Master Plumber Exam Plumbing System Design 4 — Questions and Answers
Question 1: In a multi-zone hydronic heating system, a primary-secondary pumping arrangement is used primarily to accomplish which design goal?
- Eliminate the need for zone valves
- Allow each zone to operate at different flow rates without affecting the primary loop (Correct answer)
- Reduce the boiler size required for the system
- Prevent thermal stratification in the storage tank
Correct answer: Allow each zone to operate at different flow rates without affecting the primary loop
Primary-secondary piping decouples zone flow rates from the primary loop, allowing each zone's circulator to vary flow independently without hydraulic interference.
Question 2: Which condition requires an engineered design rather than the standard prescriptive tables when using the IPC for drain, waste, and vent sizing?
- A system with more than 100 total fixture units
- A system where the drainage slope exceeds 1/4 inch per foot
- A system that combines sanitary and storm drainage (Correct answer)
- A system where developed length exceeds 50 feet
Correct answer: A system that combines sanitary and storm drainage
Combining sanitary and storm drainage in the same piping requires a special and engineered design with specific authority having jurisdiction (AHJ) approval.
Question 3: What is the minimum distance a potable water supply pipe must be separated horizontally from a sewer line when they run parallel, per most codes?
- 5 feet
- 10 feet (Correct answer)
- 12 feet
- 18 feet
Correct answer: 10 feet
Most codes, including the IPC, require a minimum 10-foot horizontal separation between parallel potable water lines and sewer lines to prevent contamination.
Question 4: A sanitary sump ejector system is required in which scenario?
- When fixture drain flow rate exceeds 10 GPM
- When fixtures are located below the upstream manhole cover elevation of the public sewer (Correct answer)
- When the building has more than three floors of drainage above the ejector
- When cast iron pipe is used for the horizontal drain
Correct answer: When fixtures are located below the upstream manhole cover elevation of the public sewer
Sewage ejector pumps are required when fixture drains are below the elevation where gravity flow to the public sewer is impossible.
Question 5: In medical gas system design, a zone valve box must be located where relative to the area it serves?
- Inside the patient care area it controls
- Outside the patient care area in the corridor (Correct answer)
- At the main gas source equipment room
- Adjacent to the nurse call station
Correct answer: Outside the patient care area in the corridor
NFPA 99 requires zone valves to be located outside the patient care area (typically in the corridor) so staff can shut off gas without entering a hazardous area.
Question 6: When calculating the water demand for a building using the Hunter's Curve method, what is the design demand in GPM for a system with 240 fixture units (all private use)?
- Approximately 48 GPM (Correct answer)
- Approximately 60 GPM
- Approximately 80 GPM
- Approximately 120 GPM
Correct answer: Approximately 48 GPM
Hunter's Curve for 240 private-use fixture units yields approximately 48 GPM of probable simultaneous demand.
Question 7: Which type of pipe joint is NOT permitted for use on a natural gas supply line inside a building per most code requirements?
- Threaded malleable iron fittings
- Brazed joints on copper tubing
- Compression fittings (flare or sleeve type) (Correct answer)
- Welded steel pipe joints
Correct answer: Compression fittings (flare or sleeve type)
Compression-type mechanical fittings (non-flare sleeve type) are generally prohibited for interior gas piping due to potential for loosening and leaks.
Master Plumber Exam Plumbing System Design 4
In a multi-zone hydronic heating system, a primary-secondary pumping arrangement is used primarily to accomplish which design goal?