Abstract: A ventilation system allows for a user adjustable minimum inlet fresh air volume inflow rate, a user adjustable minimum exhaust air volume outflow rate, for an enclosed space, and provides for automatic adjustment of the air volume flow rate(s) to maintain the air pressure inside the enclosed space at a user selected level which is measured in relation to the relatively constant soil gas pressure beneath the enclosed space, or pressure under the floor of the lowest occupied level, under which floor, soil gas is present.

Abstract: A method and apparatus for venting purge fluid from an enclosed housing to maintain a positive known reference pressure differential between the housing and the variable pressure atmosphere surrounding the housing. The apparatus utilizes a specially designed fluidized bed to vent the purge fluid while maintaining a positive known reference back pressure. The fluidized bed automatically compensates for changes in the temperature or pressure of the atmosphere surrounding the housing.

Abstract: A portable drilling apparatus 10 designed to be used in environmentally severe locations, such as the Arctic, includes provisions for heating various portions thereof, including a pipe shelter 14. The pipe shelter 14 is used to store, warm, and clean the drill pipe and/or casing prior to insertion in the well. Thus, to provide access for loading the drill pipe and/or casing into the pipe shelter 14, a significantly large opening must be provided. The large opening necessarily results in significant infiltration of arctic air and loss of heated air, thereby increasing the difficulty of maintaining the pipe shelter 14 at a comfortable working temperature. Accordingly, a high-speed spool or window-shade style door 38 is employed to seal the opening against large scale transfers of heated and cold air. Further, an indirect fired air-heater 90 having a capacity sufficient to maintain a positive pressure in the pipe shelter 14 is also used.