Exam Cheat Sheet · Quick Reference
Maryland Master Plumber / Gas Fitter
Maryland · PSI Services Contractor
Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.
Total questions
100
Passing score
70%
Exam time
240 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Maryland State Portion 100 questions
Plumbing Fundamentals and Safety
5 Q · 5%
IPC and IFGC scope, intent, and applicability provisionsPlumbing and fuel gas code administration: permits, inspections, and code official authorityKey IPC and IFGC defined terms and their code significanceOSHA construction site safety: employer responsibilities and accident prevention programsJobsite sanitation requirements: potable water, toilet facilities, and washing facilitiesOccupational health hazards: permissible exposure limits for airborne contaminantsFirst aid, medical services, and emergency action planning on construction sitesPersonal protective equipment requirements for construction workers
Materials, Uses, and Specifications
6 Q · 6%
Approved piping materials and applicable standards (steel, copper, CSST, polyethylene, aluminum alloy)Prohibited materials and material restrictions (cast iron pipe, PVC/CPVC for fuel gas, aluminum underground/exterior)Pipe and tubing identification requirements (manufacturer markings, 'Gas' labeling, spacing intervals)Metallic pipe joints and fittings specifications (threaded, brazed, welded, press-connect, flared)Plastic pipe and fitting standards (polyethylene ASTM D2513, prohibited PVC/CPVC for fuel gas)Protective coatings and corrosion resistance requirements for metallic pipingThread specifications and joint compound requirements for metallic pipeReferenced standards for plumbing materials (ASME, ASTM, ANSI standards for pipe, fittings, and valves)
Traps, Interceptors, and Backwater Valves
4 Q · 4%
Fixture trap requirements: vertical and horizontal distance limits from fixture outlet to trapProhibited trap types (bell traps, S-traps, drum traps, crown-vented traps, moving-part traps)Trap seal depth requirements and protection methods (primer valves, barrier devices)Grease interceptor requirements: where required, sizing, capacity, and prohibited additivesOil separator requirements: where required, design specifications, and capacity for garages/service stationsSand interceptors, clothes washer interceptors, and special-use interceptors (bottling, slaughterhouses)Venting and access/maintenance requirements for interceptors and separators
Plumbing Fixtures, Fixture Fittings, and Plumbing Appliances
4 Q · 4%
Minimum number of plumbing fixtures by occupancy type (Table 403.1)Fixture installation requirements — spacing, clearances, and securing methodsStandards and approval requirements for specific fixtures (water closets, urinals, lavatories, bathtubs, showers, sinks, bidets)Faucets and fixture fittings — shower valves, temperature-limiting devices, and backflow protectionFlushing devices — flushometer valves, flush tanks, fill valves, and overflow requirementsWater heater installation — location, access, clearances, seismic supports, and drain valvesWater heater safety devices — pressure/temperature relief valves, discharge piping, vacuum relief, and pan requirementsGas-fired appliances — cooking appliances, clothes dryers (exhaust duct requirements), pool/spa heaters, and unvented room heaters
Water Supply Systems
8 Q · 8%
Water supply pipe and distribution pipe materials and applicable standards (copper, PEX, CPVC, PVC, PE, galvanized steel)Pipe joining methods by material type (solvent cement, solder, braze, mechanical, push-fit, heat fusion)Water pressure regulation, booster systems, and water hammer controlFixture supply pipe sizing and minimum flow rates and pressures at outletsValve placement requirements (full-open valves and shutoff valves) and valve identificationWater pressure, head, and volume calculations (psi/head conversion, tank capacity, pipe capacity ratios)
Backflow Prevention
10 Q · 10%
Backflow preventer device types and applicable standards (air gap, reduced pressure principle assembly, double check assembly, vacuum breaker, dual check valve)Hazard classification for backflow prevention selection (high hazard contamination vs. low hazard pollution, backpressure vs. backsiphonage)Cross-connection control requirements and prohibited connectionsSpecific application requirements for backflow protection (boilers, lawn irrigation, fire sprinkler systems, carbonated beverage dispensers, chemical dispensers, hose connections)Installation requirements for backflow preventers (location, critical level height, access, freeze protection, relief port termination)Air gap requirements and minimum dimensionsIdentification and labeling of nonpotable water systemsThermal expansion control where backflow preventers are installed on water heater supply
