Repair Hanna HALO pH probe?

[Righteous]

Hi all,

So I've got the Hanna HALO pH meter, HI12302, and wondering if it can be repaired or I need to toss it. I've had it about a year, and it had been working great. I found it recently tipped on its side, so the storage solution looks like it seeped out of the holder, and it was sitting dry.

I'm now unable to calibrate it. I emailed Hanna, and they have told me that the electrode is bad and the HALO is not designed to be fixed, so it would need to be replaced.

Putting the pH meter in buffer solutions I get the following readings:

For buffer 4.01, it measures stable at 7.16 ph @ 72.9 F
For buffer 7.01, it measures stable at 9.42 @ 72.7 F

I've allowed the meter to soak in 4.01 solution for over 48 hours without any change. I've also tried a 15 minute soak in dilute HCl, again without change.

Would replacing the reference solution possibly fix this? I noticed what looks like a sealed fill hole on the side. Perhaps it would be possible to remove the seal, drain and replace, and reseal it?

 

[Dan_P]

Hi all,

So I've got the Hanna HALO pH meter, HI12302, and wondering if it can be repaired or I need to toss it. I've had it about a year, and it had been working great. I found it recently tipped on its side, so the storage solution looks like it seeped out of the holder, and it was sitting dry.

I'm now unable to calibrate it. I emailed Hanna, and they have told me that the electrode is bad and the HALO is not designed to be fixed, so it would need to be replaced.

Putting the pH meter in buffer solutions I get the following readings:

For buffer 4.01, it measures stable at 7.16 ph @ 72.9 F
For buffer 7.01, it measures stable at 9.42 @ 72.7 F

I've allowed the meter to soak in 4.01 solution for over 48 hours without any change. I've also tried a 15 minute soak in dilute HCl, again without change.

Would replacing the reference solution possibly fix this? I noticed what looks like a sealed fill hole on the side. Perhaps it would be possible to remove the seal, drain and replace, and reseal it?

Buy a new probe and then mess around trying to salvage the dead probe.

 

[Righteous]

Buy a new probe and then mess around trying to salvage the dead probe.

Yeah, I have a backup, plus the Apex, so i don't mind messing with it (I just like to tinker and experiment). Just wondering if anyone had an idea on what might work. This is listed as a gel electrolyte, which my understanding is considered disposable, but I'm not sure why.

Would it be possible to make your own gel? Something like PEG and KCL?

Here's the specifications from Hannas site.

Reference	double, Ag/AgCl
Junction / Flow Rate	ceramic
Electrolyte	gel

 

[Dan_P]

Yeah, I have a backup, plus the Apex, so i don't mind messing with it (I just like to tinker and experiment). Just wondering if anyone had an idea on what might work. This is listed as a gel electrolyte, which my understanding is considered disposable, but I'm not sure why.

Would it be possible to make your own gel? Something like PEG and KCL?

Here's the specifications from Hannas site.

Reference	double, Ag/AgCl
Junction / Flow Rate	ceramic
Electrolyte	gel

Maybe you could find the answer on the internet

 

[Randy Holmes-Farley]

You cannot usually fix a dried pH probe, but try soaking it in vinegar for 24 h, the. Some diluted salt water for another day and try to recalibrate it.

 

[Righteous]

You cannot usually fix a dried pH probe, but try soaking it in vinegar for 24 h, the. Some diluted salt water for another day and try to recalibrate it.

I had tried that as well, but it had no effect. It’s not able to recalibrate because it can’t recognize the buffer solution due to the way it’s calibration works.

I was under the impression that a dry probe has issues because the KCl creep can clog the reference junction and/or the electrolyte in the probe becomes too dilute. Or are there actually physical changes to the glass that occur?

Maybe you could find the answer on the internet

Dan, did you get grumpy while I was away?!

The internet tells me a dry probe can often be revived, but suprisingly it’s just parroted information with little in the way of actually scientific knowledge or explanation.

That’s why I come here to the finest spot on the “web” instead of the “internet”.

 

[Dan_P]

I had tried that as well, but it had no effect. It’s not able to recalibrate because it can’t recognize the buffer solution due to the way it’s calibration works.

I was under the impression that a dry probe has issues because the KCl creep can clog the reference junction and/or the electrolyte in the probe becomes too dilute. Or are there actually physical changes to the glass that occur?



Dan, did you get grumpy while I was away?!

The internet tells me a dry probe can often be revived, but suprisingly it’s just parroted information with little in the way of actually scientific knowledge or explanation.

That’s why I come here to the finest spot on the “web” instead of the “internet”.

HaHa, I hope you are not emotionally scared by the seeming withdrawal of my love Be sure to tell us if you succeeded in the repair.

 

[Righteous]

HaHa, I hope you are not emotionally scared by the seeming withdrawal of my love Be sure to tell us if you succeeded in the repair.

I cried into my beer.

 

[Randy Holmes-Farley]

I think changes in the hydrated glass itself may be hard to reverse.

https://www.hamiltoncompany.com/process-analytics/ph-and-orp-knowledge/ph-orp-sensor-storage-and-regeneration

 

[Garf]

It’s not able to recalibrate because it can’t recognize the buffer solution due to the way it’s calibration works.

I hate these gadgets that will not calibrate unless it’s within a certain range. Had the same with a Hanna conductivity meter which renders it useless.

 

[Righteous]

I think changes in the hydrated glass itself may be hard to reverse.

https://www.hamiltoncompany.com/process-analytics/ph-and-orp-knowledge/ph-orp-sensor-storage-and-regeneration

Thanks for linking to the Hamilton site. The glass chemistry stuff is interesting. I didn’t realize they relied on lithium ions in the glass.

The response of the pH sensor can sometimes be improved through alternating exposure to strong base and acids. The procedure is as follows:

Immerse sensor for 10 min in 0.1 – 1M NaOH, then for 10 min in 0.1 – 1M HCl. After regeneration, place the sensor in storage solution for a further 15 min.

I haven’t yet tried a strong base, so I may try that, but I’m not hopeful given the glass itself may be ruined.

 

[Righteous]

I hate these gadgets that will not calibrate unless it’s within a certain range. Had the same with a Hanna conductivity meter which renders it useless.

Yes! It’s still responding quickly, and seems be around 2-3ph high consistently, but maybe they’re doing it because they know at that range it means it’s no longer accurate? Or it’s just planned obsolescence.

They are cool gadgets, but warranty is only 6 months, and Hanna says to expect them to only last 1-2 years:

How long will my pH electrode last?

pH electrode lifespan depends on the amount of use, temperature of sample, types of sample, and the care and maintenance of the probe.

knowledge.hannainst.com

The app on the phone is definitely super cool, and makes calibration, measurements, logging etc very easy, but the price needs to be lower for something that’s basically disposable.