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Saturday
Nov162013

Foam 109 - Blended Fuels

What is a blended fuel? In today’s modern world of concern over the environment, fuels for the internal combustion engine are blended with polar solvents at the refinery level of development. This procedure affords these mixtures a homogenous solution so that no separation occurs while awaiting use, along with the preservation of environmentally friendly chemical characteristics.

Hydrocarbon suppliers process gasoline under the Federal Specification VVG 1690 for automotive fuels. Under this rule, additives involving everything from octane boosters to detergents can be added and range from 0 to 50% or more in the final blend. This “range” of percentage allows the industry to continue to “tweak” these fuels for better performance. These additives are all in response to the EPA’s project to reduce emissions nationwide.

Our challenge is from the additives. While these fuels have been in fact, correcting the emissions issue, they also have been increasingly difficult to extinguish using traditional NFPA application rate guidelines. Another problem becomes the question of “the location” of these fuels in YOUR response area. Notifications are not required as to when and where these “blends” are used. The DOT/ERG placard also does not offer any additional information past its identifiers for 1203. Your only clues during the colder months, (in areas that have seasonal change) are the stickers located on pump dispensers, indicating the fuel dispensed to be “oxygenated.” This at least is of some assistance to the Haz-Mat responder.

The basic concept involves the addition of the polar molecule. When “blended” with gasoline or fuel, surface tension is reduced thus affecting finished Foam formation (see past article series).  “National Foam” was asked to take-part in the initial research project to design the ideal Foam concentrate for blended fuels. The end results narrowed to AR-AFFF and FFFP Foam concentrates due to their increased heat resistance and longer ¼ drain times. It was discovered that these blended fuels have a number of commonalities that are of critical concern when using a Foam attack to extinguish fires or suppress vapors at a Hazardous Material spill. These are;

1] Blended fuels burn hotter than regular fuel

2] Blended fuels have increased vapor pressure

3] Blended fuels have reduced surface tension

4] Low level polar attractiveness (blended fuels may not activate the polymeric film of AFFF)

The NFPA has three (3) application types affecting Foam distribution.

NFPA 1 pertains to the usage of “Moeller” tubes for the gentlest application usually seen on top of storage tanks. Moeller tubes flow finished Foam down to the tanks surface by way of flexible piping.

NFPA 2 utilizes a Foam chamber, also seen on storage tanks; to discharge the finished Foam from the Tanks’ chine onto the surface of the material.

NFPA 3 deals with “ground Monitors” which also includes everything hand line oriented.

One major advantage in hand line application is the trained user. Here the firefighter can “work” the Foam line around to more thoroughly cover, extinguish, and suppress the hazard. This is a desired technique, as users do not have to rely solely on the knockdown power of the Foam. Foam systems can fail for a number of reasons, all of which have no recourse. Response personnel can think fast on their feet and correct problems as they arise. Next month we will look at the importance of Foam concentrate labeling.

                Haz Mat Mike

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