 |
The ARCAM physical infrastructure achieves its defensive capability throughl integration of all components into coordinated operational sequences. During fire front approach, the system can transition rapidly from standby through multiple defensive postures:
Initial Ember Defense (activated when ember detector triggers or external temperature exceeds 60°C): The pump starts via relay closure, taking 2-4 seconds for diesel engine ignition. RV1 holds in reduced-flow position, RV3 directs flow to sprinklers (not recirculation), RV2 activates shed cooling. The nine perimeter impact sprinklers begin rotating, delivering 170 L/min of water across all surfaces at approximately 4.5 bar pressure. This mode can sustain for 178 minutes (nearly 3 hours) on tank capacity alone, or indefinitely if mains water replenishment keeps pace with consumption.
Intermittent Conservation Mode (activated manually or by autonomous controller when threat is moderate but water conservation is prudent): Pump runs continuously, RV3 cycles between sprinkler delivery (3-8 minutes depending on configuration) and tank recirculation (7-30 minutes depending on configuration), RV1 holds in reduced flow, RV2 remains active for shed cooling. This mode extends water supply to 8-10+ hours depending on cycle ratio selected, appropriate for prolonged ember attack when continuous water application is unnecessary but periodic surface wetting prevents ignition.
Fire Front Defense (activated when external temperature exceeds 80°C or manual command): Pump runs continuously, RV1 switches to high-flow position (flow increases to ~250 L/min), RV3 delivers continuously to sprinklers, RV2 holds shed cooling active. This maximum defensive posture can sustain for approximately 30 minutes before water exhaustion, sufficient for typical fire front passage durations of 15-30 minutes based on documented case studies.
Gel-Enhanced Final Defense (activated when water level falls below 0.30m or manual emergency command): Pump runs continuously, RV1 holds reduced flow (gel application requires lower pressure), RV3 delivers to sprinklers, RV4 opens gel injection, Bringsmart booster pump activates. The system applies 2% Barricade gel solution to all surfaces, creating an adhesive fire-retardant coating that provides protection even after water evaporates. The 15.2-liter gel supply at 2% dilution provides approximately 12 minutes of application at 170 L/min flow (720 liters of diluted gel solution), or up to 42 minutes if flow is reduced further.
Each transition between modes executes through coordinated valve sequencing managed by the control system. Motorized valves require 5-15 seconds to complete travel between positions; the control logic implements appropriate delays between commands to ensure valves reach final position before flow conditions change significantly. The pump itself starts reliably within 2-4 seconds (single crank in warm conditions, occasionally two cranks in cold start), with oil pressure sensor confirmation of successful start within 5 seconds.
The ARMAC physical infrastructure seeks to combine effectiveness and water conservation, and the benefits of manual control and autonomous operation. Through integration of standoff impact sprinklers, intelligent valve control, comprehensive sensor coverage, and protective measures for critical equipment, the system aims to provide flexible response to evolving threat conditions while maintaining extended operational duration. The design decisions—copper piping over plastic for above-ground runs, diesel pump over electric for grid-independent operation, distributed sprinklers over roof-mounted spray heads, proportional gel injection over crude mixing— are all designed to create realistic defence options in the face of bushfire threats.
The approximately $31,000 AUD total implementation cost, while substantial for a residential DIY project, compares favorably to commercial fixed-spray installations often exceeding $60,000 while delivering comparable and perhaps superior protection with significantly longer operational duration. The 18-month design and construction timeline reflects the iterative testing and refinement required to optimize sprinkler positions, validate hydraulic calculations, and prove component reliability under simulated fire conditions.
Without reliable water delivery, precise flow control, accurate sensing, and thermally protected electronics, even the most sophisticated autonomous algorithms would prove ineffective. However, that physical capability would remain largely manual and reactive without some capacity for preemptive response, adaptive operation, and graceful degradation as conditions evolve. The design of the ARMAC electronic control systems that are designed ito create this capability follow next.
Emergency Shutdown (water level below 0.05m or manual cutoff): All valves close, pump stops via fuel solenoid de-energization. This prevents pump cavitation damage from dry running, preserving equipment for potential post-fire service restoration.
<< Environmental Hardening and Protective Measures | | The Electronic Control Sub-System >> |Table of Contents>