Friction loss in the fire hose is practically nil with CAFS because each bubble slides on a thin soapy film of the other bubbles. But 90 psi is too low to keep the hose firm and it will have a tendency to kink easier. Thats why some manufacturers teach the use of flow reducing small tips and higher water volumes with very little compressed air volume. Both are very bad for true CAFS applications. 120 psi on the air is a good pressure and 200 cfm in the hose is a good air volume. Water volume should start at about 40 gpm and increase or decrease to make the foam wetter or dryer. This produces approximately a 20 times foam expansion ratio to the amount of water flowing. 40 gpm of water will produce 800 gpm of dense durable CAFS foam. Start with 1/2 percent concentrate and adjust up and down to change the drainage rate of the bubbles water content for faster and slower water penetration.
Posted on: Thu, 01 Jan 2015 00:34:32 +0000
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