Pump Manual - Properties of Water Flashcards
Cubic inches in 1 gal
231
cubic inches in a cubic ft
1,728
Weight of 1 cubic foot of water
62.4 lbs
Gallons in 1 cubic foot
7.48
Weight of 1 gal
8.34 lbs
PSI in 1 ft column of water
0.434 PSI at base
1 PSI will raise a column of water how high?
2.304 ft ( = 1 / 0.434 )
Parallel hose lines reduce friction loss by what %?
75%
One gal water absorbs how many BTUs?
9,343
Heat need to raise 1 lb of water 1 degree F?
1 BTU
Heat to vaporize 1lb of water at 212 degrees
971 BTU
Heat to vaporize 1 gal of water at 212 F?
8,080 BTU
1 cubic foot of water expands to how many of steam at 212 degrees?
1700 cubic feet
1 gal water expands to how many cubic feet of steam at 212?
227
1 gal will absorb all of the heat that can be produced with available oxygen in how many cubic ft of air?
200
“Reasonable Efficiency” (80%) - how many BTUs are absorbed per gal of water with this assumption?
7,474 BTUs
Iowa Formula - what is it?
Estimates GPM needed to control a fire in a specific area
GPM = cubic feet involved / 100
Two formulas needed when estimating water for fire attack
Needed fire flow (NFF)
Total water needed for extinguishment
Needed Fire Flow (NFF)
NFF = [ (length x width) / 3 ] x % involvement
Total Water Needed for extinguishment (formula)
Total Water Needed = (Area x FLD x BTU) / 9,343
FLD = 4.3 lbs/ft (constant)
BTU/pound = 16,000 (constant)
So…
Total Water Needed = (Area x 4.3 x 16,000) / 9,343
Principles of Water Pressure #1
Fluid pressure is perpendicular to any surface on which it acts
Principles of water pressure #2
When a fluid is at rest, fluid pressure is the same in all directions
pg 10
Principles of Water Pressure #3
When there is an increase in pressure at any point in a confined fluid, there is equal increase at every other point in the container (Pascal’s law)
pg 10
Principles of water pressure #4
The downward pressure of a liquid in an open vessel is proportional to its depth
pg 10
Principles of water pressure #5
The downward pressure of a liquid in an open vessel is proportional to the liquid density
(e.g. mercury is 13.55 times as heavy as water and exerts more downward pressure)
pg 11
Principles of Water Pressure #6
The downward pressure of a liquid in an open vessel is not affected by the shape of the container
pg 11
7 types of pressure: Atmospheric
Pressure exerted on surface of earth by weight of air
- 14.7 PSI at sea level (decreases w/ increase in elevation; 1 PSI of atmosphere will raise a column of water 2.31 ft)
- Feet of water 33.9ft theoretical lift (14.7 psi x 2.31ft = 33.9)
- good pumper max lift = 22-25ft
- dependable lift = 14.7ft - Hg = 30 inches (inches of mg in vacuum gauges) – pumpers in good condition can create vacuum of 22” mg
- 1” mg on the pump vacuum gauge = 1.13 ft column of water can be lifted (1.13 x 22 = 25ft max lift)
pg 12
7 types of pressure: Elevation Pressure
0.434 psi / ft
or
5 psi / floor
pg 12
7 types of pressure: flow pressure
measurement of water coming from a discharge opening (reading on pressure gauge)
pg 12
7 types of pressure: head pressure
refers to the height of a water supply above the discharge
Convert feet to head by dividing feet by 2.304
1 / 0.434 = 2.304
pg 12
7 types of pressure: normal operating pressure
Pressure in a water system during normal consumption demands; once water starts flowing we no longer have static pressure. Difference between static pressure and NOP is friction loss
pg 12
7 types of pressure: Residual pressure
Pressure remaining in the system after water is flowing (used to estimate additional flow capacity)
pg 12
7 types of pressure: static pressure
pressure when water is not flowing; this is the pressure you read on the fire pump when no discharges are open
pg 12.
10/15/25 rule
10% drop from initial residual compound reading = additional 3x the current GPM flow
15% drop = additional 2x the current GPM flow
25% drop = additional 1x the current GPM flow
pg 13
