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DW Distribution > Distribution and Storage > Flashcards

Distribution and Storage Flashcards

1
Q

Water meters used for domestic residential services.

A
  • Displacement type:
  1. Nutating disc meter
  2. Piston meter
  • Velocity type:
    1. Turbine
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2
Q

Most common residential water meter.

A

Nutating disc meter

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3
Q

Wear in positive displacement meter will cause this.

A

Meter will under-register (record less than actual flow)

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4
Q

Only a decimal fraction of the water flows trough this type of meter.

A

Proportional meter

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5
Q

Meters designed specifically to respond accurately to low flows.

A

Displacement type meters

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6
Q

Installation of meters can minimize or reduce this.

A

Wasteful water use (Installation of meters is the first step in water conservation)

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7
Q

Distribution reservoirs are covered for these reasons.

A
  • Eliminate airborne contamination
  • Reduce loss of chlorine
  • Minimize growth of nuisance algae
  • Prevent vandalism
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8
Q

Function or purpose of distribution system reservoirs

A
  • Provide emergency and fire flow reserves
  • Provide disinfection contact times - Equalize peak flows
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9
Q

Corrosion of ductile iron pipe can be minimized by this.

A
  • The interior of the pipe can be lined with cement - The exterior of the pipe can be covered with polyethylene plastic.
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10
Q

the taste and odor problems of distribution system dead ends can be reduced with this.

A

Routine flushing

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11
Q

This should be provided at all distribution system tees and crosses.

A

Isolation valves

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12
Q

Factors that determine friction loss in distribution system piping.

A
  • Pipe diameter - Interior roughness - Flow rate or velocity - Pipe length - Number and type of fittings
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13
Q

Purpose of the isolation valve on the line to a fire hydrant.

A
  • Backup in the event of failure of the hydrant valve - Allows isolation of the hydrant for repair
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14
Q

Distribution leak detection methods.

A
  • Visual inspection during dry weather periods - Listening with various hydrophone systems - Closing off portions of the system and measuring water flow
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15
Q

Minimum maintenance on distribution system valves.

A

Operated once per year

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16
Q

Trench load on a buried pipe is determined by these factors.

A
  • Trench depth - Trench width
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17
Q

Flow measuring devices in a typical compound meter.

A
  • Velocity (turbine) meter for high flow - Displacement meter low flow
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18
Q

This must be provided at distribution system pipe bends.

A

Thrust restraint at the bend

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19
Q

Typical percent of unaccounted water in a metered distribution system.

A

10 to 20 percent

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20
Q

The minimum size water main to supply a standard fire hydrant.

A

6 inch

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21
Q

This increases the thrust at pipe bends

A

The thrust increases as the angle of the bend becomes more acute: - The thrust on a 45° bend is greater than a 30° bend. - The thrust on a 90° bend is greater than a 45° bend.

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22
Q

This should be done when rocky soil is encountered in a trench.

A

The trench should be over excavated by approximately 6 inches and replaced with a suitable back fill material, such as sand

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23
Q

Water meter designed to accurately register over a wide flow range.

A

Compound meter

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24
Q

Materials banned from use in distribution or plumbing systems.

A

Lead based pipe and solder

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25
Q

Brass plug valve threaded into a tapped water main.

A

Corporation stop

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26
Q

Used to de-water excavations and trenches.

A

Well point system

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27
Q

This can be provided to protect steel tanks and pipes from corrosion.

A

Cathodic protection

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28
Q

Rapid opening and closing of a fire hydrant valve can cause this.

A

Water hammer

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29
Q

Minimum distribution system pressure that should be maintained during fire flow.

A

20 psi

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30
Q

The purpose of distribution system valves.

A

They enable isolation of small portions of the system for maintenance or repair.

31
Q

Process of making a connection to a water line that is under pressure.

A

"Live tap" or "wet tap"

32
Q

Distance from bottom of hydrant to 4 inches below the flange that connects the upper hydrant barrel.

A

Hydrant bury

33
Q

Fire hydrant with a drain opening that allows the barrel to drain when the control valve is closed.

A

Dry barrel hydrant

34
Q

The function of distribution system booster pumps.

A

Provide pressure "boost" at higher elevation

35
Q

Recommended accuracy for residential water meter.

A

+/- 1.5% accuracy

36
Q

Acronyms for pipe used in water distribution systems. - ACP - CCP - DIP - PVC - CIP - GIP

A
  • Asbestos cement pipe - Concrete cylinder pipe - Ductile iron pipe - Polyvinyl chloride - Cast iron pipe - Galvanized iron pipe
37
Q

Used to control the water level in a storage reservoir.

A

Altitude valve

38
Q

Used to measure hydrant flow

A

Pitot meter

39
Q

Used to provide electrical continuity to ductile iron pipe water mains.

A

Metal wedges or straps

40
Q

Most common distribution system valve.

