What is the minimum perforation size required in inches?

• A. 1/8 in
• B. 3/16 in
• C. 1/4 in
• D. 1/2 in

Answer: (A)

In foam-water systems, the perforations in components that disperse or mix foam concentrate need to be large enough to avoid frequent plugging while still providing good flow and foam formation. Setting a minimum perforation size of 1/8 inch ensures the device won’t clog easily by the impurities in foam concentrate and debris, while still allowing proper distribution of foam solution. If the holes were smaller, plugging would be a constant maintenance issue; larger holes would meet or exceed the minimum, but 1/8 inch is the standard lower limit NFPA 16 specifies.