GB1438759A - Cryo-surgical apparatus - Google Patents

Abstract

1438759 Refrigerating apparatus SPEMBLY Ltd 1 June 1973 [2 June 1972] 25910/72 Heading F4H [Also in Division A5] Crysourgical apparatus comprises a body 1, Fig. 1, of, e.g. stainless steel enclosing a cavity having a wall 2 of high conductivity, and operates in cooling mode wherein cooling is due in the main to Joule-Thomson expansion of a gaseous refrigerant or in the main to evaporation of a liquid refrigerant, in the cavity. In the cooling mode, a foot-operated valve V1 in its depressed position connects the pressurized source 12 to the conduit 3 into the cavity and thence through conduit 7 and hose 8 to atmosphere. In a warming mode valve V1 is returned by a spring to the upper position, as shown, and gas now passes through circuit 7 to the cavity, where it condenses under pressure. Uncondensed gas passes through orifice 3A and conduit 3 to atmosphere. In modifications, two- or three-position valves may be used, using a third or rest position in which the apparatus is neither cooled nor warmed. A pneumatic timecontrolled detent (18), Fig. 7 (not shown), may hold the valve (V4) in warming mode for a period before moving to the "rest" position. The valve may be in two parts (V5A), (V5B), Figs. 8, 8A, 8B (not shown), one part having a movable sleeve (31) and a pneumatic time delay (38) is incorporated. As shown in Fig. 9 the apparatus may include a shuttle valve member 55 slidable in a bore 51G in a body member 51 and having a sealing ring 56, so that the valve member 55 may be moved by gas pressure to the right in Fig. 9 to make sealing contact with a lip 51C fromed round a bore 51D in the body, thus closing an exhaust passage 51E in the warming mode. At the other end of the bore is a sleeve 52 which receives a conduit 53 passing through the apparatus and through a bore 55A in valve member 55. Control of this instrument is by a two-position valve (V6) connected to a single source of refrigerant, Fig. 10 (not shown). Alternatively, there are two sources (61), (62) of refrigerant, Fig. 11 (not shown), one gaseous and one liquid, and two two-position valves (V7) and (V8), one controlling the other.