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ARMAC employs two distinct sprinkler types selected after quite a bit of testing and hydraulic analysis. Three Dural VYRSA-60 dual-nozzle impact sprinklers (3.6mm and 2.4mm nozzles) serve areas requiring longer throw distances, operating between 180-420 kPa pressure with published characteristics of 15.3-24.0 L/min flow and 13.0-14.5 meter radius. Seven Pope Heavy Duty Impact sprinklers handle closer-in coverage with specifications of 10 L/min at 100 kPa minimum pressure, 18.9 L/min at 350 kPa, and 12.5 meter maximum radius. All sprinklers feature all-metal construction with easily removable brass nozzles for cleaning, and adjustable full or part-circle spray patterns. They are designed to be easily adjustable in all horizontally and vertically.
Sprinkler positioning followed a methodical process beginning with desktop planning based on rated spray radii, followed by extensive field testing. At each proposed position, a sprinkler was mounted on a flexible pole and fed by rubber hose from a small electric centrifugal pump boosting tap water pressure. This testing phase allowed experimentation with different heights, angles, and positions to achieve optimal overall coverage before any permanent installation occurred. Even after the feeder pipe and pump became operational with posts established, sprinklers remained connected via temporary hoses until their positions were finalized, at which point copper pipe plumbing was completed.
The hydraulic design required careful analysis to ensure adequate pressure at all sprinkler locations while accounting for pipe friction losses and elevation differences. Using the measured pump performance curve (50 meters head at 130 L/min, 45 meters head at 300 L/min), calculations demonstrated that even at the hydraulically most disadvantaged sprinkler position—approximately 100 meters of 50mm internal diameter pipe from the pump—pressure remains adequate. Pipe friction loss in DN50 blue-line pipe at 200 L/min calculates to only 4.55 meters head loss over 100 meters, while elevation differences nowhere exceed 5 meters. This conservative design ensured all sprinklers operate well within their performance envelopes.
Flow balancing at individual sprinklers is accomplished through brass ball valves on each riser, allowing fine-tuning of local flow to prevent oversupply at near sprinklers (which would create excessive pressure) or undersupply at distant ones. The complete system with all sprinklers operating draws approximately 180 L/min at reduced flow, rising to approximately 250 L/min at high flow when the motorized bypass valve diverts water around the flow restriction element.
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