Problem calibrating Hanna ph meter

[Delislem]

I am trying to calibrate my hanna ph meter without much sucess. I turn it to calibation mode, then it says use 7.01. I put it in my 7.01 solution then it immediately flips to 10.01 REC and calibrates itself to 10.01 in my 7.01 solution. Anybody has an idea?

Thanks in advance, Martin

[Gregore]

I do not have that model , but I looked up the manual and did not see a reset button , it might be best to contact Hanna .

I suspect it is an easy fix as my Extech did the same thing once , and worked normal after a reset.

[Delislem]

Thanks Gregore. After a little bit of research, I found that trick but it did not succeed. I finally resorted to ordering a new probe. We'll see how that goes­.

[awakephd]

I wonder if it would work better if it were put into the solution right side up.

Sorry, couldn't resist -- on my browser, the picture is showing upside down.

[Delislem]

I almost made the joke myself... Seems the browser doesn't take into account the orientation info from the iPhone.

In reality I was fishing for an answer from the guys in the southern hemisphere   

[Gregore]

My Extech did weird stuff when it got dirty , try cleaning ithe probe in the ph meter probe cleaner or contact lense cleaner designed for cleaning proteins

[awakephd]

I almost made the joke myself... Seems the browser doesn't take into account the orientation info from the iPhone.

In reality I was fishing for an answer from the guys in the southern hemisphere   

ple


I almost referenced iPhone or iPad -- it seems like Apple-product pictures consistently have this problem.

[OzzieCheese]

We're used to seeing images that way round 

-- Mal

[pfabsits]

The HI98128 autodetects the buffer being used. A pH 7 buffer will generate a voltage close to 0 mV and the meter accepts a point withing approx. +/- 60 mv. A pH 10 buffer generates appox -180 mv (+/- mv) and pH 4 generates + 180 mV (+/- mV). The +/- mV represents some range of voltage based on the mV generated in pH 7 and the slope of 85% (150 mV) or greater. So there is a range.

Based on this information either:
1) pH 7 is not pH but some other value greater. It would to be around pH 9.
2) the pH electrode is faulty

To determine which you can do some quick checks.

1) What is the pH value when placed in pH 4 buffer. If it shows pH 7 then it is a faulty electrode
2) If it shows pH 4 then the pH 7 buffer is no good.

If you do not have pH 4 then some common items that can be used to check pH. Orange juice is around pH 4. Baking soda in water will be around pH 7.8. If the readings are in the range of +/- 0.5 pH then the buffers the buffers are the suspect. Do not use these solutions to calibrate. They are not standards of a known value that we base all of our measurements on. They are only being used to check the mV response. Using two points will confirm there is a deflection voltage (slope). If you have any questions feel free to e-mail. From the forum sign up I have allowed the e-mail feature from members.

The pHep 5 has 1 year warranty on the meter and 6 months on the electrode. Contact tech@hannainst.com and they will take care of you.

[Delislem]

Thanks, that's great info.

As my meter is a couple years old...but I never got around to use it properly...I concluded it would be best to just get a new probe. I'll install it tomorrow and see how that works.

I doubt the problem is the solution since I tried two different bottles but if it is I guess I will have paid the price of a new probe to learn.

[NCBaker]

Keep us posted.  I have the same meter and having trouble calibrating it as well.