Chp 11 Flashcards
Need for static sources
Rural area with no municipal supply
Suburban areas without full distribution network
Natural disasters break system
Lift
Difference in elevation between surface of static water and pump
Max lift determined by
Angle of intake hose
Amount of vacuum primer can make
Amount of atmospheric pressure
Theoretical lift
Max lift if true vacuum were obtained
33.9’ at sea level
Max lift
Highest water can be raised through a hose to the pump
Affected by atmospheric pressure, condition of hose pump and primer, gaskets and valves
Usually about 25’
No pressure left for firestream
L=1.13 Hg
Dependible lift
Height water can be lifted and give a reliable fire flow
Usually 14.7’
Pumps tested at 3’ lift through 20’ hose, strainer 2’ under in water 4’ deep for 70 pump capacity
Net PDP drafting
PDP + intake pressure correction
Pressure Correction
PC=(Lift + Total intake hose FL)/2.3
Takes into account the friction loss in the intake hose and the height of the lift
Net pump discharge pressure at draft formula
Good for US and metric
NPDP = PDP + PC
Natural static water supply sources
Lakes, ponds, streams, rivers and oceans
Know approach and departure routes
Adequacy of static natural sources
Lakes and rivers usually not a problem
Smaller ones may be susceptible to drought
Accessibility of natural static water
Get pumper close Soft ground on approaches Water not deep enough Silt or debris in water Frozen water Swift water Bridge too high, to weak, sandy bank Preplan to deal with all of above Boat launches are great or use floating pumps (500 gpm) or fire boats, or water eductors
Depth of water
2’ for barrel strainers
1’ for floating strainer
1-2” for low level strainer (used on water tanks) but low flow
Silt in water
Clogs strainer, pump and fog nozzle
Need strainer on intake hose, don’t rest on bottom
If clogged, back flush with tank water
Can also install dry hydrants (less water but cleaner and good approach, subject to vandalism)
Freezing water
Small ponds can freeze all the way down
Fill barrels with antifreeze
Set wooden plugs or plastic garbage cans to freeze
Cut a hole with chain saw, power auger, axe off a ground ladder
Swift water
Dangerous to work around
Hard to keep hose submerged
Artificial static water supply sources
Cisterns Private water storage tanks Ground reservoirs Swimming pools Agricultural irrigation systems
Cisterns
Underground water storage where no hydrants
Supplied by well or runoff
Usually for ag or domestic
10,000 to 100,000 gallons
Access through a utulity cover or dry hydrant
Private water tank
Residential, industrial, or ag
100 to 10k gallons
Ground level or elevated
Know, but don’t count of being full
Ground reservoirs
Artificial pond or lake
Large commercial, industrial or municipal water treatment
Millions of gallons
Good roads, dry hydrants
Swimming pools
Access limited
Family pool ok for single family home fire
May be drained in winter
Square pool capacity: 7.5xLxWxH
Round pool: 7.5 xp ix R^2 x Average Depth
Prepan, can have dry hydrant
Agricultural irrigation systems
Flow 1000 gpm via open canal
