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Topics Covered
Background
Automatic Viscometer Oil Viscosity Analyzer
Benefits and Features of the Spectro-Visc Automatic Viscometer
Performance Testing of the Spectro-Visc Automatic Viscometer in Oil Analysis
Repeatability and Accuracy Tests of the Spectro-Visc Automatic Viscometer in Oil Analysis
Short-Term Repeatability and Accuracy on N35, N100, and N350 Viscosity Standards
Long-Term Repeatability and Accuracy of Viscosity Standards
Repeatability of a Used Oil Sample
Summary
Background
Spectro designs, manufactures, sells and services analytical instrumentation. Their mainstays are optical emission spectrometers used in predictive maintenance of mechanical systems based on oil analysis. Used oil analysis is the base for a predictive maintenance program.
Spectro customers are industrial or military organizations that have oil-lubricated machines or engines. A second market consists of instruments for the analysis of contaminants in gas turbine fuels. Through the study of lubrication, friction and wear they are able to predict possible future problems of systems.
Automatic Viscometer Oil Viscosity Analyzer
The Spectro-Visc is a bench-top semi-automatic kinematic temperature bath viscometer optimized for the analysis of used and new lubricants. It conforms to the requirements in ASTM D445, D446, D7279, IP 71 and ISO 3104. It is also the ideal system for used oil analysis laboratories that need to test a wide range of lubricant viscosities.
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Benefits and Features of the Spectro-Visc Automatic Viscometer
The benefits and features of the Spectro-Visc Automatic Viscometer is outline in the following:
- Viscosity analysis of used oil provides an early warning of lubricant degradation and contamination
- Compliant with requirements for ASTM D 445, D 7279 and related specifications.
- High throughput – up to 60 samples per hour to ASTM precision.
- Small sample volume – 0.3 to 0.6 ml.
- Low solvent consumption – 2.5 ml per sample.
- Extremely easy to use.
- Automatic flow time measurement.
- Fully automatic cleaning and drying.
- Fast, easy tube replacement, no need to drain bath.
- Single or dual solvent injection system.
- No PC required for system to operate.
- Optional dual measurement capability.
Performance Testing of the Spectro-Visc Automatic Viscometer in Oil Analysis
In order to maximize sample throughput, used oil analysis laboratories often reduce run times for viscosity measurements. In this application note, viscosity standards and a used oil sample were analyzed on the Spectro-Visc Automatic Viscometer in order to demonstrate performance at reduced run times in the following circumstances:
- Short-Term Repeatability and Accuracy of Viscosity Standards
- Long-Term Repeatability and Accuracy of Viscosity Standards
- Repeatability on a Used Oil Sample
Repeatability and Accuracy Tests of the Spectro-Visc Automatic Viscometer in Oil Analysis
The viscosity standards listed below were used for the Spectro-Visc repeatability and accuracy tests. All the standards used meet the precision specifications of ASTM D 445/446 and ISO 3104/3105, and are traceable to the NIST (National Institute of Standards and Technology). Ten analyses were made in each part of the test.
Table 1. List of viscosity standards
|
Viscosity Standard |
Viscosity at 40°C |
Viscosity at 100°C |
|
N35 |
32.01 cSt |
N/A |
|
N100 |
97.21 cSt |
11.04 cSt |
|
N350 |
312 cSt |
23.84 cSt |
Short-Term Repeatability and Accuracy on N35, N100, and N350 Viscosity Standards
Ten analyses were made with each viscosity standard and the mean, standard deviation and relative standard deviations were calculated.
