What troubleshooting should be done if my CL17 analyzer is reading low or zero?


Dokument-ID TE4270


Veröffentlichungsdatum 04.01.2022
What troubleshooting should be done if my CL17 analyzer is reading low or zero?
CL17 analyzer reads low or zero troubleshooting.
Troubleshooting CL17 Reads Low or Zero
Please note, the attached document contains the same instruction as below but also includes pictures to help determine where to test things
Before you begin verify that:
  1. Sample is flowing to the CL17
  2. There is reagent in the bottles
  3. The DPD powder has been mixed with the indicator reagent
  4. The CL17 has been primed
We have identified 3 primary causes for the CL17 to read zero.
  1. Sample leaking past the pinch block
  2. No Reagent Delivery
  3. Stir issues
Technique 1) for sample leaking past the pinch block
  • Background: The CL17 read cycle is 2.5 minutes. For the first 30 seconds there will be full flow through the sample line as the colorimeter is flushed, this should be between 80-100 ml of sample during the flush. For the next two minutes the sample line is pinched closed by the pump. There should be zero flow, not even drops, coming through the sample line during these two minutes.
  • Test: Remove the sample line from the front of the colorimeter. Does sample pass through the sample line during the two minutes it is pinched closed? If yes continue to Sample Leaking below. If not go to Technique 2 Verify Reagent Delivery.
Sample Leaking
  • Background:  The most common reason that sample leaks past the pinch block is that the Sample Flow is too high.  The optimum flow rate is 250-300 mL/min.
  • Test:  Disconnect the sample line from the elbow below the pump assembly. You will need a container to collect the flow.  Collect a sample for 60 seconds.  Did you collect a volume between 250-300 mL in that one minute?  If yes go to Technique 2 Verify Reagent Delivery.  If not go to Adjusting the Flow.
Adjusting the Flow
  • Background:  The CL17 ships with a Sample Conditioning Kit as shown in the installation section of the manual.  If you do not have the sample conditioning kit you must install it, part number 5516400, before continuing.  (Note: You can also use the kit that came with CL17s built before 2000.  This kit consists of a filter/strainer and two ball valves, one red handled and the other black handled.)
  • Action:  If the volume measured is less than 250 mL open up the gray ball valve and collect a sample until it is in the desired range.  However, if the volume is greater than 300 mL close down the gray ball valve and collect a sample until it is in the desired range.  It may take several adjustments to achieve the optimum flow rate.  When the volume you collect in one minute is between 250-300 mL reconnect the sample line to the elbow at the bottom of the pump assembly and Verify Performance.
Additional reasons why sample leaks past pinch block:
  • Pressure Plate is loose.  Hand tighten the two knurled screws that hold the pressure plate against the pump tubes until you cannot tighten them further.  Never use a tool as hand tight will suffice.  Verify Performance.
  • Sample Block has worn down at corners.  This is more common in CL17s that are at least 5 years old.  The top yellow block in the pump assembly is used to hold the sample line closed during the measurement.  Run your finger across the back of the block to check for wear.  If the center of the block is worn you can get sample leakage and will need to replace all the blocks.  You will need one sample block, part number 4274200, and quantity 4 reagents blocks, part number 4274100.  After changing worn blocks please Verify Performance.
Technique 2) for no 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 zero.  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 go back to Verify Performance.  If you do not see drops forming for 5 consecutive cycles reconnect the lines and allow the prime to count down to zero.  Retest using the test at the top of this paragraph.  Once you see proper reagent delivery you can reconnect the lines and Verify Performance.  If you do not see drops forming after multiple PRIME attempts reconnect the analyzer tubing.  Retest using the test at the top of this paragraph.  If you cannot get proper reagent delivery after all these steps we recommend you contact Hach Service for repair.
Technique 3) for stirbar issues
  • Test:  Remove the rubber plug on top of the colorimeter.  Remove the magnetic stirbar inside the colorimeter using a straightened paper clip.  Verify that you are using the recommended stirbar - part number 6865600.  It is shaped like a ball.  (Prior versions were shaped like a grain of rice and could get stuck in the bottom of the colorimeter.  If you have this version replace it with the ball version.)  After you remove the stirbar lower the paperclip back into the colorimeter to make sure you don't have a second stirbar or other interfering substances.  Once you have the recommended stirbar (and only one), Verify Performance.
Verify Performance
  • Test:  You may need to re-test chlorine concentration using your bench or hand held instrument.   Let the CL17 run through 3 complete cycles to verify performance.  If the CL17 is giving valid readings you are done.  Otherwise re-test for sample leaking into the colorimeter.
  • If you still see sample leaking go to the next troubleshooting step that you have not attempted.
  • If you have stopped sample from leaking and you are still getting zero readings go to Technique 2) Verify Reagent Delivery.
  • If you have completed the steps in Technique 2) Verify Reagent Delivery and are still getting zero residual go to Technique 3) Stirbar issues.
  • If none of these techniques resolve the issue please call us at 1-800-227-4224.

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