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Fuel Tank Regulations

Gravity Feed Systems – Legal or Not Legal?

Transfer Flow Inc. has designed, manufactured, and installed aftermarket and original equipment gasoline and diesel auxiliary fuel systems worldwide since 1983. As a result, Transfer Flow has invested hundreds of thousands of dollars in testing and engineering to be compliant with North American regulatory agencies while maintaining engineering best practices used in the automotive industry. Many state and federal agencies regulate fuel systems, including the US Department of Transportation (DOT), the National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations (CFR), Federal Motor Vehicle Safety Standards (FMVSS), California Code of Regulations (CCR), and the California Air Resources Board (CARB), to name a few. Due to DOT ambiguity, the absolute legality of gravity fed systems remains unclear. However, Transfer Flow believes safety and legality issues can occur with gravity feed auxiliary fuel systems that may violate portions of US DOT regulation 49 CFR 393.67, a requirement of ALL fuel systems.

From a vehicle performance standpoint, gravity feed fuel systems can adversely affect federally mandated, manufacturer implemented, on-board vehicle diagnostic systems. In the case of many newer vehicles, a gravity fed system keeps the main fuel tank overfull and will likely result in a diagnostic trouble code. In addition to being a nuisance, drivers may miss valid vehicle issues because the check engine light remains on.

In all diesel fuel systems there is a rollover valve which is normally open to atmosphere. The rollover valve utilizes a combination of float weight, spring force, and buoyancy to function properly. When the float is immersed in fuel, the float (valve) closes, effectively preventing fuel leakage in the event of a rollover. The overfill tendencies of gravity fed systems leads some users to seal (effectively eliminate) the rollover OEM valve(s). In the absence of a rollover valve, the auxiliary tank will likely continue to flow fuel into the vapor space of the main fuel tank. If the vapor space in the main tank is diminished, it violates the “overfill restriction” requirement of 49 CFR 393.76(12)(i).

A properly functioning rollover valve will close when the fuel level reaches the float of the valve. Some rollover valves are designed to leak above a certain pressure to meet the “safety venting” requirements of 49 CFR 393.67(8). Capping the rollover valve causes a non-compliance with the “overfill restriction” portion of 49 CFR 393.67(12) (i) and (ii), and is also a violation of the 1990 Clean Air Act.

Safety concerns reach beyond simply spilling fuel during normal operation of gravity fed fuel systems. If the transfer fuel hose in a gravity fed system is damaged, fuel would NOT stop flowing until the transfer tank is empty, resulting in a hazardous condition, and a violation of the 1990 Clean Air Act.

In order to meet more stringent emissions requirements, new diesel pickups utilize some type of active Diesel Particulate Filter (DPF). To maintain performance, the DPF unit has to go through a regeneration cycle where in some vehicles fuel is injected into the catalyst bed of the DPF and burned. During regeneration, many DPF units reach temperatures of 600°C (1,112°F). Diesel fuel has an autoignition temperature of approximately 260°C. Fuel leaking from a rollover valve on a gravity fed system would be in close proximity to the DPF and the possibility of fire is significant. If the gravity fed system overfills the main tank by introducing fuel into the vapor space, there is a potential for fire.

Another consideration is tank pressure. Insufficient vapor space in gravity fed systems might create pressure build-up in the main fuel tank, causing fuel to leak past the anti-siphon/anti-expulsion valve thus, when removing the fuel cap, the operator may be sprayed with fuel.

We believe in the value of NHTSA’s Fuel System Integrity testing utilizing the FMVSS 301 standards. Product development confirmed by FMVSS 301 has been instrumental in Transfer Flow designing the safest aftermarket fuel tanks and fuel systems available. We are proud of our investment in crash tests, and are confident in the safety and legality of our fuel systems. Transfer Flow’s engineering staff has evaluated on-road gravity fed auxiliary fuel systems and has determined that due to safety, environmental, and legal concerns, which are inherent in the design and performance of gravity fed auxiliary fuel systems, Transfer Flow Inc. will not endorse or promote the design, installation, or use of on road gravity fed auxiliary fuel systems. Customer safety and fuel system legality continue to be our priorities after more than 175,000 fuel systems sold and more than 30 years in business.

