Journeyman Plumber ExamWater Supply SystemsMedium
A plumber is installing a water distribution system in a commercial laundry facility. The facility's washing machines require a continuous supply of hot water at a minimum temperature of 140°F (60°C). Which of the following pipe materials is generally NOT considered suitable for this application due to its temperature limitations and potential for degradation?
- AStainless Steel (Type 316)
- BCross-linked Polyethylene (PEX)
- CChlorinated Polyvinyl Chloride (CPVC)
- DCopper (Type L)
Show answer & explanationAnswer & explanation
Correct answer: C. Chlorinated Polyvinyl Chloride (CPVC)
CPVC piping has temperature limitations that can make it unsuitable for continuous hot water applications above certain thresholds, especially in commercial settings where sustained high temperatures are common. While rated for hot water, its long-term performance can degrade at temperatures consistently at or above 140°F (60°C).
Why the other options are wrong
- A. Stainless steel is highly resistant to temperature and corrosion, making it an excellent, though often more expensive, choice for high-temperature applications.
- B. PEX, particularly PEX-A and PEX-B, is generally rated for continuous hot water up to 180°F (82°C) at specified pressures, making it suitable.
- D. Copper is a widely accepted and durable material for hot water distribution, easily handling 140°F (60°C) and higher.
CPVC Temperature Limits
Chlorinated Polyvinyl Chloride (CPVC) piping has specific temperature and pressure ratings that must be observed to prevent degradation, especially for continuous hot water applications.
- Rated for hot and cold water distribution.
- Temperature and pressure ratings are inversely related (higher temp = lower pressure rating).
- Continuous exposure to high temperatures (e.g., 140°F/60°C and above) can accelerate degradation.
Memory trick: Hot water demands the right pipe, or it'll burst its type.