Potable Water Distribution Systems Flashcards
Define Velocity and pressure
Velocity is the rate at which fluid flows
Pressure is the force exerted to the walls of the pipe.
What effect does un reamed pipe have on the flow of water in a pipe?
Turbulence
When does water hammer occur?
When water is forced to change direction or stop suddenly.
List 3 ways to prevent water hammer.
Use shock arresters
Open valves slowly
Air chambers
List 4 causes of water hammer
Quick closing valves
Sudden changes in direction
Temperature difference of liquids
Water stopping suddenly
How do you recharge an air chamber
Drain the system and refill
What 5 things must be known to size a water supply system?
Total developed length of water service pipe
Minimum static pressure at the property line
Length of distribution pipe from building isolation to furthest fixture served
Water pressure at highest fixture served
Total hydraulic load
The minimum working pressure at the fixture is what?
Conforms to the manufacturers specifications
The maximum working pressure at the fixture is what?
Never exceeds 550 kPa static pressure
What table would you find the fixture unit value for a urinal with a direct flush valve?
Sizing of water distribution systems for urinals with direct flush valves.
When sizing multiple water closets with direct flush valves, does the furthest water closet from the distribution supply pipe have the largest or smallest load?
The largest load. This will ensure that the minimum required flow rate is maintained.
What is the minimum air gap required on a lavatory?
25mm or 1”
How must the water supply to pan sinks be protected from back flow ?
Using an approved back flow preventer
How would you find the hydraulic load, fixture units for a commercial dish washer?
Refer to manufacturers recommendations
How do you find the hydraulic load for a 1/2” hose wye?
Use hose Bibb , 1/2” private use fixture unit total from table 2.6.3.2A times 2
Which tables are used to size a water distribution system using the method for small commercial buildings?
Tables 2.6.3.2A 2.6.3.2B 2.6.3.2C 2.6.3.2D A-2.6.3.1.(2)A.
What is the minimum size of the supply line to a water closet using a flush valve?
1”
What term is used to describe the water piping inside a building?
Distribution piping
What is the metric equivalent to pressure expressed as?
KiloPascals (kPa)
What is the minimum size of a water meter ?
5/8”
What does a water meter do?
Measures and records the volume of water passing through a pipe.
Which is the most used type of meter?
Positive displacement
What is the primary use of a turbine meter?
Used as a monitoring device for large flow volumes.
Do water meters have to be accessible?
Yes. There needs to be enough room for maintenance or removal and reinstallation of the meter assembly.
Do water meters have to be electrically grounded?
Yes. To prevent injury to personnel working on the water meter.
How far must a a water meter be from any entrance, wall, or grade wall?
12”
For a 5/8 water meter, how much space is required between adapters?
12”
How many valves are required for a bypass?
3 valves
What types of valves are required on a bypass?
Full port gate valves or ball valves
What is installed on domestic waterlines to prevent condensation?
Insulation
What causes condensation on water lines?
Humidity condensing on the surface and f clod pipe:
Can a public water system be connected to a private water system?
No. 2.6.2.5(1) clearly states this is not acceptable under the NPC regulations.
Provisions shall be made to protect the water distribution system from the adverse effects of.
Water hammer
The hot water supply must be on which side of the fixture?
Left.
A water distribution system must be capable of meeting ____demands.
Peak demands
A newly installed part of a potable water distribution system shall be ______before the system is put into operation
Cleaned
What 2 methods can be used to maintain temperature in a hot water line that is longer than 30 meters ?
Recirculation
Self regulating heat trace system.
What are the 2 types of water distribution systems.
Gravity and forced.
How much pressure is produced by a column of water 1’ high?
.433 psi
What is head loss?
Loss of pressure due to friction in pipes calculated in feet per 100 feet.
What does an about air vent do?
Eliminates air locks
When is a vacuum breaker required?
When the waterline is hooked up to a fixture with no air gap protection.
When is an air test acceptable instead of a water test?
In freezing conditions
What are the requirements for an air test?
No less than 700 kPa for at least 2 hours
When sizing a water distribution system which column on table 2.6.3.2.A should be used
The total column for individual fixtures. Not hot or cold or bathroom groups.
When sizing a water distribution system who’s specifications must you conform to.
The fixture or device manufacturer , but not exceed 550 kPa.
The total developed length of the water service pipe is measured from where to where?
From the property line be or private water supply system to the entry point in the building, usually the building isolation valve or water meter.
From where to where is the pressure in water distribution pipe measured?
From the entry point in the building, the building isolation valve or water meter to the furthest fixture served by the system.