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Vehicle Fuel Tank Regulations

In order to address the question of which federal or state regulations a fuel system must meet or exceed, it is necessary to know the particular vehicle and fuel system being used. The following information is divided into two main categories, Vehicles less than 10,000 GVW, and vehicles greater than 10,000 GVW. Be advised that this information is not intended to be a complete list, but rather a general overview.

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Vehicles Less Than 10,000 GVW

Transfer Flow inboard chassis frame and in-bed tank systems meet and exceed the OEM systems in the following areas:

  1. Transfer Flow fuel tanks are designed using, as a minimum, 14-gauge aluminized steel.
  2. Aluminum diamond plate in-bed fuel tanks are 1/8” thick aluminum.
  3. Transfer Flow fuel tanks are fully baffled unlike OEM tanks which have no baffles.
  4. Transfer Flow fuel tanks are drop tested as high as 44 feet, filled with water, and cannot leak.
  5. Many Transfer Flow fuel tank systems have been crash tested to FMVSS 301 standards.
  6. Transfer Flow fuel tanks are pressure tested for leaks.
  7. Transfer Flow fuel tank systems meet the fastener (strap) regulations specified by ANSI and NFPA, and are required by RVIA.
  8. Our fuel tank systems meet CARB, DOT and EPA emissions regulations.
  9. We design our fuel tank systems with the correct emission canister capacity necessary for gasoline applications.
  10. Transfer Flow fillneck designs meet CARB fuel fill regulations. We design our fillnecks with proper alpha and beta angles and correct inclination angles for gasoline and diesel applications.
  11. Transfer Flow fuel tank systems meet CARB and EPA requirements concerning fuel fill rates. These tests verify our fillneck systems fill at a minimum rate of 10 gallons per minute for gasoline and 20 gallons per minute for diesel.

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Vehicles Greater Than 10,000 GVW

Transfer Flow inboard mounted systems meet or exceed the following tests:

  1. Transfer Flow inboard frame rail mounted fuel systems are tested following RVIA regulations and standards.
  2. Transfer Flow fuel tanks are drop tested as high as 44 feet, filled with water, and cannot leak.
  3. Transfer Flow fuel tanks are pressure tested for leaks.
  4. Transfer Flow fuel tank systems meet the fastener (strap) regulations specified by ANSI and NFPA, and are required by RVIA.

Plus, Transfer Flow fuel systems for vehicles greater than 10,000 GVW are designed with the following criteria in mind:

  1. Transfer Flow fuel tanks are designed using, as a minimum, 14-gauge aluminized steel.
  2. Aluminum diamond plate in-bed fuel tanks are 1/8” thick aluminum.
  3. Transfer Flow fuel tanks are fully baffled on all four sides.
  4. Transfer Flow fuel tanks are pressurized to as high as 5 PSIG with air to check for leaks.
  5. Our fuel tank systems meet CARB, DOT and EPA emissions regulations.
  6. We design our fuel tank systems with the correct emission canister capacity necessary for gasoline applications.
  7. Transfer Flow fuel tank systems meet CARB and EPA requirements concerning fuel fill rates. These tests verify our fillneck systems fill at a minimum rate of 10 gallons per minute for gasoline and 20 gallons per minute for diesel.

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Refueling Tanks

Transfer Flow refueling tanks meet and exceed DOT standards for Intermediate Bulk Containers. Our refueling tanks must adhere to the following guidelines:

  1. The Department of Transportation has issued Transfer Flow Special Permit SP-11911 to manufacture and sell refueling tanks that can store gasoline, diesel, gasohol, methanol, ethanol, jet fuel and kerosene.
  2. Per US DOT SP-11911 “Safe Zone” provision, Transfer Flow refueling tanks must be mounted near the head gate in a pickup box, flat bed or utility box.
  3. Transfer Flow refueling tanks meet or exceed the testing and certification requirements specified in 49 CFR 178.803.
  4. All refueling tanks, including Transfer Flow’s, must be retested every 2.5 years in accordance with 49 CFR 180.352.
  5. DOT requires that Transfer Flow refueling tanks must be attended at all times during loading and unloading by a qualified person. Attended and qualified shall have the meanings described respectively in 49 CFR 177.834 (i), (3), and (4).
  6. A copy of Transfer Flow’s DOT Special Permit SP-11911 must be carried aboard each motor vehicle used to transport a refueling tank.

