Average daily consumption (ADC)
Average of the total amount of water used in a water distribution system over the period of 1 year
Peak hourly consumption (PHC)
Max amount of water used in any 1 hr interval over the course of a day
__% of all firefighter injuries and deaths are cause by vehicle collisions while responding to or from emergency calls
20-25%
The primary determinant of friction loss is ___
The volume of water flowing per minute
3 methods of moving water in a system are:
- Direct pumping system 2. Gravity system 3. Combination system
Fire apparatus collisions can be grouped into 5 basic causes
- Improper backing
- Reckless driving by public
- Excessive speed by fire app operator
- Lack of driving skill
- Poor app design or maintenance
Elevation pressure formula Equation B
EP = 0.5H
H = height
Elevation pressure formula Equation C
EP=5 psi x (# of stories -1)
Friction loss coefficients -1 3/4” hose w/ 1 1/2” couplings - 2 1/2” hose
-1 3/4” hose w/ 1 1/2” couplings = 15.5 - 2 1/2” hose = 2
Friction loss coefficients - Siamesed lines - Two 2 1/2” - Two 3” lines w/ 2 1/2” couplings
- Two 2 1/2” lines = .5 - Two 3” lines w/ 2 1/2” couplings = .2
Maximum daily consumption (MDC)
Maximum total amount of water that was used during any 24 hour interval within a 3 year period
Equation A - friction loss
FL = CQ²L
- C = FL coefficient
- Q = flow rate in hundreds of GPM (flow/100)
- L = hose length in hundreds of feet (length/100)
Equation D - Pump Discharge Pressure
PDP = NP + TPL
Equation I
% drop = (static - residual)100 static
Equation F (3” inch hose)
FL per 100 ft = Q²
- Q = # of hundreds of GPM
Equation G (4” hose)
FL per 100 ft = Q squared divided by 5
Q = # of hundreds of GPM
When using 2½” or 3” hoselines to supply the pumper directly off hydrant pressure, it is recommended that the lines be no longer than:
300 ft
Selecting the drafting site factors
- Amount of water available - MOST IMPORTANT factor; There should be a minimum of 2 ft of water over the strainer; Also desirable to have 2 ft of water all around the strainer
- Type of water - Most common type of contamination, and possibly worst damaging, is dirty or sandy water
- Accessibility - As the amount of lift increases the following occur
- Elevation pressure increases
- Less friction loss can be overcome
- Capacity of the pump decreased
All pumps are rated to thier capacity at 10 ft of lift; If lift is less, capacity is higher and vice versa; Max lift is 20 ft at that height pump capacity is 60%
Recommended sizes for fire hydrant mains
- Residential: 6” with 8” cross-connecting mains every 600 ft
- Industrial: 8” with cross connecting mains every 600 ft
- 12” mains may be used on principal streets and in long mains not cross connected at frequent intervals
Once the pump has been made operational, the transfer valve should be in the ___ position during priming
Volume
Possible causes for inability to prime
- Insufficient fluid in the priming reservoir
- Engine speed (rpm) is too low
- LIft is too high
- A high point in the hard intake hose creating an air pocket
Flow pressure
That forward velocity pressure at a discharge opening while water is flowing
Residual Pressure
That part of the total available pressure not used to overcome friction loss or gravity while forcing water through pipe, fittings, fire hose, and adapters
Static Pressure
Pressure in a water system before water flows; Stored potential energy available to force water through pipe, fittings, fire hose and adapters
