Fire hydrants Flashcards
Fire hydrants
• Fire hydrants provide a connection point where fire
fighters can tap into a water supply
• The options:
• Spray the water directly on the fire
• Attach to a pumper truck to boost the pressure
• Attach to a pumper truck and then into the FD connection
Types
- Compression type – only dry barrel in Canada
- Water is kept at the base
- An important part is the drain
Types
Dry Barrel Hydrant - valve below the frost line
Flow Hydrant - flow and flow measurements of water
Private Hydrant - private property
Public Hydrant - fire department
Residual Hydrant - measuring static and residual pressures
Wet Barrel Hydrant - used where there is no danger of freezing weather
Pumper Outlet
An outlet on the hydrant intended to be connected to the fire department pumper for use in taking supply from the hydrant
Rated Capacity
the flow that is available at the designated residual pressure
Testing
Flow Test - how much water is available
Flushing test - clean out piping
Hydrostatic test
Hydrant Butt
hose connection outlet of the hydrant
Sizing, outlets, threads.
• The smallest permissible size for our use is 6”, with a 6”
connection attached to the fire protection main.
• Occasionally 8” fire hydrants are used.
• usually have more than two 2 ½” hose outlets
• A typical hydrant in our area will have 1-4” and 2-2 ½” outlets
• The 4” outlet is provided for FD pumper units
• Outlets as per NFPA 1963, or as approved by AHJ
• If the hydrant outlets are facing the street, they are public
hydrants
• if the outlets are facing the building, they are private hydrants.
Testing and Maintenance
• ANNUALLY - In springtime, after any danger of frost, the hydrant is checked
to determine
• If it is opening and closing properly
• If the barrel drain is working correctly
• If it flows equivalent to the original install
• Again, in the autumn
• Sometimes hydrants are filled with an antifreeze solution.
• In some locations the AHJ has limitations on testing the hydrants and the water discharged.
• Check with AHJ, there are some very large fines for noncompliance
• The water from a hydrant will likely be chlorinated=bad for fish
Location and Spacing
• Typically, 40’ from a building for FD access
• Exception: When hydrants cannot be placed at this
distance, they may be located closer, or wall hydrants
may be used.
• However, the locations must be safe and accessible
• Try to avoid dead end mains; loop them
• Spacing is determined by AHJ,
• NFPA 1 18.5
• but in no case no greater than 500’
• Install a shut off valve within 20’
Installation
• Set the hydrants on flat stones or concrete slabs with about half
a barrel of small stones (or equivalent) placed around the base
to ensure quick drainage.
• Ensure frost protection from the surface, and vertical walls
• Hose outlets shall be set
• 18” or more above grade
• Not more than 36” NFPA 24 A.7.3.1
• If a hose house is installed, it shall be >12” above the floor
• Ensure it is clamped and braced as per NFPA 13 6 – Underground
• Protection – freezing, corrosion, bollards
Hydrant Houses
• They shall be of a size and arrangement which will provide
necessary shelves, racks or brackets for the hose and
equipment.
• PG 9 ILM
• Sufficient 2 ½”cotton rubber-lined fire hose with approved
couplings attached (usually 250 feet, 5x50’).
• Two 2 ½” underwriter’s play pipes
• Two spray nozzles for each size of hose
• One fire axe - recommended
• One crowbar - recommended
• Two hydrant wrenches
• Four coupling spanners
• Two spare hose washers, for each size of hose
City of Calgary Requirements
• Hydrant Flow Tests
• 2 purposes
1. Annually to ensure the supply hasn’t changed significantly and that
the hydrant functions properly
2. To determine the supply flow and pressure when designing a
system
• Flow at times of highest demand
• Compare design with actual
• How do you determine pressure and flow requirements?
Determining the system requirements
- Ordinary group 2 with minimum design area 19.3.3.1.1
- Maximum SS head coverage area 10.2.4.2.1 (b)
- Two inside hose valves 19.3.3.1.2
- 5.6K sprinklers are used
- Elevation from supply to remote area = 40’
- Pressure loss through backflow = 6psi
- It’s an amazing system where there is no friction losses
- What residual pressure is required?
- What could you do if the residual pressure is not sufficient?
- How many sprinklers in the design area will open?
Hydrant Flow Tests
Hydrant A is closest to the property • Determine the static pressure at A • Flow the water from B • Determine the residual pressure at A • At B Determine the residual pressure and with a pitot tube or hose monster determine the flow
