Discharge nozzles must be provided with an upstream device to prevent entrance of grease vapors, moisture, environmental contaminants, or other foreign materials into the piping. Which option is acceptable as that upstream device?

• A. Caps
• B. Vents
• C. Seals
• D. Filters

Answer: (A)

The key idea is protecting the discharge piping from contamination when the system is idle. Discharge nozzles are part of a kitchen fire suppression system and sit in an environment with grease vapors, moisture, and debris. Providing an upstream barrier that can seal the line keeps those contaminants from entering the piping and potentially clogging or fouling the nozzles and orifices. A cap serves this purpose well: it physically closes off the discharge path, is simple, passive, and can be quickly removed or opened when the system discharges.

Vents would work against the goal by letting air and contaminants into the piping. Seals alone don’t offer a reliable barrier for ingress into the upstream piping—they’re not intended to block contaminants entering the line. Filters could theoretically remove some particles, but they introduce maintenance needs, potential clogging, and aren’t the standard upstream protection specified for this purpose. That’s why a cap is the appropriate upstream device.