What is a foam fire suppression system and what makes it important?
A foam fire suppression system is much like a wet sprinkler system in that stored water flows through a network of pipes where it is then discharged through nozzles. It combines both water and a foaming agent for large scale fire extinguishment. This water-based fire sprinkler suppression system can extinguish extensive fires in mere seconds with incredible efficiency.
A foam-water system is a special system of pipe connected to a source of foam concentrate and water supplies. Piping is connected to water supply through a control valve, such as deluge, wet, dry, preaction or flow control, that is operated by automatic detection equipment that is installed in the same areas as the discharge devices.
Types of foam suppression systems
There are 3 different types of foam suppression systems:
- Low expansion
- Medium expansion
- High expansion
Low expansion foam solutions are easily discharged through a variety of devices, while medium and high expansion foam solution can only be discharged through special generators.
The codes and standards of foam systems can be found on the NFPA website (NFPA 11), which covers the design, installation, operation, testing, and maintenance for all three types of foam systems.
How does a foam suppression system work?
Foam fire suppression systems work by separating the fuel from the oxygen. These foam systems are used to cool the fire and coat the fuel that the fire is consuming to prevent contact with oxygen and reduce combustibility.
The extinguishing agent, in this case the foam, smothers the surface of the fuel. The water content of the foam then cools the fuel and the area of foam covering the fuel to prevent reignition via flammable vapors.
While low expansion systems form a film or skin across the fuel or object surface, high expansion system’s achieve fire control and extinction due to rapid smothering and cooling.
What are the advantages of foam systems?
When a fire ignites, it will continue to burn as long as both the fuel and oxygen are present. With separating the fuel from the air, a foam fire suppression system can effectively extinguish a fire.
A foam sprinkler system uses a mixture of water and low expansion foam concentrate, resulting in a foam spray being released once the sprinkler has been activated. This makes them great for environments which use flammable liquids as the foam will suppress the fire.
The latter also has a positive impact on the environment as it saves the amount of water used versus a fire sprinkler system.
Foam is more effective at putting out hotter fires due to its ability to cool a fire quickly. The rapid extinguishing of fires means less property damage due to fire.
What are the disadvantages of foam systems?
Cost and clean up.
Foam suppression systems are known to be more costly due additional materials, equipment, and foam, not required in a standard fire sprinkler system.
They can also be messy to clean up due to the foam dispersed to extinguish fires.
What type of facility can benefit from a foam suppression system?
Foam systems are beneficial in hazardous areas such as:
- Refineries
- Chemical plants
- Flammable liquid storage
- Warehousing
- Aircraft hangers
- Helidecks
- Tanker loading racks
- Paint spray booths
- Diesel generator rooms
- Loading jetties
- Recycling facilities
Other facilities where water is not an option.
Foam Systems Impact the Environment
Fluorinated foams are a synthetic-based foam that contains fluorinated and hydrocarbon-based surfactants, including perfluoroalkyl or polyfluoroalkyl substances (PFAS). These fluorinated foams such as AFFF’s, are known to have a negative impact on the environment.
It has been previously shown that the same properties that make AFFF excellent at extinguishing fires also make them persistent in and harmful to the environment. This has led to extremely adverse health effects on land and water, but also to human lives. Some states in the United States have started to implement strict regulations on the use of AFFF and others have banned it altogether. They have however changed its formulation over the years with six or less carbons to reduce potential toxicity.
The alternative to AFFF in the ever-changing environment is fluorine-free foam such as SFFF.
Since there aren’t any PFAS in fluorine-free foam, it does not form an aqueous film to extinguish fires like AFFF and relies on a blanket of bubbles. This blanket of bubbles has been proven to be slightly less effective than AFFF’s film, however, the foam is non-corrosive, non-toxic, and biodegradable. Fluorine-free foam requires more volume and special equipment to make it effective, but doesn’t pose any risk to the environment
While the type of foam and its impact on the environment might be one to consider, remember as discussed in our blog post last month, fire protection itself is considered as a sustainable practice and has a positive impact on the environment.
The aim of fire protection systems is to protect a building’s occupants and minimize the damage associated with fires, by extinguishing or controlling fires, and preventing them from spreading. Preventing, extinguishing, or controlling fires reduce greenhouse gases, carbon dioxide (CO2) emissions and other greenhouse gases.
Whether you choose AFFF or SFFF the clean-up requirements are the same.
