It’s the beginning of your shift on the engine, and you have just finished a thorough check off of your SCBA; after all, that’s the most important piece of equipment you will use today. Your gear is set up for flawless donning because you “have that feeling that you’re going to make one.” A quick glance at the crosslays has the appearance that everything is in order, but you are feeling extra motivated; you even climb up to check that the teeth on the fog nozzle are free-spinning and verify that the pattern is set where you want it. Now, you confidently check that box confirming that the hose lines are in working order.
Most of us are comfortable assuming that our hose lines are in working order without ever flowing water through them as a part of the daily checks. Admittedly, I often include myself in that thinking. There are, however, a number situations that will pass the “ol’ eye test” that could still equate to fire-ground issues. I will be discussing three of these situations.
Having a Variety of Hose Types in Use
Any quality engine firefighter should be able to rattle off the correct operating pressure and corresponding GPM flow for the nozzles on the end of their lines. Not all will have their department’s pump chart memorized, but it certainly helps. Unless you are blessed to work for a department that replaces all of their sections of hose at the same time, it is likely that you have a fairly significant spread of in-service hose sections, both in terms of age and condition; perhaps, included in that spread is a variety of hose manufacturers and models.
In an effort to simplify that previously mentioned pump chart, it is typical for a single friction loss value to be provided for each size of hose at various GPM flows. To assume that this one-number-fits-all is not accurate. Factors such as age, condition, jacket type and material, and internal diameter will all have an influence on how the engine must be pumped to achieve desired flow rates. During a recent training at my station, it was found that by replacing two of the four hose sections on our first crosslay with newer hose sections, we were able to flow the same GPM using 40 psi less pump discharge pressure. The only way to determine if your lines are operating as expected is by pulling them off the apparatus, flowing some water, and checking the values (yes, this means dusting off the pitot gauge and flow formulas or using a flow meter). By flowing water through each line, you can have more confidence that you are getting the GPM flow you had expected all along.
Separation of the Hose Jacket
Over time hose sections will deteriorate. Each imperfection carries with it a resulting decrease in the overall performance of the hose. Melted fibers and most abrasions are fairly visible examples of common imperfections. One of the lesser visible imperfections, though a somewhat common occurrence, is caused by the inner jacket or friction reducing lining of the hose separating from the outer jacket. Indicators of possible separation include reduced flow volume, higher pump pressure requirements, lumps in the hose section when empty, and especially difficult areas in the hose to fold or flatten. Visually inspecting the inner lining at either couple will also hint at the condition of the entire section. If you suspect jacket/liner separation, remove that section of hose from service.
Hose Section that is Prone to Kinks
Even when a hose lay is created using seemingly identical sections of hose, each will operate differently when water is flowing through it. This may or may not result in a noticeable impact to the crew operating the hose line; it should be considered though when creating your hose loads. Continuous usage and folding of the hose weakens the hose fibers, reducing the hose’s ability to hold its shape. Kinks could become a regular occurrence in these portions of hose with weakened fibers. In a test done by Tim Pillsworth of the Winona Lake Engine Company #2 in Orange, NY, it was found that even a single kink in an 1 3/4″ hose line will reduce total GPM output by anywhere from 3-50% (1). Every effort should be made to keep kinks from occurring. Rotating through all of your departments in-service hose sections on a regular basis will help aide in even wear and keep a hose from being repeatedly folded in the same place.
Particular attention should be given to the section chosen as the lead length of hose on your attack lines. This hose section will encounter the greatest number of obstacles and is tasked with supporting the nozzle. Further, nozzle reaction created by flowing water puts a great amount of stress on the hose in two locations. The first is directly behind the male coupling attached to the nozzle, and the second is two to three feet behind the nozzle. Proper hose handling techniques will help support these stress points, and hopefully keep the line from kinking, but it is not guaranteed. An intimate knowledge of how each hose section operates allows you to order the sections selected for your attack line in manner that reduces the likelihood of kinks in the sections engaged in the majority of the work. This allows firefighters to focus more attention on the task at hand and less on hose performance. As Aaron Fields puts it, “if you are fighting fire hose, you are not fighting fire (2).” Time and effort are spent fine tuning tools like saws, axes, and halligans; your hose lines should be no different.
- “How Kinks Affect Your Fire Attack System,” Tim Pillsworth, Fire Engineering, October 2007
- “Drilling for Function,” Aaron Fields, Fire Service Warrior, March 2012.