- Certified Irrigation Technician Irrigation Principles and Components Flashcards

Head-to-head spacing in sprinkler design means that:

Answer: Each sprinkler's throw reaches the adjacent sprinkler heads, providing overlapping coverage

Head-to-head spacing means each sprinkler throws water far enough to reach the next sprinkler head. This overlap is essential because a single sprinkler applies the most water near its base and the least at the edge of its throw, so overlap ensures uniform coverage.

A zone valve (also called a control valve) in an irrigation system is typically what type of valve?

Answer: Globe valve operated by a solenoid

Irrigation zone valves are typically globe-pattern valves operated by a 24 VAC solenoid. The solenoid controls a small pilot flow that opens or closes a rubber diaphragm, which in turn controls the main water flow through the valve.

What is the function of a filter (screen or disc type) in a drip irrigation system?

Answer: To remove particulate matter that could clog the small orifices in drip emitters

Filters in drip systems remove sand, sediment, algae, and other particles that would clog the tiny orifices in drip emitters (typically 0.5-1.0mm). Screen filters and disc filters are the most common types, with mesh ratings matched to the emitter orifice size.

The term 'distribution uniformity' (DU) in irrigation refers to:

Answer: A measure of how uniformly water is applied across the irrigated area, expressed as a percentage

Distribution uniformity (DU) measures how evenly water is applied across the irrigated area. A DU of 100% means perfectly even application. Typical well-designed spray systems achieve 55-65% DU, while rotors achieve 65-75% DU and drip systems can reach 85-95% DU.

PVC (polyvinyl chloride) pipe used in irrigation systems is rated by which classification system?

Answer: Schedule rating (Schedule 40, Schedule 80) for pressure class

PVC irrigation pipe is rated by schedule (Schedule 40, Schedule 80) or by pressure class (Class 125, 160, 200, 315). Schedule rating indicates wall thickness relative to diameter, while class rating directly states the maximum working pressure in PSI.

What is the primary advantage of using polyethylene (PE) tubing instead of PVC pipe for irrigation laterals?

Answer: PE is flexible, frost-resistant, and can be installed without fittings for direction changes

Polyethylene tubing is flexible, allowing it to be curved around obstacles and routed through landscapes without rigid fittings for every direction change. It is also more resistant to freeze damage because it can expand and contract without cracking.