Figure 1 - Oil transmission comparisons. Click on picture for expanded view. In this plot, "Bid Marcol 7" is Marcol 7B, "Batch 1 Marcol 7" is Marcol 7D, and "Karns City Marcol 7" is Marcol 7K.
| Oil Name | Description |
|---|---|
| Marcol 7B | Sample received with Boncosky Proposal |
| Marcol 7S | 1 gallon sample from batch prior to loading rail cars |
| Marcol 7T | 2 - 1 galllon samples taken from tanker cars |
| Marcol 7D | 10 gallon sample from batch recieved after first telephone conference |
| Marcol 7D-filtered | Sample of Marcol 7D filtered with a 1.2 micron filter |
| Marcol 7D-ultrasound | Sample of Marcol 7D processed in an ultrasonic bath for 55 minutes |
| Marcol 7K | 10 gallon sample from Karns City plant |
| Marcol 6-EXP | 10 gallon sample of Marcol 6 |
As we will see below, the amount of filtering seems to make a difference in the measured attenuation length of these oils. The best filtering history that we can reconstruct is the following. It is believed that all of the oils were filter with a nominal 50 micron filter going into the batch tank. The Marcol 7T received an additional 20 micron filtration step going from the batch tank into the tanker cars. It is believed that both the Marcol 7B and the Marcol 6-EXP received similar filtration. None of the other samples received this step. Anna Pla from Fermilab filtered a small protion of the Marcol 7D through a 1.2 micron filter. It is that sample that is called Marcol 7D-filtered.
The attenuation at 460 nm was measured for all oils in the "Alabama" tester. They are summarized in the following table.
| Oil Name | Attenuation Length | Number of Measurements |
|---|---|---|
| Marcol 7B | 25.5 m | 6 |
| Marcol 7S | 16.1 m | 2 |
| Marcol 7T | 19.7 m | 4 |
| Marcol 7D | 14.5 m | 2 |
| Marcol 7D-filtered | 19.0 m | 2 |
| Marcol 7D-ultrasound | 14.0 m | 1 |
| Marcol 7K | 9.2 m | 1 |
| Marcol 6-EXP | 19.0 m | 2 |
Below is a plot that compares the relative transmission spectrum of the various oils that we have received from Exxon. In this plot, the higher the line, the better the transmission is at a praticular wave length. The absolute attenuation length cannot be determined from this plot. For the absolute attenuation, we use the test results given in the previous section.
Figure 1 - Oil transmission comparisons. Click on picture for expanded view. In this plot, "Bid Marcol 7" is Marcol 7B, "Batch 1 Marcol 7" is Marcol 7D, and "Karns City Marcol 7" is Marcol 7K.
Anna Pla from Fermilab has made some very preliminary measurements of particulate matter in the various oils that we have received. Her apparatus can measure the concentration of particles of sizes from sub micron to 25 microns in diameter. She has tested the Marcol 7B, 7D, and 7D-filtered. The results are presented in the following table.
| Oil | Relative Number of Particles of Size: | ||
|---|---|---|---|
| 1 micron | 2 micron | 4 micron | |
| Marcol 7B | 35 | 3 | .5 |
| Marcol 7D | 500 | 50 | 5-6 |
| Marcol 7D-filtered | 50 | 1 | <<1 |
The Marcol 7K is an inferior oil. It would have been immediately rejected both on the basis of its poor attenuation length and its high transmission cut-off. The Marcol 6-EXP has the additional step of filtration and at 460 nm has an attenuation length equivalent to the Marcol 7T sample (which has the equivalent amount of filtration). It too would have been rejected because of the high transmission cut-off. Thus, neither of the substitute oils are suitable.
An additional stage of filtering seems to change the attenuation length of the present Marcol 7's from about 15 m to about 19 m. However, even filtering at 1.2 micron does not bring the attenuation length up to the level of the Marcol 7B oil. This either means that the particle density below 1 micron is very important or that there is a real chemical difference between the two oils. The later seems to be indicated by the difference in transmission curves of the two oils.