pH calibration

Booboo33062 · 02-16-2006, 08:48 PM

I got a pen style pH meter. I need to calibrate it, but don't know how. I got it off e-bay. It has a little screwdriver to set it, but I don't know what it will take to get water that I know the pH of to be able to set it.

HELP!!!!!

If I can't set it I have know use for it. I bought it so I wouldn't have to do the regular pH test. I like the fact that it is hot pink too.

Geoff · 02-16-2006, 09:21 PM

Tom has posted the easy way to calibrate them somewhere. i will see if i can find it. i know he has posted it many times. try a search for something like pH calibration and Borax. this should pull it up. borax has a pH of dead on 10, i think, so it is used to calibrate pH meters.

G~

Booboo33062 · 02-16-2006, 09:40 PM

I found one that said to use Borax. It said it had a pH of
9.19+/-0.02

Does that sound right? I'll try it cause I can get that stuff no problem.

Geoff · 02-16-2006, 10:14 PM

that sounds like Tom answer, so i would go with it.

G~

Loverotties · 02-16-2006, 10:18 PM

You need to know what that unit needs to calibrate to?It could be 4 ,7 or 10.Once you find what they use ,that's what you need to put it into to adjust that screw to read.!email the company that makes it.or ask here if anybody has that make.

tdwyatt · 02-17-2006, 12:03 AM

UHHH actually...

The use of 1/2 level teaspoonful of borax in 2 cupts (=1 pt=~500ml) RO/DI will make a test solution that does not require much in the way of EXACT measurements due to it's buffer nature.
This solution is only intended to test the function of the pH meter, not to calibrate it.

To calibrate the meter, you need to first establish the pH center (7.000) then establish the slope for the logrithmic increase (or decrease) by using a pH solution that is 1x10^-3 greater [H+] or less than 1.000x10^-7.000 (1.000x10^-4.000 or 1.000x10^-10.000 ). pH meters measure the difference between these very small numbers as a calculated difference between a reference battery and the current established through an ion-selective semipermeabile membrane for protons (H+) based on the concentration of the ionized H portion of water molecues. pH is an interpretation of these numbers that is easily understood from the values of the water's concentration of the dissociated water molecules as protons. The pH is the negative log of that value. The concentrations of the preceeding values would be:

1.000x10^-7.000 = 7.000 pH
1.000x10^-4.000 = 4.000 pH
1.000x10^-10.000= 10.000 pH

To summarize, you need the central pH value (7) as a buffer, and either 4 or 10 as well to establish the slope of the difference of the values.

Make sure your probe is clear of calcium dposits and biofilms prior to calibration.

HTH

three90s&125sump · 02-17-2006, 01:41 AM

I can't find that borax anywhere. Does anyone have any idea where to find it.

I have looked at Target, Walmart and Farm & Fleet.

tdwyatt · 02-17-2006, 02:11 AM

Try:
http://www.soapsgonebuy.com/product_p/d1002.htm

If you get really hard up for some of the Mule, send Me a SASE and a sixpack of a GOOD local dark beer and I'll send you an ounce (enough to last a while, 1 oz=2 tablespoonsful = 6 tsp = 12 each of 1/2 tsp. I am surprised tht wallyworld or your local grocer does not have this.

Geoff · 02-17-2006, 08:32 AM

Quote:

Originally Posted by tdwyatt

Try:
http://www.soapsgonebuy.com/product_p/d1002.htm

If you get really hard up for some of the Mule, send Me a SASE and a sixpack of a GOOD local dark beer and I'll send you an ounce (enough to last a while, 1 oz=2 tablespoonsful = 6 tsp = 12 each of 1/2 tsp. I am surprised tht wallyworld or your local grocer does not have this.

Dude!! so let me get this straight. he sends you an envelope with a $.39 stamp and a 6 pack of beer, at least $7.00. all for a $.10 portion of Borax. how can i get in on this racket.

at least you can do is pay for the stamp.

G~

tdwyatt · 02-17-2006, 11:07 AM

Quote:

Originally Posted by Geoff

Dude!! so let me get this straight. he sends you an envelope with a $.39 stamp and a 6 pack of beer, at least $7.00. all for a $.10 portion of Borax. how can i get in on this racket.

at least you can do is pay for the stamp.

G~

The 6-pack is part of the maturation process...

and besides, as often as I use stamps, it would mean that I'd have to drive into town to go to the post office...

...and tom is such a tight wad...

Booboo33062 · 02-17-2006, 09:46 PM

The type I have is a PHmeter----PH-009(l) Pen type meter. On the picture on the front of the info sheet inclosed it shows the unit with a reading of 7.0 so I'm guessing that is what I should calibrate it to. I guess I'll get on e-bay and find a solution to calibrate it with.

tdwyatt · 02-18-2006, 01:34 AM

better to get some standard buffer packs from a reliable source.
Check Marine Depot for the pinpoint packetts, get a pack of 7.000 and 10.000 or 4.000 and use the protocol listed in the archives.

tdwyatt · 02-18-2006, 01:41 AM

btw, they're relatively cheap, so go ahead and get several to cut the shipping cost,I usually keep 5 or 6 sets here most of the time.

http://www.marinedepot.com/md_viewIt...product=AM1415
http://www.marinedepot.com/md_viewIt...product=AM1417
http://www.marinedepot.com/md_viewIt...product=AM1413

I notice that a 10 pack of the 7.000 and the 10.000 are ~$9 USD, but the 4.000 is $14, so you can save a few bucks using the 7 and the 10 rather than the 4...

HTH