CSLB C-27 Landscaping ContractorIrrigation SystemsMedium
A C-27 contractor is installing a drip irrigation system for a planter bed containing drought-tolerant shrubs. The design calls for 0.5 GPH (gallons per hour) emitters. If the zone has 40 emitters and operates for 30 minutes, how many gallons of water will be applied to the planter bed?
- A10 gallons
- B40 gallons
- C30 gallons
- D20 gallons
Show answer & explanationAnswer & explanation
Correct answer: A. 10 gallons
Total flow rate = (Emitters) × (GPH per emitter) = 40 emitters × 0.5 GPH = 20 GPH. Total water applied = (Total flow rate) × (Operating time in hours) = 20 GPH × (30 minutes / 60 minutes/hour) = 20 GPH × 0.5 hours = 10 gallons.
Why the other options are wrong
- B. This is an incorrect calculation, possibly multiplying emitters by flow rate and then by 1 hour incorrectly.
- C. This is an incorrect calculation, likely from using 3/4 hour or other errors.
- D. This would be the total GPH if operated for a full hour, not the amount for 30 minutes.
Drip Emitter Output Calculation
Calculating the total water applied by a drip irrigation zone by multiplying the number of emitters by their individual flow rate (GPH) and the operating time in hours.
- Emitter flow rates are typically measured in GPH.
- Operating time must be converted to hours for accurate calculation.
- Essential for determining appropriate watering schedules and water use.
Memory trick: Emitters, rate, and time: the recipe for drip's total drink.