pressure utilities - university of toledo

PRESSURE UTILITIES

CET-2030 Construction Graphics

• 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

Types of Pressure Utilities

• Pipe flow occurs due to contents of the pipe being pressurized

• System cannot have a free connection to the atmosphere

PRESSURE UTILITIES


• Location (Horizontally): Dimension or station & offset

• Pipe size (sometimes material spec) • Not needed: Length & slope

Plans require specifying:

WATERLINE DESIGN


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)

Ohio EPA Peak Flows – Domestic Water

WATERLINE DESIGN


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

ISO Method – Fire Protection

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 networkBeyond scope of this class!!

WATERLINE STANDARDS


Standard Working Pressures:35-80 psiStandard Test Pressures150-250 psi

Minimum Pipe Sizes:Fire Hydrant Lead-in - 6” Diameter Residential Grid – 6” Diameter (600’ grid)Commercial Loops – 8” DiameterTransmission 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

• 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

BUILDING

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 set-

screws into pipe

FITTINGS & APPURTENANCES


Fitting Connections

• Tees & Crosses (with or without reductions) • Reducers• Bends 90° , 45° or 22.5° only!!



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!



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!



Gate Valves – Curb Boxes

• Curb Boxes or Valve Boxes are used to access top of valve stem with wrench (key) for valve operation



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



Fire Hydrants



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



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)



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

pressure utilities - university of toledo

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