Patent ID: 7533702

Claim:
An apparatus for manipulating heavier than air gas, comprising: a chamber ( 1 ) having a closable cavity ( 2 ), a source of heavy gas ( 4 ) which communicates with the chamber and allows introduction of the heavy gas into the cavity, control apparatus ( 6 , 7 ) movable between a first position and a second position to respectively close and open communication between the source ( 4 ) and the cavity ( 2 ) of the chamber, wherein the chamber ( 1 ) comprises an upward opening and closure means ( 3 ) movable between a closed position in which the upward opening is closed and an open position in which the upward opening is left open, wherein when the control apparatus ( 6 , 7 ) is moved to the first position closing said communication, the closure means ( 3 ) can be moved to the open position, and when the control apparatus ( 6 , 7 ) is moved to the second position opening said communication, the closure means ( 3 ) when in the closed position cannot be moved to the open position, a negative pressure source ( 35 ) and means of establishing a negative pressure ( 17 ) in a peripheral area at the top of the chamber , which are supplied by the negative pressure source and which suck heavy gas escaping from the chamber ( 1 ) through the top into a confined enclosure, wherein the means of establishing a negative pressure comprise a frame ( 17 ) formed by a hollow profile which is supported by the chamber at the periphery of its upward opening and which, on three sides ( 21 - 23 ), overhangs part of the cavity ( 2 ) of the chamber and therefore the cover ( 3 ) in the closed position, whilst, on a fourth side ( 25 ), it is subjacent to a cover in the closed position, and in that the said hollow profiled section is provided, facing the cover in the closed position, with suction openings ( 24 , 28 ), whilst it is in communication with the said source of negative pressure through an appropriate pipe ( 30 ).