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101 Cards in this Set
- Front
- Back
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Why must a continuous positive water pressure be maintained in the distribution system at all times? |
To prevent entrance of toxic and other undesirable substances |
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Water distribution system mains are laid out in what three types of systems? |
Grid, Loop, tree |
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What type of water meter is used if water flow fluctuates widely? |
Compound meter/combination meter |
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What is the advantage of a Venturi type of water meter? |
Will not interfere with the flow of water if the meter fails |
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When is the solid sheeting shoring method used? |
When excavating materials that will not stand in a vertical position |
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What does galvanize mean? |
To coat a metal, especially iron or steel, with zinc |
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Why should tree or branching distribution systems be avoided |
They produce dead end water mains |
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What problems can be created by excessive pressures in the distribution system? |
Damage to customers facilities and plumbing fixtures |
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What causes friction loss in pipes? |
Roughness of the interior of the pipe High C-factor is smooth |
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What causes thrust in a pipe? |
Any point in a pipe where water changes direction, increases velocity, or the flow decreases or stops |
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Water hammer can be caused by what actions? |
Pumps suddenly starting or stopping Valves quickly opening or closing |
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Why are booster pumps installed directly on mains? |
To increase the available system pressures |
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Why should dead end water mains be avoided? |
To prevent taste and odor problems |
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How can the requirements for operational storage be reduced? |
Through the use of Wells |
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What type of material is commonly used for large water transmission mains? |
Concrete with a steel cylinder |
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How can the storage of water in covered distribution reservoirs help with disinfection? |
Provides extended contact time |
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What precautions should be taken with distribution reservoir drains and overflows? |
They should have no cross connections to any potential source of contamination They should be screened |
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What is the most common pump used in distribution systems? |
Centrifugal pumps |
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What is the best source of power for distribution system pumps? |
Electric motors |
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What is the main advantage of grid or loop water distribution systems? |
Permit greater flow to an area where there is a fire or other source of high demand |
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List the four important installation features of pipes |
Weight Jointing characteristics Available sizes Ease of tapping the line |
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How can the external corrosion of ductile iron pipe be reduced? |
Bituminous coatings Polyethylene wrap |
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Steel pipe may be lined with what three types of materials? |
Bituminous material Cement mortar Epoxy |
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What four types of coatings may be applied to steel pipe? |
Epoxy mastic They can be galvanized Protective wrap |
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List the four major disadvantages of concrete pipe |
Pipe is heavy Hard to tap Needs special fittings May deteriorate in aggressive/corrosive soil |
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List the three types of plastic material used for plastic pipes |
PVC PE PB |
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What are the five most common materials used for service lines? |
Copper PVC PE PB Reinforced plastic pipe |
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List the four basic requirements for a good pipe joint |
Watertight seal Easy installation Durability Corrosion resistant |
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What are the two primary and four secondary types of joints that are most commonly used for ductile iron pipe? |
Primary: push on joints, mechanical joints Secondary: flanged joints, restrained joints, flexible joints, sleeve joints |
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What eight types of joints are used to join steel pipe? |
Bell and spigot lap welded joint Bell and spigot rubber gasket joint Harness joint-bell and spigot Carnegie shape rubber gasket joint Butt welded joint Butt strap joint for welding Mechanically coupled joint Flanged joint for bolting |
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How much deflection is allowed in the couplings of asbestos cement pipe? |
Couplings 3 to 12 inches: 5° Couplings 14 to 24 inches: 3° |
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What types of joints are used for PVC pipe? |
Solvent weld joints Bell and spigot joints |
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List the five commonly used corrosion control techniques and materials for pipe protection |
Nonmetallic pipe materials Non-metallic coatings Metallic coatings Chemical treatment Cathodic protection |
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What seven kinds of underground lines should be located prior to excavation? |
Waterlines, sewer, gas, power, telephone, cable TV, storm drains |
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How would you check metal pipe for damage? |
Gently tap each length of pipe with a hammer. If it does not ring or Hum, the pipe is damaged |
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What are the two major causes of underground construction deaths? |
Lack of shoring Shoring failure |
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What are the four components of a typical trench shoring system? |
Sheeting Uprights Horizontal crossmembers Longitudinal members/stringers |
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Uprights must extend how close to the bottom of the trench? |
As near as possible to the bottom of the trench, but not more than 2 feet from the bottom |
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All trenches deeper than_______ feet must be shored |
5 feet |
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How can operators be protected is shoring is not practical? |
The walls of an excavation maybe sloped 3/4 foot horizontal to 1 foot vertical |
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List the six different types of common shores |
Hydraulic, screw jacks, air, solid sheeting, cylinder, shield |
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When laying pipe with a bell, the bell should point in what direction? |
In the direction that the work is proceeding If being laid down hill, the bell should face up hill |
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At what six locations should thrust blocks be installed? |
Tees, Bends, caps, plugs, hydrants, other fittings that change flow direction or stop flow |
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How deep is the first layer of backfill? |
Should be compacted up to the horizontal centerline of the pipe |
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What water pressure is used for a leakage test? |
At least 50% higher than expected operating pressure, or 150 psi; whichever is larger |
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How can a tap be installed in a water main under an operating water pressure? |
In a wet tap, a valve is bolted to the tapping saddle and the actual drilling of the pipe through the valve is done with the pipe under pressure |
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How can new service connections be installed in existing plastic mains? |
By using a drilling machine to drill into the main through a combined clamp and Corporation stop |
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List the seven types of valves |
Plug valves, Ball, butterfly, diaphragm, globe, gate, check |
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What is the main application of gate valves? |
