Leak test apparatus

A total of four Co and Fe based alloys were procured from a commercial source. Disks were punched from the foil and mounted into VCR vacuum fittings, with a nickel gasket on one surface and the sample in direct contact with the VCR sealing surface on the other. The sample assemblies were leak tested and verified leak tight to 2x10 7 sscm He prior to intallation in the permeation test apparatus. 

Today leak tests for vacuum systems are usually carried out with helium leak detectors and the vacuum method (see Section 5.7.1). The apparatus is evacuated and a test gas is sprayed around the outside. In this case it must be possible to detect (on the basis of samplings inside the apparatus) the test gas which has passed through leaks and into the apparatus. Another option is to use the positive-pressure leak test. A test gas (helium) is used to fill the apparatus being inspected and to build up a slight positive pressure the test gas will pass to the outside through the leaks and will be detected outside the device. The leaks are located with leak sprays (or soap suds, 5.4.5) or - when using He or H2 as the test gas - with a leak detector and sniffer unit (5.7.2). 

Details on pumps, manometers, vacuum gauges, special apparatus, and leak testing are given in Chapters 6-10. It is the purpose of the remainder of this chapter to describe the transfer of condensable and noncondensable gases, trap-to-trap fractional separation of volatiles, and the use of vapor pressure in the characterization of volatile compounds. These operations are basic to practically all chemical vacuum line work. 

The TECP suit is visually inspected and modified for the test. The test apparatus is attached to the suit to permit inflation to the pre-test suit expansion pressure for removal of suit wrinkles and creases. The pressure is lowered to the test pressure and monitored for three minutes. If the pressure drop is excessive, the TECP suit fails the test and is removed from service. The test is repeated after leak location and repair. 

Before starting laboratory work with phosgene, it is recommended that the individual is equipped with fresh-air breathing apparatus, a bottle of strong ammonia (or an alternative reagent) for leak testing, and a supply of 10% aqueous ammonia solution (or 15% sodium hydroxide solution) for decontamination purposes [Ij. 

Piping, regulators and other apparatus must be kept gas-tight to prevent leakage. This can be confirmed by the use of a compatible leak-test solution, or an appropriate leak-detection instrument. 

Figure 4 shows how the heat leak varies with surface area. The points plotted are the extreme values obtained for the heat leaks for each size of line and wind condition. The tare heat leak (obtained by heat leak tests with no test section in the apparatus) has been subtracted in this figure. The lines drawn are for the constant average heat flux, which is l.lw/cm (3490 Btu/hr-ft ) for still air and 1.9w/cm (6020 Btu/hr-ft ) for the 15-mph wind tests. 

Assemble the empty apparatus and conduct a leak test as described in Annex A3, paragraph A3.3.2. 

A3.3.2 Ensure that the test manifold is leak-free and can be maintained at a steady pressure at the required level. A suitable leak test is to pump down to a pressure below 0.1 kPa and isolate the pump. Observe the pressure inside the unit for at least 1 min. If the pressure rises no more than 0.01 kPa in that period, the apparatus is considered acceptable. 

The minute capillary leaks found with a Tesla coil should be plug d with a blob of hot glass the whole joint then needs heating and annealing. When assembhng complex apparatus, parts which will become inaccessible to the flame must be tested for leaks before they are put in their final positions. 

As explained on p. 22, thin glass phials cannot be tested for leaks directly with a Tesla coil, and must therefore be tested by the other method (Section 2.3.2) if they are suspected of being leaky. If a phial is leaky, it must be fused off and discarded. Because of the deleterious effect of a narrow tube on the pumping speed, the apparatus for filling phials should be joined to the vacuum line as close as possible to the pumps. 

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