What is the maximum allowable difference when diffusing a spray head?

The correct answer is 25%. This figure, representing the maximum allowable difference in the output of spray heads, is significant for ensuring uniformity in irrigation systems. Using spray heads with varying output capacities can lead to irregular irrigation patterns, affecting plant health and water efficiency.

The 25% threshold allows for some variability in performance among different spray heads while still maintaining acceptable distribution uniformity across the landscape. This is particularly important in large irrigation systems where consistency is critical for avoiding overwatering or underwatering areas, which could damage plants or waste water resources.

The standards for allowable differences like this are based on research and best practices in irrigation design, which aim to promote efficiency and effectiveness in landscape and agricultural irrigation.