What troubleshooting can be done if my CL17 is reading high?

Document ID

Document ID TE4271

Published Date

Published Date 27/05/2017
Question
What troubleshooting can be done if my CL17 is reading high?
Summary
CL17 reads high
Answer
Troubleshooting CL17 Reads High 
 
This document is a supplement to the CL17 User Manual.  If the following procedures do not lead to a resolution, please call technical support at 1-800-227-4224 so we may review the results and assist with troubleshooting.   
 
It is common to verify your CL17 against a handheld or bench instrument.  At times these can disagree.  To troubleshoot these disagreements please use the steps below.
 
Troubleshooting
 
We have identified 5 primary causes for the CL17 to read high.  It can be due to:
  1. Dirty Colorimeter.
  2. Gain greater than 1 and/or offset does not equal 0.
  3. Inaccurate Sample Point.
  4. Incorrect Lab Procedure.
  5. Improper Reagent Delivery.
 
Below are techniques to address these causes.
 
Technique 1) for Dirty Colorimeter
 
  • To clean the colorimeter please refer to the 11 step process In the maintenance section of the manual.  As supplemental instructions use 2-3 eye dropperfulls of 19.2 N Sulfuric Acid in step 6.  Additionally you can leave the acid inside the colorimeter for 45 minutes before swabbing for a more thorough cleaning.  Lastly, if your sample contains Manganese or Iron we recommend you use a mixture of 2 parts household white vinegar mixed with 1 part hydrogen peroxide in place of the Sulfuric Acid.  After cleaning, allow the CL17 to go through at least 5 cycles to see if it can read correctly.  If it still reads high continue to the next technique.

Technique 2) for Gain greater than 1 And/Or Offset does not equal  0
 
  • Verify the current offset and gain MENU>SETUP>OFFSET (should be zero) and GAIN (should be one).  If either one of these is not at it’s default values please select CAL DEFAULTS.  After defaulting the calibration allow the CL17 to go through at least 5 cycles to see if it can read correctly.  If it still reads high continue to the next technique.
 
 
Technique 3) for Inaccurate Sample Point 
 
  • Sometimes people take a grab sample at a location at a distance from the CL17.  It is important to grab the sample as close to the instrument as possible.  The recommended grab sample location when verifying a CL17 is off of the sample line going to the instrument.  If you are not grabbing your sample at this location repeat your verification using this location for your grab.
 
 
Technique 4) for Incorrect Lab Procedure
 
  • There is some complexity to carrying out a verification on a lab instrument.  Variables include glass vs. plastic sample cell, amount of sample, and time to wait after adding DPD.  Please carefully review the lab method to confirm there has not been any confusion.
 
Technique 5) for Improper Reagent Delivery 
 
  • Test:  Press the MENU button.  Arrow down to the MAINT menu and press enter.  You will see the word PRIME on the display – press enter.  You will see the number 38 displayed and below it the word PRIME will flash.  The CL17 will count down from 38 to 0.  Disconnect the two reagent lines from the Y on the front of the colorimeter so that you can observe each of these lines.  Each time the prime cycle counts down by one you should see one drop form on each of the two reagent lines.  If you see drops forming on both tubes for at least 5 consecutive cycles reconnect the lines, exit out of PRIME, and verify if the CL17 goes back into normal correct operation.  However, if you do not see drops forming after multiple PRIME attempts we recommend you contact Hach Service for repair.