Potable Water Distribution Systems Flashcards
How many psi does a column of water 1ft high produce
0.433 psi
How do you calculate pressure for gravity feed water system
Pressure = height X density
Ex 100 ft x 0.433 psi/ft
Water running through a large smooth pipe at low velocity is what type of flow
Laminar or smooth streamlined flow
When the pipe is rough, small in diameter and the velocity of the water is high what is this type of flow?
Turbulent
Lower floor, hot water is fed from the same supply as the upper floors, but the water pressure is controlled through a PRV
The result is a system in which up feed risers supply, the lower floors and downfeed risers supply the upper floors
Combination up feed/down feed PRV system
This system is recommended for use on buildings that are only a few stories too high for adequate municipal supply pressure or in areas of municipality where water pressure is normally low
This system is adequate for buildings up to 20 standard stories high with the maximum static pressure at any fixture 80 psi
Up feed booster system
This water system has supply means that are located at the top of the building with the booster pump at ground level
Supplies water to down feed risers
Downfeed booster system
The system, water is pumped from ground level and a PRV is installed in each hot and cold downfeed riser at a level that allows reasonable pressure to be maintained to the lower floors
PRV down feed booster system
Some tall buildings are supplied by a combination of main pressure and booster pump pressure systems
Cold water for the lower floors is fed directly from the municipal supply upper floors are fed through distribution means located at the top of the building supplied by booster pumps
Lower floor, hot water is supplied from the top story with PRV’s
Combination of up feed/down feed system
These are a necessary part of the plumbing system and required whenever a waterline is hooked up to a plumbing fixture with no air gap protection
Vacuum breakers
The plumbing code specifies that there must be an air gap between the spout and the flood level room of fixture how large?
The air gap is to be at least two times the effect of opening, but never less than 1 inch
Where can the test requirements for potable water distribution systems be found in the plumbing code
2.3.7
Where is the water distribution pipe measured from?
From the entry point in the building, the building isolation valve for the water metre to the furthest fixture in the building, served by this water distribution system
Who usually designs booster pump systems?
Engineers
For booster pump systems what things must be installed per code at the bottom of each riser
Shut off valves, building has return line balancing valves are also required
What parameters requires a hot water recirculation system?/self regulating heat tracing.
If the system has a developed length greater than 30 m or is more than four stories in height
Most problems associated with hot water recirculation systems over the result of what
Oversizing recirculation pumps
The type of metre chosen for any installation industrial depends on what
Size of the service or supply pipe and on the expected flow rate through the metre
These metres were commonly used for consumer billing were the size of the building service was 2 inch trade size or smaller
Rotating disc metre
This metres installed where freezing may occur
Available in 5/8, 3/4, and 1 inch sizes
Cast-iron base metres
The primary function of this metre is to serve as a monitoring device for industrial pumps and equipment
Turbine metres
These metres are primarily used for consumer billing where the water service is larger than 2 inch
Consist of a turbine metre and a positive displacement metre in one casing
Compound metres
To prevent accidental shock to metre service personnel, what must you do?
Bypassed the metre to provide for permanent electrical grounding
Minimum distance of centre line of piping adjacent to metre setting to be how far on small metre settings
12 inches
What’s the minimum footage with no obstruction in front of small meter settings?
3 feet
For large metre settings what pipe sizes must be threaded
Sizes from 1/2” to 2 1/2 inch
For large metre settings pipe sizes 3 inch and larger must be what
Flanged
For large metre settings, main pipe alignment must be a minimum of what from any wall partition fixture or other piping
18”
When large metres are installed in vault what provision should be made?
At least 20 inches of clearance to the vertical walls and 24 inches of headspace from the highest point on the metre to the vault cover
Some water utility providers require a valve on the outlet side of the metre setting on piping what size
1 inch and over
The valve is optional on piping under 1 inch
Any valve used upstream or downstream of a water metre should be of what designed to prevent a flow restriction
Full port
Buildings with more than one water metre must have a metal or plastic tag showing what
Must have the service address engraved on it in letters or numbers at least 5 mm in height
What should you do to the pipe before flex rubber insulation is installed on iron or galvanized pipe
Painted with an asphalt based primer to prevent corrosion due to condensation
How should every water service pipe be sized?
Shall be sized according to peak demand flow, but shall not be less than three-quarter