Table 2. N35 Standard Using Nominal 0.5k Tube
N35 Standard Using Nominal 0.5k Tube
Cannon N35 Viscosity at 40°C = 32.01 cSt |
|
Trial |
Kinematic Viscosity (cSt) |
Run Time (s) |
|
1 |
31.98 |
63.849 |
|
2 |
31.98 |
63.844 |
|
3 |
31.98 |
63.854 |
|
4 |
31.98 |
63.844 |
|
5 |
31.98 |
63.849 |
|
6 |
31.97 |
63.839 |
|
7 |
31.98 |
63.849 |
|
8 |
31.96 |
63.819 |
|
9 |
31.98 |
63.844 |
|
10 |
31.99 |
63.864 |
|
Mean |
31.98 |
|
|
SD |
0.007888 |
|
|
RSD % |
0.02467 |
|
Table 3. N100 Standard Using Nominal 0.5k Tube, Calibrated with N350
N100 Standard Using Nominal 0.5k Tube, Calibrated with N350
Cannon N100 Viscosity at 40°C = 97.21 cSt |
|
Trial |
Kinematic Viscosity (cSt) |
Run Time (s) |
|
1 |
|
18.183 |
|
2 |
|
18.233 |
|
3 |
|
18.228 |
|
4 |
|
18.228 |
|
5 |
|
18.228 |
|
6 |
|
18.218 |
|
7 |
|
18.223 |
|
8 |
|
18.228 |
|
9 |
|
18.233 |
|
10 |
|
18.223 |
|
Mean |
97.57 |
|
|
SD |
0.08053 |
|
|
RSD % |
0.08253 |
|
Table 4. Using Nomianl 0.5k Tube, N350 Standard on 5 Tube
Using Nomianl 0.5k Tube, N350 Standard on 5 Tube
Cannon N350 Viscosity at 40°C = 312 cSt |
|
Trial |
Kinematic Viscosity (cSt) |
Run Time (s) |
|
1 |
312.0 |
58.349 |
|
2 |
312.0 |
58.334 |
|
3 |
311.7 |
58.284 |
|
4 |
311.7 |
58.284 |
|
5 |
311.4 |
58.234 |
|
6 |
311.7 |
58.279 |
|
7 |
311.8 |
58.299 |
|
8 |
311.9 |
58.319 |
|
9 |
312.0 |
58.339 |
|
10 |
311.9 |
58.324 |
|
Mean |
311.8 |
|
|
SD |
0.1912 |
|
|
RSD % |
0.06132 |
|
Spectro-Visc repeatability and accuracy is excellent at reduced run times as can be seen from the above analyses of the N35, N100 and N350 viscosity standards. Repeatability at these reduced run times still exceeds the repeatability requirements of D445 for formulated oils.
Long-Term Repeatability and Accuracy of Viscosity Standards
The test as performed in Part A for the N35 viscosity standard was repeated two hours later using the same N35 viscosity standard. As can be seen by comparing the data, the long-term accuracy is excellent.
Table 5. N35 Standard Using Nomianl 0.5k Tube
N35 Standard Using Nomianl 0.5k Tube
Cannon N35 Viscosity at 40°C = 32.01 cSt |
|
Trial |
Kinematic Viscosity (cSt) |
Run Time (s) |
|
1 |
32.01 |
65.733 |
|
2 |
32.00 |
65.703 |
|
3 |
31.91 |
65.528 |
|
4 |
31.99 |
65.698 |
|
5 |
31.98 |
65.663 |
|
6 |
31.92 |
65.538 |
|
7 |
31.95 |
65.598 |
|
8 |
3198 |
65.678 |
|
9 |
31.86 |
65.418 |
|
10 |
31.94 |
65.583 |
|
Mean |
31.95 |
|
|
SD |
0.04719 |
|
|
RSD % |
0.1477 |
|
Repeatability of a Used Oil Sample
Although still very good, the repeatability on a used oil sample is not quite as good as on a viscosity standard. This is to be expected since by definition, a used oil sample may contain particulates and is seldom completely homogeneous.
Table 6. Used Diesel Oil 15W-40 Using Nomianl 0.5k Tube
Used Diesel Oil 15W-40 Using Nomianl 0.5k Tube
Measured at 40°C |
|
Trial |
Kinematic Viscosity (cSt) |
Run Time (s) |
|
1 |
85.55 |
15.978 |
|
2 |
85.55 |
15.978 |
|
3 |
85.79 |
16.023 |
|
4 |
85.76 |
16.018 |
|
5 |
85.79 |
16.023 |
|
6 |
85.55 |
15.978 |
|
7 |
85.79 |
16.023 |
|
8 |
85.65 |
15.998 |
|
9 |
85.60 |
15.988 |
|
10 |
85.55 |
15.978 |
|
Mean |
85.66 |
|
|
SD |
0.1119 |
|
|
RSD % |
0.1307 |
|
Summary
The repeatability and accuracy of the Spectro-Visc is excellent even when run times are reduced to increase sample throughput in used oil analysis applications.
A complete set of references and results can be found by viewing the source document
Source: Spectro-Visc Repeatability and Accuracy Application Note
For more information on this source please visit Spectro Incorporated