GB1126505A - Improvements in liquid seals between regions of different pressure - Google Patents

Abstract

1,126,505. Liquid seals. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. 17 May, 1967 [14 June, 1966], No. 26540/66. Heading F2B. [Also in Division H1] Apparatus suitable for providing a liquid seal and allowing the continuous passage of a cable 11 between a region of reduced pressure in an enclosure at 9 and atmospheric pressure outside the enclosure, comprises an open vessel 3 containing a quantity of liquid, a first duct 1 having one end 2 extending into the vessel below the liquid surface and the other end 8 connected to the enclosure; and a second duct 5 which connects with the first duct via tubes 7 and 4 at one end and via a pump 6 at the other. Means 10, such as rollers, are provided to guide the cable 11 in a continuous manner between the surface of the liquid in the vessel and the enclosure through duct 1. In use the liquid drawn up the first duct due to pressure difference is continuously returned to the vessel by the pump 6 and duct 5, the cross-sectional area of this second duct 5 being greater than that of the first duct 1. The liquid used in the apparatus is an electrically insulating impregnant material, and in cases where it freezes at a temperature above ambient the ducts are enclosed in jackets 12 through which steam is passed. In an alternative embodiment (Fig. 3, not shown) the tubes 7 and 4 are combined in the form of a hollow closed tank (14) to which the upper ends of ducts 1 and 5 are connected ; A series of rollers (15) in the tank serve to guide the cable through it into the tube leading to the enclosure at 9. In a further embodiment, (Fig. 5, not shown), the hollow closed tank (18) is connected at its lower end to two very short ducts (20, 21) in place of ducts I and 5 and at its upper end to the low pressure enclosure via a short pipe (19).