What are the differences between refillable and gel filled pH electrodes?

Document ID

Document ID TE8267

Published Date

Published Date 09/20/2018
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Question
What are the differences between refillable and gel filled pH electrodes?
Summary
Refillable verses gel filled pH probes.
Answer
Gel filled probes are non-refillable, have a shorter life and warranty, and a lower maintenance requirement. The gel filled probe warranty is six months and the average life is about one year. They have a lower cost per probe. Proper storage and cleaning is important with these electrodes, however they do have the maintenance requirements of a refillable probe.

Refillable probes have a one year warranty, and an average life of two to three years. Refillable probes have a higher cost per probe, buy they need to be replaced less often, leading to more savings long term. In addition to proper storage and cleaning, these probes have an internal filling solution to maintain. The additional maintenance includes remembering to open the fill hole when in use and closing it again when not in use, adding filling solution to the probe as needed, and occasionally completely replacing the filling solution.

The trade off is expected life and maintenance requirement. For most applications either a gel filled probe or a refillable probe can be used, although this is not the case for all applications. The most common application this is not the case for is low ionic strength (LIS) samples. These samples consume electrolyte at an accelerated rate. Because of this gel filled probes have a much shorter life and have stability issues. All the probes recommended for this application are refillable.

See also:
What is the warranty period for Hach pH electrodes?
What is the expected life of Hach electrodes?
When should the filling hole on a refillable electrode be open or plugged?
What is the procedure for replacing the filling solution in a refillable pH probe?
Which combined pH electrode can be used in pure water (low ionic strength water)?
What are the special considerations for measuring pH in low ionic strength samples?
Is the IntelliCAL™ catalog number PHC10101 a good probe to use in low ionic strength samples?

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