An Introduction to Fuel Cells and Certification

Radium Engineering offers top of the line fuel delivery solutions for the motorsports market, including fuel cells. Many consider fuel cells as a simple metal container, when in fact a proper motorsports fuel cell is more complex. A basic aluminum, stainless, or mild steel container is more susceptible to fracturing in the event of a collision. This would create leak(s) and could lead to a dangerous fire situation. Even a minor fender bender or the flexing of the chassis during hard driving could create enough force to distort and crack the metal container. Fuel weighs 6.3~6.6 lbs per gallon. With a 14 gallon fuel cell that is 90 lbs of fuel sloshing, flexing the walls, and applying strain to the welds. When that much weight is subject to g-loading, the resulting forces are very large and can damage a poorly designed metal container. Furthermore, the thermal expansion created by elevated fuel, exhaust, and ambient temperatures put excessive stress on the can. Lastly, chemical compatibility, weld quality, and corrosion are concerns when using a metal container for fuel storage. In short, Radium Engineering does not recommend these types of fuel containers on performance vehicles.

Fuel cells used in motorsport racing often require FiA or SFI certification to ensure safety requirements are met. The guide below helps explain how a fuel cell works and why certification is necessary.

What is a Fuel Cell?
As shown, competition-grade fuel cells are generally comprised of three components: the outer shell (enclosure or can), the bladder (where fuel resides) and the foam baffling.
Radium Engineering fuel cell enclosures are made from lightweight aluminum, but other brands may use steel or other materials. The enclosure is the first part of the fuel cell to absorb damage and help prevent a catastrophe. This layer is similar to the construction of a helmet. The outer enclosure aids in safety but is not the most critical part. FIA and SFI specifications do not cover the outer can material alloy or thickness, only the internal bladder. Other governing bodies require a certain outer can thickness. For instance, SCCA requires a fully enveloped enclosure comprised of 0.036” steel or 0.059” aluminum.
The fuel cell bladder contains the fuel and protects from spills. The bladder must be resilient against impacts, punctures, and tears. The material also needs to be flexible enough to prevent cracking or fuel leakage in the case of impact and thermal expansion. These requirements have led to the development of different high-tech bladder materials used in the industry. Radium Engineering chose to only focus on molded polymer bladders as they have the best chemical compatibility and still meet all the structural testing requirements put forth by SFI and FiA.

The foam baffling is essentially a large open-cell sponge inside the fuel cell and serves several purposes. If catastrophic failure were to happen, this porous foam helps absorb the fuel and prevent an explosion. It also suppresses explosion potential by preventing fuel vapor buildup inside the cell. As an added benefit, it helps prevent fuel slosh which can cause fuel starvation. Fuel cell foam is a wear part and should be inspected periodically to ensure integrity. Loss of elasticity or degradation of any kind are signs the foam should be replaced.

What is FiA?
The Federation Internationale de l’Automobile (FiA) has been around for over a century. It is an international organization that promotes road safety around the world and creates rules and regulation governing all forms of motorsports. FIA's most prominent role is licensing and sanctioning of Formula One, World Endurance Championship, World Rally Championship and various forms of sports car and touring car racing.
For the safety of the driver, FiA homologation (certification) is required in many forms of racing. This covers many safety related components including fuel cell bladders. FiA has a few distinct classifications regarding fuel bladders: FT3, FT3.5, and FT5. There are other standards required by other sanctioning bodies, but FiA is the gold standard.
All of the ratings clearly define the requirements for materials, construction, and testing. The only difference between the ratings is the strength of the bladder material. All tests utilize the same procedures but the levels of certification are based on test results. FT3 is the first level requiring the lowest minimums while FT5 requires the highest. For example, Formula-1 requires FT5, but SCCA requires FT3 (although FT3.5 and FT5 are also acceptable.) Check with your sanctioning body to see what requirements your vehicle must meet.

What is SFI?
The SFI Foundation, Inc. (SFI) is a non-profit organization established to issue and administer standards for the quality assurance of specialty performance and racing equipment. The SFI Foundation has served the automotive aftermarket and the motorsports industry since 1978. Their service to the industry is a system of developing and administering various standards, certifications and testing criteria for use in motorsports.

Like FiA, SFI has a few different specification levels. SFI Spec 28.1 is the lowet and is for polymer foam-filled fuel cells. SFI Spec 28.2 is for crash resistant fuel cells and SFI Spec 28.3 is for competition fuel cells. Radium Engineering RA-Series fuel cells are certified SFI Spec 28.3.

Testing and Quality Control
Both SFI and FiA evaluate the bladder's structural integrity and perform rigorous mechanical testing including: tear, puncture, tensile, and compression.

Radium Engineering takes this process one step further. Before they leave our facility, every individual bladder is quality control tested as shown above.

Fuel cell certification expires 5 years after the date of manufacture. Check the label on the fuel cell bladder for the expiration date.

Heat, UV light, vibrations, and fuel are all factors that contribute to elastomers breaking down in a bladder. Water and alcohol fuels also can cause deterioration. Fortunately, all Radium Engineering bladders are made from a special polymer that are not as susceptible to chemical deterioration like coated fabric bladder variations (shown below) that are glued together.

However, all fuel cell bladders should be regularly inspected and replaced as needed.

Fuel cells generally require some level of maintenance. Regular maintenance ensures the fuel cell will last the full 5 years or longer in non-certified applications.
Maintenance tips: The fuel cell should be drained whenever the vehicle is stored for a long period of time. This will extend the life of the fuel cell. Alcohol is most damaging to the foam. Proper care of this part of the cell is crucial for maintenance. Foam breaks down over time and particles can clog the fuel system so it is imperative to use pre pump filtration. It is ideal to periodically replace the foam in the cell to increase cell longevity. Always follow the guidelines included with every Radium Engineering fuel cell.
Inspection: While replacing the foam, always inspect the bladder for any signs of wear, damage or degradation.

