Perforations shall be no larger than the smallest orifice in the system and no less than what size?

• A. No less than 3/16 in
• B. No larger than 1/4 in
• C. No larger than the smallest orifice in the system and no less than 1/8 in
• D. No limit

Answer: (C)

In a foam‑water system, perforations in the foam‑making orifice path must be controlled both for balance and reliability. They should not be larger than the smallest orifice in the system, so no single perforation bypasses the intended restriction and disrupts the designed foam‑water proportioning. At the same time, they must be large enough to prevent clogging and ensure a steady discharge, which is why a minimum size of 1/8 inch is specified. If perforations were larger than the smallest orifice, flow could favor that path and upset the foam concentration and overall performance; if they were smaller than 1/8 inch, debris or concentrate residue could clog them, reducing flow and consistency. So perforations are limited to no larger than the smallest system orifice and no less than 1/8 inch.