HYDRANT VALVE SETUP
Plug kits are pretty standard, right?
Hydrant wrench, check.
Double female, check.
Double male, check.
Hose wrench, check.
In-line valve, check.
3” to 5” adapter, check.
Cheater bar… unofficially, check.
Over the past two years, I’ve started to rethink how we set up our hydrant bag for both efficiency and practical use. A slight modification that I have experimented with has been attaching our 3” to 5” adapter directly to the in-line hydrant valve and running the hydrant wrench through the middle of it (see picture).
What’s been great is the number of conversations this has jump-started as guys/girls swing into our station and check out the engine each morning.
“Hey, Capt! What the hell is up with this!?!”
WHY DO WE USE THIS DEVICE IN THE FIRST PLACE?
To answer this question, I want to look at the two reasons we would utilize this appliance:
1) The first is to allow a second engine to connect to the same hydrant as the primary water supply engine without interrupting their operation. I’ve done this previously because it was the only hydrant within a reasonable distance of the fire. We needed to supply a master stream on the charlie division while the rest of the operation was attacking from the alpha side.
2) The second reason would be to capture more water via a second supply line from the same hydrant that we are already connected (as the primary water supply engine).
Now, the question arises, “What size supply hose do we lay off that 2 1/2” side discharge holding our gated hydrant valve in either of these scenarios listed above?”
We have two options… 3” supply line OR a 5” supply line (utilizing the 3” to 5” adapter that should be in our plug kits)
Let’s look at the raw numbers to help us determine why I believe it is often a 5” supply line that we should be laying off that side discharge in BOTH of the scenarios we discussed above. We’ll start with the following chart taken directly from NFPA regarding the potential volume we can expect from a 2.5” side discharge on a fire hydrant at 50 psi.
You’ll notice that it says we should be in the ballpark of 1319 GPM available @ 50psi of discharge pressure (the very bottom number in the red box I’ve highlighted).
Now, look at a 3” pipe's volume capacity at 50psi…
767 GPM is the capacity of that 3” supply line @ 50psi. That means we are losing over 550 GPM simply because our hose cannot handle the volume our hydrant is supplying. Also, it is important to note that 767 GPM is NOT the target flow for our ladder pipes. Here in Dallas, we are targeting (depending on the truck), ~ 1200 GPM. Therefore the 3” hose becomes a limiting factor on the fire ground.
Now, look over one column and notice the 4” supply capacity @ 50psi. You’ll see we’re well above the amount our hydrant can supply. This means that whether you carry 5” or 4” supply hose, if you have the choice between it or 3” AND NEED TO MAXIMIZE the water you are getting from the hydrant, you should go with the larger supply line.
Plain and simple.
Note - if you are only planning to supply an additional 1-2 hand lines… then, by all means, roll with the 3” supply line. But, if you anticipate anything beyond 400-500 GPM, you need to utilize the 5” supply hose.
In Conclusion
I hope this article challenges you to think through the real-world application for our in-line adapters There will be times when utilizing these “as-is” makes complete sense. However, there are times when we will need to combine two appliances in order to maximize our volume on the fire ground. Next time you’re at the station, grab your plug kit off the engine and discuss different scenarios with the crew. Chances are, you’ll spark a host of stories from the senior members that will increase your knowledge and give you real-world applications for these tools.
Hold Fast & Raise The Bar,
