PRESSURE UTILITIES Pipe flow occurs due to contents of the pipe being pressurized System cannot have a free connection to the atmosphere Types of Pressure Utilities Domestic Water: Clean/drinkable water Fire Water: Water for fire protection Process Water: Used in industrial processes Cooling Water: Used for AC or manufacturing Natural Gas, Compressed Air, Steam
PRESSURE UTILITIES Plans require specifying: Location (Horizontally): Dimension or station & offset Pipe size (sometimes material spec) Not needed: Length & slope
WATERLINE DESIGN Ohio EPA Peak Flows Domestic Water Average Daily Demand = OPEA Estimated Flow x Units Peak Daily Demand = Average Daily Demand x 2 (GPD) Peak Hourly Demand = Average Daily Demand x 10/1440 (GPM)
WATERLINE DESIGN ISO Method Fire Protection Required Flow = 1111 cc AA (GPM) A = Floor Area (SF) C = 1.5 Wood Construction = 1.0 Ordinary Construction = 0.6 Non combustible Construction Maximum Flows 6-8000 GPM Required flow rate may depend on insurance carrier
WATERLINE DESIGN Flow amount based on: Pipe Size Working Pressure Length of pipe Pipe Material Pipe Routing Use Hardy-Cross Method with Hazen-Williams equation for balancing flow in a pipe network Beyond scope of this class!!
WATERLINE STANDARDS Standard Working Pressures: 35-80 psi Standard Test Pressures 150-250 psi Minimum Pipe Sizes: Fire Hydrant Lead-in - 6 Diameter Residential Grid 6 Diameter (600 grid) Commercial Loops 8 Diameter Transmission Lines - 12 Diameter
WATERLINE STANDARDS Minimum Depths: 4 Cover (OEPA) 5 Cover (Toledo) 10 Cover in Eveleth, MN Avoid possibility of contamination!!!! 10 Min. laterally from parallel Sanitary Sewer 18 above a crossing Sanitary Sewer 12 clear to a crossing Storm Sewer
WATERLINE LAYOUT Looped Systems BUILDING Avoid dead end branches by looping systems Provided for multidirectional flows and redundancy in case of a line break Isolate sections of system with proper valve placement
WATERLINE LAYOUT Valve Placement Tell me where the breaks are going to be and I ll tell you where the valves should go! Roy Sidener Place valves to shut down sections of the system with least amount of disruption to operating lines 500 1000 intervals on straight lines In-line valves: Place on 2 branches of a Tee Place on 3 branches of a Cross Minor branches first Spurs to buildings on all 3 branches
WATERLINE Pipe Ductile Iron with gasketed joints Cement lined with zinc outer coating Standard push-on bell & spigot
WATERLINE Pipe: Ductile Iron with mechanical joints Provides extra secure connection
WATERLINE Pipe: Ductile Iron with restrained joints Requires retainer gland with setscrews into pipe
FITTINGS & APPURTENANCES Fitting Connections Tees & Crosses (with or without reductions) Reducers Bends 90, 45 or 22.5 only!!
FITTINGS & APPURTENANCES Gate Valves Rising Stem Wedge (gate) rises into body of the valve housing But the stem rises too! And we can t have a wheel underground!
FITTINGS & APPURTENANCES Gate Valves Non-rising Stem Stem is threaded into wedge Stem stays in place and gate rises into housing Still can t have a wheel underground!
FITTINGS & APPURTENANCES Gate Valves Curb Boxes Curb Boxes or Valve Boxes are used to access top of valve stem with wrench (key) for valve operation
FITTINGS & APPURTENANCES Post Indicator Valves PIV s are used on fire protection lines to clearly show the status of valve operation (OPEN or CLOSED) Valve body has a plate for indicator base flange attachment Many are monitored back to a central control station
FITTINGS & APPURTENANCES Fire Hydrants
FITTINGS & APPURTENANCES Fire Hydrants
FITTINGS & APPURTENANCES Fire Hydrants - Locations Local fire marshal dictates spacing: 300-500 Depends on line sizes and pressures Usually 50-75 from burning building Place behind curb at least 2-3 and accessible for pumper truck suction hose connection Locate in sight for ease of location clear of obstructions
FITTINGS & APPURTENANCES Tapping Sleeve & Valve Connection to existing lines can be done either by: Shutting down line, cutting out pipe and inserting a tee Using a Tapping Sleeve & Valve (Hot Tap)
FITTINGS & APPURTENANCES Tapping Sleeve & Valve
PRESSURE UTILITIES Hydrostatic Pressure Pressure in pipes can be compared to a height of water in a tank feeding the pipe If the pipe is capped at its outlet end, there will still be pressure on the cap trying to move it off the pipe If the cap is affixed to the pipe, then the pressure will try to move the pipe instead Joint restraints need to be used where pressure can push against the pipe and make it move
PRESSURE UTILITIES Thrust Blocks Thrust blocks are used to prevent buried pipe from moving under pressure are bends, tees and caps. The required bearing area is determined by Test pressure of the pipe Diameter of the pipe Fitting type Bearing capacity of the soil
PRESSURE UTILITIES Thrust Blocks Thrust blocks are used to prevent buried pipe from moving \
PRESSURE UTILITIES Thrust Blocks Sizing Rules of Thumb Height : Less than ½ trench height but greater than pipe diameter Width : 1 to 2 x block height
PRESSURE UTILITIES Thrust Blocks Practice Sizing Problem Determine the thrust block size for 45 Bend 8 Pipe Diameter Silt Soil 200 psi Test Pressure