# Thread: Friction Loss in Pre-piped Waterways

1. ## Friction Loss in Pre-piped Waterways

What kind of friction loss is in your pre-piped waterways. How many GPM? How tall is your Ladder? What is the friction Loss? How big is the piping?

My dept. runs a 75ft quint (please no quint bashing). It has a 4" waterway and has a 2" tip. It has a flow meter so all we do is throttle up until the gauge reads 1000GPM.

Thanks in advance! Stay Safe!

2. Are you asking for a rule of thumb or how much your loss should be?

Easy way to figure yours would be to calibrate both the pressure gauge and flow meter and set the stick out.

Then using the 2" tip, throttle up to 1,000gpm. The 2" should then be flowing 70.86psi. Subtract that from your gauge pressure and you have your FL in the piping from the gauge inlet on.

Then put the stick in any other configuration you want and do the same thing.

3. Don't forget to add/subtract pressure changes do to head from differing tip elevations.

4. Our job uses 100' Smeal prepiped aerials. The manufacturer states that the friction loss in the waterway is 550 kPa (80 psi) This number must be added to the friction loss portion of the equation used to calculate pump pressure.

Pump Pressure = Nozzle Pressure + Friction Loss + Back Pressure (Head) + Appliances

5. Hey FIRE
What type of nozzle is on your ladder?
I always thought that friction loss was based on flow. The friction loss will not be the same flowing 300 gpm versus 1200 gpm. We also have a Smeal, 75'. We use an automatic nozzle 350 - 1250 gpm, and depending on what i want to flow, we increase pressure...correspondingly the friction loss will increase.

6. BrianMacc,

We also run an automatic fog on the end of our Smeals. (Big Daddy Jumbo Remote). Because the prepipe is steel pipe the friction loss is negligible.

1400 kPa @ 20 metres elevation will give us 3800 lpm. We use the flow minder to fine tune the flow after that.

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