Abstract: A mine stopping comprising a wall extending across a passageway in a mine to close the passageway. The wall has an opening therein. A door is hinged adjacent the opening for swinging between a closed position in which the door closes the opening to inhibit the passage of air therethrough, a first open position in which the door is moved in one direction away from the closed position, and a second open position in which the door is swung in an opposite direction away from the closed position. The door is movable to either of the first and second open positions when the door is subjected to substantial concussive air pressure thereby to permit concussive air to pass through the opening in both directions.

Abstract: The geothermal heat transfer system comprises a plurality of heat exchange loops placed in the ground at an angle of less than a 20 degrees, but greater than a 5 degrees. Each loop has an out flow line and a return line, and a fluid tight, tapered end, U-turn juncture connecting the lines. A pair of distributors connects to inlet and outlet lines at a lower end and a plurality of outlet members at the upper end. A heat exchange device connects to the loops through the inlet and outlet lines. A liquid-oil-gas separator uses cup member and deflector to create a Venturi fluid inlet to separate the oil, returning it to the compressor. A bore hole drilling device comprises an hollow drilling bit with a cutting member at one end, a central fluid passage, and connecting means. The bore hole drilling device has a swivel member with a body portion and housing with a central bore and an inlet, connect to a water line. The body is position within the central bore and mounted for rotational motion within the housing.

Abstract: A restrainable manhole, handhole cover and open/close device therewith provides vertical pads at predetermined positions along a bottom edge of a manhole/handhole cover, which are integrally molded with a cover body. This forms an inclined a third edge which is longer than an inner diameter of a manhole/handhole neck such that it can prevent the cover body to bounce up and displace when being overlaid by a vehicle. Furthermore, a plurality of pre-molded flat plates are provided on predetermined locations perpendicular to the neck. A pre-punched hole is provided for each flat plate for accepting the vertical pad of the cover body for restraining the cover body in its position at the same time the cover body is overlaid by a vehicle.