GB874626A - Improvements in or relating to apparatus for indicating leakages in the tubes of heat exchanger systems - Google Patents

Abstract

874,626. Indicating leakages in tubes. SIMON-CARVES Ltd., and GENERAL ELECTRIC CO. Ltd. June 2, 1960 [June 2, 1959], No. 18824/59. Class 99(2). In a method of indicating leakages in a heat exchanger system which is leaking and which is of the kind having a bank of tubes 2 arranged to be surrounded by a heat transfer fluid and communicating with a tubular header 1 at the each end of the system a purge gas is introduced into any of the tubes of the system and the gas emerging from the tube is sampled whereby the presence in the emerging purge gas of any of the fluid surrounding the tubes of the system provides an indication of a leak in the tube. As shown in Fig. 1, a traversing probe 3 consisting of a central rod 4, on which is mounted a pneumatically operated piston-and-cylinder device 5, Fig. 2, and two cruciform spiders 6 adapted to support the rod 4 on the axis of the header, introduces the purge gas into a tube 2. The portion 7 of the rod 4 is drilled to receive the cylinder 8 of the device 5 which is adjustably positioned by a bracket 9. A spring-loaded piston 15, to which is attached a rubber nozzle 16, is movable in the cylinder 8 by means of compressed air from supply pipe 12. The nozzle 16 incorporates a small bore tube 18 connected by a pipe 19 to a supply of purging gas. The spiders 6 comprise legs 20, screwed into collars 21 rigid with rod 4, on which are attached spring-biased feet 22. By adjusting the bracket 9 and interchanging the legs 20 the probe 3 can be adapted for varying diameters of headers. The probe 3 is movable axially and angularly and is positioned in these respects by a grub screw (not shown), and a screw 27 in one of the circumferentially arranged holes 28. The probe 3 is therefore moved to a position so that the nozzle 16 is in alignment with a particular tube 2 and, after the nozzle 16 has been urged into the end of the tube by compressed-air, purge gas is introduced into the tube. A second similar traversing probe with a different nozzle 30, Fig. 4, is fitted into the header of the heat exchanger remote from header 1 to sample the gas emerging from the tube 2 under test. The tube 31 is connected to an infra-red continuous gas analyser and the drillings 32 ensure a small positive pressure inside the tube 2 under test besides eliminating any " in-leakage " of air around the nozzle 16. Several tubes 2 may be tested simultaneously by providing several piston and cylinder devices 5 on one probe. According to the Provisional Specification the apparatus may be used with a heat exchanger which is not pressurised externally. The inside of the tubes 2 and one of the headers are evacuated and the increase in flow into the evacuated header when pumping from a leaking tube 2 is noted, the other end of the tubes 2 being blocked off.