Abstract: Air is compressed in a compressor, cooled in a main heat exchanger, partially condensed in a reboiler-condenser, introduced into a higher pressure rectifier, and separated therein into nitrogen and oxygen-enriched liquid. Resulting nitrogen is condensed in further reboiler-condensers. One part of the condensate is used as reflux in the higher pressure rectifier and another part as reflux in a lower pressure rectifier. A stream of oxygen-enriched liquid is withdrawn from the high pressure rectifier and sent to an intermediate pressure rectifier which is reboiled by one of the further reboiler-condensers and in which further nitrogen is separated. A stream of liquid further enriched in oxygen is withdrawn from the bottom of the intermediate pressure rectifier and is separated in the lower pressure rectifier and impure and pure oxygen products are withdrawn respectively therefrom.

Abstract: Cooled and purified air is introduced into a higher pressure rectifier in at least partly vaporous state and is separated therein into oxygen-enriched liquid air and nitrogen. One part of the nitrogen so separated is condensed in a reboiler-condenser and another part in a reboiler-condenser. Some of the condensate is used as reflux in the high pressure rectifier, and the rest of the condensate as reflux in a lower pressure rectifier. Oxygen-enriched liquid air is taken from the bottom of the higher pressure rectifier and is separated into oxygen and nitrogen in the lower pressure rectifier. A liquid argon-enriched oxygen stream is withdrawn from the lower pressure rectifier through an outlet and is separated into argon and oxygen fractions in a further rectifier. The further rectifier is reboiled by the reboiler-condenser.

Abstract: A rotary vacuum pump having a low vacuum stage and a high vacuum stage. Each stage includes a stator body having a bore and a rotor mounted eccentrically in the bore to form a cavity between the stator body and the rotor. The rotor of each stage has two vanes slidably positioned in diametrically opposed slots in the rotor which in use of the pump are substantially in contact with an inner wall of the stator body during rotation of the rotor. The stator body of each stage has an inlet and an outlet to allow, in use of the pump, fluid being pumped to enter into and be expelled from the cavity by means of the rotating vanes. Oil to be injected into the low vacuum stage and, when required, into the high vacuum stage also. Differential flow rates (including zero) of ballast gas are introduced to the low vacuum stage, for example in an amount in excess of ten percent of the overall vacuum pump capacity (which equates to the capacity of the high vacuum stage).

Abstract: Air is introduced through an inlet into a higher pressure rectification column. A stream of oxygen-enriched liquid is withdrawn through an outlet from the higher pressure rectification column. A part of this stream is introduced into a low pressure rectification column through an inlet. The stream is separated in the column low pressure rectification into oxygen and nitrogen. In addition, an argon-enriched vapor stream is withdrawn from the low pressure rectification column through an outlet, and is at least partially condensed in a reboiler-condenser which reboils oxygen separated in an argon column. One part of the resulting at least partially condensed argon-enriched oxygen stream is reduced in pressure by passage through a valve and is introduced through an inlet into an intermediate mass exchange region of the argon column in which it is separated into argon and oxygen.

Abstract: A portable chilling unit for chilling either the whole or a selected portion of the interior of a container comprises a plurality of eutectic elements adapted for pre-chilling by exposure to liquid cryogen, a height adjustable inlet and an outlet towards the base of the unit. An insulating blanket is attachable to the inlet such that, in operation, the blanket may be placed over the cargo to be chilled and only atmosphere from under the blanket is drawn through the unit for chilling.

Abstract: An apparatus for depositing solid carbon dioxide on items to be refrigerated comprises a device (10) operable to convert a stream of liquid carbon dioxide into a forward flow of gaseous carbon dioxide containing entrained particles of solid carbon dioxide, a carriage (8) upon which said device (10) is mounted for translating in opposite directions and means for moving said device so as to direct said stream towards a plurality of individual items to be refrigerated.

Abstract: A stream of air is compressed in compressor and has water vapor and carbon dioxide removed therefrom in purification unit. A part of the resulting purified air is cooled by passage through heat exchanger and is employed to heat an intermediate reboiler in a lower pressure rectification column. The air flow from the reboiler passes into a higher pressure rectification column which supplies a stream of oxygen-enriched liquid air for separation in the lower pressure rectification column. Liquid nitrogen reflux for the higher pressure column is provided by taking nitrogen vapor from this column through an outlet and condensing it in another intermediate reboiler located above the reboiler in the lower pressure rectification column. The condensed nitrogen is returned to the top of the column.

Abstract: Air is compressed in a compressor, purified in a purification unit, cooled by passage through a main heat exchanger and separated in a double rectification column comprising a higher pressure rectification column and a lower pressure rectification column. A stream of argon-enriched oxygen vapour is withdrawn from the lower pressure rectification column through an outlet and an argon product is separated from it in an argon rectification column provided with an argon condenser. Argon is condensed in the condenser by indirect heat exchange with a second stream of air at a pressure between the operating pressures of the columns. The second air stream is partially condensed and passed into a phase separator. A stream of liquid phase is withdrawn from the phase separator, is passed through a throttling valve and the condenser, in sequence. Further cooling for the condenser is thus provided.

Abstract: A medical device, for example, an IV cannula or a syringe which has a hollow needle 4 with a sharp distal end 6 for piercing the skin of a patient includes means for protecting the sharp end 6 of the needle 4 after use to minimise the possibility of accidental needle stick. The means includes a rod 12 mounted for movement through the needle 4 between a needle end protection position and a retracted position within the hollow needle 4; and means for maintaining the rod towards the needle end protection position.

