By Greg Roche on

Compressed natural gas (CNG) is a commonly selected fuel system for natural gas vehicles. CNG is simple to operate, offers flexibility to scale fuel storage capacity, and is easy to refuel. Truckers will want to know how CNG fuel systems function so that they can make the right selection for their trucks.

CNG is stored on the vehicle as a pressurized gas. This requires the use of special high strength cylinders. If you are a SCUBA diver, think of large SCUBA tanks made of high-tech composite carbon fiber. Fuel is passed from the cylinders through a high-pressure filter to remove any water or heavy oils in the fuel, and through a pressure regulator to reduce the pressure to the level needed for the engine.

Fuel capacity is measured in diesel gallon equivalents, or DGE. In sizing a fuel system, fleets need to know that the last approximately 10% of fuel needs to remain in the tanks to support enough fuel pressure to run the engine. In addition, CNG heats up and expands a bit while the tanks are being filled so that a little less than full fill is reached after the warmed gas cools down. The combination of these two effects means that the usable fuel capacity is about 80% to 85% of the nameplate DGE capacity of the fuel system. A CNG system with a rated 100 DGE capacity will deliver 80 to 85 usable gallons.

CNG fuel systems do weigh more than diesel tanks. The extra tank weight is offset by some weight savings since the DPF and SCR systems on diesel trucks are not used on CNG trucks. There is also a 2,000 pound weight allowance for alternative fuel vehicles allowing a GVW of 82,000 pounds, so overall there is little to no weight impact on hauling capacity in most applications.

Continue reading to learn about CNG fuel systems available from Agility, Momentum and Quantum.

Agility Fuel Solutions

Agility® Fuel Solutions is the leading global manufacturer of composite CNG cylinders and CNG fuel systems for commercial vehicles, having provided product for over 60,000 trucks and buses worldwide. Agility is headquartered in Costa Mesa, California, and is a subsidiary of Hexagon Composites, a publicly-traded company with global operations and headquarters in Norway. Agility has over 500 employees focused on clean transportation for commercial vehicles, including over 70 engineers.

  • CNG Freightliner Cascadia sleeper with Agility ProCab and ProRail CNG fuel systems

For the CNG truck market, Agility offers a family of ProRail™ frame rail mounted fuel systems ranging from 17 DGE to 60 DGE in capacity. Agility also offers a family of ProCab™ behind-the-cab fuel systems ranging from 60 DGE to 175 DGE. These compact, lightweight systems can be combined in a modular way to provide up to 295 DGE for long-range applications. Agility’s products are designed for high performance, durability, and reliability, with pressure relief devices for fire safety, integrated crash protection, and vibration isolation. Because Agility supplies major truck OEMs’ factory-line CNG programs, Agility’s products have gone through extensive OEM product validation including crash testing and durability track testing for over 1 million simulated miles. Optional Blue iQTM features include an in-cab gauge with accurate distance-to-empty and driver feedback, as well as diagnostics and parts & service documentation integrated into Cummins Insite™ and QuickServe® Online. Agility also has a full-service customer care group that provides parts, service, warranty support, and CNG training across North America to help fleets get the most out of their CNG trucks.

  • Agility’s carbon fiber composite CNG cylinders

Contact Les Stinson
(949) 233-8875

Momentum Fuel Technologies

More Range, Less Time at the Pump
In an industry where time is money, every moment counts. Momentum’s CNG fuel systems are engineered to increase driver confidence, reduce range anxiety and eliminate the need to make continual top-offs on the road.

Significantly more range than similar capacity competitor systems

Exclusive GreenLync™ technology that provides real-time information to drivers on the road and fleet managers at home including a live pressure reading, temperature-compensated fuel level and distance-to-empty

Greater Aerodynamics
To maintain truck aesthetics and increase fuel efficiency, we obsessed as much over the design details as we did the system function.

Systems are aerodynamic and match OEM designs so they look as good as they perform

Durable, lightweight construction designed to decrease maintenance and downtime

Contact Ryan Waltz
Regional Sales Representative – Momentum Fuel Tech

  • Back of cab and side mount systems

Quantum Fuel Systems

Beyond Zero and Quantum Fuel Systems
Quantum’s Q-Cab and Q-Rail CNG storage modules are integrated CNG fuel systems for heavy duty truck applications. The Q-Cab product line is installed behind the cab allowing for a larger capacity of CNG (and available in 123 DGE, 160 DGE and 180 DGE). The Q-Rail product line is installed on the traditional open rail-space of the truck (and available in 42 and 46 DGE).

Both systems have integral fuel receptacles, pressure relief devices, pressure gauges, fuel metering subsystems (including pressure regulator and thermal management) and a single harness truck-wiring interface to utilize the Original Equipment Manufacturer (OEM) fuel gauge. Additionally, both modules are equipped with Quantum’s proprietary, ultra-light Q-Lite® CNG storage cylinder, which minimizes weight, while increasing fuel capacity.

And we stand behind what we sell. Our service group has regional representatives on call to support our warranty repair centers. When you call we move into fast action.

Contact us today to discuss how we can help you make the move to CNG!

Contact Clean Energy today and learn more about our Incentives & Grants at 949.437.9064 or