned on.
IMC 2018 Section 507.1.1Vented wall furnaces, Category I furnaces and draft-hood-equipped water heaters require venting systems, while direct-fired makeup air heaters are listed in Item 9 as not required to be vented; however, where appliances in Items 5 through 11 exceed an aggregate 20 Btu/h per cubic foot of room volume, one or more must be provided with venting.
IFGC 2018 Section 501.8Key Terms
Formulas to Know
QOA = 0.01 × Afloor + 7.5 × (Nbr + 1); example: 0.01(2,400 sq ft) + 7.5(4 + 1) = 24 + 37.5 = 61.5 cfm (omitting the '+1' gives the 54 cfm distractor)Q = 100 × √G, where G = design mass of refrigerant (lb) in the largest system with any part in the room; examples: 100 × √900 = 3,000 cfm; 100 × √625 = 2,500 cfm (30 ACH applies only to ammonia systems)Not less than 1 cfm per 12 cubic feet of room volume (lighter-than-air fuels other than hydrogen); examples: 60 × 30 × 10 = 18,000 ft³ ÷ 12 = 1,500 cfm; 4,800 ft³ ÷ 12 = 400 cfmcfh = total connected Btuh ÷ 1,000 (natural gas, 1,000 Btu per cu ft); examples: (65,000 + 40,000 + 50,000) ÷ 1,000 = 155 cfh; 247 cfh × 1,000 = 247,000 Btuh of capacityMaximum straight duct = 35 ft total equivalent length − sum of fitting equivalent lengths; example: two 4-in. radius mitered 90° elbows (5 ft each = 10 ft) + one 4-in. radius mitered 45° elbow (2 ft 6 in.) = 12 ft 6 in.; 35 − 12.5 = 22 ft 6 in.Test at 1.5 × maximum system design pressure but not less than 100 psi, for not less than 15 minutes; example: 1.5 × 60 psi = 90 psi, so the 100 psi floor governsApproximately normal duct temperature + 50°F, but not less than 160°F; examples: 140 + 50 = 190°F; 100 + 50 = 150°F → 160°F governsOne-permanent-opening method: 1 in² per 3,000 Btu/h total input and not less than the sum of all vent connector areas (example: 90,000 ÷ 3,000 = 30 in²); two-opening horizontal duct method: 1 in² per 2,000 Btu/h per opening (90,000 → 45 in²); vertical two-opening figure is 1 in² per 4,000 Btu/h (22.5 in²)Gross area = required net free area ÷ assumed free area (wood louvers 25 percent; metal louvers/grilles 75 percent); example: 100 in² ÷ 0.25 = 400 in² for wood (÷ 0.75 = 133 in² for metal)Opening between rooms = not less than 8 percent of the interior room floor area but not less than 25 sq ft (0.08 × 240 = 19.2 → 25 sq ft governs); openable area to outdoors = 4 percent of the TOTAL floor area ventilated (0.04 × (240 + 360) = 24 sq ft)