Why does the APA6000 Low Range Hardness analyser keep showing "Standard X Fail Accuracy"?

Document ID

Document ID TE5795

Published Date

Published Date 21/01/2019
Question
Why does the APA6000 Low Range Hardness analyser keep showing "Standard X Fail Accuracy"?
Summary
"Standard X Fail Accuracy" on APA6000 Low Range Hardness analyser.
Answer
With "Standard X Fail Accuracy", try replacing the standard to see if it helps.  If it doesn't, feed the standard into the analyser in place of the sample to see if it can read the standard as it should.  If it does not, the steps below should be performed before considering any kind of service.
  • Perform the maintenance on the analyser.  Change the rotor and replace the seals before you go further with anything else.  Do this even if it has not been a full three months.
  • Check the mixer.  Is it filling up with blue liquid?  If it's low range, it will be a deep blue color.  If it's harder, it will be purplish progressing to red as the sample concentration goes higher.  It should be obvious.
  • If not, check the indicator reagent, which is the dark red solution.  Sometimes it can settle at the bottom and can get bacterial growth in it.  This can create a gooey material that can get pulled into the bottom of the feed straw.  If the tube is pulled out, it will be a blob of red 'jelly'.  If this happens, replace the indicator reagent with a fresh one and cut off the bottom half inch of the tube.
  • If sample is coming from a softener effluent that is regenerated with brine, it is a good idea to run an entire bottle of the cleaning solution (this can take 12-16 hours) in place of the sample.  If brine gets into the analyser, it can contaminate the inside of the analyser and cleaning can help with that.