Mixed Deck — All CIT Topics Flashcards

What is the typical flow rate range for a standard drip emitter?

Answer: 0.5–2 gallons per hour (GPH)

Standard drip emitters flow at 0.5–2 gallons per hour (GPH), delivering water very slowly to minimize runoff and maximize absorption.

What is the purpose of a master valve in an irrigation system?

Answer: To act as a safety valve that opens only when the controller activates a zone, preventing water flow when no zones are running

A master valve is installed on the mainline and is controlled by the controller's master valve circuit. It opens only when the controller activates a zone, ensuring that no water flows through the mainline when the system is idle, preventing waste from leaks or broken pipes.

A client's irrigation system is causing a fine mist to come from the spray heads, leading to poor water distribution and significant waste from wind drift. Which of the following is the MOST likely cause of this issue?

Answer: High water pressure

High water pressure is a common cause of misting or fogging from spray heads. This occurs when the pressure exceeds the manufacturer's recommended operating range, causing the water to atomize. Low pressure would result in a weak spray and reduced radius, while clogged nozzles would typically create an irregular or blocked pattern.

At what point during mainline installation should a hydrostatic pressure test be performed?

Answer: Before the trench is backfilled, while all fittings and joints remain visible

Pressure testing before backfilling allows the installer to visually inspect every fitting, joint, and glued connection for leaks while they are still exposed and accessible, avoiding costly excavation if a failure is found after the trench is covered.

What is the most common cause of dry spots in a zone when run time appears adequate?

Answer: Low distribution uniformity from improper spacing or worn nozzles

Dry spots despite sufficient run time usually result from poor DU caused by improper head spacing or worn nozzles leaving low-coverage areas under-irrigated.

Heat stress in outdoor workers performing irrigation installation or maintenance is best prevented by:

Answer: Regular hydration, scheduled rest breaks in shade, appropriate clothing, acclimatization, and recognizing early symptoms of heat illness

Heat-related illness is a serious risk for outdoor irrigation workers. Prevention includes drinking water before feeling thirsty (16-32 oz per hour), taking regular shade breaks (per OSHA guidelines), wearing light-colored loose clothing, gradually acclimatizing to heat, and watching for symptoms in yourself and coworkers.

A sprinkler head is not retracting fully after the zone turns off. The most likely cause is:

Answer: Dirt, debris, or a worn spring in the sprinkler body preventing the riser from retracting

A sprinkler head that doesn't retract properly usually has dirt or debris between the riser and the body, or the internal spring that forces the riser down has weakened or broken. Cleaning the head and replacing the spring (or the entire head) resolves the issue.

Pushing a screwdriver or soil probe into the ground is a simple field method to quickly estimate:

Answer: Soil compaction and moisture level

Easy probe penetration indicates moist, non-compacted soil, while significant resistance indicates dryness or compaction, providing a quick field diagnostic.

In a two-wire decoder-based irrigation system, what does the single pair of wires running through the field carry?

Answer: Both power and digital address signals that activate specific decoders

Two-wire decoder systems multiplex both power and digitally encoded address signals on one wire pair. Each decoder is assigned a unique address; when the controller broadcasts that address, only the matching decoder energizes its valve, allowing hundreds of zones on a single wire path.

When installing irrigation components near a swimming pool, what minimum setback distance is typically required for sprinkler heads?

Answer: Sprinkler spray should not reach the pool deck or pool water — typically 5-10 feet depending on local code, and drip or subsurface irrigation is preferred near pools

Sprinkler heads must be positioned so their spray does not reach the pool deck (slip hazard) or pool water (introduces fertilizer, debris, and pathogens). Most codes require 5-10 feet setback, and drip or subsurface irrigation is preferred for pool-adjacent landscaping.

A technician measures 0.5 ohms resistance when testing an irrigation solenoid in the field. What does this reading indicate?

Answer: The solenoid coil is shorted (a direct short circuit exists in the winding)

A reading near 0 ohms indicates a short circuit within the solenoid coil. A healthy solenoid typically reads between 20–60 ohms. Near-zero resistance means the coil windings are shorted together, which will cause the controller output to overload or trip a fuse.

What is the primary function of an air/vacuum relief valve in a drip irrigation system?

Answer: Release trapped air on startup and prevent vacuum from drawing soil into emitters at shutdown

Air/vacuum relief valves vent trapped air during startup and prevent negative pressure at shutdown from siphoning soil particles back into emitter orifices.

When inspecting a drip irrigation system, a technician finds emitters that are discharging inconsistently — some clogged, others weeping at the base. The first corrective action should be:

Answer: Flush the mainline and clean or replace clogged emitters

Flushing the mainline removes accumulated sediment and debris. Clogged emitters should then be cleaned with diluted vinegar or replaced — increasing pressure can worsen leaks and damage low-pressure drip components.

When wiring multiple electronic zone valves to a standard irrigation controller, a single wire provides the shared electrical return path for all solenoids. To which terminal on the controller is this wire connected?

Answer: C (Common)

The 'C' or 'Common' terminal is the connection point for the common wire. This wire is connected to one lead on every solenoid in the system, creating a shared return path for the electrical circuit that activates the valves.

What is the benefit of 'predictive watering' or 'weather-based scheduling' in a smart controller compared to a fixed timer schedule?

Answer: It automatically adjusts irrigation run times based on real-time and forecasted weather data, applying only the amount of water plants have lost to evapotranspiration

Weather-based scheduling (using ET data and weather forecasts) automatically adjusts irrigation daily based on actual conditions. On hot, dry, windy days run times increase; on cool, humid, or cloudy days they decrease. This typically saves 20-40% water compared to fixed schedules.

Which soil texture is most recommended for turfgrass because it balances drainage and moisture retention?

Answer: Sandy loam

Sandy loam provides adequate drainage to prevent waterlogging while retaining enough moisture and nutrients to support healthy turfgrass growth.

What causes 'root intrusion' in subsurface drip emitters?

Answer: Plant roots growing into and blocking emitter orifices

Root intrusion occurs when plant roots grow toward moisture and into drip emitter orifices, physically blocking water flow.

An Atmospheric Vacuum Breaker (AVB) must NOT be installed in which of the following conditions?

Answer: Where the device will be subject to continuous pressure for more than 12 hours

An AVB is not designed to remain under continuous supply pressure. When subjected to pressure for more than 12 continuous hours, the internal float or poppet can become seated and fail to open when backpressure or backsiphonage occurs, defeating the device's purpose. It must be installed in systems that cycle off regularly.

What is the primary purpose of the test cocks on a testable backflow prevention assembly?

Answer: To provide connection points for differential pressure testing equipment

Test cocks are small valved ports on the assembly that allow a certified tester to connect differential pressure gauges. These connection points enable measurement of the pressure differentials across check valves and the relief valve opening point.

How should an irrigation system be tested for leaks?

Answer: By visually inspecting for leaks while pressurized

The most effective way to test an irrigation system for leaks is to run the system with water pressure and then visually inspect all components. Leaks, whether from pipes, fittings, or sprinkler heads, will typically be visible as water seeping or spraying, allowing for precise identification and repair.