14.7 psi at sea level
Psi to inches of Hg conversion
- 1 psi raises mercury 2.04 inches
- 14.7 psi= 29.9 inches of mercury
height of H20 supply above discharge oriface
convert head to psi
- Head in feet/2.304= psi
- Feet x .434 = psi
Stored potential energy when water not moving
Normal operating pressure
pressure in distribution system during normal use
that part of total available pressure not used to overcome firction or gravity while forving water through pipe, appliances, etc.
it that forward velocity pressure at a discharge opening.
Altitude effect on atmospheric pressure
Above sea level, 0.5 psi per 1,000 ft
Things that cause friction loss
- Movement of water molecules against each other
- Linings in hose
- Sharp bends
- Change in hose size or orifice by adapters
- Improper gasget size
Standing water capicity in gallons
- Gallons= Length x width x height x 7.5
- 7.5= gallons per cubic foot
- Gallons= pie x radius 2 x 7.5
- First pumper hooks to hydrant
- Second pump hooks to 2nd intake of first pump
- must have very strong hydrant
- First pump hooks to hydrant, hooks to second pump nearby to boost pressure.
- Used for high pressures (high rise)
Types of relay pumping
- Max Distance Relay method
- Constant Pressure Method
Max flow flow for 5 inch lay
- at 185 psi, 750 gpm for 3,650 feet
- if shorter lay, and using 150 psi discharge, 1250 gpm possible.
Foam application techniques
- Rain-down- class b foam shot into air above fuel not accessable by other methods (above ground tanks), allowed to gently rain down.