CSLB C-27 Landscaping ContractorIrrigation SystemsMedium
A landscape contractor is troubleshooting a sprinkler zone where several heads are not popping up or are spraying weakly. The pressure gauge at the backflow preventer reads 60 PSI, but the pressure at the sprinkler farthest from the valve is only 15 PSI. What is the most likely cause of this significant pressure drop?
- AThe backflow preventer is faulty.
- BThe irrigation controller is malfunctioning.
- CThe sprinkler heads are clogged with debris.
- DThere is a significant leak or a partially closed valve downstream.
Show answer & explanationAnswer & explanation
Correct answer: D. There is a significant leak or a partially closed valve downstream.
A large pressure drop between the backflow preventer (main line) and the end of a zone, especially when heads are not popping up, strongly indicates excessive water loss. This is commonly caused by a major leak in the lateral line or a valve that is not fully open, restricting flow.
Why the other options are wrong
- A. A faulty backflow preventer might affect the entire system's pressure, but a localized drop within one zone suggests an issue further downstream.
- B. A malfunctioning controller would prevent the zone from turning on, but wouldn't cause a pressure drop within an active zone.
- C. Clogged heads would reduce spray, but a 45 PSI drop suggests a larger issue than just individual head blockages.
Pressure Drop Troubleshooting
Diagnosing a significant loss of water pressure in an irrigation zone, often indicating a leak, obstruction, or improperly sized components.
- Measure pressure at various points to isolate the problem area.
- Common causes include leaks, partially closed valves, clogged filters, or undersized piping.
- Insufficient pressure leads to poor coverage and inefficient watering.
Memory trick: Pressure drops like a rock, look for what's blocking or leaking.