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fault tree chart

AZFlow coolers and Fail safe operations

Aspen pad and recirculating evaporative coolers have a history of failures that range stuck float valves resulting in flooding and water damage; thrown blower drive belt physically damaging the float valve and recirculating pump; to galvanic corrosion causing structural failure of motor vibration dampers resulting in separation of the drive motor from the foundation. Without constant attention and preventive maintenance some failure should be expected for each operating aspen pad or recirculating cooler during the course of the cooling season even when the coolers start with new pads, pumps, floats, and belts.

The failure consequence of aspen pad and recirculating coolers covers a broad spectrum from loss of cooling to flooded and damaged equipment and building areas. Some failure modes include flooded electrical circuits such that electric shock hazards may be created.

Contrary to the above, AZFlow coolers have no pumps, floats, or blower belts (tubeaxial fan models) and requires no maintenance to last the full season. AZFlow coolers incorporate features such that no single active failure can result in consequence beyond cooler shutdown. These features include: a) features to shutdown the cooler on loss of power that include design of the solenoid and block valves to spring closed on loss of power; b) features to shutdown the cooler if something happens to the drain line that keeps water from flowing out the drain and the level of water raises in the drip pan; and c) features to avoid scaling if something happens to the instrumentation that could upset the balance of water application and cooler heat load.