How can the flow sensor for the TU5300 or TU5400 turbidimeter be cleaned?

Document ID

Document ID TE5138

Version

Version 3.0

Status

Status Published

Published Date

Published Date 06/05/2019
Question
How can the flow sensor for the TU5300 or TU5400 turbidimeter be cleaned?
Summary
Instructions on completing cleaning of the flow sensor (Catalog Number/ Order Code LQV160.99.00002) for the process TU5 Series turbidimeters.
Answer

The flow sensor for a TU5 series turbidimeter may need to be cleaned when the following issues occur:
  • The flow sensor delivers no signal
  • The flow sensor window appears dirty
  • Water flow is out of range
Notice: to prevent damage, do not open the flow sensor.

Items to collect:
The following items are required to perform a Flow Sensor cleaning:
• Syringe, 60 mL
• Tube, <20 cm, 6 mm (0.24 in.) OD
• 30 mL of HCl (5%)
• 120 mL of distilled water
• Container to collect waste liquid


Procedure
1. Switch off the influent flow.
2. Disconnect the tubes of the Flow Sensor. Push the blue ring to release the tubes. Refer to the documentation supplied with the Flow Sensor if additional instructions are needed. .
3. Remove the Flow Sensor from the mounting bracket.
4. Connect the syringe with the tube.
5. Fill the syringe with 30 mL of HCl (5%).
6. Connect the syringe and tube with the inlet of the Flow Sensor.
7. Inject 20 mL of HCl slowly in the Flow Sensor, collecting HCl in the waste liquid container
8. Inject 5 mL of HCl in the Flow Sensor, collecting HCl in the waste liquid container. To move the HCl in the Flow Sensor pull the plunger of the syringe in a quick sequence in and out.
9. Wait 5 minutes.
10. Inject the last 5 mL of HCl in the Flow Sensor, collecting HCl in the waste liquid container. To move the HCl in the Flow Sensor pull the plunger of the syringe in a quick sequence in and out.
11. Dispose of waste HCl according to local laws and regulations.
12. Fill the syringe with 60 mL of distilled water and inject the water quickly in the Flow Sensor, collecting the distilled water in the waste liquid container. 
13. Repeat step 12.
14. Reattach the Flow Sensor to the mounting bracket and reconnect tubing.
15. Switch on the influent flow.
16. Go to SENSOR SETUP>[INSTRUMENT-ID]>DIAG/TEST>SIGNALS>FLOW RATE to check the flow rate.

Example below of a dirty (left) and cleaned (right) flow sensor

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