Journeyman Plumber ExamWater Supply SystemsHard
A plumber is designing a water distribution system for a medical clinic. The clinic requires a high level of water quality and consistent pressure for sensitive equipment. The design includes a water treatment system. Which component is crucial to prevent the treated water from flowing back into the municipal supply during a pressure drop in the main?
- APressure Reducing Valve (PRV)
- BThermal Expansion Tank
- CReduced Pressure Principle Backflow Preventer (RPZ)
- DWater Softener
Show answer & explanationAnswer & explanation
Correct answer: C. Reduced Pressure Principle Backflow Preventer (RPZ)
A medical clinic represents a high-hazard cross-connection due to the potential for severe health risks if contaminated water enters the public supply. An RPZ offers the highest level of protection against both back-siphonage and backpressure, making it the required device for such critical applications.
Why the other options are wrong
- A. A PRV regulates incoming pressure, it does not prevent backflow.
- B. A thermal expansion tank manages pressure increases from heating, it does not prevent backflow.
- D. A water softener treats water hardness; it has no backflow prevention capabilities.
RPZ for High Hazard
A Reduced Pressure Principle Backflow Preventer (RPZ) is mandated for preventing contamination from high-hazard cross-connections, such as those found in medical facilities or chemical plants.
- Highest level of mechanical backflow protection
- Protects against back-siphonage and backpressure
- Required for high-hazard applications (e.g., medical, industrial)
- Includes two check valves and a relief valve
Memory trick: Medical means maximum, so RPZ is the minimum!