Journeyman Plumber ExamDrainage, Waste, and Venting (DWV) SystemsMedium
A plumber is designing a DWV system for a new medical laboratory. The lab will generate corrosive chemical waste that requires special handling. Which of the following piping materials is most suitable for this chemical waste system?
- ABorosilicate Glass
- BSchedule 40 PVC
- CCast Iron with Acid-Resistant Coating
- DType L Copper
Show answer & explanationAnswer & explanation
Correct answer: A. Borosilicate Glass
For highly corrosive chemical waste, borosilicate glass piping is often the most suitable material. It offers exceptional resistance to a wide range of acids, bases, and organic solvents, and its transparency allows for visual inspection of flow and blockages, which is crucial in laboratory settings. While some plastics or coated cast iron might be used for less aggressive chemicals, glass provides superior resistance for highly corrosive applications.
Why the other options are wrong
- B. Schedule 40 PVC has good chemical resistance to some chemicals but can be degraded by strong acids, bases, or certain organic solvents, making it unsuitable for highly corrosive waste.
- C. Cast Iron with an acid-resistant coating can handle some corrosive chemicals, but the coating can be compromised over time, and the underlying iron is highly susceptible to corrosion, making it less reliable for extreme conditions.
- D. Type L Copper is used for potable water and some drainage, but it is highly susceptible to corrosion from most acids and many common laboratory chemicals, making it completely unsuitable for chemical waste.
Chemical Waste Piping Materials
Specialized piping materials designed to safely convey corrosive, toxic, or otherwise hazardous chemical wastes from laboratories or industrial processes.
- Must be highly resistant to chemical attack.
- Must withstand a wide range of pH and temperatures.
- Common materials include borosilicate glass, polypropylene, PVDF, and sometimes specially lined metals.
- Selection depends on the specific chemicals being discharged.
Memory trick: Chemical Waste: Choose Wisely, or Pay a Price.