Drain, Waste, and Vent Systems
13 Q · 13%
Drainage fixture unit (DFU) values and load calculationsSizing of building drains, sewers, and horizontal branchesSlope requirements for horizontal drainage pipingCleanout requirements, placement intervals, and access clearancesVent types, sizing, and developed length requirementsIndirect waste piping, air gaps, and waste receptorsPipe length calculations including fitting allowances and offsets for DWV systems
Special Topics
3 Q · 3%
Storm drainage system sizing and rainfall rate designRoof drain types, installation, and secondary (emergency) overflow systemsSubsoil drains, building subdrains, and sump pumping systemsNonpotable water system general requirements: signage, permits, and cross-connection protectionNonpotable water storage tank requirements: location, access, venting, overflow, and testingOn-site nonpotable water reuse systems: approved sources, prohibited sources, filtration, and disinfectionRainwater collection and conveyance systems: collection surfaces, first-flush diverters, debris excluders, and storageSubsurface landscape irrigation systems: percolation testing, absorption area sizing, and site location requirements
Gas Appliances and Piping
40 Q · 40%
Gas piping materials and allowable pipe types (steel, copper, CSST, polyethylene)Pipe sizing methods and use of capacity tables for natural gas and LP-gasGas piping pressure requirements, pressure drop, and testing proceduresCombustion air requirements for gas appliances (indoor, outdoor, and mechanical methods)Venting systems for gas appliances: types, sizing, and termination requirementsAppliance installation requirements: clearances, location restrictions, and prohibited locationsSpecific appliance requirements (furnaces, water heaters, fireplaces, dryers, pool heaters, and other Chapter 6 appliances)Safety inspection procedures for existing gas appliance installations
Plumbing Mathematics
7 Q · 7%
Fitting allowances for threaded, copper, PVC, and welded pipe fittingsOffset calculations using 45°, 60°, 22½°, and other angle constantsPipe length unit conversions between feet, inches, fractions, and decimalsVolume, capacity, and weight calculations for water and cylindrical containersWater pressure, head, and force calculationsGrade, drop, run, and elevation calculations for drainage pipingGas piping sizing methods and pressure drop calculationsRatio of pipe capacities and pipe sizing by units of flow
Key Distinctions
Longest Length MethodvsBranch Length Method
The Longest Length Method sizes every section using the overall longest system length, while the Branch Length Method uses the longest length only for the initial parts of the system and then sizes each remaining branch by the actual distance from the meter to the most remote outlet in that branch (less conservative).
IFGC 2018 Appendix A, Section A.3.2S-trapvsDrum trap
Both are prohibited traps, but the S-trap is prohibited with no exception, while drum traps are permitted by exception when used as solids interceptors or serving chemical waste systems.
IPC 2018 Section 1002.3Potable water-supplied trap seal primer valve (ASSE 1018)vsWaste water-supplied trap primer device (ASSE 1044) / barrier-type trap seal protection device (ASSE 1072)
Potable water-supplied primer valves must conform to ASSE 1018, waste water-supplied primer devices to ASSE 1044, and barrier-type trap seal protection devices to ASSE 1072.
IPC 2018 Section 1002.4.1.1Cast-iron pipe in fuel gas systemsvsSteel, copper, and aluminum-alloy pipe in fuel gas systems
Cast-iron pipe shall not be used for fuel gas at all, while steel, copper, and aluminum-alloy pipe are permitted under specific conditions and standards.
IFGC 2018 Section 403.4.1PVC and CPVC plastic pipe for fuel gasvsPolyethylene (ASTM D2513) and polyamide (ASTM F2945) for fuel gas
PVC and CPVC pipe, tubing and fittings shall not be used to supply fuel gas, whereas polyethylene conforming to ASTM D2513 (marked 'Gas' and 'ASTM D2513') and polyamide conforming to ASTM F2945 are permitted.
IFGC 2018 Section 403.6Gas with 0.3 grains or less hydrogen sulfide per 100 scfvsGas averaging more than 0.3 grains hydrogen sulfide per 100 scf
Copper and copper alloy pipe may be used at or below the 0.3-grain average, but is prohibited where the gas contains more than an average of 0.3 grains of hydrogen sulfide per 100 standard cubic feet (e.g., 0.5 grains).
