Quick decisions and multiple considerations need to be made, sometimes within seconds, while you are advancing the initial handline in a bid to achieve successful fire attack outcomes. Among those considerations are what size the hose-line (how much of it) and what type of nozzle you should use (whether a standpipe is needed), or even where you can force entry into a building? In fact, there are no easy answers. The fire conditions and the building on fire determine how you make the right decisions.
First thing first, effective initial handline operations is the key to a successful fire attack. Such a quick initial attack to effectively suppress the fire can limit firefighters’ chances of exposure to further damage and hazards and ensure that trapped victims can wait safely for rescue. As a decisive phase in the fire attack, initial hand-line operation should be supported by all necessary means upon arrival on the fire ground to lay a solid foundation for what is to come next.
“Big fire, big water” is a phrase in wide circulation among firefighters, which means the 2½-inch handline rather than the smaller 1¾-inch one will be used. Which size of the hose should be used is determined by how big the water flow you need to put the fire out based on the National Fire Academy (NFA) standard of [(length x width) / 3] x percent of involvement or on the Iowa standard of (length x width x height) / 100.
Of course, you can always refer to the official guidelines when selecting handlines for different flow rates. When guidelines are referred to, the hose-line selection should be done based on the type of building in which the fire breaks out and on the flow rate needed.
Before the size of the hose-line is selected, you also need to consider the length of the hose stretch. Even though a 1¾-inch handline can do a good job of containing and extinguishing the fire, a leader line of a 2½-inch hose-line is needed initially for the hose stretch exceeding 300 feet, and later it wye off into a 1¾-inch handline for the fire attack.
The resources available are a decisive factor in what type of nozzle should be used because multiple nozzles might not be found in all the fire departments. Furthermore, department culture to a certain degree influences the selection of nozzles. Smoothbore nozzles might be some departments’ favorites while others are inclined to use fog nozzles. There is nothing wrong with different choices of nozzles made by these departments because they understand how each type of nozzle works and which they should select for specific fire attack operations.
Smoothbore nozzles provide a smooth path for water to pass from the coupling connection all the way to the hose-line until it exits at the tip of the nozzle like a flow of stream. This type of nozzle can be operated at a nozzle pressure of 50 psi, perfect at low or limited pressure conditions. Its multiple tips, made of different sizes, can discharge water at various flow rates as follows:
1. 1¾-inch hose-line:
(1) 7/8-inch tip: 162 gpm
(2) 15/16-inch tip: 185 gpm
2. 2½-inch hose-line:
(1) 1-inch tip: 210 gpm
(2) 1 1/4-inch tip: 327 gpm
(3) 1 1/8-inch tip: 265 gpm
On the other hand, fog nozzles do not have an open path from the coupling connection to the nozzle tip as smooth nozzles do above mentioned. What is good about this type of nozzle is that it can produce multiple stream patterns rather than a single solid pattern that the smoothbore nozzle creates. Therefore, its internal parts are much more sophisticated than those of the smoothbore nozzles.