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<div class="moz-cite-prefix">On 6/12/21 2:50 PM, Phillip
Hallam-Baker wrote:<br>
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<div class="gmail_quote">I spent some time on the colonial site.
They send multiple types of fuel down their pipes in batch.
Different fractions. So the unleaded and leaded and aviation
fuel all go down the same pipes under turbulent flow so they
don't mix. The interfaces between the fractions are diverted
for reprocessing
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<div class="gmail_default" style="font-size:small">So mess
up and stick the wrong fraction into the wrong tank and
the whole tank is contaminated, useless. Could cause an
air crash.</div>
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<p>When I had some dealings with Midwest oil pipeline companies
years ago they used "oil pigs" - rubber balls the same size as the
inside of the pipe - between different types or grades of product.
The pig would run the length of the pipeline with, say,60-grade
crude in front and 40-grade behind, and then the back pressure
would ram it into a switch mechanism which it blocked open causing
a valve to divert the 40-grade batch to a different tank. It was
fairly automatic, but fully mechanical. <br>
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<p>There was no software involved in that system in its legacy form
at all, beyond the messages notifying the far side about what was
in the pipeline. The update at that time was the first time
software was even involved in it. The new oil pigs contained
RFIDs that could be read when they passed through points in the
pipe where sensors were installed, so timing estimates could be
precise to a tenth of a second instead of a tenth of a minute and
the destination would be automatically notified about a switchover
(and a pig) instead of relying on somebody to pick up the phone. <br>
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<p>Colonial's got a very different operation of course; for starters
they're looking at much more highly refined products, not just
different grades of crude oil. Second they're running pipelines
bigger than 30cm wide, and I think the rubber-ball system stopped
working somewhere around there. And third they're running NOW
instead of 20 years ago when legacy systems involving the absence
of computer control were still a thing.</p>
<p>But anyway, yeah however they do it, almost every pipeline in the
world runs different products in the pipe at the same time, with
some system to try to keep them separate. And they pretty much
always have.</p>
<p>Bear</p>
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