초록 ▼

A system for automatically purging heating mantles and other apparatus including an enclosed volume capable of low level pressurization. The system comprises a pressure sensor for sensing the fluid pressure within the enclosure, which may be the space between a heating mantle poncho and the enclosed

A system for automatically purging heating mantles and other apparatus including an enclosed volume capable of low level pressurization. The system comprises a pressure sensor for sensing the fluid pressure within the enclosure, which may be the space between a heating mantle poncho and the enclosed flask, and a fluidic logic circuit which is responsive to a low pressure condition within the enclosure to deactivate the heating element in the mantle. At the same time, the logic circuit causes a predetermined volume of purging gas to flow through the enclosure and, after this has been accomplished, reactivates the heating element and reestablishes the minimum pressure conditions by flowing a small volume of purging gas into the enclosure. The system is particularly intended for use in hazardous locations where explosion-proof electrical equipment enclosures are normally mandatory. In order to avoid the enclosing of the purging system in an explosion-proof enclosure, all of the control functions are accomplished by fluidic-mechanical logic and control components, thereby virtually eliminating the necessity for electrical control equipment. In cases where electrical switches and relays are used to disconnect the heating element from its source of supply, these may be located remotely from the hazardous location and controlled by fluid pressure signals transmitted thereto over control tubing.

대표청구항 ▼

A heating apparatus comprising a sealed heating enclosure, an electric heating element in said enclosure and a purging system for said enclosure, said purging system comprising: means for sensing the fluid pressure within the enclosure and developing a first control pressure when the pressure within

A heating apparatus comprising a sealed heating enclosure, an electric heating element in said enclosure and a purging system for said enclosure, said purging system comprising: means for sensing the fluid pressure within the enclosure and developing a first control pressure when the pressure within the said enclosure falls below a predetermined pressure level, interrupt means responsive to said first control pressure for deactivating said heating element, high volume flow means responsive to said first control pressure for flowing a predetermined volume of purging gas through said enclosure, low volume flow means for flowing a purging gas into said enclosure to reestablish and maintain said predetermined pressure level after said predetermined volume of purging gas has been flowed through said enclosure by a said high volume flow means, and means for activating the heating element when said predetermined pressure level has been established, said means for sensing and said high and low volume flow means consisting of fluidic and mechanical components.