Evaluating Booster Tank Use While Getting Water Supply
The Volunteers Corner
What does a 500-gallon—or any other size—booster tank mean in terms of time and what can you do with that time on the fireground? In a variety of ways, booster tank water can put a stream into operation quickly while buying some time for you to set up an adequate water supply in areas without a hydrant system.
Dividing the number of gallons of water in the booster tank by the flow rates of various size streams will give you the number of minutes that a tank will supply each size stream, but that is only half the solution to hose stream problems. The other half is the determination of how long it takes men in your department to stretch lines, set up master stream equipment and provide an adequate water supply.
The time measurement that is basic to all others is the time the second-due pumper or the first-due tanker or hose wagon takes to reach different areas in the first-due pumper’s district. The difference between the response times of the first-due pumper and the other companies is, of course, the length of time the first pumper has to wait before the work of increasing a fireground water supply can get under way.
Checking response times: There are two ways you can determine average response times. If your operating procedure requires each company to notify the communications center—by radio or an electronic response device—and to radio its arrival on the fireground, then the communications center can provide the data you need. Otherwise, you can make timed runs with a car to representative sectors of each company’s first-due district and some more runs representative of the second pumper or first tanker or hose wagon. These test runs by car at allowable road speeds will be somewhat slower than runs made by apparatus under response conditions, but at least the test times will have a built-in safety factor.
The time difference between the arrival of the first pumper and the next plus the time it takes for the second-in piece to provide an additional water supply becomes the length of time a fire attack must depend on booster tank water in areas without hydrants.
If all companies respond from the same station on the first alarm, then we are talking about an inconsequential time lag between the first-in and other companies. In this case, a line—or lines—on a fire must depend on booster tank water only for the length of time it takes to set up an additional water supply either by pumper relay or tanker shuttle.
Operational time checks: Once you have determined representative response time lags between the first pumper and the other units, then you can identify an average time lag. Where runs are long, you should also consider the maximum time lag. With these figures determined, you now have to get some average times for putting various size lines or streams into operation and for establishing a continuous water supply.
You’ll be on the safe side to ignore the time it takes to put a 1 1/2 or 2 1/2 -inch preconnected line, or even a deluge gun mounted on the pumper, into operation because that can be done in less than a minute. If any of these operations take longer under unusual situations, then the booster tank water will last a bit longer from the time the pumper stops on the fireground.
What you do have to measure is how long it takes to establish a pumper relay with 1000, 2000 or more feet of large-diameter hose, how long it takes to get first water with assurance of continuation with a tanker shuttle, and the time necessary to set up master stream equipment. For example, whatever time it takes to set up a deluge gun 300 feet from the first-in pumper to protect a rear exposure leaves that much more time before a continuous water supply must be established.
Clocking operations: When you time the various fireground operations mentioned during a drill, make certain that the men work efficiently and quickly but without undue haste. Above all, no one should run for any reason, just as they must not run on the fireground.
The number of men participating in the evolutions you check for time should be the number you can reasonably expect to be available at any fire. It would be deceptive to have five men put a deluge gun into operation at a timed drill when you can expect only three men to be available at a fire.
How does the first-in officer use this information? If his pumper has a 500-gallon booster tank and it will take 10 minutes to set up a tanker relay, then the officer has to decide whether the fire can be darkened down and kept from flaring up with 500 gallons of water, or whether he must protect exposures for 10 minutes with a 50-gpm stream while waiting for a water supply to be established.
On the other hand, with the same pumper and a 2000-gallon tanker immediately available, the officer might attack a fully involved barn with a 500-gpm stream from a deluge set if the next tanker could be expected within four minutes. If it took three minutes to position the deluge gun a couple of hundred feet from the pumper, the officer would then have three minutes of deluge gun posit ioning time and five minutes of pumping time—or a total of eight minutes from his arrival time before running out of water. If the pumper relay could be expected to be in operation for six minutes after the arrival of the pumper, then the use of the 500-gpm stream is feasible.
Any combination of hand lines and total gpm can be evaluated in this way to determine how heavy the initial attack with booster tank water can be.