Water Supply & Distribution Systems Flashcards
7 cards from real CPD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Water Supply & Distribution Systems flashcards as text
In a downfeed water distribution system, where is the storage tank located?
Answer: At or above the highest fixture served
A downfeed system uses gravity flow from a rooftop or elevated tank, so the tank must be located above the highest fixture to provide positive pressure.
The Hazen-Williams coefficient 'C' for new smooth PVC pipe is approximately:
Answer: 140
New smooth PVC pipe has a Hazen-Williams C value of approximately 140–150, reflecting its very smooth interior surface and low friction resistance.
Which backflow prevention assembly provides the highest level of protection for a high-hazard cross-connection?
Answer: Reduced pressure principle assembly (RPPA)
A reduced pressure principle assembly (RPPA) is required for high-hazard cross-connections because it uses a monitored relief valve between two independently operating check valves.
What is the recommended maximum water velocity in a copper supply branch to minimize erosion corrosion?
Answer: 8 fps
ASHRAE and industry guidelines recommend limiting water velocity in copper branch piping to 8 fps to prevent erosion corrosion of the pipe wall.
A hydropneumatic tank in a water supply system is used to:
Answer: Store pressurized water and reduce pump cycling
A hydropneumatic (pressure) tank stores water under a captive air charge, supplying system demand between pump cycles and reducing pump wear from short-cycling.
When designing a tempered water system for emergency eyewash stations, the required water temperature range per ANSI Z358.1 is:
Answer: 60–100°F (16–38°C)
ANSI Z358.1 requires tempered flushing fluid between 60°F and 100°F (16°C to 38°C) for emergency eyewash and shower equipment.
What is the primary reason for installing a thermal expansion tank on a closed water heater system with a PRV?
Answer: To absorb pressure buildup from thermal expansion of heated water
When a PRV or backflow preventer creates a closed system, heated water cannot expand back into the street main, so a thermal expansion tank is required to safely absorb the increased volume.