Mixed Deck — All IA Topics Flashcards

Net Positive Suction Head Available (NPSHa) must always be:

Answer: Greater than NPSHr (required) to prevent cavitation

NPSHa must exceed NPSHr by at least 2–3 feet of safety margin to ensure the pump does not cavitate.

Which backflow prevention assembly provides the highest level of protection against both back-pressure and back-siphonage?

Answer: Reduced Pressure Zone (RPZ) assembly

The RPZ assembly provides the highest mechanical protection because it maintains a zone of reduced pressure between two check valves and vents any backflow to the atmosphere via a relief valve.

A zone fails to activate but others work fine. What is the likely cause?

Answer: Broken solenoid or wire

If only one irrigation zone fails to activate while all other zones function correctly, the most likely cause is a localized electrical issue specific to that zone. This typically points to a broken wire preventing the electrical signal from reaching the valve, or a faulty solenoid on that particular valve that cannot open even if it receives power.

What is the definition of a cross-connection?

Answer: Any physical connection between a potable water supply and a non-potable source

A cross-connection is any physical link between a potable water system and any source that could introduce contaminants into the drinking water supply.

Total Dynamic Head (TDH) in a pump system is the sum of which components?

Answer: Static head + friction losses + velocity head + pressure head at discharge

TDH = static head + friction head losses + velocity head + any pressure required at the point of delivery, representing total energy the pump must supply.

What is the purpose of the 'pump start relay' output on an irrigation controller?

Answer: To send a low-power signal to a relay that activates the irrigation pump whenever a zone runs

The pump start relay (PSR) output sends a 24 VAC signal to an external relay, which in turn switches line voltage to the pump motor whenever irrigation is active.

Which sprinkler nozzle type produces the lowest precipitation rate and is most appropriate for clay soils?

Answer: Rotary nozzle (e.g., MP Rotator)

Rotary nozzles like the MP Rotator apply water at very low rates (0.4–0.5 in/hr), well suited to clay soils with low infiltration rates.

Which controller feature allows a user to temporarily increase or decrease all run times by a percentage without reprogramming each zone?

Answer: Seasonal adjust (water budget) percentage

The seasonal adjust or water budget feature multiplies all station run times by a set percentage, allowing quick seasonal changes without editing each station individually.

In an ET-based smart controller, what is a 'reference ET station'?

Answer: A weather station or network that provides ET data the controller uses to adjust run times

A reference ET station (on-site or remote) measures or calculates ETo data that the smart controller uses to compute and adjust daily irrigation run times.

What is the primary purpose of adjusting irrigation run times seasonally?

Answer: To match changing ET demand throughout the growing season

Seasonal run-time adjustments ensure applied water matches actual crop or turf ET, which varies significantly from spring through summer to fall.

The Irrigation Association defines a landscape irrigation audit as a process to evaluate:

Answer: How efficiently and uniformly an irrigation system applies water

An IA landscape irrigation audit evaluates system performance including uniformity, application rates, scheduling, and overall water use efficiency.

Why is it important to consider soil type in irrigation design?

Answer: It controls water infiltration and retention

Soil type significantly impacts how quickly water infiltrates the ground and how much moisture it can retain. Understanding this helps in selecting appropriate sprinkler types, application rates, and run times to prevent runoff or underwatering, ensuring efficient water delivery to the plant roots.

What is the primary function of an irrigation controller?

Answer: To automatically open and close valves according to a programmed schedule

An irrigation controller (timer) operates solenoid valves on a preset schedule, automating the opening and closing of irrigation zones without manual intervention.

How does compaction affect soil-water-plant relationships?

Answer: Reduces infiltration and root development

Soil compaction decreases the pore space within the soil, making it harder for water to infiltrate and for plant roots to penetrate and grow. This leads to increased runoff, reduced water availability for plants, and stunted root development, negatively impacting plant health and water efficiency.

Landscape water use efficiency (WUE) is expressed as the ratio of:

Answer: Water beneficially used to total water applied

WUE = beneficial water use / total water applied × 100%; the goal is to maximize plant water use and minimize waste from runoff, deep percolation, and evaporation.

Central control irrigation software used on golf courses and large commercial properties allows managers to:

Answer: Monitor and adjust all controllers on a property from a single computer or mobile device

Central control systems provide remote monitoring, scheduling, and diagnostics for multiple controllers across large properties from one interface.

What is the purpose of a pressure relief valve on an irrigation pump discharge?

Answer: To protect the system from over-pressure caused by water hammer or valve closure

A pressure relief valve opens automatically when system pressure exceeds a set point, protecting pipes, fittings, and emitters from damage.

Which certification exam does the Irrigation Association offer that is most focused on landscape irrigation system installation and maintenance?

Answer: Certified Irrigation Technician (CIT)

The CIT exam covers installation, maintenance, troubleshooting, and basic design of residential and commercial landscape irrigation systems.

Why is soil texture important in irrigation planning?

Answer: It controls water retention and movement

Soil texture, determined by the proportion of sand, silt, and clay, directly influences how well soil retains water and how quickly water moves through it. This knowledge is crucial for setting appropriate irrigation schedules and application rates to prevent water waste and ensure plants receive adequate moisture.

What is the main benefit of drip irrigation systems?

Answer: Delivers water efficiently to root zone

Drip irrigation systems deliver water slowly and directly to the plant's root zone, minimizing evaporation and runoff. This targeted application significantly reduces water waste compared to overhead sprinklers, making it highly efficient for watering individual plants or rows.