LARE LARE Irrigation Design 1 — Questions and Answers
Question 1: What is the primary purpose of a pressure vacuum breaker (PVB) in a landscape irrigation system?
- To increase water pressure at the heads
- To prevent backflow contamination of the potable water supply (Correct answer)
- To filter debris from the water supply
- To regulate flow rate to each zone
Correct answer: To prevent backflow contamination of the potable water supply
A pressure vacuum breaker prevents contaminated irrigation water from siphoning back into the potable water supply through backflow protection.
Question 2: Which irrigation head type is most appropriate for large, open turf areas?
- Drip emitters
- Pop-up spray heads
- Rotor heads (Correct answer)
- Bubbler heads
Correct answer: Rotor heads
Rotor heads are designed for large open turf areas because they throw water 15–50 feet using rotating streams, efficiently covering wide spaces.
Question 3: What does 'precipitation rate' refer to in landscape irrigation design?
- The amount of natural rainfall expected per year at a site
- The rate at which irrigation heads apply water to an area, measured in inches per hour (Correct answer)
- The percentage of applied water absorbed by plant roots
- The speed at which water moves through the soil profile
Correct answer: The rate at which irrigation heads apply water to an area, measured in inches per hour
Precipitation rate is the rate at which irrigation heads apply water to a given area, expressed in inches per hour, and must be matched to the soil's infiltration rate.
Question 4: What is the typical operating pressure range for standard pop-up spray heads?
- 5–15 PSI
- 30–45 PSI (Correct answer)
- 60–80 PSI
- 100–120 PSI
Correct answer: 30–45 PSI
Pop-up spray heads are designed to operate at 30–45 PSI; pressures outside this range cause misting, fogging, or reduced arc coverage.
Question 5: Which soil texture has the highest water infiltration rate?
- Clay
- Silt
- Sandy loam
- Sand (Correct answer)
Correct answer: Sand
Sand has the largest particle size and greatest pore space of all soil textures, resulting in the highest infiltration rate but the lowest water retention.
Question 6: What is the primary purpose of a master valve in an irrigation system?
- To individually control each irrigation zone
- To serve as a main supply shutoff that closes whenever the controller is not actively running a zone (Correct answer)
- To boost static water pressure throughout the system
- To filter sediment from the water supply line
Correct answer: To serve as a main supply shutoff that closes whenever the controller is not actively running a zone
A master valve installed at the main supply line automatically closes when no zones are running, preventing water loss from leaking or damaged downstream zone valves.
Question 7: Which irrigation scheduling approach uses real-time or historical weather data to calculate plant water demand?
- Calendar-based scheduling
- Evapotranspiration (ET)-based scheduling (Correct answer)
- Fixed-interval scheduling
- Soil-texture-based scheduling
Correct answer: Evapotranspiration (ET)-based scheduling
ET-based scheduling uses evapotranspiration data derived from weather conditions to precisely calculate how much water the landscape needs, avoiding over- or under-irrigation.
LARE LARE Irrigation Design 1
What is the primary purpose of a pressure vacuum breaker (PVB) in a landscape irrigation system?