IFGC 2018 Section 403.4.3Maximum vertical distance, fixture outlet to trap weirvsMaximum horizontal distance, fixture outlet centerline to trap inlet centerline
The vertical distance from fixture outlet to trap weir shall not exceed 24 inches, while the horizontal distance from the fixture outlet centerline to the trap inlet centerline shall not exceed 30 inches.
IPC 2018 Section 1002.1Standard tee (DWV)vsTee-wye (DWV)
A standard tee has three equal allowances, while a tee-wye has two long allowances and one short allowance, with a 1/4-inch-per-foot slope built into the branch.
Mathematics for Plumbers and Pipefitters (8th ed.), Unit 23Regular wyevsReducing wye (branch size differs from run size)
A regular wye uses the same allowance for the branch, while a reducing wye requires a different allowance for the branch (the E dimension), using Data 9 for reduced-branch wyes.
Mathematics for Plumbers and Pipefitters (8th ed.), Unit 23General code requirementvsSpecific code requirement
Where a general and a specific requirement conflict, the specific requirement governs; where different sections specify different materials or methods, the most restrictive governs.
IFGC 2018 Section 102.1Wet ventvsCircuit vent / combination waste-and-vent
A wet vent carries the discharge of one fixture while venting others (classically a single bathroom group), whereas circuit vents serve batteries of fixtures and combination waste-and-vent is a different, more restricted system.
Administrative or engineering controls for noisevsPersonal protective equipment for noise
Where sound levels exceed Table D-2 limits, feasible administrative or engineering controls must be used first; PPE is provided and used only if such controls fail to bring levels within the table.
29 CFR 1926, §1926.52(b)General underground gas piping burial depthvsIndividual line to an outdoor appliance (light, grill)
The general minimum burial depth is 12 inches, but individual lines to outdoor lights, grills and similar appliances may be not less than 8 inches below finished grade where approved and not susceptible to physical damage.
IFGC 2018 Section 404.12.1Key Terms
Competent person (OSHA) OSHA 1926 CFR 29, Page 31
One who is capable of identifying existing and predictable hazards in the surroundings or working conditions that are unsanitary, hazardous or dangerous to employees and who has authorization to take prompt corrective measures to eliminate them.
Pressure-reducing valve (water supply) IPC 2018 Section 604.8.1
A valve on the building water supply that must be designed to remain open to permit uninterrupted water flow in case of valve failure.
EHD (Equivalent Hydraulic Diameter) IFGC 2018 Table 402.4(15) Notes
A measure of the relative hydraulic efficiency between different CSST tubing sizes; the greater the EHD value, the greater the gas capacity of the tubing.
Fan-assisted combustion appliance IFGC 2018 Chapter 2, Section 202
An appliance equipped with an integral mechanical means to either draw or force products of combustion through the combustion chamber or heat exchanger.
Hot water heating boiler IFGC 2018 Chapter 2, Section 202
A boiler in which no steam is generated, from which hot water is circulated for heating and returned, operating at water pressures not exceeding 160 psig and temperatures not exceeding 250°F at or near the boiler outlet.
Wet vent
A pipe that vents one or more fixtures while also carrying the discharge of another fixture, classically a single bathroom group.
Permit expiration (fuel gas) IFGC 2018 Section 106.5.3
A permit expires by limitation and becomes null and void if the authorized work is not commenced within 180 days of the permit date, or is suspended or abandoned for 180 days after commencing.
Trap seal primer valve discharge connection IPC 2018 Sections 1002.4.1.1 through 1002.4.1.3
The discharge pipe from a potable water-, reclaimed/graywater-, or waste water-supplied trap seal primer valve must connect to the trap above the trap seal on the inlet side of the trap.
Oil separator (garages and service stations) IPC 2018 Section 1003.4.2.2
A separator sized at not less than 6 cubic feet for the first 100 square feet of floor area plus 1 cubic foot for each additional 100 square feet, with not less than an 18-inch water seal at the outlet opening.
Clothes washer interceptor IPC 2018 Section 1003.6
An interceptor with a wire basket or similar device that prevents passage into the drainage system of solids 1/2 inch or larger, string, rags, buttons, or other materials detrimental to the public sewage system.
Bottling plant interceptor IPC 2018 Section 1003.7
An interceptor required for bottling plant process wastes that provides separation of broken glass or other solids before the waste discharges into the drainage system.
