Foamex Polyurethane Safety Foam has a 30 year record, built on combat experience, of suppressing explosions in military aircraft and land vehicles. It adds minimal weight, reducing usable fuel by less than 4%. Because it is a passive, maintenance-free system, Safety Foam is always active, allowing the pilot or operator to concentrate on his primary assignment. This increases the survivability of the air-craft or vehicle. Safety Foam is a fully reticulated, flexible polyurethane foam composed of a skeletal matrix of tiny lightweight interconnecting strands. These act as a three dimensional fire screen. The material is a passive, self healing, explosion suppression system capable of withstanding multiple hits. It is always on guard — no gauges to check, no leaks, no mechanical malfunctions. Foamex Polyurethane Safety Foam is a combat proven system, refined from experience, that will help prevent fuel explosions caused by:

• Gunfire
• Electrical Ignition
• Lightning Strike
• Static Discharge

Proven Success Through Evolutionary Development

Early Development—The United States Air Force has successfully used Foamex Polyurethane Safety Foam to suppress fuel tank explosions in combat and special mission aircraft since 1965. The original concept of fully packed Safety Foam (Type I, orange) reduced fuel volume by 4% (displacement and surface fuel retention) and increased net weight approximately 0.08 lb. per gallon of tankage compared with today’s designs that increase net weight only 0.03 lb. per gallon or less in gross voided systems.

Lighter Weight Safety Foam—In 1970, Foamex developed lower density Type II (yellow) and Type III (red) polyester polyurethane Safety Foams. Type III’s finer pore size enabled the use of gross voiding techniques. The foam’s lighter weight, combined with new voiding techniques, offered a weight reduction of up to 25% and, depending on the voiding method used, lowered fuel displacement and fuel retention. Compared to the original fully packed (Type I, orange) technique, the new development allowed customers to reduce foam use by up to 70%.

Longer Life—In 1974, the United States Air Force, in conjunction with Scott Paper Company (Foamex Technical Products Group’s previous parent company), initiated the development of new polyether Safety Foams. The new polyether polyurethanes, offer substantially better hydrolytic stability than polyester type foams and increased service life. Since these foams could exceed the expected service life of many aircraft, the use of polyether Safety Foam can eliminate the cost of foam retrofitting often necessary with polyester Safety Foams. 

Conductive Safety Foam—Beginning in late 1980, the Air Force began to experience a series of static ignitions in A-10 and C-130 aircraft. While no aircraft were lost or serious injuries sustained, there was mounting concern over the increasing number of ignitions reported and the maintenance time required to replace burned or scorched foam. 

Foamex and the U.S.A.F. spent extensive time investigating the problem and determined that the electrical resistivity of Type IV and V blue polyether polyurethane foam was one of the contributing factors. 

Responding to customer’s needs, Foamex Technical Products Group developed the first state-of-the-art conductive foam for use in fuel cells. So unique was this material, Type VI and VII CSF 204 Beige Conductive Safety Foam, that the company was awarded U.S. patent 4,578,406 for the new concept. 

Foamex Polyether Polyurethane Conductive Foams have been 100% successful in solving the electrostatic ignition problem. From 1988–1994, Foamex developed black and dark grey FSX and FSX2 (Inherently Conductive Safety Foam), to meet the demanding Class 1 environmental conditions of 0°F. 

Lower Cost—Recent studies have substantiated that improved manufacturing techniques provide safety foam products that exhibit up to 50% less fuel retention than the maximum allowable in MIL-B-83054B and MIL-F-87260. This means that Foamex Safety Foam, together with the latest gross voiding techniques, provides a cost-effective product compared to earlier types. Also from a weight/volume penalty aspect, the new polyether polyurethane Safety Foams should provide an overall system that offers equal or lower life cycle costs than complex OBIGGS, (On-Board Inerting Gas Generating Systems) or other gas systems such as the LN2 (liquid nitrogen) with its ground logistics requirements. 

As quoted from Air Force Wright Patterson Aeronautical Report AFWAL-TR- 85-2060, "Life Cycle Cost Analysis, based on best available data and projections, revealed that the OBIGGS costs would be about seven times higher than foam, that foam would be comparable to liquid nitrogen systems, and would be one-third the cost of Halon Systems." Safety Foam is the clear cut, cost-effective choice!

Foamex Safety Foam: A Passive System, Always on Guard

Safety Foam is always there, always "turned on," and has the following advantages:

• No moving parts
• Nothing to turn on or off
• No pressure lines
• No pressure relief valves
• No explosion sensing devices
• No functional components to fail, maintain or monitor other than periodic inspection
• No pilot distraction
• No need to handle the logistics of large quantities of LN2 and the special safety requirements during refueling
• No failure modes if properly installed
• No corrosion from powders
• No metal mesh to leave filings that plug filters and injectors
• No onboard high pressure storage vessels to protect

Safety Foam is a passive security system, always there to reduce vulnerability and increase survivability.  The new Foamex Polyether Urethane Foams are easier to install (pack) in fuel tanks than the earlier foams because their volume swell characteristics permit the undersizing of foam components. When fuel wetted, the foam swells approximately 6% - 12% by volume to completely fill the tank cavity.

