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OHA Drinking Water Services
Contact Report Details |
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| PWS ID: | OR41 00492 | ||
| PWS Name: | LOWELL, CITY OF | ||
| Who Was Contacted and Phone: | Willie Hartwig (541) 937-2776 | ||
| Contact Date: | 11/06/2006 | ||
| Contacted By: | NELSON, TERRY (DWP) | ||
| Contact Method/Location: | Office | ||
| Assistance Type: | CIRCUIT RIDER ASSISTANCE | ||
| Reasons: | N/A N/A |
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| Details: | SUMMARY: System needed assistance with controls and automation problems DETAILS: BACKGROUND/PROBLEM: System has requested help on answering a puzzle about erroneous flow rates into and out of the plant. The flow meters appears to be working yet one or the other or both must be wrong because the displayed finished water flow total is only about half of the raw flow rate total. There should be some difference due to backwash water which is wasted, but the difference is too much to account for. Contractors and equipment representatives have been consulted but the problem remains. ACTIONS PERFORMED:We looked at SCADA charts. We talked about what had been done, I uploaded the ladder logic to my laptop and determined that both flow meters are scaled and linearized outside the PLC by external components. I verified that the signals sent to the PLC were being correctly interpreted by the PCL. We tried to find programming manuals for the flow meters and were partially successful but I needed to contact the manufacturer it was on the east coast and was closed. It became apparent that a portable flow meter would be needed to test reported flows to actual flows. I requested and received authorization from DWP to spend another 10 hours on the problem. On the second visit, I compared reported flows with actual flows, using the portable flow meter. The raw flow meter was working but in error by 17 Percent. I calibrated it to within 2 Percent. The finished water flow meter was found to be working but defective, having errors as high as 74 Percent. It could not be calibrated. I provided a report to the CWS which explains the cause of the contradictory flow totals and offers three recommendations to remedy the problem. ACTION NEEDED: Answer Questions |
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