Maintaining proper storage conditions is vital to ensuring the lifespan of firefighting foam. Each foam manufacturer has recommendations in their product’s technical datasheet that typically discuss storage material, storage temperature, and any other special considerations for storing the foam. Understanding how each of these items impacts the foam can help identify potential problems before they happen.
Storage Materials
Firefighting foam should be stored in its original shipping container or in a container designed for foam storage. Foam manufacturers recommend a variety of construction materials including specific types of fiberglass, polyethylene, stainless steel, carbon steel pipes and aluminum.
The technical data sheet for the foam being stored should be consulted before choosing a storage container since each manufacturer recommends specific materials depending on the product. This is due to the fact that each firefighting foam formulation can vary in composition with the ingredients being used reacting differently with the materials. Any foam concentrate piping needed should also be in conjunction with the manufacturer’s recommendations. Specific types of brass, stainless steel, plastic and black iron are all common types.
One type of material to avoid is galvanized piping. When galvanized piping is in contact with foam concentrates, corrosion will occur. This corrosion can impact your foam’s performance as any metal ions picked up in the foam can impact the surfactant similar to how hard water can affect your household soaps. Whenever sampling a foam for annual testing, it is best to avoid any possible metal ion pickup that could impact your results.
To take a good representative sample of the foam concentrate, avoid collecting foam that has been sitting in the piping by either running an adequate amount of foam through the pipe first or by taking a sample directly from the storage container.
Storage Temperature
Along with what material the firefighting foam comes in contact with, the temperature at which the foam is stored is also important. Again, each manufacturer has recommendations for storage temperatures based on their formulation. Any deviation from their guidelines can lead to a reduction in the foam’s lifespan.
Specifically, excess heat can be a big problem for firefighting foam. Heat can provide the necessary energy for reactions to happen and for ingredients to break down or separate. Surfactant breakdown in a foam will lead to lower foam performance. Care should also be taken to avoid any possible freezing of the foam. Some foam manufacturers claim their product shows no loss of performance after thawing but others recommend that the product be inspected after thawing. It is best to avoid freezing the concentrate but if it happens, the concentrate should be inspected for any possible separation.
If there is some concern about the foam’s performance or separation, sending the sample in to Dyne for testing would be beneficial to help ease any fears. Note that there are freeze protected foams manufactured if cold weather is a concern. These foams are specifically designed for cold climates and will freeze at a much lower temperature than standard foams.
Special Storage Considerations
The technical data sheet for firefighting foams will also discuss any other special considerations that should be taken into account when storing and handling the concentrate. Evaporation of the solvent in the concentrate is typically a concern addressed. Often manufacturers will recommend minimizing evaporation by sealing the tank or applying a layer of mineral oil. When sampling for the annual concentrate test, mineral oil should be avoided when collecting the sample. Mineral oil is not designed to perform like firefighting foam so the performance results could be impacted.
Another special circumstance to consider is foam compatibility. It typically is recommended that each tank be filled with the same product of foam throughout. If the need for topping off the tank occurs, consult the product’s technical datasheet for compatibility recommendations with other types of foam. Some manufacturers claim their product can be mixed with various types of foams while others do not recommend mixing. If the foams are incompatible, the ingredients can react with each other, thus changing the chemical’s properties and resulting in decreased performance. If two foams are being mixed, also ensure the equipment is listed for both concentrates. When sampling for the annual concentrate test, if a color or viscosity difference is seen between different areas of the tank, this can be a good indicator that different foams have been mixed. While it is recommended to test different areas of the same tank during the annual test to ensure the tank is uniform throughout, it is imperative that different areas of the tank are tested if different foams are mixed to ensure neither has reacted with the other.
Foam is often stored for several years and sometimes decades. Having a better understanding of how this storage impacts the concentrate’s chemical ingredients can help eliminate any potential problems that can reduce the foam’s lifespan. This article discussed general guidelines for foam but each foam is unique. Consulting the firefighting foam’s technical datasheet or the manufacturer’s technical services can provide more information specific to your particular foam.
Any actions taken should be in accordance with NFPA’s storage requirements or any other overriding standard that might be in effect. Contact a Dyne chemist at (800) 632-2304 or lab@dyneusa.com to get help finding specific data sheets or obtaining manufacturer contact information.
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