Detect and suppress
FMNA’s patented system identifies and attacks the “fire triangle”
By Ray Melleady
FMNA, a division of USSC Group, Exton, PA, manufactures and installs water mist fire suppression systems for transit buses, motor coaches, small and midsize buses and also has industry leading technology to protect CNG transportation vehicles. FMNA’s system is built to protect enclosed spaces. The system is geared toward the engine compartments, battery boxes and the HVAC area.
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The company identifies the “fire triangle” as a crucial part of understanding fire suppression. The fire triangle consists of oxygen, heat and fuel. While other systems suppress fire by attacking two of the three elements of the fire triangle, FMNA’s water mist system attacks all three parts of the fire triangle.
FMNA is UL approved as a complete automatic fire suppression system (AFSS). The approval covers both suppression and detection. Testing of the system covered multiple scenarios as well as over 100 component level tests.
“Our system is unique,” says Jeff Krueger, FMNA’s director of engineering. “The suppression element knocks out the fire using high pressure environmentally friendly water mist. The mist is driven with our piston accumulator, the key piece of our system, which sends close to a 1000 PSI pressurized stream of water into a thermal event through our patented nozzle technology. The mist meets and knocks down the fire, creates steam which chokes off oxygen, and rapidly reduces temperatures below re-flash point.”
Detection is another unique element of the FMNA fire suppression system. The primary method of detection is loss of pressure (LOP) tubing. The tubing is routed around any potential risk area. The LOP system is 100 percent self-activating, failsafe, and needs no electricity to operate the system. Unlike other systems, if the bus is turned off with no operator present and a thermal event occurs, the system will still activate.
While the vehicle is in operation, FMNA’s system uses electrical output, which includes a user-friendly panel for the operator. It provides clear visual indicators to the operator that the system is active and functioning correctly, or that service is required. In the case of a thermal event, the system indicates deployment and activates both an audible and visual alarm.
The FMNA electrical systems are 100 percent output only (the system requires zero electrical input). This is an advantage of the FMNA system when compared to other systems on the market today. FMNA’s system minimizes the risk of human error.
“Our system will not accidentally activate if there are any issues due to vehicle electrical systems,” Krueger says. “This is integral to our FAILSAFE mission.”
FMNA offers multiple types of methane detection systems. These detection systems are custom designed for both large and cut-away bus applications. The systems can be either stand-alone or they can tie into the FMNA AFSS control panel. These CNG systems utilize advanced technology for detection of methane fumes.
FMNA’s methane detection sensors are designed to easily demonstrate the system status with incorporated LED indicators providing visual confirmation. The system continually monitors for fault detection. The control panel also indicates any methane detected showing, ‘zero trace’, ‘20% Lower Explosive Level’ (“LEL”) or ‘50% LEL’. The control panel also shows, ‘system ok’, ‘fault’ 20% with visual alarm’, ‘50% LEL with visual and audible alarm’ and has an optional external audible warning system. The detection system is durable, waterproof and temperature resistant. FMNA’s AFSS control panel complies with all applicable APTA specifications.
FMNA deployment cleanup
In the event of a discharge, cleanup is easy and fast. Cleanup requires simply power washing the area, flushing and recharging the system. The recharge and maintenance costs of a water mist system are superior to most any other systems on the market today. FMNA strives to always minimize the life cycle cost of any fleet.
Ray Melleady serves as managing director of FMNA North America.