Accession Number:

AD0002008

Title:

EXPERIMENTS WITH A DIFFERENTIAL PIRANI GAUGE LEAK DETECTOR

Descriptive Note:

Corporate Author:

ATOMIC ENERGY RESEARCH ESTABLISHMENT HARWELL (UNITED KINGDOM)

Personal Author(s):

• TURNBULL, A. H.

Report Date:

1950-03-01

Pagination or Media Count:

15.0

Abstract:

A differential leak detector was developed in which 2 matched Pirani gages having their filaments connected in adjacent arms of a balanced Wheatstone bridge were connected to the same point in a vacuum system. A lime soda trap was placed between the vacuum system and 1 gage to absorb the COsub2 which was used to probe the leak. The COsub2 could make its way only into the untrapped gage to cause a differential change in the indication of the 2 gages. With the detector located on the backing side of a diffusion pump where the average pressure was 15 micro Hg, the noise level of pressure fluctuations registered by the galvanometer in the detector control circuit was 7 times less than that registered by a single Pirani gage. The minimum air pressure change detected by the differential arrangement was 10 to the -5th power mm Hg. With the optimum leak-hunting conditions employed, this value corresponded to a leak on the high- vacuum side of about 10 to the -3rd power lusec 1 lusec the leak causing a pressure rise of 1 micro Hgsec in an isolated volume of 1 liter.

Descriptors:

• *LEAK DETECTORS
• LEVEL(QUANTITY)
• FILAMENTS
• DIFFUSION
• UNITED KINGDOM
• PUMPS
• AIR PRESSURE
• GALVANOMETERS
• VACUUM APPARATUS
• NOISE

Subject Categories:

• Test Facilities, Equipment and Methods

Distribution Statement:

APPROVED FOR PUBLIC RELEASE