Abstract: A vent device comprising at least one control member pivotably supported in an opening in a frame, for movement, in response to differential gas pressure between opposite sides of the opening, between a closed position in which the control member(s) substantially blocks the opening and an open position in which the control member(s) leaves the opening substantially unobstructed for flow of gas therethrough, wherein the or at least one of the control members has associated therewith a restraining mechanism, operable to apply a force to the control member to influence movement thereof between its open and closed positions.

Abstract: A gas flow control system (10) for controlling the flow of a gas through an opening of an environment (14), comprising a flow control member (22) adapted to be mounted in the opening and moveable to adopt any of a plurality of positions, a gas pressure indicator (30, 32) which produces at least one indication of the pressure of the gas in the environment (14), and a controller (28) which receives and acts upon the indication of the gas pressure to control the position adopted by the flow control member (22) to control the flow of the gas through the opening.

Abstract: An air pressure stabiliser device is adapted to be located in a aperture in a wall, which may be provided by ductwork, extending into and from a room within which the pressure is to be maintained in excess of atmospheric pressure, but which is vented when the pressure rises above a predetermined maximum. The stabilising device comprises two bearing assemblies defining a longitudinal axis, and a control member extending between the bearing assemblies, being supported thereby for rotation about said axis. Adjustment means are provided positionally to adjust the control member in a direction extending at right angles to the pivot axis, to adjust the excess pressure to which the control member responds and the threshold opening pressure. These adjustment means are provided to enable the control member to open fully in response to the detection of the desired excess pressure within the room being controlled.

Abstract: A cooling device of the kind used in transportation vehicles, designed to maintain the transportation space of such vehicles cool over prolonged periods, includes an elongate housing of generally rectangular cross-section, having side walls and first and second end walls. The cooling device further includes a cooling pipe of elongate "U"-shape, having a curved portion and parallel arms. The ends of the cooling pipe are secured within one end wall, and the central portion of the pipe is supported in relation to the opposed wall by a supporting means.