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These 10 free MN-JP questions are organized by exam domain, so you can see how each part of the Minnesota Journeyworker Plumber License Exam blueprint is tested. Reveal the answer and explanation under each question.
A piping installation requires a 90-psi hydrostatic test. Four calibrated dial gauges are available. Considering both graduation size and full-scale range, which gauge meets the plumbing-code requirements for this test?
Correct answer: D - A 0-160 psi gauge with 0.5-psi graduations
A site-built shower over a wood subfloor passes its receptor water test. Before tile is installed, a plumber finds that the liner lies flat; all slope has been formed in the mortar above it. The drain's weep holes are open. The installer argues that passing the water test proves the receptor is acceptable. What correction is still needed?
Correct answer: C - Support the liner on a surface pitched 1/4 inch per foot toward the weep holes.
After a check valve is installed at a building's water service, pressure on the building side rises from 58 psi to 108 psi during each water-heater recovery cycle. Opening a faucet immediately returns it to 58 psi. Pressure upstream of the check valve remains steady, and the heater's temperature controls operate normally. Which modification addresses the cause of this pressure pattern?
Correct answer: B - Install a properly sized expansion tank on the building side of the check valve.
A water heater's 3/4-inch temperature-and-pressure relief outlet has an independent, full-size hard-drawn copper discharge pipe. It drains by gravity, has no valve or trap, and ends downward with an unthreaded outlet 14 inches above the mechanical-room floor. The location is protected from freezing, and discharge will not injure anyone or damage the building. Under Minnesota's discharge-piping rule, how should this termination be treated?
Correct answer: A - Accept it; the outlet is within the permitted 18 inches above the floor.
A greenhouse irrigation system injects liquid fertilizer downstream of its potable-water connection. A booster pump can raise irrigation pressure above supply pressure, and the connection remains continuously pressurized. The design retains a direct connection rather than an air-gapped break tank. Select the backflow assembly appropriate for these conditions.
Correct answer: A - Reduced-pressure-principle assembly, ASSE 1013
A water-supply sizing worksheet uses 64 psi at the service under design flow. The controlling urinal flushometer is 22 feet higher, has a 3/4-inch inlet, and requires 25 psi residual pressure. Allow 0.5 psi per foot of rise and 17 psi for meter, backflow, and equipment losses. Pipe-and-fitting losses at design flow are: 3/4 inch, 35 psi; 1 inch, 14 psi; 1-1/4 inches, 5 psi; and 1-1/2 inches, 2.5 psi. All candidates meet the velocity limit. Which is the smallest that preserves the required residual pressure?
Correct answer: C - 1-1/4 inches
Plans for a new office show four 1.6-gallon-per-flush water closets and several lavatories discharging through one 3-inch horizontal drain at 1/4 inch per foot. The verified total is 24 drainage fixture units (DFU). The designer points to the 35-DFU horizontal capacity in Table 703.2. What should the plan reviewer require?
Correct answer: D - Increase the drain to 4 inches; a 3-inch horizontal drain is limited to three water closets.
An office's basement floor is at elevation 96 feet, with all basement fixture flood rims below 100 feet. Its first-floor level is 106 feet. The cover of the next upstream public-sewer manhole is at 102 feet. Both floors can drain by gravity. The owner requests sewage-backflow protection. Which piping arrangement complies?
Correct answer: B - Put a backwater valve on the basement branch; bypass it with first-floor drainage.
Two restaurant bins hold unpackaged ice used in drinks. Each bin has a 1-inch indirect waste pipe with its own trap. The two pipes join at a wye into a 2-inch common pipe, which discharges through an adequate air gap into an accessible, trapped, and vented floor sink sized for both bins. Identify the defect that remains.
Correct answer: B - The bin drains combine instead of running separately to the receptor.
A single bathroom group is proposed for horizontal wet venting. Reading downstream along the 3-inch wet-vented branch, the connections are: dry-vented lavatory, water closet, then shower. All fixtures are on the same floor, and the proposed pipe sizes, slope, and trap-arm lengths otherwise comply. To retain this wet-venting method, how must the layout change?
Correct answer: A - Move the water-closet connection downstream of the shower connection.
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