ASTM D6595 Method for Wear Metals and Contaminants in Used Lubricating Oils
ASTM D6595 Standard Test Method for Determination of Wear Metals and Contaminants in Used Lubricating Oils or Used Hydraulic Fluids by Rotating Disc Electrode Atomic Emission Spectrometry
7. Apparatus
7.1 Electrode Sharpener - An electrode sharpener is necessary to remove the contaminated portion of the rod electrode remaining from the previous determination. It also forms a new 160° angle on the end of the electrode. Electrode sharpeners are not required for instruments using a pre-shaped disc electrode as the counter electrode.
7.2 Rotating Disc Electrode Atomic Emission Spectrometer, a simultaneous spectrometer consisting of excitation source, polychromator optics, and a readout system. Suggested elements and wavelengths are listed in Table 1. When multiple wavelengths are listed, they are in the order of preference or desired analytical range.
7.3 Heated Ultrasonic Bath (Recommended), an ultrasonic bath to heat and homogenize used oil samples to bring particles into homogeneous suspension. The ultrasonic bath shall be used on samples containing large amount of debris and those that have been in transit or stored for 48 hours or longer.
8. Reagents and Materials
8.1 Base Oil, a 75 cSt base oil free of analyte to be used as a calibration blank or for blending calibration standards.
8.2 Check Samples, An oil standard or sample of known concentration which is periodically analyzed as a go/no go sample to confirm the need for standardization based on an allowable more or less 10 % accuracy limit.
8.3 Cleaning Solution, An environmentally safe, non-chlorinated, rapid evaporating, and non-film producing solvent, to remove spilled or splashed oil sample in the sample stand.
8.4 Disc Electrode, a graphite disc electrode of high-purity graphite (spectroscopic grade). Dimensions of the electrodes shall conform to those shown in Fig. 1.
8.5 Glass Cleaning Solution, capable of cleaning and removing splashed oil sample from the quartz window that protects the entrance lens and fiber optic. Isopropyl rubbing alcohol or ammonia based window cleaner has been found to be suitable for this purpose.
8.6 Organometallic Standards, single or multi-element blended standards for use as the high concentration standard for instrument standardization purposes or for use as a check sample to confirm calibration. Typical concentrations in the upper calibration point standard for used oil applications is 100 mg/kg for wear metals and contaminants, and 900 mg/kg for additive elements.
8.6.1 Standards have a shelf-life and shall not be used to standardize an instrument if they have exceeded the expiration date.
8.7 Counter Electrode - The counter electrode can be either a rod or a disc. The counter electrode must be high-purity graphite (spectroscopic grade). Dimensions of the counter electrodes shall conform to those shown in Fig. 2.
8.8 Specimen Holders - A variety of specimen holders can be used for the analysis of used oil samples. Disposable specimen holders must be discarded after each analysis and reusable specimen holders must be cleaned after each analysis. All specimen holders must be free of contamination and shall be stored accordingly. Specimen holder and covers shall be used on hydraulic oil samples that may catch on fire during the analysis.
9. Sampling
9.1 The used oil sample taken for the analysis must be representative of the entire system. Good sampling procedures are key to good analyses and samples must be taken in accordance with Practice D4057.
