Can I trigger my 5500sc analyzer to run only when there is sample flow and not all the time?

Document ID

Document ID TE2263

Version

Version 4.0

Status

Status Published

Published Date

Published Date 05/15/2018
Question
Can I trigger my 5500sc analyzer to run only when there is sample flow and not all the time?
Summary
5500sc AMC, Silica and Phosphate analyzers and flow trigger
Answer
Intermittent operation of the analyzer is possible, but there are some limitations:
1. Amino Acid reagent (R3) has a limited useful life after it is prepared. (This is why we ship it as a two-part package.) When the analyzer is in standby for lack of sample, the reagent continues to age. The analyzer is designed to consume its reagents within 90 days in continuous operation. The analyzer does not measure reagent life based on time, but on remaining fill level in the bottle. If intermittent operation does not consume the Amino Acid reagent within the normal 90-day usage period, this reagent can deteriorate and return inaccurate sample readings. Since the analyzer does not know how old the reagent is, but only how full the bottle is, our customer must track a calendar and perform timely reagent replacements. Customers may also find that it is necessary to properly dispose of bottles that have not been completely consumed.
2. If sample flow to the analyzer is interrupted, the analyzer may not be able to flush its sample cell at the end of the current measurement cycle. For short sample interruptions (up to a few hours) this is not a problem, but longer durations result in reaction byproducts staining the sample cell. Stains and stale reacted sample in the cell can cause unstable or inaccurate readings after the analyzer is restarted. This staining is the most significant problem that can occur from long-term sample interruptions. If stale reacted sample is left in the cell for a week or more, it’s usually more practical to replace the sample cell than to attempt cleaning it.
3. A flow switch and the analyzer’s Mark End of Measure relay function could be used to trigger an external valve to flush the cell when sample is interrupted. (e.g. No flow + End of Measure = close flush valve for 3 minutes.) The external flush valve would need to be connected to an available alternate sample, low in silica or phosphate, and with sufficient head pressure. This alternate sample would also need to be separately plumbed to the analyzer so the cell could be flushed (possibly by a tube to dispense into the grab sample funnel). If the sample outage were to last for several days, it would be a good idea also to use an external relay to remove power from the analyzer.
4. The setup in #3 above requires hardware, assembly, and maybe a little ingenuity, but it can be done if our customer determines it Is worth the effort. Depending on the frequency and length of sample outages, he may find that turning off the power switch and manually flushing the cell (pouring about 200 ml of DI water into the grab funnel) is less of an inconvenience than constructing an automated shutdown setup.

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