To conclude, metal box style "fuel cells" are prevalant on the discount market, however, they offer little to no engineering in regard to safety. The added cost of a certified bladder-style fuel cell can be easily justified in the event of a collision or other disaster.

Refueling options from Radium Engineering
Radium Engineering has been hard at work developing products to make fuel cell filling easier and faster. These new parts work seamlessly with the Radium Fuel Cell Surge Tank (FCST) and associated fuel cells, which have proven to be a popular fuel delivery solution for performance vehicles.

In the past, it was left up to the installer to design and fabricate a custom remote filling solution for the Radium FCST, often requiring additional parts from other companies and making something work. This new product line means the installers can purchase all parts from Radium Engineering and know everything is going work perfectly together.

Because vehicles have different priorities when it comes to refueling, Radium has released several solutions to suit most needs. With so many new products to choose from, Radium has developed this simple explanation to help select the correct products for the customer. By answering a few questions, the customer can be assured they are getting the parts they need.

Understanding Terminology
Filling of the fuel cell can be done one of two ways; "direct fill" or "remote fill". The terms "direct" and "remote" are used often when describing Radium Engineering fuel fill products. Direct fill uses a screw-off cap to pour fuel directly into the cell, while remote filling refers to a body-mounted fill point connected to the fuel cell fill neck with a large diameter hose.
                                                                                        Direct Fill Example
Example of Direct Fill                                                                                         Remote Fill Example
Example of Remote Fill"Standard fill" or "dry break" refer to how the fuel is delivered to the fuel tank from the dump can (or fuel jug). Dry-breaks are handy when refueling needs to be completed quickly in a competitive environment. No caps need to be unscrewed, and fuel is forced into the tank with gravitational pressure. In the past, standard fill options were convenient due to compatibility with common fuel jugs and gas station nozzles. However, the Radium dry-break filler's female dry-break receptacle can be unscrewed. This allows filling with a standard gas station nozzle or non dry-break spout. This is a unique feature to Radium dry-breaks.

Radium Engineering standard remote mount filler using a fuel jug (shown below).

Radium Engineering standard remote mount filler (p/n 20-0505-V) can be used with a standard gas station pump nozzle (shown below).

Radium's dry-break fuel fill connectors, shown below, are an excellent choice when refueling needs to be completed quickly. These require special dump cans and fuel cell vents which can evacuate air quickly during the filling process.

Fuel Fill Product Lineup

Radium has assembled 4 "Complete Fuel Cell Refueling Kits" as detailed below. These comprehensive kits include all parts needed to make a complete filling and venting system that works as designed. The quick fill systems will fill at a rate of approximately 20 gallons per minute using the supplied high-flow venting accessories.

The product page for these complete fuel cell filling kits can be FOUND HERE.
The complete kits include everything needed, including a dump can and vent line, to handle the refueling and venting of a fuel cell equipped with a Radium FCST. 

Other Options
If a complete kit is not an ideal solution, then a custom filling system can be constructed using the products shown below.

A fuel neck bolts directly to the top of the Radium FCST via the 6-bolt hole pattern. Several different fill necks are available for direct and remote fill applications.
All direct mount fill necks can be FOUND HERE.
All remote fill necks can be FOUND HERE.

For remote fill applications, Radium offers the two remote (body) mounted fill points shown below, one for quick-fill dry breaks and one for standard filling. Each are designed to be used with a 1.5" ID fill hose. These products can be FOUND HERE.
The two options below share the same outer "shell", meaning that the dry-break recepticle in 20-0504-V can be unscrewed and replaced with the flush-mount cap from 20-0505-V, or vise-versa. This modular design is unique to Radium products and provides flexibility in what fill method can be used.

These remote fill points feature a very small pressure equalization hole for venting the fuel cell when the main vent may be closed, such as after quick filling. These small holes have a ball that will plug them in the event of a roll-over.

Proper venting is an important part of fuel cell refueling. Fuel can only get in as fast as air can get out. Large high-flow vents are needed for quick filling. A Dynamic Safety Vent (DSV) valve not only offers venting of the fuel cell, it closes the vent in case of rollover, preventing fuel loss. The Radium internal high-flow DSV (P/N: 20-0535) features a floating ball that closes the vent when fuel level reaches a certain calculated point, stopping fuel flow into the cell. This prevents over-pressurizing of the cell during gravity-powered quick filling.
An external vent such as 20-0462 will not automatically shut off fuel flow at a calculated point and is more suited for systems needing a high-flow vent, but without the aut-shut-off control.

NOTE: Radium increased the vent port size on the FCST December 2018 to make it compatible with quick filling. For older 20-014X-XX FCST units that want to use quick filling, an additional vent needs to be added. See part number 20-0439 below. The vent kits are a convenient solution for plumbing a vent line from the fuel cell vent port to outside the vehicle.
Dynamic Safety Vent valves can be FOUND HERE.
Vent Kits can be FOUND HERE.

The accessories below can be useful when putting together a custom system, or when replacement parts are needed. They can be found on various product pagesHERE.

Please contact for assistance with selecting products.

VIDEO: JTP Drifting the Radium Turbo Elise

Here is a test and tune session with Portland Speed Industries at an abandonded lumber mill in Packwood, Washington. Our long-time friend, Pro Drifter Justin Pawlak (JTP) was on hand to give our car a good work out. He did very well putting on a show despite several characteristics that make the Elise a less than ideal drift car.

More information on this event can be found here.