THE VOLUNTEERS CORNER
THERE ARE TWO QUESTIONS that should be answered before buying nozzles: How much water is usually available and, how much water is usually required from each hose line?
The first question is the more important one because it can save you from buying equipment that may outrun your water supply. I’ve seen deluge sets in towns with water mains that would be hard pressed to supply a couple of hand lines after taking care of the demands of a 1⅛or lS-inch tip.
With 6-inch mains and runs to dead ends, hydrants often lean to volume flows of 300 to 500 gpm. In these extreme cases, the mains won’t supply the needs of a Ill-inch tip adequately.
Yet, the lure of keeping up with the Joneses leads to the purchase of equipment that can be used only from draft in some towns . . . And some of these towns don’t even have enough good drafting spots to make the carrying of heavy stream equipment sensible.
I have seen a Bresnan distributor carried on a truck in a department that depended on a 2000-gallon tanker for its principal water supply. Figuring on about a 300to 350-gpm flow from the Bresnan distributor you get less than six minutes water.
If you could be dead certain of knocking down a fire in two minutes with the distributor, then there might be enough water left to complete the extinguishment.
Where water is in short supply, small hand lines with good working pressures make more sense. A great deal of fire can be extinguished with an 1 ½-inch line.
Experience shows that if the flow for an extended fire attack is limited to about 250 gpm, several Ill-inch lines are more effective than one 2S-inch line with a Us-inch tip, which also demands about 250 gpm.
With three to five 1 ⅝-inch lines you can employ two attack lines, a backup line and another line above the fire to forestall vertical extension of the blaze. A backup line, if 50-gpm nozzles are used, can be used to protect exposures.
However, even with a small water supply, such as from a single tanker, there is often an advantage in mounting a t full-scale attack at once to make a j quick knockdown. If you are too slow in getting what water power you have into action at once, you may find that much of the effect of the first line can be wasted. And when there is a limit on the available water, there is no excuse for wasting j any water.
In cases like this, ventilation, which we base discussed in previous columns, can be tremendously effective in getting hose lines into the fire rapidly and reducing the amount of time needed for applying water.
Here is where coordination of attack makes every motion count. And it allows ever)’ gallon of water to do its most in extinguishing the fire.
We have mentioned the limitation of inadequate mains, with which most towns are plagued. But remember, tire same limitation on the gpm that can be delivered to a fire also exists w’hen relaying water or when using a succession of tankers to bring water to the fireground.
Generally, if you can deliver 200 gpm to a fire through a relay, you are doing a good job. To deliver more water in a relay, you have to use parallel 2Hinch lines or use 3-inch or larger supply j lines in the relay. Most departments in suburban or rural areas don’t carry 3-inch lines.
However, with the growing popularity of synthetic fabric-jacketed hose, more ! 3-inch hose will probably be used. This i size using man-made fibers results in hose that is now light enough to make its use no more of a burden than 2⅛inch cotton hose. The difference in friction makes the delivery of larger gallonages feasible.
Earlier, we mentioned the question of how much water is needed to extinguish your average fires. Your records will help answer this. And here is where you may have to compromise a little for first-due apparatus and depend on second-alarm or mutual-aid response for the really big fires.
There are two good reasons—besides j limited water supply—for not using excessively large nozzles in volunteer departments. At the same nozzle pressure, the greater the flow, the more difficult it is to handle the hose line. This is particularly important when you’re short-handed. The other reason is the greater danger of excessive water damage when hose streams are larger than necessary. ExI cessive water damage is painfully apparent after the fire is out.
The increasing difficulty of handling lK-inch lines, which should be easy to move, can be tested quite simply. Use the same nozzle pressure, but try two or three nozzles of different gallonage ratings. Work the nozzles around and have one man at a time move the hose lines. The larger gallonage nozzles will be definitely more difficult to handle.
All this should not be regarded as an argument against using heavy streams where the fire demands them and the water is available. But we do say that your selection of nozzles should fit both the needs and the water supply of your own department. □ □