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Additional Information

  1. The 1990 Clean Air Act states that an individual owner of a vehicle may modify the fuel system only if it complies with all federal regulations. Failure to meet these regulations will risk state and federal penalties.
  2. When an auxiliary fuel system is added to a gasoline powered vehicle, the fuel must be drawn through a pipe at the top of the tank.
  3. Gravity feeding gasoline or diesel fuel from one tank to another, using a balance line, is illegal for all systems except ICC diesel systems. ICC is the abbreviation for the Interstate Commerce Commission, now known as the Interstate Operating Authority.
  4. Replacement fuel systems are acceptable as long as they meet the previously mentioned regulations.
  5. Should non compliance with FMVSS or the 1990 Clean Air Act be discovered, the owner would be liable for civil penalties up to $2,500 for each violation.
  6. Do not sleep in the bed of a truck if an in-bed fuel tank is installed inside a camper shell.
  7. Transfer Flow fuel tanks are NEVER to be used in conjunction with fuel tanks made by other manufacturers.

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Caution Information

Each Transfer Flow fuel tank system comes with a complete set of installation instructions. These instructions must be followed with no exceptions. Transfer Flow fuel tank systems must be used as intended. Always follow State and Federal guidelines for installation of fuel tank systems. Always follow existing recommendations from the manufacturer concerning fuel tank system installations. Failure to adhere to these additional Transfer Flow guidelines and instructions will invalidate all Transfer Flow warranties and responsibilities:

  1. Do not weld or torch any fuel tank or fuel system component.
  2. Always check fuel lines for restrictions or kinks. A restriction or kink can result in either fuel returning to the wrong tank or loss of power when pulling heavy loads.
  3. Always use proper venting procedures (gas cap and/or rollover emissions valves) to prevent over pressurization of the tank.
  4. Never connect a hot wire with 12 volts directly to the sending unit as this will permanently damage the sending unit resistor.
  5. Never apply more than 5 psi to any Transfer Flow fuel tank.
  6. Do not install fillnecks within 3 feet of any heat source or open flame.
  7. Do not install fuel lines within 3 inches of an exhaust system.
  8. Fuel lines should never be routed on the outside of the vehicle body.
  9. Transfer Flow fuel tanks are NEVER to be used in conjunction with fuel tanks made by other manufacturers.

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Links to Regulation Information:

http://www.gpo.gov/fdsys/granule/CFR-2011-title49-vol5/CFR-2011-title49-vol5-sec393-67
http://www.gpo.gov/fdsys/pkg/CFR-2012-title49-vol6/xml/CFR-2012-title49-vol6-sec571-301.xml
http://www.gpo.gov/fdsys/granule/CFR-2011-title49-vol3/CFR-2011-title49-vol3-sec178-803/content-detail.html
http://www.gpo.gov/fdsys/granule/CFR-2010-title49-vol2/CFR-2010-title49-vol2-sec180-352
http://www.ecfr.gov
http://www.ecfr.gov/cgi-bin/text-idx?SID=2624e667666b84323b8dcf64cacbd4b2&node=se49.5.393_167&rgn=div8
http://www.fmcsa.dot.gov/regulations/title49/section/393.67
http://www.nhtsa.gov/cars/rules/import/FMVSS/#SN301
http://www.nhtsa.gov
http://www.arb.ca.gov/homepage.htm
http://www.transferflow.com/Content/PDF/Transfer%20Flow%20DOT%20special%20permit.pdf

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