The Equation
EP = NP + FL + APP + ELEV
If more than one size of hose is used, ________________ for each size will need to be figured.
Friction Loss
A proper fire stream:
Flow enough water to quickly and efficiently extinguish the fire without causing unnecessary water damage.
To be called a fire stream, the hose line must have a ______________ attached.
Nozzle
Nozzles give a fire stream its:
Shape, reach, and velocity.
Fire streams are affected by…
- Discharge pressure
- Nozzle design
- Nozzle setting
- Gravity
- Wind
Standard Nozzle PSI
Smoothbore - 50 psi
Fog Nozzle - 100 psi
Smoothbore Master - 80 psi
A good solid stream is
- A stream that has not lost its continuity by breaking into showers or spray
- A stream that shoots 9/10 of whole volume inside a 15in. diameter circle and 3/4 its volume into a 10in. diameter circle at it’s breakover point
- A stream stiff enough to attain, under fair conditions, the named height or distance, even through a breeze
- A stream that, with no wind blowing, will enter a room through a window and strike the ceiling with enough force to splatter well
As a general rule, the max nozzle diameter should not exceed ________ of the hose to which it is attached.
1/2
Momentary Nozzle Reaction
When the nozzle is first opened and their is a greater nozzle reaction.
Momentary Nozzle Reaction is about ______ higher than the nozzle reaction from the flowing stream.
20%
Steam Expansion Ratios
Temp / Coefficient Factor
212 / 1,700:1
500 / 2,400:1
1200 / 4,200:1
Laminar Flow
Relatively low velocities
Friction Loss (FL) in a fire hose is governed by
- FL varies with the quality of the hose.
- FL varies directly with the length of the hose (measured in 100ft lengths)
- FL varies with the square of the velocity (if velocity is doubled, FL is quadrupled)
- For a given flow, the FL varies inversely as teh fifth power of the diameter of the hose (most important factor when limiting the effects of FL)
- For a given velocity, FL is independent of the pressure
FL varies with quality of hose
- Thickness of inner lining
- Age of hose
- Weave of the jacket
Coefficient Formula
FL = CQ2L
Coefficients of Hose Sizes
1 3/4in = 15.5
2 1/2in = 2
3in = 0.80
4in = 0.20
5in = 0.08
The only accurate way to figure the FL in any length of hose is to:
place pressure gauges on each end of the line and subtract the difference.
How to test FL in hose
- Place pressure gauges at both ends of 100ft of hose
- Flow desired GPM
- Subtract pressure from nozzle end from the starting end
- Bingo. FL for the 100ft section.
Combination Hoseline
Multiple hoselines that join into one or one that divides into two or more. (most common is multiple into one)
Using multiple supply lines drops the FL.
Mistake people make is not dividing the GPM by the number of supply lines.
Appliance
Devices designed to work in conjunction with hoses to deliver water. (Placed in middle or at the end)
Averaged FL for various Appliances
Siamese - 5psi
Wye - 5 psi
Deck Gun - 10 psi
Ladderpipe - 15 psi
Standpipe System - 25 psi
Elevation
Pressure created by gravity
