| MPC Test |
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| OELCHECK Test equipment:
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Fluitec iLab 475 |
| Sample quantity needed: |
50 ml |
| Unit: |
No |
| Test result: |
MPC-Index; Luminanz L, red value a, yellow value b, solid contaminations (weight in %) |
| Operating time: |
9 hours |
| Analysis of: |
Gas and steam turbines; Circulation systems; Hydraulic systems |
| Brief description: |
After arriving in the lab the sample is stored for minimum 5 hours to be sure that the auto degradation process is finished and all soft contaminants have been become insoluble. Before measurement the sample has to be homogenized e.g. through shaking. Now 50 ml of the sample and 50 ml of filtered heptane is slowly steered together. A membrane with a pore size of 0,45 µ is dried and weighted. The oil and heptane mixture is filtered under a vacuum of 710 mbar. After drying the membrane for 3 hours at 80°C it can be weighted again to calculate the increase of weight in percent.
The color of the residues on the patch is analyzed with a spectral sensor. A LED light source consisting out of three LED’s emits light within the visible spectrum. A typical human eye will respond to wavelengths from about 380nm to 750nm. The residue on the membrane reflects or absorbs the light at specific wavelengths. A sensor detects the reflected light over the whole visible light spectra. The software of the device gives the raw data of the spectrum as output and calculates the CIELAB coordinates according ASTM E308.
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| Statement: |
The increase of the MPC-factor correlates to the potential of the oil to form residues or varnish. A high MPC-Index means that a high amount of coloured bodies is concentrated on the filter material.
These soft particles are very polar and have a high molecular weight. They become oil insoluble by conglomerating together and form a hard and sticky deposit on oil wetted surfaces. The deposit is called varnish and can be the reason for malfunctions of valves and handicap the oil based control of the turbine.
Varnish on bearing-seats of friction-type bearings change the geometry of the bearing and influence the load carrying capacity of the bearing.
Typical Indications for varnish are e.g. decreasing service life of filters, or residues at the tank wall.
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