"Is a water flow meter really necessary?”  

It’s a good question. If you’re wondering why you need a water flow meter, how you can use one, or how they can be a tool for you when training and testing equipment, this article is for you. 

Here are three reasons you need a flow meter at your fire department:  

Know Your Flow 

“How do I know what I’m flowing?” is a common question in the fire service. Flow is important on the fire ground because you need enough water to cool the fire and overwhelm one of the basic elements that fire needs to burn – heat. If you don’t provide enough water on the fire, it will continue to burn. 

Need a refresher on the fire tetrahedron? Read more here. 

A water flow meter allows you to test and train with real-time flow data. This gives you and your crew a solid understanding of how much you flow at a set PDP with your nozzle and hose combination. 

Calculate Friction Loss 

When you calculate friction loss in your fire hose, one of the key pieces of information you need for the friction loss formula is flow rate. 

Friction loss = friction loss coefficient * (flow rate / 100)2 * hose length / 100. Or FL = C*(Q/100)2 *L/100. 

Equipment manufacturers often provide friction loss information for their products. Some departments choose to use this information, but it’s hard to get an accurate number when you are adding together averages for multiple hoses or trying to account for appliance friction loss. Sometimes, this information isn’t available at all! 

With a water flow meter, you can use the actual flow rate based on the combination of equipment you are using to calculate your friction loss.  You can also update your information and continue testing as the equipment ages, ensuring that you have the most accurate friction loss information possible. 

Set your Pump Discharge Pressure (PDP) 

While flow doesn’t change over distance, your pressure does. Your PDP is the pressure you need to set at the pump to overcome distance and friction loss while getting the pressure and flow rate you want at the nozzle. So how does a water flow meter help with this?  

One way to set your PDP is to determine your target flow rate.  When your flow meter is connected in your system, you can increase your PDP until you achieve that flow rate. A flow meter allows you to see when you hit your target flow. You can then document the PDP used to achieve the flow and make simple, easy-to-reference charts for your pump operators!  

Where to Find a Water Flow Meter 

Your fire department can do some online research (we recommend the Firefighter Learning Hub Water Flow section on our website) or can reach out to your trusted firefighting equipment dealer to ask about available water flow meters, their features, and how to get a demo.