Journeyman Plumber ExamWater Supply SystemsHard

A plumber is selecting piping material for a new hot water distribution system in a commercial laundry facility. The system will operate with water temperatures consistently above 140°F (60°C) and requires high durability against corrosion and abrasion from potential chemicals. Which of the following materials would be the most suitable choice?

  1. AGalvanized Steel
  2. BType M Copper
  3. CPEX (Cross-linked Polyethylene)
  4. DCPVC (Chlorinated Polyvinyl Chloride)
Show answer & explanation

Correct answer: D. CPVC (Chlorinated Polyvinyl Chloride)

CPVC is highly suitable for hot water distribution, especially in commercial/industrial settings, due to its excellent resistance to high temperatures (up to 200°F/93°C), corrosion, and many chemicals. Type M copper is thinner walled and less resistant to abrasion/chemical attack than CPVC in such demanding environments. PEX has temperature limitations and may not be ideal for continuous high-temperature commercial applications, especially with chemical exposure. Galvanized steel is prone to internal corrosion and scaling, making it a poor choice for hot water and chemical environments.

Why the other options are wrong

  • A. Galvanized steel is highly susceptible to corrosion and scaling in hot water systems, leading to reduced flow and premature failure.
  • B. Type M copper is suitable for general hot water but less resistant to abrasion and chemical attack than CPVC in a commercial laundry setting.
  • C. PEX has temperature limitations (typically 180°F at 100 PSI) and its chemical resistance varies, making it less suitable for continuous high-temperature commercial chemical exposure than CPVC.

Hot Water Pipe Material Selection

Choosing the appropriate piping material for hot water distribution based on temperature, pressure, chemical resistance, durability, and code requirements.

  • CPVC is excellent for high-temperature and chemical resistance.
  • Copper (Type L or K) is durable but can be susceptible to certain chemical corrosions.
  • PEX has temperature and pressure limitations, and varying chemical resistance.
  • Galvanized steel is generally unsuitable for modern hot water systems.

Memory trick: For hot water and chemicals, choose carefully, not just any pipe will do.

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