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The MD-MP exam has 100 questions and runs 4 hours.
These 10 free MD-MP questions are organized by exam domain, so you can see how each part of the Maryland Master Plumber License Exam blueprint is tested. Reveal the answer and explanation under each question.
Immediately before a planned construction entry into a sewer wet well, a verified atmospheric meter reads 20.8% oxygen and 14% of the lower flammable limit. Toxic-gas readings are below the applicable limits. No one has entered, and ventilation has not yet controlled the flammable atmosphere. What should the entry supervisor do now?
Correct answer: A - Keep workers out until the atmosphere is controlled and acceptable entry conditions are verified.
On a new building's drainage plan, the basement finished floor is at elevation 98 feet, the first-floor finished floor is at 110 feet, and the next upstream public-sewer manhole cover is at 102 feet. The basement water closet, lavatory, and floor drain can all discharge by gravity. Applying the ordinary 2018 IPC backwater-protection rule, how should these floor levels be handled?
Correct answer: A - Protect the basement branch; route first-floor drainage around that backwater valve.
During a hotel shower test, flushing a nearby toilet causes the shower temperature to rise sharply. The shower has an ordinary manual mixing valve. A central tempering valve already limits the hot-water supply to 120°F, but the contractor argues that this makes a compensating shower valve unnecessary. Which change provides the required individual-shower protection under the 2018 IPC?
Correct answer: B - Install an ASSE 1016 compensating shower valve and set its maximum discharge to 120°F.
Since a check valve was installed at the water service, a building's pressure rises from 58 psi to 106 psi whenever its storage water heater recovers with all fixtures closed. An existing pressure-reducing valve continues to deliver 58 psi upstream of the check, and the stored-water temperature remains normal. There is no expansion-control device. Which alteration addresses the cause of the pressure rise?
Correct answer: C - Add a properly sized expansion tank to the heater's cold supply downstream of the check.
The field-test record for a reduced-pressure principle backflow assembly shows: first check tight at 6.4 psid; second check tight against backpressure; relief valve begins opening at 1.3 psid. The gauge is calibrated, the shutoffs hold, and the readings were obtained under valid test conditions. Using the EPA Cross-Connection Control Manual's acceptance criteria, how should the assembly be recorded?
Correct answer: A - Fail: the relief valve opens at too low a differential pressure.
Two bathroom groups on the same floor share a horizontal wet vent that otherwise complies with the 2018 IPC. A nearby kitchen sink has its own properly sized trap and individual vent. Its drain must join the bathroom drainage system. Which tie-in preserves the permitted wet-vent arrangement?
Correct answer: D - On the common drain downstream of the entire wet-vented bathroom section.
A furnace operates normally when it is the only gas appliance firing. With the range and water heater also firing, pressure immediately downstream of the meter remains at 7.0 inches water column, but pressure at the furnace inlet falls to 3.0 inches. The furnace requires 5.0-10.0 inches at its inlet while operating. These simultaneous readings most strongly direct the investigation toward:
Correct answer: C - Excessive pressure loss in the piping between the meter and furnace inlet.
Size the common gas main from the meter to the first tee using the 2018 IFGC longest-length method. That segment is 20 feet long; the longest meter-to-appliance route is 60 feet, including the required sizing allowance. The main supplies a 100,000-Btu/h furnace, an 80,000-Btu/h range, and a 40,000-Btu/h water heater; all ratings are input. Natural gas has a heating value of 1,000 Btu/ft³ and specific gravity 0.60. For Schedule 40 metallic pipe at less than 2 psi inlet pressure and 0.3 inch water-column pressure drop, the applicable capacities are: at 20 feet, 1/2 inch = 90, 3/4 inch = 188, 1 inch = 353, and 1-1/4 inches = 726 ft³/h; at 60 feet, the same sizes carry 50, 104, 195, and 400 ft³/h, respectively. What is the smallest listed size for the common main?
Correct answer: D - 1-1/4 inches
An older gas boiler using a Type B vent is being replaced. The new boiler is labeled Category IV. Before selecting an approved replacement vent system, the installer must identify the operating conditions associated with that category. Which pairing applies?
Correct answer: B - Positive vent pressure; capable of excessive condensate production.
An equipment room contains a 90,000-Btu/h room-air furnace, a 40,000-Btu/h atmospheric water heater, and a 70,000-Btu/h direct-vent boiler with its own sealed outdoor air intake. All figures are input ratings. Combustion air for the room-air appliances will come through two horizontal ducts directly outdoors, one high and one low, using the 2018 IFGC two-opening method. Each duct and opening meets the other dimensional requirements. The selected louvers provide 60% free area. Available louver gross areas are 75, 100, 125, and 175 square inches. Which is the smallest acceptable louver for EACH opening?
Correct answer: C - 125 square inches
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