Compressed Air Foam System
Compressed Air Foam System
- Understand the uses for Compressed Air Foam - Understand the basics of the foam concentrate used by the GFD - Understand basic components of the CAFS - Understand the basic operation of the CAFS - Understand the daily and monthly maintenance
Advantages of Compressed Air Foam
Based on studies starting back in the 1970’s through the 2000’s by numerous agencies which included:
- Texas Department of Forestry - Boston Fire Department - Los Angeles City Fire Department - Los Angeles County Fire Department
Advantages of Compressed Air Foam
- Uses less water - extinguishment of given test fire (Boston Fire) 69 gallons = Water 30 gallons = CAF
- extinguishment of given test fire (Boston Fire) 100 gallons = Water 36 gallons = CAF - extinguishment of given test fire (LAFD) 75 gallons = Water 16 gallons = CAF
- Less accumulated weight (reduced chance of structural collapse)
Advantages of Compressed Air Foam
- Absorbs heat more rapidly due to greater surface area of a given volume of water
- cool a test fire from 1000 degrees F to 212 degrees F (NIFC) 222.9 seconds = Water 38.5 seconds = CAF - cool a room from 600 degrees F to 200 degrees F (LAFD) 363 seconds = Water 88 seconds = CAF
Advantages of Compressed Air Foam
- Reduces the weight of hose lines
- Reduces water and smoke damage
- Reduces property damage
- Deceases rekindle
- Clings to surfaces for exposure protection
- Forms a vapor barrier and excludes oxygen
Disadvantages of Compressed Air Foam
- Adds expense to apparatus - Hose reaction can be erratic if air ratio is off - Accentuates reaction of hose is it ruptures - Is under utilized do to lack of training
CAF can be mixed either wet or dry
- Wet CAF - Fire Attack - Mansards - Attic Fires - Basement Fires - Overhaul
- Dry CAF - Pre-treating - Overhaul
Phos-Chek WD-881
Phos-Chek WD-881 - Manufactured by ICL ( was acquired from Monsanto)
- Class A
- Can be used at 0.1 – 1.0% ( recommended 0.2 -0.5% for CAFS)
- 85% reverts to carbon dioxide within 28 days of exposure to ambient conditions in the environment
- Can be used on Class B but will breakdown and must be reapplied (consider accumulation of water due to repeated applications)
Phos-Chek WD-881
- Health effects and Toxicological Information:
Ingestion: “practically nontoxic”
Skin Contact: “no more than slightly toxic” and moderately irritating
Eye Contact: severely irritating
Inhalation: may cause nose and upper respiratory irritation
- These are greatly reduced when mixed at foam solution concentrations
3 Subsystems Of The Hercules CAFS
- Water Pump
- Foam Proportioning System
- either Husky 10 or 12 depending on year
- Air Compressor System
Air Compressor System (basic components)
Control Panel
- Turning the compressor on/off
- Setting foam or tool mode
- Displaying the air flow - capable of at least 140 SCFM at 150psi
- Oil Temperature - 165 to 210 degrees F normal range
- High oil temperature warning - Activates at 250 degrees F
Pressure Control Valve
- Operates compressor through a range of 60 to 150psi - Matches air pressure to water pressure (+ or - 5%)
Check Valves
- Keeps water from flowing into the air circuit
- Keeps air from pressurizing back into the pump
Air Compressor
- Rotary screw type
- Hydraulically driven off transmission PTO
- Oil cooled with thermostat and oil/water heat exchanger that uses discharged pump water to control its temperature
4 Steps to producing Compressed Air Foam - Flow Water
- Add Foam
- Add Compressed Air
- Adjust product to desired consistency
Flow Water
- Check compressor oil (sight gauge) and foam tank levels: part of pre-check
- Engage pump and establish water supply (tank or hydrant) Intake gated down to 50psi Note: Manual states 70psi
- Cannot flow additional lines when using CAF
- Flow water from discharge (Front or Rear)
Add Foam
- Turn on Husky Foam System - Adjust percentage to .2 to .5% (default is .5%) - Confirm foam solution is flowing
Add Compressed Air
- Turn on Hercules System (must be under 1000 RPM and less than 30psi air in system)
- Set to “Foam” (“Auto” on some engines)
- Confirm air pressure is building on gauge
- Open CAFS air to Discharge
Adjusting product to desired consistency (Dry)
- Initial pump discharge at 100 psi
- Gate discharge down to produce dryer foam
- Adjust foam percentage (0.2 – 0.5%) - Good dry foam can be made as low as .2%
- There tends to be a fine line between good dry CAF and a hose that pulses with air pressure
Adjusting product to desired consistency (Dry)
- Use a nozzle ball valve without the nozzle or a smooth bore tip (1 3/8”)
- Fog nozzles will strip the air - Lob foam from a distance or bank off an object if trying not to disrupt the foam blanket
Check compressor oil - Daily and after every use
- oil should be between ½ and ¾ on sight gauge
- wait 10 minutes is it was just used
Check hydraulic fluid reservoir
- Daily and after every use
- Visually inspect hoses, filter, compressor for leaks
Operate Husky 10 / 12 monthly - Prevents foam concentrate from congealing in lines
Operate compressor monthly
- Uncap CAFS Discharge
- Put in pump gear
- Open the discharge air supply valve
- Turn on the compressor
- Bring pump pressure up to 125psi while recirculating of flowing water
- Run for 10 to 20 minutes
- Monitor pump and compressor temperatures
It’s not on the F-295, but exercise the system monthly
- The more it is used, the better it works
- It keeps components and valving moving freely
There is no perfect setting for dry foam
- Each rig is slightly different
- Will require manipulation to dial the system in for good quality foam
- May require periodic adjustment while in use