Geology Reference
In-Depth Information
New Method of Foam Generation
T
he new method of generating compressed foam, developed by Mark Cummins, in the early 1970
s is very simple
and reliable. The reason this method of foam generation is superior to other standard techniques and other fire
suppressant materials, cooling materials, swelling clays; sand grout mixtures, water slurry mixtures; liquid nitrogen
fluxion; alternate pumping of water and sand, inert gas, injection, simple backfilling is for the simple reason, that
generating compressed foam has many variables that can be changed. Compressing the foam gives us the ability to
change its properties to be a heavy, solid and dense, material to a light and fragile bubble. It was discovered that
pumping a foamable solution of dishwashing detergent mixed with water into a common
'
“
T
”
fitting, where the
second inlet of the
“
T
”
was connected to an air compressor, where the soapy water and compressed air mixed in the
“
This mixture was then discharged into a fire hose that lead to a bore hole that was drilled from the surface
down into the burning coal mine. It was discovered that the friction inside of the fire hose and pipe caused intense
mixing and compression of the foam.
T.
”
An interesting phenomenon of the compressed-foam technique was that the soapy bubbles that cling to the inside
of the hose, act like little ball bearings and caused a laminar flow of fast moving foam in the core of the hose.
This fast moving stream in the center of the hose has practically no friction loss and is able to be pumped though
extremely long hose lays or long pipelines, without deterioration. In fact, the further the foam goes, the better
it becomes.
Experimental Fires
O
ne of our early firefighting experiments occurred in the early 1980s in cooperation with the US Bureau of
Mines, Kentucky. This taught us a valuable lesson. We drilled a single bore hole into an old historical coal-
mine fire. We began pumping compressed foam in the bore hole and shortly after the first volume of wet foam
went into the combustion area; we saw a great steam column exploding from around the bore hole. Mark
thought he could see the ground bulging and several trees leaning away from the bore hole. We immediately
reduced the water content which produced very dry foam that looked like shaving cream. This insulated the
bore hole, and the steam was reduced to a manageable release. Additional bore holes were drilled to ventilate
the confined, poorly ventilated area in the mine to relieve the steam buildup. There were several other
experiments conducted in cooperation with the US Bureau of Mines, until the agency was terminated. Some
of the experiments were published, but sadly, much of the knowledge gained by those valuable experiments
was shelved, or lost.
We used the compressed-foam-injection method to extinguish a hidden source of ignition in an active coal mine,
the Pinnacle Mine near Pineville, West Virginia (Hookham, 2004). Between August 31 and September 7, 2003 a
series of explosions occurred in the active longwall district of the Pinnacle Mine. Carbon monoxide readings in the
bleeder entries of the active longwall district indicated that there was a small but active fire at an unknown location.
From the surface, the operator began drilling holes into the longwall to detect the heat source. National Institute
for Occupational Safety and Health (NIOSH) used transducers lowered into the mine to detect pressure
changes. These transducers were able to locate with pin point accuracy the position of an explosion as it happened.
This was the perfect opportunity to use compressed foam in this area.
We used nitrogen to inflate the foam in order to prevent any oxygen from being injected into the area of the ignition
source, and began pumping operations to fill the areas with nitrogen foam. We had two complete nitrogen
membrane systems and pumped two bore holes simultaneously. At each site, the foam was batch mixed at 1 or
2% in four 79 493 L (21 000 gallon) frac (fracturing) tanks (Figure 19.1.1) and pumped into the mine using a
21.2m
3
(750 ft
3
) per minute nitrogen membrane separation unit. The foam was pumped at an average rate of
about 18 927 L (5000 gallons of expanded nitrogen foam) per minute for 9 days. In total, ~68 million liters (18
million gallons) of nitrogen foam was pumped into the mine. After the foam injection, the monitoring systems
indicated the mine was safe to reestablish complete coal production.
At another very large coal-mine fire in Virginia, we used the same compressed-nitrogen method to inject over 2650
million liters (700 million gallons) of compressed-air foam and compressed-nitrogen foam to displace carbon
monoxide and toxic gasses out of the mine and into a gas recovery system which had the capability of separating
