Patent GB-750820-A (GB)
Title: Improvements relating to oxygen tents
IPC: A61G10/04
Filed: 1953-11-26
Abstract: 750,820. Oxygen tents. SPENCER, T. H. N. Nov. 26, 1954 [Nov. 26, 1953], No. 32810/53. Class 81(2). Apparatus for maintaining the atmosphere within an oxygen tent wherein ventilation of the tent is maintained at a substantially constant rate comprises means for withdrawing air from the tent, circulating it through the apparatus and returning it to the tent, the temperature of the atmosphere being controlled by regulating the proportion of circulating air which is passed through cooling treatment apparatus. The interior of an oxygen tent 10 is in communication with conditioning apparatus 11 through a delivery opening 12 and an extraction opening which are provided in a headpiece 24 which can be raised or lowered to suit the type of bed used, extensible ducts 25 being provided to connect the openings with the rest of the apparatus 11. Air is circulated through the oxygen tent 10 and the conditioning apparatus 11 by a fan 18 operated by an electric motor. Withdrawn air passes through a bed of sodalime 15 and then through valve openings 27, 28, the proportion passing through each opening being controlled by manually operated valve plates 29, 30 which are interconnected so that the opening of one enlarges as that of the other reduces. Air passing through one opening 28 passes down a duct 32 adjacent a box 35 of ice. Moisture in the air condenses on the walls of the duct 32 and the dry air leaves the duct 32 and enters the ice box 35 through an aperture 53. Air passes upwardly through the ice and then through an opening controlled by a sliding plate 41 into an antechamber 31 on the suction side of the fan 18. Air passing through the other opening 27 passes directly by way of the antechamber 31 to the fan 18 where it joins the cooled, dried air and is forced into the oxygen tent 10. Water collecting in the duct 32 and produced by ice melting in the box 35 drips on to a floor 34 whence it runs to a drain 36. The drain 36 comprises a rubber pipe 43 which extends into a cup 44 which is normally full of water. As water overflows the cup 44 it falls through a surrounding opening 46 into a removable sump 54. The ice box 35 is detachably secured to a door 37 hinged at the bottom so that ice can be replenished. As the door 37 is opened the plate 41 which is attached to it is drawn over the opening by which air leaving the ice box 35 enters the antechamber 31 so that the circulation of air through the apparatus is not hindered. Fresh oxygen from a cylinder 20 is supplied by a duct 40 to the delivery side of the fan 18. A device to give warning of the failure of the oxygen supply is located between the cylinder 20 and the duct 40. It comprises a flat rubber bag 48 which is normally kept distended by the oxygen flow. A blade 49 rests on the bag 48 and is carried by a pivoted arm 50 at the other end of which is a mercury switch which is arranged to be on open circuit when the bag is distended. When the circuit is closed due to collapse of the bag an audible or visible warning is given. According to the Provisional Specification the orifice through which oxygen is discharged into the apparatus may be arranged coaxially within a venturi, so that in the event of failure of the fan, some circulation round the system may be induced.