Computing Volume and Its Corresponding Water Weight Flashcards
Rectangular Shaped Containers
Capacity in gallons = L’ x W’ x D’ x 7.5 (number of gallons in a cubic foot of water).
Example 1: How many gallons of water are in a swimming pool that is 40’ long, 20’
wide, and 10’ deep? Capacity = 40’ x 20’ x 10’ x 7.5 gallons/cubic ft.
= 8000 cubic/ft. x 7.5 gallons/cubic ft. = 60,000 gallons
How many gallons of water are in a swimming pool that is 40’ long by 20’
wide, 3’ deep in the shallow end and 9’ deep in the deep end? Capacity = L’ x W’ x average depth’ x 7.5 gallons/cubic ft.
= 40’ x 20’ x ([3’ + 9’] / 2) x 7.5 gallons/cubic ft.
= 40’ x 20’ x 6’ x 7.5 gallons/cubic ft. = 4800 cubic ft. x 7.5 gallons/cubic ft.
= 36,000 gallons
What is the weight of water on a flat roof of a townhouse that is 30’ long,
25’wide and 11⁄2’ deep? (Hint: Keep all measurements in feet.) 30’ x 25’ x 1.5’
= 1125 cubic feet
One cubic foot of water weighs 62.5 pounds; therefore by multiplying 1125 by 62.5, we determine that there is 70,312 pounds of water on the roof. 1125 cubic ft. x 62.5 pounds/cubic ft. = 70,312.5 pounds
Cylindrical Containers
Capacity in gallons = π x r2 x H’ (or L’) x 7.5 gallons Where: π (Pi) = 3.14
r = radius or 1/2 of the diameter in feet H = average height / depth in feet 7.5 = number of gallons per cubic foot Example 4: How many gallons of water are in a cylinder that is 40’ in diameter and
80’ high?
Capacity in Gallons = π x r2 x H’ x 7.5 gallons
= 3.14 x 202 x 80’ x 7.5 = 3.14 x 400 x 80 x 7.5 = 3.14 x 1256 x 80 x 7.5 = 100,480 x 7.5 = 753,600 gallons
Smooth Bore Nozzle Discharge
gpm = 29.7 x d2 x √NP 29.7 is a mathematical constant derived for a round opening.
Example 6: An 11⁄4” smooth bore tip on a master stream with a nozzle pressure of 80psi will discharge how many gpm?
gpm = 29.7 x 1.252 x √80
= 29.7 x 1.56 x 8.94
= 414.21
Theoretical Calculations Fire Ground Calculations Tip Size gpm
Tip Size gpm Hand Line @ 50psi
1/2” 53………1/2” 50…….. 7/8” 161……..7/8” 150……15/16” 185
15/16” 185…….1” 210……1” 200……
11/8” 266……. 11/8” 250 ……..11/4” 328 ……..11/4” 325
Master Stream @ 80psi
11/4” 415……..11/4” 400………13/8” 502……..13/8” 500…….11⁄2” 598
11⁄2” 600……..13/4” 814……..13/4” 800
2” 1062……..2” 1000
By increasing the nozzle pressure the gpm for each nozzle can be increased. Caution must be used to prevent increasing nozzle reaction to a dangerous level. As an example this is a 1⁄2” nozzle that the nozzle pressure was increased to 80 psi:
gpm = 29.7 x .52 x √80
= 29.7 x .25 x 8.94 = 66.38 gpm
Fog Nozzle Discharge
The 1” adjustable gallonage fog nozzle is an adjustable flow nozzle that can be set to deliver 12-60 gpm.
The 11⁄2” Akron Assault Nozzle flows 175 gpm. The 21⁄2” Akron Fog Nozzle is an adjustable flow nozzle that can be set to deliver 125-250 gpm.
The Akron Quick – Attack Mercury Monitor flows 500 gpm. Master stream fog nozzles have an operating range of 150 - 2000 gpm.
Booster Reels
Booster reel lines are usually a 150” long, 1” rubber line with an adjustable gallonage fog nozzle that can flow between 12 to 60 gpm with a 100 psi nozzle pressure; however, other nozzles may be present.
1” Forestry Hose
Forestry hose comes in 50 and 100’ sections. A 1” adjustable gallonage fog nozzle that can flow between 12 to 60 gpm or the 22 gpm red fog nozzle can both be used at 100 psi.
Decon Shower
The decontamination showers are used for hazardous materials incidents or to decontaminate firefighting personnel. They flow 270 gpm at 75 psi.
Piercing Nozzle Also called penetrating nozzles
they are commonly used to apply water to areas that are otherwise inaccessible to water streams, such as voids and attics. They flow 125 gpm at 100 psi.
Cellar Nozzle / Distributor Nozzle
Often used on basement and attic fires.
The 21⁄2” distributer nozzle flows 250 gpm at 100 psi. The 11⁄2” distributer nozzle flows 95 gpm at 50 psi.
The 21⁄2” cellar nozzle flows 350 gpm at 100 psi. The 11⁄2” cellar nozzle flows 160 gpm at 100 psi.
