calibration ?

calibration ?

Post by theodore.l.. » Sun, 16 Sep 2007 19:47:02



Just got a hannah phep ph meter , set it up and did 2 point
calibration with pre packaged buffers....7 and 4.01 according to
dorections.after calibration is "locked in" , i tested some tap
water , then both buffers...the 4.01 tested just that , but the 7
tested like 7.3 . is this normal deviation ?
 
 
 

calibration ?

Post by Joe Sallusti » Sun, 16 Sep 2007 20:42:13



Quote:
> Just got a hannah phep ph meter , set it up and did 2 point
> calibration with pre packaged buffers....7 and 4.01 according to
> dorections.after calibration is "locked in" , i tested some tap
> water , then both buffers...the 4.01 tested just that , but the 7
> tested like 7.3 . is this normal deviation ?

No, unless it's a 'checker'.  The prpbe on that meter is not very
stable in my experience.  Most Hanna meters have an accuracy (or
precision) of 0.1 pH or better.  Recalibrate it and see if it works
better.

The pHep5 has an annoying habit of shutting down through an auto time;
if it powers off you need to recalibrate it.   There is a work
around.  Just press hold.  It keeps it up several minutes longer.  I
wrote a pH meter FAQ a while ago, just search the archives or i can
repost.

Joe

 
 
 

calibration ?

Post by homebrewdud » Mon, 17 Sep 2007 02:56:49


Also,

If it is a new meter the probe was probably dry.

The readings are more stable after the probe has been hydrated

Quote:


>> Just got a hannah phep ph meter , set it up and did 2 point
>> calibration with pre packaged buffers....7 and 4.01 according to
>> dorections.after calibration is "locked in" , i tested some tap
>> water , then both buffers...the 4.01 tested just that , but the 7
>> tested like 7.3 . is this normal deviation ?

> No, unless it's a 'checker'.  The prpbe on that meter is not very
> stable in my experience.  Most Hanna meters have an accuracy (or
> precision) of 0.1 pH or better.  Recalibrate it and see if it works
> better.

> The pHep5 has an annoying habit of shutting down through an auto time;
> if it powers off you need to recalibrate it.   There is a work
> around.  Just press hold.  It keeps it up several minutes longer.  I
> wrote a pH meter FAQ a while ago, just search the archives or i can
> repost.

> Joe

 
 
 

calibration ?

Post by AxisOfBeagle » Mon, 17 Sep 2007 03:24:53


I would add that, in my experience with my Hannah meter, it is
important to keep the sensor stored in appropriate storage solution.

I've also found that if the meter gets a little flaky, soaking it for
30 minutes in storage solution, then re-calibrating helps. It often
requires two successive two-point calibrations to get it accurate.


Quote:

>  Also,
>  If it is a new meter the probe was probably dry.
>  The readings are more stable after the probe has been hydrated

--
I'm using an evaluation license of nemo since 113 days.
You should really try it!
http://www.malcom-mac.com/nemo
 
 
 

calibration ?

Post by theodore.l.. » Mon, 17 Sep 2007 19:23:31



Quote:

> > Just got a hannah phep ph meter , set it up and did 2 point
> > calibration with pre packaged buffers....7 and 4.01 according to
> > dorections.after calibration is "locked in" , i tested some tap
> > water , then both buffers...the 4.01 tested just that , but the 7
> > tested like 7.3 . is this normal deviation ?

> No, unless it's a 'checker'.  The prpbe on that meter is not very
> stable in my experience.  Most Hanna meters have an accuracy (or
> precision) of 0.1 pH or better.  Recalibrate it and see if it works
> better.

> The pHep5 has an annoying habit of shutting down through an auto time;
> if it powers off you need to recalibrate it.   There is a work
> around.  Just press hold.  It keeps it up several minutes longer.  I
> wrote a pH meter FAQ a while ago, just search the archives or i can
> repost.

> Joe

The guy at grape and granary said this meter wouldn't need calibrated
each time I use it...is this accurate?
 
 
 

calibration ?

Post by AxisOfBeagle » Tue, 18 Sep 2007 01:22:51


Must be a different Hannah than any I've used. Mine needs calibrating
on any day I intend to use it - if I expect the readings to be
accurate.

In article

Quote:

>  The guy at grape and granary said this meter wouldn't need
> calibratedeach time I use it...is this accurate?

--
I'm using an evaluation license of nemo since 113 days.
You should really try it!
http://www.malcom-mac.com/nemo
 
 
 

calibration ?

Post by homebrewdud » Tue, 18 Sep 2007 01:54:00


I actually calibrate mine twice before using.
And I calibrate it everyday I plan on using it.
Quote:

> Must be a different Hannah than any I've used. Mine needs calibrating
> on any day I intend to use it - if I expect the readings to be
> accurate.

> In article


>>  The guy at grape and granary said this meter wouldn't need
>> calibratedeach time I use it...is this accurate?

 
 
 

calibration ?

Post by Joe Sallusti » Thu, 20 Sep 2007 01:10:24



Quote:


> > > Just got a hannah phep ph meter , set it up and did 2 point
> > > calibration with pre packaged buffers....7 and 4.01 according to
> > > dorections.after calibration is "locked in" , i tested some tap
> > > water , then both buffers...the 4.01 tested just that , but the 7
> > > tested like 7.3 . is this normal deviation ?

> > No, unless it's a 'checker'.  The prpbe on that meter is not very
> > stable in my experience.  Most Hanna meters have an accuracy (or
> > precision) of 0.1 pH or better.  Recalibrate it and see if it works
> > better.

> > The pHep5 has an annoying habit of shutting down through an auto time;
> > if it powers off you need to recalibrate it.   There is a work
> > around.  Just press hold.  It keeps it up several minutes longer.  I
> > wrote a pH meter FAQ a while ago, just search the archives or i can
> > repost.

> > Joe

> The guy at grape and granary said this meter wouldn't need calibrated
> each time I use it...is this accurate?- Hide quoted text -

> - Show quoted text -

No, it's not accurate.  You are really calibrating the probe, not the
meter.  You need to get the offset and slope set right for the
readings to mean anything.  The pH7 buffer sets the offset and the pH
4 sets the slope.