To isolate sections of mains to permit emergency repairs without interruption of service |
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What are the two main uses of globe valves? |
Flow and pressure regulation |
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How many valves should be located at pipe crosses? |
Three |
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How are valves opened or closed? |
Manually or by actuators |
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List the three uses of fittings |
Connect pipes of similar or different sizes Change direction of flow Stop flow |
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List the three uses of hydrants |
Fires Flush pipelines Provide water to water trucks or other construction equipment |
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What are the four parts of a hydrant? |
Inlet pipe connection from the water supply Main The main valve The barrel The head |
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At what five points should meters be used? |
Main supply lines Pumping stations Reservoir outlets Connections to other utilities Each customer's service |
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What is the main difference between low flow meters and high flow meters? |
Low flow meters are of the displacement type High flow meters are of the velocity type |
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List the two types of displacement meters |
Nutating disc Piston |
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List the five types of velocity meters |
Turbine Propeller Venturi Electronic Insertion |
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Under what type of flow conditions are compound meters installed? |
In places where there are predominately low or intermediate flows and only occasional high flows |
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What are the two major types of electronic flow meters? |
Magnetic and sonic |
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Fire lines use what type of meter? |
Proportional meters |
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What is a corporation stop? |
A water service shut off valve located at a street water main |
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What is a curb stop? |
A water service shut off valve located in a water service pipe near the curb and between the water main and the building |
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Where are backflow prevention devices normally installed? |
At the service connection directly downstream from the meter |
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List the three backflow prevention devices that are approved for use at service connections |
Double check valve assembly Reduced pressure device Air gap device |
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Why are two check valves required for the double check valve assembly and the reduced pressure device? |
The failure rate of a single check valve is too high |
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What is the distance of the vertical gap in an air gap device? |
Twice the diameter of the discharge pipe, but no shorter than 1 inch |
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What are the two advantages of displacement type water meters? |
They are accurate in registering low flows in sizes up to 2 inches They can measure wide variations of flow within their rated capacity |
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What five types of shores are approved by OSHA? |
Air, cylinder, hydraulic, screw jacks, solid sheeting |
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Water should be delivered with a working minimum pressure of_______ psi to all points in a distribution system |
35 PSI |
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Which direction does the hydraulic grade line slope? |
Downward in the direction of flow in a pipe |
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What are the psi regulations? |
Minimum desirable pressure of 35 psi Absolute minimum pressure of 20 psi A maximum pressure of 100 psi |
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What is the minimum diameter of pipe, excluding service lines? |
6 inches |
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How far apart should fire hydrants be located? |
No more than 500 feet apart |
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Fire demands are usually more than________ The normal user demands |
Two times |
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What type of distribution system layout is most common? |
Grid |
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What type of distribution system out produces dead end water mains? |
Tree |
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With pipes, what four classes of working pressures are commonly encountered? |
100 psi, 150 psi, 200 psi, and 250 psi |
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What is the normal size range of service pipe? |
3/4 to 1 1/2 inches |
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With plastic pipes, what is the usual type of joint used for PVC pipe? |
A gasketed joint |
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What type of PVC pipe may be threaded? |
Schedule 80 and heavier |
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What are the regulations for water and sewer line separation? |
Water mains parallel to sanitary sewers should be installed at least 10 feet horizontally away from the sewers and at least 1 foot higher than any nearby sanitary sewer line |
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What are the regulations for water and sewer line separation? |
Water mains parallel to sanitary sewers should be installed at least 10 feet horizontally away from the sewers and at least 1 foot higher than any nearby sanitary sewer line |
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Water mains need at least_______ inches of cover over the top of the pipe |
30 inches |
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What is the minimum spoil set back from the edge of a trench? |
2 feet |
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What type of shore is frequently used? |
Hydraulic shores |
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What are the regulations for pressure and leakage tests? |
When testing, pipes should not be filled at a rate greater than 1 foot of pipe length per second After the pipe is full, it should sit idle for at least 24 hours before the test starts |
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What are the two main categories of shut off and flow regulation valves? |
Rotary and linear stroke the valves |
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What are the two main categories of shut off and flow regulation valves? |
Rotary and linear stroke the valves |
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What are the three types of rotary valves? |
Plug, Ball, butterfly |
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What are the four types of linear stroke valves? |
Diaphragm, globe, gate, and check valves |
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What is the most common important type of linear stroke valve used? |
Gate valves. They isolate sections of mains to permit emergency repairs without interruption of service |
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Why are gate valves used? |
So that repair work will not shut down a feeder Main or length of pipe greater than 1000 feet |
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What are the two types of fire hydrants? |
Dry barrel and wet barrel Wet barrel hydrants in areas where winters are mild |
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What are the two types of fire hydrants? |
Dry barrel and wet barrel Wet barrel hydrants in areas where winters are mild |
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What is the most commonly used fire hydrant type? |
Post hydrants |
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What accuracy requirements pertain to small meters? |
Does not register less than 98.5% or more than 101.5% of water passing through them Meters of 1 inch and smaller should have a head loss not exceeding 15 psi, and the head loss of larger meters should not exceed 20 psi |
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With service lines, where are backflow prevention devices installed? |
Between the meter and the customers line |
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What size water meter is common with service lines? |
3/4 inch |
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Of the three types of backflow prevention devices, which provides the greatest degree of protection and which provides the least? |
Double check valves provide the least degree of protection Air gap devices provide the greatest degree of protection |
