ASTM International

Standard Practices for Examination of Electrical Insulating Oils by Infrared Absorption
 N D2144

Annotation

These practices are to be used for the recording and interpretation of infrared absorption spectra of electrical insulating oils from 4000 to 400 cm 1 (2.5 to 25 m).

NOTE 1—While these practices are specific to ratio recording or optical null double-beam dispersive spectrophotometers, single-beam and HATR (horizontal attenuated total reflectance), Fourier-transform rapid scan infrared spectrophotometers may also be used. By computerized subtraction techniques, ratio methods can be used. Any of these types of equipment may be suitable if they comply with the specifications described in Practice E932.

Two practices are covered, a Reference Standard Practice and a Differential Practice.

These practices are designed primarily for use as rapid continuity tests for identifying a shipment of oil from a supplier by comparing its spectrum with that obtained from previous shipments, or with the sample on which approval tests were made. They also may be used for the detection of certain types of contamination in oils, and for the identification of oils in storage or service, by comparison of the spectra of the unknown and known oils. The practices are not intended for the determination of the various constituents of an oil.

Warning—Infrared absorption is a tool of high resolving power. Conclusions as to continuity of oil quality should not be drawn until sufficient data have been accumulated so that the shipment-to-shipment variation is clearly established, for example.

The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.