Foamex Polyurethane Safety Foam Attenuates Fuel Sloshing

As a surge mitigator, it attentuates sloshing fuel and in some cases eliminates the need for structural baffles in the tank. Safety Foam gives the fuel a smooth sine wave motion and helps prevent sudden redistribution of mass. It acts as a hydrodynamic ram suppressor reducing the possibility of fuel cell rupture.

Foamex Polyurethane Safety Foam Acts as a Foreign Object Debris (FOD) Barrier

As a lightweight, easy to install barrier, the skeletal foam structure acts as a natural roughing filter; it can prevent the movement of loose debris from one compartment to another inside the fuel system. The wetting characteristics of reticulated foams (open pore) are a function of porosity; a finer pore size will retain more fluid than a coarse pore foam at a constant density. The finer pore foams, (Type III, Type V and Type VII), are designed for use where total tank voiding exceeds 40% by volume. Finer pore size foams offer improved inerting performance, when combustion, void volume, foam thickness, and initial pressure limits are not exceeded. 

Foamex Safety Foam Offers Easy Installation

A comparison demonstrates increased volume swell (in fuel) characteristics of polyether polyurethane Safety Foams. In practice this can create new efficiencies in packing (installation) since these foams may be installed slightly undersized (2% to 4% lineal) into fuel tanks. When fuel wetted, the foam expands to full fuel tank configuration size. Safety Foam can be fabricated into parts of various shapes and sizes for installation into intricately shaped fuel tanks. It can be easily fabricated to fit around sensors, vents, and other fuel tank hardware. Also Foamex Polyurethane Safety Foam is currently in wide use with flexible bladder tankage systems.

Conductive Safety Foam— State-of-the-Art

With Foamex’s introduction of state-of-the-art Conductive Safety Foams, the problems and concerns of electrostatic ignitions are a thing of the past. The product has been fleet tested in military aircraft, such as the C-130, P-3L, and A-10, under the most severe Arctic conditions. Not a single instance of aircraft static ignition has been reported since the inception of critical testing in 1986. 

New Black FSX Type VI and Dark Gray Type VII Conductive Safety

Foam offers maximum benefits and protection:

• Virtually no electrical activity in temperatures from -30^oF to +160^oF.
• Greater service life — an accelerated aging laboratory hydrolysis test indicates a potential life of 5 to 10 times that of polyester polyurethane foams, and equal to polyether polyurethane foams. Aircraft with Foamex polyether polyurethane foam have now been flying for 19 years without a reported instance of foam failure due to hydrolysis.
• Greater low temperature flexibility than polyester-based urethane foams.
• Anti-fungal characteristics as part of the conductive treatment an option.
• Ballistic and flame tube testing indicate that polyether-based urethanes are equal to polyester foams of the same pore size and density in explosion suppression characteristics. 

MIL-B-83054B

Foamex polyurethane Safety Foam Types I, II, III, IV and V all meet the requirements of Military Specification, "Baffle and Inerting Material, Aircraft Fuel Tank" MIL-B-83054B and Amendment 2 dated 7 March 1984. 

MIL-F-87260 (U.S.A.F.)

New Foamex FSX and FSX 2 (Types VI, VII) Inherently Conductive Polyurethane Class 1 Safety Foam meets all the requirements of military specification MIL-F-87260 titled "Foam Material, Explosion Suppression, Inherently Conductive, for Aircraft Fuel Tank and Dry Bay Areas," dated 7 February 1992. "Reticulated Polyurethane Foam Explosion Suppression Material for Fuel Systems and Dry Bays." Copies of MIL-B-83054B and MIL-F-87260 in their entirety can be ordered free of charge from the Naval Publications and Forms Center, Philadelphia, PA 19120.

SAE AIR-4170

Complete guidelines for installation and other Technical Data reported by the Society of Automotive Engineers are available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Telephone (412) 776-4841.

Other Uses: Foamex polyurethane Safety Foam has been used in the flexible bladder-type fuel tanks of racing cars to reduce surge, to improve handling, and to help prevent explosion in serious crashes. In boats, Safety Foam is used for baffling in fuel tanks to reduce fuel surge and slosh, thereby significantly improving performance. It also is used to provide traditional explosion suppression protection. Safety Foam is used in special purpose aircraft to reduce fuel surge in stunt and agricultural dusting craft, and to help protect against possible explosion from lightning strikes on weather reconnaissance planes. Foamex polyurethane Safety Foam is used in stationary fuel storage tanks and sumps to reduce the risk of explosion. Other applications include flashback protection in gasoline can filler spouts. Safety Foam has been used for discrete armored vehicles, presidential limousines, military wheeled and tracked vehicles, as well as in service station island pumps.

For more information or to request a sample(s) contact:

TECH LINE 1-800-767-4997 
techline@foamex.com