Ch. 11 Static Water Supply Sources

Question 1

Principles of Lift

Answer 1

-If water does not rise to level of pump intake, drafting will not be possible
-Lift is difference in elevation between the static water source and the pump intake
-Air must be exhausted from the intake hose and fire pump
-Water rises until the pump is full of water or pressure within pump equals atmospheric pressure

Question 2

Theoretical Lift

Answer 2

-Calculated by atmospheric pressure and multiplying by waters pressure per square foot
-At sea level a pump can lift water 33.9 feet
-Every 1,000 feet atmospheric pressure decreases 0.5 psi
-Pumpers cannot lift water 33.9 feet below the pump

Question 3

Max Lift

Answer 3

-Greatest height to which any amount of water may be raised through an intake hose to pump
-Maximum lift is approximately 25 feet
-Maximum lift is approached when volume of water may be too low to be of value for fire pump
Formula
L= 1.13(Hg)
L= height of lift in feet
1.13= a constant
Hg= mercury

Question 4

Dependable Lift (Biggest Concern)

Answer 4

-Height water may be lifted in sufficient quantity to provide reliable water flow
-Fire pump should have dependable lift of 14.7 feet
-Fire pumps rated when drafting from a lift 10 feet through 20 feet hard intake hose
-Pump only delivers 70 percent capacity if lift increase by 5 feet to 15 feet, and 60 percent at a 20-foot lift

Question 5

Determining Net Pump Discharge Pressure

Answer 5

-The sum of the pump discharge pressure and the intake pressure correction
Formula
Pressure correction = Lift + total intake hose friction loss (from table) divided by 2.3
Draft pump discharge pressure plus intake pressure correction

Question 6

Natural Static Water Sources

Answer 6

• Two factors: adequacy and accessibility
• Smaller natural sources more suseptible to periods of drought will affect drafting
• Positioning Pumper
  -Bridges to high or unable to support weight
  -High banks around water source
  -Terrain not allowing reach to source, unstable may cause rollover
  -Physical barriers
  -Dry hydrants may be placed at some natural water sites
  -May need portable pumps if apparatus cannot make approach
• Inadequate Depth for Drafting
  -Barrel types strainer requires a depth of 2 feet above and below the strainer
  -Low level strainers can draw water down to a 1 to 2-inch depth
  -Floating strainers allow drafting from water as shallow as 1 foot
  -Using salvage cover and ladder to create a dam to raise water level
• Silt and Debris
  -The intake hose with a strainer is brought through the bottom rungs so strainer doesn’t rest on the bottom to keep from debris
  -Back flush with tank water to dislodge debris
  -Preferable method is installation of dry hydrants

Question 7

Artificial Static Water Supply Sources

Answer 7

• Cistern- underground water storage (10,000-100,000 gallons)
  -Used for domestic or agricultural purposes
  -some are specifically for FD use, where area isn’t serviced by a hydrant system
• Private water storage- residential or industrial (several hundred- tens of thousands)
• Ground reservoirs- artificial installations (millions of gallons)
  -Characteristics of pond or lake found on large commercial or industrial properties
• Swimming Pools- provide a ready source of water for drafting
  -Difficult to draft
  -Portable or floating pumps

Formula square pools
C= (7.5) (L) (W) (D)
C= Capacity in gallons
7.5= gallons cubic feet
L= length
W= width in feet
D= Average depth

Formula round pools
C= (7.5) (3.14) (radius)²(D)
7.5= number of gallons
Pi= 3.14
R= radius (1/2 diameter)
D= Average depth