A

Gate valve

41
Q

Used to replace sections of a distribution system main during repair

A

“Dresser” style coupling

42
Q

Distribution system piping and pumping can be downsized if this is properly located and designed.

A

Distribution system storage reservoirs.

43
Q

These conditions can contribute to freezing of water distribution mains.

A
  • Extreme cold weather - Shallow pipe bury - Lack of snow cover - Intermittent or low flow
44
Q

These conditions can result in a reduction in the “C” factor for distribution system water mains, with subsequent increase in friction loss.

A

Tuberculation (deposits formed by corrosion of iron or steel) or scale deposition

45
Q

Distribution system air and relief valves should be placed here.

A

At high points

46
Q

Trenchless construction method used to install a water main under a road or railroad.

47
Q

Purpose of thrust blocking.

A

Keep pipe joints from separating

48
Q

Recommended spacing interval for distribution system isolation valves in a residential area.

A

Every 800 ft

49
Q

Permanent point of known elevation.

50
Q

Substance added to water to produce a protective film on the pipe wall, to minimize corrosion.

A

Passivator or inhibitor

51
Q

Used for water main repair: - Localized leak - Insert new pipe section

A
  • Localized leak: Split sleeve repair system - Insert pipe section: “Dresser” style couplings
52
Q

Controls the level in a water storage tank when the water surface in below the hydraulic gradient.

A

Altitude valve

53
Q

Important safeguards for a water distribution system.

A
  • Maintain disinfection residual - Maintain continuous pressure - Implement an active cross connection program - Regularly test for disinfection residual and bacteriological quality.
54
Q

The control valve for a dry barrel hydrant is located here.

A

In the hydrant head

55
Q

Used to “passivate” or provide a protective protective film on distribution system mains to reduce corrosion.

A
  • Silica compounds - Polyphosphates
56
Q

Steps to perform before a newly installed distribution water main is backfilled.

A
  • Perform pressure or leak test - Flush main - Disinfect - Flush main - Collect bacteriological sample
57
Q

Purpose of a dry barrel hydrant.

A

Protects the hydrant from freezing

58
Q

Maximum rated flow for a 5/8 x 3/4 inch residential meter.

59
Q

Criteria for selecting hydrant types: - Dry barrel - Wet barrel

A
  • Dry barrel hydrants are used where there is a danger of hydrant freezing. - Wet barrel hydrants are used in warm climates where there is no danger of freezing.
60
Q

Use of distribution system maps: - Plan view. - Section or elevation view.

A
  • Used to determine horizontal dimensions and layout. Example: What is the distance from the curb to a water main in the street. - Used to determine depths and elevations. Example Is a sewer line above or below a water main.
61
Q

Purpose of OS & Y gate valves.

A

gate valve with open stem and yoke, used when it is important to see at a glance if the valve is open or closed.

62
Q

Used to regulate system pressure that exceeds the recommended maximum water service pressure at 80 psi.

A

Pressure regulating valve

63
Q

Important requirements for water storage tank overflow piping.

A
  • Should be sized to handle maximum fill rate - Should include a “backwater” valve on the outlet
64
Q

Minimum recommended residual system pressure during hydrant flow testing.

65
Q

Purpose or function of altitude valves.

A

Control the maximum filling level in a distribution system storage tank or reservoir.

66
Q

Advantages-disadvantages of ductile iron.

A
  • Able to withstand extreme internal and external stress loads - Can be used in extreme trench conditions. - One of the heaviest pipe materials - Subject to internal or external corrosion unless steps are taken to provide corrosion protection
67
Q

Advantages-disadvantages of concrete cylinder.

A
  • Available in large diameters - High strength, able to withstand internal and external stresses - Resistant to corrosion unless cement lining is damaged
68
Q

Advantages-disadvantages of asbestos cement.

A
  • Light weight - Corrosion resistant except in very acid soils or low pH water - Easily damaged by rough handling during installation, or by trench rocks
69
Q

Advantages-disadvantages of PVC.

A
  • Light weight , easy to handle and install - Complete corrosion resistance - Not suitable for soils with petroleum residues
70
Q

Valve with lowest friction loss when open.

A

Gate valve

71
Q

Common joint methods used for distribution system piping.

A
  • Mechanical joint - Flange - Rubber ring “push on” - Bell and spigot, with poured lead - Solvent weld
72
Q

Purpose or function of pipeline air/vacuum relief valve.

A
  • Allow pipeline air to escape - Allow air to enter a pipeline to reduce risk of pipe collapse, in the event of sudden loss of pressure
73
Q

Methods used to clean distribution system mains.

A
  • Hydrant flushing - Water main pigging
74
Q

Causes of drinking water contamination.

A
  • Inadequate water treatment or disinfection - Cross connections - Water main break or repairs

DW Distribution (8 decks)

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