IE31862B1 - Apparatus for testing the fluid tightness of containers - Google Patents

Abstract

1,173,376. Apparatus for pressure testing containers. COSMOPOLITAN ASSURANCE CO. Ltd and P.G. DAVEY. April 9, 1968 [April 18, 1967], No. 17851/67. Heading G1S. Apparatus for testing a container 9 comprises an air compressor 1, a regulator 2, a flow detector 3 containing a thermistor, and a valve 8 connected to a terminal port 4. Valves 7 and 12 are connected in a conduit 6 by passing the flow detector 3 and valve 8, and a valve 10 may be vented to atmosphere. An automatic switch 14 operated by a differential pressure device 15-19 controls valves 7 and 8, and a manual switch 13 operates valves 10 and 12, these pairs of valves being operated alternately by their respective switches so that when say valve 7 is open valve 8 is shut and vice versa. Air-pressure greater than the test pressure is supplied by a second regulator 26' which supplies both the switches, these switches comprising two way valves which selectively apply greater than test pressure to the valves 7, 8 and the valves 10, 12. In Fig.2 the flow detector 3 comprises a chamber 20 with inlet and outlet conduits and thermistors 23, 24, the thermistor 24 being used as reference and being located out of the path of airflow through the chamber so that the thermistor 23 is cooled preferentially and the differential change in the resistances of the thermistors 23 and 24 is used to provide an indication of the flow. In Fig. 3, and Fig.4 (not shown) three thermistors are used and located as shown, the thermistor 30 being a heating element which when air is flowing transfers more heat to the downstream thermistor than to the upstream thermistor, the differential change in resistance being used to indicate flow and being measured by bridge circuits as in Figs.5, 6 (not shown). [GB1173376A]