Chapter 9 Fireground Hydraulic Calculations Flashcards
How do flowmeters help driver/operators concerning calculations?
They reduce the amount of calculations required
NFPA 1901, Standard for Automotive Fire Apparatus, allows flowmeters to be used instead of pressure gauges on all discharges up to what size?
3”
What are the two types of flowmeters?
Paddlewheel
Spring probe
Flowmeters should be accurate to a tolerance of what?
3%
In what 3 applications can flowmeters be helpful to drivers?
- diagnose water flow problems
- relay pumping
- standpipe operations
When using a flowmeter in relay pumping, how does the driver set the pump to the correct discharge pressure?
increase the engine speed until the flowmeter reading no longer increases
When relay pumping using flowmeters, the driver must also watch the master intake pressure gauge to make sure it doesn’t drop too much below what pressure?
20 psi
Describe the hand method for determining friction loss for 2 ½” hose.
Starting with the thumb
- -100 gpm increments
- -multipliers 2-4-6-8-10
(gpm/100) x multiplier
per 100 ft section
Describe the hand method for determining friction loss for 1 ¾” hose.
Starting with the thumb
- -100, 125, 150, 175, 200 gpm
- -multipliers 1-2-3-4-5
multiplier that corresponds to the given gpm x 12
per 100 ft section
What is the condensed “Q” formula for 3” hose?
100 ft sections
FL=Q²
What is the condensed “Q” formula for 4” hose?
100 ft sections
FL=Q² / 5
What is the condensed “Q” formula for 5” hose?
100 ft sections
FL=Q² / 15
In the condensed “Q” friction loss formula, what does Q stand for?
hundreds of gpm
When using the “GPM Flowing” method, what does the driver need to know to figure friction loss for 2 ½” hose?
only the flow fpm from a nozzle at a specified pressure
Describe the “GPM flowing” method for flows over 160 gpm for 2 ½” hose.
subract “10” from the first two numbers of flowing gpm to determine friction loss in 100 ft sections
ex. 250 gpm per 100 ft = 15 psi friction loss per 100 ft