Abstract: A method for the treatment of a stream of exhaust gases including phosphine in which the stream is heated to a sufficiently high temperature to decompose the phosphine to phosphorus vapor and the stream is then passed into a reactor containing calcium oxide heated to above about 100.degree. C. An oxygen containing stream is also passed into the reactor.

Abstract: Air is compressed in compressors, cooled in a main heat exchanger, and separated into oxygen and nitrogen products in a double rectification column comprising a higher pressure rectification column and a lower pressure rectification column. A liquid oxygen product is withdrawn from the lower pressure column via a conduit. A liquid nitrogen product is also formed. An argon-enriched oxygen vapour stream is withdrawn from the lower pressure column through an outlet and has argon separated from it in an argon column. In order to help meet the requirements of the higher pressure column for reflux, a nitrogen vapour stream is withdrawn from the top of the lower pressure column, is warmed by passage through the heat exchanger, is recompressed in a compressor, and is liquefied by passage back through the heat exchanger from its warm end to its cold end and passage through a valve. A high liquid make and a high argon recovery can both be achieved.

Abstract: A substantially U-shaped immersion freezer having an inlet and an outlet and an immersion zone filled with liquid refrigerant. Product to be frozen is passed into the freezer through the inlet and raised by at least one paddle member to the outlet. The resulting frozen product and some liquid refrigerant is then passed out of the outlet to a conveyor having holes provided therein which allow the liquid refrigerant to be drained from the frozen product for recycling back to the inlet side of the freezer.

Abstract: An improved apparatus for the introduction of a gas into a liquid comprising a mixing device formed by a first generally convergent section and a second generally divergent section, said first section having a narrow outlet end of smaller diameter than an inlet end of said second section and extending thereinto so as to form an annular gap therebetween, and supply means for supplying said gas to said annular gap so as to facilitate the mixing of said gas with any liquid passing therethrough. The mixing device is preferably positioned at or near the surface of the liquid so as to avoid problems associated with hydrostatic head. The apparatus is advantageous in the treatment of a liquid with oxygen which is preferably generated by a Pressure Swing Adsorption device.

Abstract: An anaesthetic vaporizer includes a concentration dial for controlling the concentration of anaesthetic leaving the vaporizer. The vaporizer is adapted to be mounted on a back bar of an anaesthesia machine. An exclusion pin is mounted adjacent the back bar and forms part of an interlock system for preventing rotation of the concentration dial when a second vaporizer is also mounted on the back bar and is dispensing anaesthetic vapor. A button assembly is mounted on the concentration dial and must be depressed before the concentration dial can be rotated. The button assembly incorporates an overload device which, if excessive force is applied to the button assembly in order to override the effect of the exclusion pin will render the button assembly inoperative.

Abstract: An air separation method and apparatus in which a stream of air is compressed in a compressor and purified in a unit. One stream of the resulting air is cooled in a heat exchanger and is separated in an arrangement of rectification columns comprising a higher pressure rectification column, a lower pressure rectification column, and a further rectification column for separating argon from an argon-enriched oxygen stream withdrawn from the lower pressure rectification column and the stream of resulting air is introduced into the higher pressure rectification column through an inlet. A second cooled, compressed, purified air stream is expanded in an expansion turbine and is introduced into the lower pressure rectification column. A third cooled, compressed, purified air stream is expanded in a second expansion turbine and is introduced into the higher pressure rectification column.

Abstract: A method and apparatus suitable for sweetening sewerage which avoids the need for pumping the sewerage. The method comprises the steps of passing the sewerage under a gas-tight enclosure and causing it to fall as a stream through a first passageway, passing bubbles of a gas, such as oxygen, up through the descending sewerage to dissolve in the liquid stream to form a gas-liquid stream and causing the gas-liquid stream to ascend through a second passageway in which further bubbles of the gas are passed therethrough to dissolve further gas in the stream to balance the liquid density in the descending and ascending streams.

Abstract: During a purge step of a PSA plant the waste gas being vented is analyzed to identify when a preselected volume of the waste gas contains purge gas after which the purge step is stopped.

Abstract: Nitrogen is separated from a first stream of compressed air in a higher pressure rectification column and from a second stream of compressed air in an intermediate pressure rectification column. Oxygen-enriched liquid is taken from the columns and separated in a lower pressure rectification column. An impure oxygen product is withdrawn in liquid state from the lower pressure column through an outlet. A part of the first air stream is condensed in a first condenser-reboiler, and a part of the second air stream is condensed in a third condenser-reboiler. Nitrogen separated in the higher pressure rectification column is condensed in a second condenser-reboiler, and nitrogen separated in the intermediate pressure rectification column is condensed in a fourth condenser-reboiler. The resulting nitrogen condensate is used as reflux in the columns. The condenser-reboilers provide reboil for the lower pressure rectification column.

Abstract: A nitrogen PSA system uses a back-fill step only on start-up conditions or when a minor fault has caused the plant to temporarily lose purity. The plant utilizes an oxygen analyzer which controls valves allowing the initiation and cancellation of the back-fill step.

Abstract: A method treating effluent gases including exposing the gases to silicon or a silicon rich alloy or substances at an elevated temperature.