CSLB C-36 Plumbing ContractorRough-in PlumbingMedium
A plumbing contractor is installing a new water supply system for a multi-story commercial building. The plans indicate the use of cross-linked polyethylene (PEX) tubing for the hot and cold water distribution. What is the maximum allowable working pressure for PEX tubing in a typical commercial potable water system?
- A80 psi
- B125 psi
- C100 psi
- D160 psi
Show answer & explanationAnswer & explanation
Correct answer: C. 100 psi
PEX tubing manufacturers typically rate their products for a maximum working pressure at a specific temperature. For potable water systems, 100 psi at 180°F is a common rating for PEX, aligning with standard building code requirements for water pressure.
Why the other options are wrong
- A. This pressure is generally too low for the maximum allowable working pressure of PEX in most applications.
- B. This pressure is higher than the typical maximum working pressure for PEX in hot water applications.
- D. This pressure is generally the maximum working pressure at lower temperatures (e.g., 73.4°F), not typically for hot water distribution.
PEX Tubing Working Pressure
The maximum internal pressure that cross-linked polyethylene (PEX) tubing can safely withstand during continuous operation in a potable water system at a specified temperature.
- Pressure rating is temperature-dependent.
- Common rating: 100 psi at 180°F.
- Ensures system integrity and safety.
Memory trick: PEX handles pressure, 'Hot or Cold, it's Bold'.