A chemical filter assembly (24) mounted in a breather opening in a housing for a magnetic storage device (10) or other device to permit pressure equalization with the surrounding environment comprises at least one filter medium (32) for removing particulate matter, and a unitary filter medium (34A) of a fabric of activated carbon fibres that is impregnated with a chemical that in combination with the carbon provides protection against both organic and inorganic gaseous or vapor pollutants, said fibres having a pore size small enough prevent significant penetration by aqueous solutions so that during impregnation the pores will not become clogged with the chemical.

Ein Atemschutzgerät mit einer Schutzhülle, insbesondere einer Rauchschutzhaube, dessen Atemanschluß mit einem den Wasserdampf und das CO₂ aufnehmenden sowie sauerstoffabgebenden Chemikal verbunden ist und dessen Hüllen- bzw. Haubenmaterial aus einem beschichteten Verbundwerkstoff mit einem Trägergewebe aus reißfesten, hitzebeständigen und wasserdampfabweisenden Fasern besteht, soll derart verbessert werden, daß das Material für die Schutzhülle und die atemgasführenden Bauteile sowohl eine geringstmögliche Wasserdampfspeicherung bzw. -abgabe aufweist, und bei seiner Elastizität und Geschmeidigkeit bruch- und reißfest ist und sich leicht verarbeiten läßt. Zur Lösung der Aufgabe ist vorgesehen, daß der Verbundwerkstoff ein Trägergewebe (1) aus Glasfasern (2) besitzt, welches eine Zwischenschicht (5) aus Silan als Haftvermittler aufweist, auf welche einseitig zur Umgebung hin eine PVC-Beschichtung (3), und auf der der PVC-Beschichtung (3) abgewandten Fläche eine Silikon-Beschichtung (4) aufgetragen ist.

Device for absorption of carbon dioxide in a breathing apparatus and including a hose (1) for the breathing air. The hose (1) is at least partly filled with an absorption mass (4) including a carbon dioxide absorbing stuff (6) in granular form (5) which is mixed with a spacing substance (6) being of such character that it offers the breathing air a relatively low resistance. Alternatively the absorption mass (4) is in the shape of a porous framework with a plurality of granules (5) which are in pont contact with each other.

@ Acarbon-dioxide absorber,particularly intended for extracting carbon dioxide from respiratory gases in respirators, apparatus for administering anaesthetics, breathing apparatus and like apparatus, comprises a container (1), having an inlet (2) and an outlet (3) forthe respiratory gas and enclosing an absorbent medium (5) in the form of a fibre structure in which there is absorbed and retained in liquid form a liquid solution of one or more substances capable of chemically binding carbon dioxide. An advantage is afforded when the liquid solution comprises an aqueous solution of one or more hydroxides of alkali metals and/or alkaline earth metals; a particular advantage is afforded when an aqueous sodium hydroxide solution is used. The fibre structure may comprise both fibre material highly capable of absorbing and retaining liquid and fibre material exhibiting but slight liquid-absorbing properties, this latter fibre material being arranged to form a matrix which separates the liquid-absorbing fibre material and ensures that the fibre structure as a whole obtains the desired degree of gas permeability. The liquid-absorbing and liquid-retaining fibre material may comprise, for example, a mixture of rayon and cotton fibres having bound thereto a highly liquid-absorbent cellulose derivative, for example carboxymethyl cellulose.

A catalyst device for purifying a carbon monoxide containing atmosphere, e.g. for use in breathing apparatus for underground workers, comprises a chamber containing a catalyst bed for low temperature oxidation of carbon monoxide and having an inlet for permitting ingress of air from the atmosphere and an exit for connection to the face of the user, e.g. by means of a face mask. When the mask (for example) and the chamber are in pneumatic connection, inhalation through the mask causes airto enter the chamber via the inlet, to contact the catalyst bed for catalytic oxidation of CO therin, if present, and thence pass to the mask.

In order to provide resistance to deactivation by water vapour and obviate the need for a drying agent, the catalyst bed comprises one or more platinum group metals in combination with tin (IV) oxide e.g. Pt and Pd in combination with tin (IV) oxide.

Catalysts adapted to catalyse the oxidation of carbon monoxide to carbon dioxide comprise palladium, one or more of the metals platinum, ruthenium, rhodium and iridium and one or more of the metals copper, nickel, cobalt, iron, manganese, silver, lanthanum, cerium, praseodymium and neodymium on substantially chloride-free stannic oxide supports.

Catalysts adapted to catalyse the oxidation of carbon monoxide to carbon dioxide comprise palladium, one or more of the metals platinum, ruthenium, rhodium and iridium and one or more of the metals copper, nickel, cobalt, iron, manganese, silver, lanthanum, cerium, praseodymium and neodymium on substantially chloride-free stannic oxide supports.

A carbon monoxide-contaminated breathable gas (that is a gas or gas mixture containing sufficient oxygen to support human life) is purified by bringing it into contact with a bed of a catalyst, whereby to oxidise carbon monoxide to carbon dioxide and reduce the carbon monoxide contamination of gas, the catalyst being a promoted tin IV oxide-support precious metal catalyst in which the promoter is one or more metals of group 1 b, 3b, 7bb and 8 of the Periodic Table (especially copper, nickel, manganese, silica or lanthanum) and the precious metal is platinum, palladium, rhodium, iridium or ruthenium.