IMPROVED APPLIANCE FOR LPG TRAINING
TRAINING
How often do actual LPG fires resemble the “Chrismas tree appliance” type of massive training fire with a convenient valve at the base? Not very often.
In rural areas, the standard gas emergencies are a ruptured service line, a burning service line or relief valve, or a ruptured and burning household-size LPG tank. The normal size is about 500 gallons. With this in mind, the Georgia Fire Academy went to work on engineering a better gas training appliance.
Lynn Pardue and Larry Williams of the Georgia Fire Academy got Ossie DeLay, a part-time instructor, interested in the project. DeLay then got in touch with other members of the Cherokee County fire departments, including Grady Pearson and Larry Collett, who both work with the Doxol Gas Company in Canton, and are members of the Ball Ground Volunteer Fire Department and the Circle 5 Fire Department, respectively. They in turn got together with Carl Popham of Ball Ground, J.T. Whidby of Circle 5, and Danny Hester of the Holbrook Campground Fire Department to decide what was needed. Plans were drawn up for a safe but effective training appliance that could be operated at a fire scene and give some variety to the training exercise.
The Doxol Gas Company donated a 500-gallon tank and the project was under way. The Georgia Fire Academy purchased about $470 worth of gas valves, schedule 80 piping and various fittings needed for the operational piping.
A hole approximately 3 feet square was cut in one side of the tank, both for access and to make sure a BLEVE would not occur during the training operation. The hole is on the back of the tank away from the student attack on the flaming gas. The relief valve, regulator and the line to a simulated rupture hole are manifolded together 30 feet from the tank itself, where an instructor operates the variables.
As noted on the diagram, either gas or a water/air mixture is available. The water/air mixture allows students to approach the tank in a vapor cloud but without risking actual ignition. To control the vapor cloud, the regular service valve must be shut off.
The operator also has the option of having a burning service line and suddenly opening the valve feeding the relief valve, so that burning gas goes straight up. A third line feeds the simulated rupture in the side of the tank, which is 1/8 inch by 1 foot. This line should not be opened with students near the tank. It shoots gas out parallel to the ground about 15 feet and could injure someone, as a real rupture could. If the training attack is to be on a ruptured gas tank, then it should be burning prior to the suppression effort. Its operation valve has a safety pin to prevent accidents.
The simulated rupture area is cut into the wall of the tank on the students’ side. Behind this split or rupture, a leak box was constructed of 4-inch channel iron. The box measures 1 inch deep, 4 inches wide and 12 inches long to cover the entire split length. This box was then welded to the interior of the tank, with the split/rupture centered in the 4-inch width. Piping was then attached to the box and extended to the control manifold.
The spring was removed from a standard tank relief valve, and the travel of the relief valve was restricted to 3/8 inch. With the relief valve stem threaded and a lock nut arrangement used, the valve can be adjusted for clearance and the gas opening controlled as needed. Gas piping was mounted to the relief valve inside the tank and extended to the control manifold.
Piping was also run to the standard service valve, with a bleeder and vapor equalizer valve from the interior of the tank. This valve must be operational, since the students will be using it to shut off the burning fuel.
The service line connection on the valve is equipped with a piece of ½-inch copper tube, as is normally used on these installations. After a few tests on the appliance, it was noted that this line must be secured down to the side of the tank or the flow of gas will cause the line to bend and whip around. The easiest solution was to use a piece of tube long enough to go down under the side of the tank, around the foot and then extend up the side of the tank about 12 inches to an open end.
TRAINING
The tank is engineered with all threaded piping so that it can be easily dismantled and moved for other training classes. The threading will also allow parts to be interchanged as needed due to normal wear and tear.
The appliance was first used in October 1981 at a Ninth District Fire School in Canton. All operations went well but the operator took a beating from the heat. And the students soon learned that if they watched the operator they would be aware of when a relief valve flare-up was going to occur. This took away some of the planned surprise element of the training appliance. Soon the operator was behind a temporary barricade, and students were then watching the tank rather than the operator.
From these initial operations it was also learned that the length of the piping between the manifold and the tank should be increased to keep the operator farther away from the heat and from the immediate vision of the students. With that exception, the entire operation went well and gave much more realistic training The usual Christmas tree appliance will consume about 30 to 35 liquid gallons of propane a minute, while the gas tank appliance consumes about 10 to 17 gallons per minute. This depends on whether all gas valves are open to the rupture, service line and relief valve. Therefore more burns can be made with the new appliance on the same amount of propane.
The Doxol Gas Company supplied the fuel for the initial session and the Petrolane Gas Company of Cummings the fuel for the next session. Petrolane made available to the academy for a token fee a straddle buggy so that the appliance can be transported throughout the state for other district and individual department fire schools.
Additional information on this tank appliance may be obtained from Larry Williams or Lyn Pardue at: The Georgia Fire Academy, 1112 Clay Street, Marietta, Ga. 30060; (404) 424-7315.
