Abstract: The gas treatment installation operating on a treatment cycle, in which part of the cycle is performed at a pressure below atmospheric pressure, particularly a PSA, TSA or VSA installation, includes one or more gas treatment vessels containing adsorbent. Each vessel has at least one orifice, at least one gas pipe communicating with the orifice, at least one valve arranged on the gas pipe and controlling the flow of the gas flowing through the pipe. The valve comprises a shaft for operating the valve and sealing elements. A device for maintaining a protective gaseous atmosphere is arranged around the sealing elements and the operating shaft to create and to maintain a protective gaseous atmosphere around these items and thus prevent the ingress, into the treatment vessel, of contaminants harmful to the adsorbent, particularly the ingress of moisture liable to deactivate the molecular sieve, that is to say the adsorbent.

Abstract: A plant for the separation of gases by adsorption, which is of the PSA type, includes, in a container (1) of vertical axis, at least one annular bed of particulate material (5, 6) supported on a lower wall (9) which is itself supported by a perforated prismatic wall (11) bearing on a domed end (2) of the container. A lower wall (9), advantageously in the form of a very wide inverted V (9A, 9B), has no part forming an angle (.alpha., .beta.) in excess of 15.degree. with the horizontal. The plant is useful in the separation of gases from air.

Abstract: A fluid distributor for heat and material exchange columns, more particularly of the packed type, comprising profiled elements (2) of inverted U shape with substantially vertical walls (4), and a base (1) in which are formed a plurality of parallel slots (9). Each slot is covered by one of the profiled elements, secured to the base by the walls (4) in a permanent and sealed manner. The base (1) is a flat plate. Each profiled element (2) is fixed to the two opposite edges of its slot (9) by welding. Each of the walls (4) terminates in at least one foot (7) turned inwardly of the element (2) and parallel to the surface of the base (1), the feet (7) serving to attach the elements to the base.