ROD CARRINGER, VP OF SALES & MARKETING EXPLAINS THE CAFS FORCE NOZZLE
The only automatic nozzle combination designed specifically for Compressed Air Foam (CAFS) and water applications, CAFS-Force is engineered to provide optimal foam stream performance, as well as offering low pressure nozzle operations when using water alone.
Ideal for 1-1/2”, 1-3/4” or 2” lines
Automatic dual pressure control with a water flow capacity of 70-200 gpm
Offering 7/8”, 15/16”, 1”, 1 1/8” and 1 3/8” smoothbore options
Distinctive white pistol grip and handle cover
Two piece nozzle allows for Break-and-Extend operations
CAFS, continue to be evaluated by fire service professionals worldwide for use in interior structural attack operations. With over 4% of all pumping apparatus being delivered today with CAFS capabilities, there are several
common misconceptions about the overall versatility of this manner of Class A foam application.
CAFS is a high-energy delivery system for Class A foam. Just as a nozzle or a nozzle with a foam aspiration tube is a low-energy delivery method. Class A foam is nothing more than the soap agent that makes the water foam up as it is agitated. Often, departments do not realise that common pumping systems and regular nozzles and attachments will work fine with Class A foam.
As has been proven many times in testing done by NFPA/UL and the National Institute for Standards and Technology, the foam application method has no effect on the necessary critical application rate. It is important to
remember that the chemical chain reaction we call fire requires a minimum application rate of water to absorb the BTUs being generated.
Foam (water) either from a CAFS attack or from a standard nozzle must be applied in sufficient quantity for successful suppression to take place. Class A foam is an enhancement to, not a replacement for, water.
Hose handling characteristics of high-energy CAFS lines require additional training and understanding for crews to be safe and effective. Thought lightweight and easy-to-maneuver, these lines are actually storing the energy of
the air compressor’s pressurisation. When opened and the stored energy is released, substantial nozzle reaction can be expected. Crews need to be prepared for this force. Additionally, kinking of a CAFS line will certainly change
both foam quality and flow rate and ultimately could cause “slug flow.”
Slug flow is an inconsistent mixture of air, water,, and foam concentrate in the hose that causes the line to react uncontrollably. Many firefighters that have viewed finished CAFS streams are amazed by the consistent bubble structure of the highly expanded “shaving cream” quality foam.
This “dry” foam is outstanding for exposure pretreatment, but often lacks the necessary water within the bubble structure to drain into the fuels to which it was applied. It is not uncommon to have a fire continuing to burn in fuels that have had CAFS foam applied to them.
This is due to the limited drain out of water in the bubble structure and can lead to rekindling and overhaul
challenges. Using a wetter foam is often more preferable when dealing with deep-seated fires.
The best source of information on the use of CAFS in structural firefighting is “NFPA 1145 – Guide for the Use of Class A Foams in Manual Structural Firefighting – 2000 edition.” This guide offers suggested nozzle choices for different manual firefighting challenges.
Exterior or interior direct attack
When using a high-energy foam system (CAFS), the system should be adjusted to provide a wet foam. A conventional nozzle can be used to provide a protective fog pattern, though reach and foam quality may diminished.”
Exposure protection
“The appropriate foam can be produced by varying the mix ratio, and/or changing the discharge device. Smooth bore nozzles or open ball valves should be used for the delivery of dry foam in CAFS.”
Ultimately, the selection of the nozzle used in CAFS applications is key to the successful suppression of the fire. Task Fire Tips, Inc. recommends a combination of their VITG series of integral smooth bore/ball valve in combination with their CAFS Force Dual-Pressure Automatic tip. This break- apart combination will provide maximum performance for all CAFS applications.
The smooth bore inserts can be customised to your system for dry foam applications and the Dual-Pressure tip can provide a protective fog pattern for your attack crew or wetter foam for penetration.
Factors that can affect quality of finished foam through a CAFS line
Quality of the class A foam concentrate
• -Cheap foam often has to be used at a higher injection ratio (up to 1%) to make good foam. Potential
cost savings can go right out the window. Cheaper may not be the most cost effective.
Water quality
Very hard water (ph or mineral content) has a negative effect on making lots of bubbles.
Water/air temperature
The colder it is, the harder it is to make bubbles. Often injection percentages have to be increased dramatically in cold weather to produce an acceptable quality/quantity of finished foam. Hose Length too short or too long of a pre-connect and you may not get proper bubble creation in the hose line.
Construction
rougher interior hose linings produce more consistent bubble structure, smoother linings less consistent.
Kink resistance
kinking can cause stripping of bubbles in the line resulting in an “unsafe” slug flow at the tip.
Pump/air compressor operations
Though many of the commercially available integrated CAFS systems provide automatic air/water pressure
and flow balancing and control, operator error can easily generate “unsafe” slug flow, poor foam quality or foam concentrate waste.
Foam proportioning systems
Proper concentrate injection accuracy and adequate mixing of the solution with air is imperative for the
best foam performance. Thought systems are often pre-engineered and designed to work.
The Nozzle
The wrong nozzle choice can negate the performance of the entire engineered CAFS system. The more nozzle “directs”, “constricts” or “shapes” a CAFS stream, the more it will strip out the bubble structure ultimately creating a “wetter” type of foam.
