During downtime of a UV disinfection system, what must be kept in the chamber to protect the lamp?

• A. Power off the UV lamp immediately.
• B. Vent the chamber to atmosphere to prevent pressure buildup.
• C. Disconnect the piping and drain the chamber.
• D. Hold water in the chamber if the flow stops to reduce the risk of thermal shock and breakage of the quartz tube and bulb.

Answer: (D)