Grease interceptor flow-control device IPC 2018 Section 1003.3.5.2
A device required on a hydromechanical grease interceptor to control the rate of water flow; it must be vented and terminate not less than 6 inches above the flood rim level, or be installed per the manufacturer's instructions.
CSST bonding jumper IFGC 2018 Section 310.2.2
For CSST gas piping not listed with an arc-resistant jacket or coating system, the bonding jumper to the grounding electrode system shall be not smaller than 6 AWG copper wire or equivalent.
Sheathing (piping isolation) IPC 2018 Section 305.1
Plastic material not less than 0.008 inch (8 mil) thick used to prevent direct contact between metallic piping and steel framing members or masonry.
Gas piping identification label (other than steel pipe) IFGC 2018 Section 401.5
A yellow label marked 'Gas' in black letters applied to exposed non-steel gas piping at intervals not exceeding 5 feet.
Baseline specific gravity for low-pressure natural gas tables IFGC 2018 Appendix A, Section A.2.2
0.60 specific gravity gas; when the gas specific gravity differs from 0.60, a gravity factor multiplier from Table A.2.4 must be applied to the table capacities.
Static head
The vertical elevation of the water surface above the point of measurement, which alone determines static pressure (horizontal pipe length and tank width do not affect it).
NSF 14 IPC 2018 Section 303.3
The standard to which plastic pipe, fittings and components used in plumbing systems must be third-party certified as conforming.
Formulas to Know
Static pressure from water column height (and the reverse)
Static pressure (psi) = vertical height of water above the point (ft) × 0.433 psi/ft; Height (ft) = pressure (psi) ÷ 0.433 (e.g., 60 × 0.433 = 26 psi; 20 ÷ 0.433 = 46.2 ft; 30 ÷ 0.433 = 69.3 ft)Simple offset travel and run using fitting constants
Travel = set × constant (45° = 1.414, 22½° = 2.613, 60° = 1.155); Run for a 45° offset = set × 1.000 (run equals set)Rolling offset true offset and travel
True offset = √(set² + roll²); then travel = true offset × fitting constant (e.g., √(12² + 9²) = 15 in; 15 × 1.414 = 21.2 in at 45°, 15 × 1.155 = 17.3 in at 60°)Total fall of a graded drain and resulting invert elevation
Total fall = grade (in/ft) × run (ft); Downstream invert = upstream invert − total fall (e.g., 1/8 in/ft × 32 ft = 4 in; 1/4 in/ft × 48 ft = 12 in = 1.00 ft, so 100.00' − 1.00' = 99.00')Grade expressed as percent slope
Percent slope = (rise per foot in inches ÷ 12 in/ft) × 100 (1/4 in per foot = 0.25 ÷ 12 × 100 = 2.08%)Cut length of pipe between two fittings
Threaded: cut length = center-to-center − (takeoff × 2 fittings) + (thread engagement × 2 ends) (42 − 4½ + 1 = 38½ in; 36 − 4 + 1 = 33.00 in). Sweat: cut length = center-to-center − (fitting allowance × 2 ends) (24 − 1 = 23.00 in)Cylinder volume and gallon capacity
V = 0.7854 × d² × h (equivalent to π r² h, since 0.7854 = π/4): 0.7854 × 24² × 36 = 16,286 cu in; in feet V = π × r² × h (π × 2² × 6 = 75.4 cu ft); gallons = cubic feet × 7.48 (75.4 × 7.48 ≈ 565 gal; half height uses h ÷ 2)Water heater recovery rate (gallons per hour at a given temperature rise)
GPH = (input BTU/hr × efficiency) ÷ (8.33 lb/gal × temperature rise °F) = (40,000 × 0.75) ÷ (8.33 × 70) = 30,000 ÷ 583.1 = 51.4 GPHMinimum oil separator capacity (garages/service stations)
Capacity = 6 cu ft for the first 100 sq ft + 1 cu ft for each additional 100 sq ft (500 sq ft: 6 + 4 × 1 = 10 cu ft)Spare (or short) gas pipe capacity from a sizing table
Spare capacity (cfh) = table capacity at that pipe size and length − appliance demand (44 − 40 = 4 cfh spare; 117 − 40 = 77 cfh spare), using Table 402.4(2) Schedule 40 metallic pipe, natural gas, inlet < 2 psi, 0.5 in. w.c. drop, SG 0.60