During the past 15 years or so, mobile in-plant spectrometers have been increasingly used for industrial applications. For the past 5 years approximately, in addition to mobile spectrometer, portable spectrometers have become available.

In contrast to stationary spectrometers, which require the material to be examined to be bought to the equipment, mobile spectrometers can test the material on site.

Both types of spectrometer differ in their measurement principle and analytical performance data:

-Stationary spectrometers usually work with SDAR and obtain RSD of 1% or better. The calibration curves have SR(1-3%) over large concentration ranges. Sparking must be carried out on flat metal surfaces.

-Mobile spectrometers usually work with ADA. These lead to oxidation in the region of the burn spot, depending on the composition of the test sample and its affinity for O.

On metal with ground, milled or turned surfaces, RSD 3-5% are obtained; the calibration curves for approximate analyses have SR of about 10%, if quality calibration is carried out.

This analytical performance, at a lower level compares with stationary spectrometers, in adequate for the tasks performed by mobile spectrometers, sorting and identity testing, since measurements are carried out.

This analytical performance, at a lower level compared with stationary spectrometers, is adequate for the tasks performed by mobile spectrometers, sorting and identity testing, since measurements are carried out against comparison samples.

If analyses are to be carried out on-site, the test probe operating with ADA can be used, by means of an adaptation comprising an Ar-flushed chamber only a few cm³ in size, with a W electrode with SDAR under the same discharge conditions as with stationary spectrometers.

This is for relatively large workpieces eg. plates, shafts, axles, blades and similar materials, from which no sample pieces can be removed for investigations using stationary spectrometers.

The main fields of application are analysis and testing for:

-low and medium-alloy steels,

-stainless steels, tool steels, Mn steels,

-Ni and Ni alloys,

-Co and Co alloys,

-Cu and Cu alloys,

-Ti and Ti alloys,

-testing of welded joints,

- the element C to be included in the test.

For SDAR, satisfactorily prepared surface and measurement times about 10 s are necessary. Identity testing with ADA can be carried out in most cases with a test time of 2 s on “any” surfaces.

If test job include alloys with a number of bases, because of the number of channels required a suitable spectrometer must be selected.