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Old November 8th, 2018, 06:03 PM   #16
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I had to write code for a system with multiple storage tanks, pump stations at various elevations, some of which feed each other, and there were valves. It was a little bit tricky to control everything right and not overpressure certain lines. I had to have different setpoints for the pressure target at one pump station depending on how many valves downstream were open, and I had to have a really long ramp up time (4-6 minutes) during which I ramped the pressure setpoint from the minimum entry to the presently selected target. I also had to condition the logic with the measured flow with shutdown alarm settings for high or low flow. So at least if a line did break, or if a valve stuck shut, the out of range flow rate should indicate that. I was lucky in that the system operator had a good handle on how everything should work, but there were still things that were in his head that didn't quite jive with reality, so a few things had to be edited after commissioning to get it all smoothed out.

The better handle you can get on how the system is laid out up front the better. I highly recommend studying any drawings that exist and creating at least a good sketch if there aren't any or if they are inaccurate.
It's not all the variables I am most concerned with, it's the undiscovered constants.
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