By Larry Stevens

      In Phoenix, troops on the apparatus committee can't cut CAFS. Brunacini said, "The policy comes down from God, and She says, 'Fire trucks are red, and they shall have CAFS.'"    

     CAFS is the future of firefighting. All pump manufacturers offer integrated, engineered systems. They've all invested in a big way in the technology. CAFS is produced at the pump by mixing compressed air, Class A foam solution and water. The result is shaving cream-like foam that will extinguish a fire with less water. Why? The mixture doesn't run off onto the floor. It stays where it's sprayed. The solution allows absorption of water into the fuel surface instead of running off. High-quality foam keeps the water on the burned and unburned fuel surface. Our job is as much about reducing collateral damage as fighting a fire.

     What's accomplished when you drench everything in a room with water, other than creating more damage? Spraying a few hundred gpm into the attic ensures the destruction of everything below the ceiling. Picture a world where a room turns white when you spray Every firefighter knows smoke results from incomplete combustion, and the greatest release of incomplete combustion is at the time of knockdown. With everything white, buried under foam, the products of combustion  aren't 

released at the same rate. With CAFS, interior temperature drops five times faster than without using the foam. Simply reapply if you see steam coming off the fuel surface or an area that's not white. We've all been told not to spray water on smoke. But when you see smoke and steam continue to spew under pressure, it's hard to resist wet\-ting everything down over and over again. The CAFS bubbles remove that temptation. More importantly, blowing CAFS into an attic means the ceiling stays up.

     Attack lines are lighter when two-thirds of what they're holding is air. Crews can advance a CAFS line quicker than a water line. About five to seven times less water is needed to overhaul a fire. Whatever the figures, a reduction in water used is a reduction in damage done. Also, CAFS means less water hauling. It's hard to imagine a rural department that would consider buying a rig without CAFS.

     The biggest drawback with most current and nearly all older CAFS designs is that engineers face too many steps to make suds. Anything more than engaging the pump, throttling up and opening an attack line or deck gun will fail. Bubbles on all fires should be operating policy, as well as simple CAFS design. Create a system that defaults to CAFS, not water.

    Once, a group was at the station investigating CAFS and asked the engineer how he made CAFS so fast. The engineer replied, "l don't know, I just flip those two switches in the cab." The pump operator's life also gets easier with CAFS. All that's needed to produce four identical streams on a 400-, 250-, a 200- and a 50-foot line operating at the same time is a pump pressure of 90 psi.

    For CAFS, hydraulics isn't important. Laying out the 

ultimate structure-fire fighting CAFS pumper of the future iseasy: First you can do away with the pump panel as we know it. Instead, use a small pump panel in the cab. It needs only an inlet and an outlet gauge, a pump and compressor engagement switch, a pressure governor preset at 90 psi, a water-level gauge and a foam-metering knob. The preconnected attack lines and pump suctions would have gate valves at the point of use. You could still have the big water lines for lost causes and public relations fires. The debates over smooth-bore or fog nozzles and fixed flow vs. automatics would be over: High-quality CAFS streams can be made out of all of them.

     You may wonder why you shouldn't just "stay with Class A foam. It certainly is a step in the right direction, but it isn't as efficient as CAFS. Class A foam requires twice the amount of concentrate. You don't get the benefits of lightweight lines, common pump pressures and reduced fire flow. Also, ceilings will still collapse under Class A foam. Class A foam from a foam tip or nonaspirated nozzle isn't nearly as efficient at holding water and resisting wind as CAFS. Also, it only partially reduces the amount of water needed, and the temperature drop is only half of CAFS.

     Fire releases a known amount of British thermal units (Btu) for a given room. Tactical fire stream deployment should be based on the smallest and easiest attack line that will absorb the Btu. We should use whatever method accomplishes that task with the least collateral damage and the greatest impact on the fire.

     After all, Bruno said we should.

FIRE-RESCUE MAGAZINE   MARCH 1999