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Foam Storage & Compatibility for Non-Fluorinated Foams, Gels, and Powders

There are many issues needing review for firefighting Foams when moving from fluorinated to the new non-fluorinated versions. Storage in existing tanks previously dedicated to fluorinated products, intrinsic “workability” of the tanks structure, volume enhancements needed for plant expansion, pump capacity and lines, exterior seals to environment, and automated monitoring updates. But let’s start with the basics.

As always, long term storage of various types of Foam concentrates mixed together is not recommended. Due to chemistry differences, one can never be sure changes detrimental to appliances and bubble formation will not occur under changing environmental conditions. Since conditions vary, this practice as a general rule is discouraged. Foam storage tank material can only be accurately assessed by your Foam concentrate manufacturer. Important Note: Failure to install the correct tank materials that come into direct contact with the Foam concentrate in storage can result in contamination and performance issues in the final Finished Foam application.

Fluorinated Foam concentrates are excellent firefighting foams, but are biologically persistent and therefore have negative environmental impacts. For a number of years these compounds have used long-chain Fluoro-surfactants causing this issue. In 2006 the EPA established a voluntary stewardship program to reduce the use of these “long-chain” elements because of the bio-accumulative toxic problems. By substituting “short-chain” Fluoro-surfactant elements in Foam, 40% more volume was required to meet UL (Underwriters Laboratory) UL 162 standards for firefighting. Thus, this trade-off was not positive. The solution was to create a halogen free Foam concentrate. The creation of “Green” Foams for firefighting and hazardous material vapor suppression satisfied both issues. The resulting product created firefighting performance and environmental compatibility.

The initial question for storage sites is to replace old with new or, use existing up first? Cost for business minds is always foremost, so let’s start from “after” the older Fluorinated Foam concentrates are gone. To insure “trouble-free” storage and future application during an incident there are number of elements to evaluate. These range from tank integrity, location, volume, pumps, transport lines, exterior seals, all the way to automated monitoring.

Once your storage tank has been emptied and is free from all halogenated Foam concentrates a thorough interior tank cleaning and inspection should be considered. Not only will a power-washing remove remaining cross-contaminants from the older product, but it affords an acute inspection of the interior of the tank walls and bottom. Check all interior surfaces for corrosion and tank course thickness against the original designed needs. If these measurements fall below your standards replace the damaged tank course shell (section). Do not forget to check the proper conical shape of the tank bottom as well as material thickness. Is the slope the same? Are there any indentations from load or pressure over the years? New advances in ultra-sound technology now have the ability to evaluate tank wall thickness due to corrosion or damage from the outside walls of your existing tank. This should limit any dangerous confined space entry to evaluation of the tank bottom interior. Any deviations found from the original design/construction should be properly replaced or serviced by a storage tank fabricator.

Once corrections have been made, consider your site. Storage tank location is critical to both loading and unloading. Over the years have your plant facilities grown? Is there a more centralized position to newly added fire hazards? Foam storage tank re-placement may benefit your facility if it is of equal distance to all fire hazards. A long transfer of product could be interrupted during an emergency in multiple places that are impinged by fire. Can the plumbing be more protected if placed under ground? These fail-safe operations should be considered before final placement is made. The goal is to have a system that cannot fail under any disaster situation. Is tank movement a possibility? Designed portable tank(s) could be moved to new platforms accommodating the facilities site, depending on projected growth and future plans. Should you increase Foam storage tank volume to match site/hazard growth? If your hazard volume has increased, you must be sure that you have enough Foam concentrate on hand to deliver to multiple tanks that are involved in fire. A change in storage tank location may be for you. What about needed upgrades in transfer Foam concentrate plumbing? If hazard volume has increased, do you need more or a larger supply transfer line(s) from storage tank to your induction process? Does this need adapt to newly constructed roadways or improvements? If roadways are in the plans, make sure that your system does not need to be off-line while road construction is being completed. This can often take your system out-of-service for long periods creating extensive unsafe protection issues. Loading areas may now be in the way of other plant operations? In the advent of a major fire situation, is your storage tank loading area free from plant operation obstructions allowing frequent replenishment of incoming Foam concentrate? All of these issues should be considered before final storage tank placement is decided. Once your storage tank is completed you will have to work around any of these problems, during an emergency.

Once these issues have been worked out, be sure to check for the appropriate exterior tank hatch seal material of your Foam concentrate storage tank. This should have been done on a bi- or annual basis from sample testing. According to your facilities SOP (Standard Operating Procedure) a sample of concentrate stored should be taken from your bulk storage tank and sent to the Foam Company’s lab for analysis. This procedure informs you of the intrinsic safety of the exterior tank seal against environmental affects or contaminants.

Auto-monitoring leak detection is an excellent upgrade for needed future tank leak/security issues. With automated leak detection in place, an operating facility can now have real-time data analysis of tank integrity and quick response to any leakage minimizing Foam concentrate product loss. Automated tank leak detection is the best way to assess problems as they happen.

When storing large volumes of Foam concentrate, bulk storage accomplishes two (2) main goals.

1] Eliminates the need for on duty emergency response personnel to load and transport five (5) gallon containers to the induction site, and

2] The pump transfer, Eduction, and application are immediate and unmanned yielding a fast response and a safer one for emergency response personnel.

As flammables must have an automated Foam application system in place anyway, an additional automated system for Foam concentrate supply to the induction system just makes sound sense.

Before the Foam concentrate is loaded into your tank, consideration of proper exterior ventilation and tank opening seals should be evaluated. Improper seals on containers of Foam concentrate are the same as leaving a can of paint open. Foam manufacturers have a complete system for proper sealing of Foam concentrate storage tanks. If yours does not, you should change Foam manufacturers. NFPA 1901 has storage tank recommendations that will assist this process. There are four (4) basic components that should be present in any Foam storage tank system;

1] Minimal air to concentrate interface, is the concept of always attempting to keep your storage tank as full as possible. This concept minimizes air to concentrate interface, resulting in no or minimal “skinning over” on the concentrate surface. Drying or “skinning over” in this manner will negatively affect all appliances and finished Foam application.

2] Inner protective screen, this shielding of the raw Foam concentrate from particle contamination that can occur whenever sampling or general human monitoring is done. Objects of contamination are restricted from entering the concentrate tank and negatively “tainting” the product.

3] Air tight hatches, must be sealed with the appropriate seal material such as Buna N or an EDPM gasket composition. Check with your manufacturer for the proper gasket material to install.

4] Lastly, a pressure/vacuum relief device permanently affixed to the exterior of the air tight hatch cover. This enables the tank to adjust automatically to changes in pressure or vacuum when filling or withdrawing Foam concentrate from the tank. This device should only allow air movement with natural pressure changes due to temperature. No direct openings to the atmosphere are allowed, such as overflow tubes or other open pathways to the environment.

 Storage is critical to deliver a quality finished Foam blanket for the successful outcome of your emergency incident, always consider your storage. 

         Haz Mat Mike

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