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*****UPDATE: I'm a big enough man to admit when I'm wrong. I was challenged on the ability to put 100 psi in a can overfilled with water so I experimented.  It is possible to fill a can with 100 psi regardless of how much water is in it, so proper pressure does not equate to a properly filled can. The only way to accurately check a can is to weigh it and check the pressure with a gauge to make sure the cheap gauge on the can is accurate.*****

Do you know how to fill the can?  We all know the can is a valuable piece of equipment on the truck.  The can can be used on small fires to extinguish them before the engine gets the line stretched.  It can also be used to protect the search by helping keep fire in the room of origin.

But in order to fully tap into its potential the can needs to be filled properly.

Do you know how long a properly filled 2.5 gallon can last? About 50 seconds

What about the initial stream reach? About 50 feet

How many PSI of air is in a properly filled can?

How much does it weigh? Do you know what a properly filled, under filled, and over filled can feels like just by pulling it off the rig?

Below are two videos. The first is an overfilled can. Its an overfilled and under pressurized can that has a pressure was 35 psi.  The second video is a properly filled can with a pressure of around 100. Notice any difference? Notice the stream quality, the reach, the penetration of the properly filled and pressurized  can.

So how do you fill it properly every time? I like to measure it.  1/2 gallon milk jugs or a spare DEF container is perfect. DEF jugs are 2.5 gallons.

If you are completely at a loss, the fill tube, that thing that you normally use to see if its wet at the bottom as you use trial and error trying to see if there is enough water in it, is made for filling the can.  When you pour water into the can, when it is at 2.5 gallons, water will over flow through the fill tube.  Don’t worry, the cans not full, but for some reason physics makes this work. Don’t ask me how, I’m not a scientist.  

As far as weight, a full pump can weighs approximately 28 to 29 lbs based on manufacturer. 

The best way to know for sure.  Every time you fill it up, measure the water put in either with a known volume such as the DEF jug or learn how to properly use the fill tube and check the  pressure with a tire gauge. You’re looking for that 100 psi. Hold it to get use to feeling what a properly filled can feels like. Don't trust other shifts when they tell you it's right. Weigh it and check the pressure.  

Also, before you charge it with air, put some foam or dish soap in there. 1/4 cup of foam or dish soap would give you an approximate mixture of 0.5%.

Video of can overfilled with water and under pressurized:

Video of properly filled Can:

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