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


Dokument-ID TE2263


Veröffentlichungsdatum 06.01.2022
Can I trigger my 5500sc analyzer to run only when there is sample flow and not all the time?
5500sc AMC, Silica and Phosphate analyzers and flow trigger
Intermittent operation of the analyzer is possible, but there are some limitations and considerations that must be made to ensure proper function of the analyzer.
  1. Reagent shelf life -
    1. The analyzer is designed to consume its reagents within 90 days in continuous operation.  Some 5500 reagents are shipped in a 2 part package because of their limited shelf life after preparation.  Once prepared, these reagents will continue to age regardless of how much is used.  If intermittent operation does not consume reagents within the 90 days they can deteriorate and return inaccurate sample readings.  The analyzer does not measure reagent life based on time, but on remaining fill level in the bottle.  Since the analyzer does not know how old the reagent is, but only how full the bottle is, the 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 consumedExamples of reagents that have a limited useful life after preparation are Amino Acid reagent (R3) in the Silica Analyzer or the Ascorbic Acid reagent (R3) in the Low Range Phosphate Analyzer.
  2. Sample cell staining -
    1. 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 can 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.  Sample cell staining is more of an issue with Silica  and Phosphate analyzers.  
  3. Capillary tubing clogged -
    1. When a 5500 analyzer is in standby the reagents will sit in the capillary tubes.  Because these capillary tubes are so small they can easily become clogged.  A complete or partial clog will result in no reagent delivery or  delivery of incorrect reagent volumes.  Generally a clogged capillary tube will result in a failed calibration.  Additional reagent delivery testing and/or calibrations may be necessary to ensure proper function after shut down periods. 
  4. Setting up automatic flush -
    1. 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.
The above mentioned automatic flush requires hardware, assembly, and maybe a little ingenuity, but it can be done if the customer determines it Is worth the effort. Depending on the frequency and length of sample outages, they 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. 
Note - the flush setup for a 5500 AMC analyzer may be more involved that what is mentioned above because of the sample holder and pump assembly.

See the following articles for more information on intermittent sample flow and troubleshooting
How does the 5500 or 961X Silica or Phosphate analyzer react to a loss of sample?
5500 Silica Analyzer Frequently Asked Questions
Why is my 5500 AMC analyzer failing calibration?
What is reagent 3 used for on the AMC 5500sc?


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