Importance

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Abstract

A purge control system providing a non-hazardous environment within an electronics enclosure comprises a purge air box housing non-electrical components having fluid communication lines between them. An outlet supplies inert gas under pressure from a supply to the enclosure and an inlet receives inert gas under pressure from the enclosure. A pressure regulator mounted in the box in fluid communication with the supply provides the air to a manifold distributing air to a flow meter providing flow of air to the enclosure through the outlet and determining rate of flow to the outlet; a signal valve having one inlet communicating with the manifold and another inlet communicating with the inlet; the signal valve having an outlet providing a pneumatic signal when pressure is received at the inlet; a first pneumatic light on the box connected to the outlet of the signal valve indicates the status of air coming from the enclosure; a time-delay pneuamtic relay connected to the outlet of the signal valve providing a delayed signal responsive to the signal received by the signal valve; an explosion-proof, pneumatically operated switch connected to the output of the time-delay relay providing electrical power to the enclosure responsive to the delayed signal; a second pneumatic light on the box responsive to the delayed signal indicating the status of electrical power. The system includes a two-way valve actuating an alarm when pressure from the enclosure falls below a predetermined value.

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First Claim