Which statement accurately describes foam-proportioning devices?

• A. They must be installed inside the main water line
• B. They are never subject to maintenance
• C. They include inline eductors and external (standalone) proportioners
• D. They require no power to operate

Answer: (C)

Foam-proportioning devices are used to mix foam concentrate with water to create the foam solution used by foam-water sprinkler systems. They come in two common configurations: inline eductors installed in the water line that draw concentrate into the flow, and external standalone proportioners that meter concentrate and feed the mix into the water downstream. This explains why describing both types is the most accurate statement. The other descriptions aren’t universally true: some systems use external proportioners, some put devices in the main line but not always; maintenance is required to keep metering and concentrate levels accurate; and many systems do rely on power for pumps or controls, so operating with no power isn’t universally true.