I have two PWTs
#1 is about 4 year old.
#2 is virtually new
In calibration solution HI 7033 [8...@77deg F]...
actual solution temperature at time of test is 65deg F
#1 reads 47.2 uS
#2 reads 45.7 uS
Very close!
According to the temperature chart on the calibration solution bottle
they should read between 73 and 74 uS at 65 deg F.
According to Hanna specs, the PWT is temperature compensated so, logically,
the calibration solution should get a reading of around 84 uS
.
I would assume that they are calibrated at the factory but can't seem to
find a claim made by Hanna to that effect.
They both read virtually the same over a 4 year difference in manufacture
dates. That should say something.
IMO, sending out uncalibrated testing equipment would be beyond
negligent unless there was also some warning in great big red letters that
it had not been calibrated and you also NEED the calibration solution or
your new meter is way beyond inaccurate. [But extremely repeatably so]
Here we have 3 completely contradictory ways of looking at the same
thing. Depending on who I ask, I get all three answers in triple speak
with each contradiction framed with utmost authority that each view is the
correct one.
Hanna tech emails imply that I'm an idiot but refrain from directing my
eyes in any given direction. [What you are saying can't be true, so how
dare you ask?]
Tongue in cheek conclusions:
1] Hanna very accurately mis calibrates all its meters?
2] Hanna expects you to calibrate the accurately mis calibrated meters but
doesn't say so in any sort of clear manner or supply the solution with
every new meter.
3] The calibration solution is worthless, and/or Temperature compensation
claims are untrue [why the temp chart?]
Regardless of all that...any one answer screws all the meters.
I get a very clear picture of 'something' but can't tell what the picture
is of.
....testing the very old DIST 1 PPM/ TDS meter...reads 25PPM [x2 = more or
less 50 uS]...again, very close to the other 2 meters!
Now, doesn't that just spell out infallable technology in spades?
Oh golly. Ignorance IS bliss!
Bless my bald spot. [Scratches head repeatably]
OK, here it is...the answer to the question "Should I buy the calibration
solution?"
Stay ignorant. You won't be sorry.
Ken
At 11:00 PM 4/14/2003 -0400, you wrote:
Thanks everyone for all your support.
Another question, though :)
The silvergen site also has a "standard calibration solutions so you can
make sure your meter is always reading correctly. A 230 ml bottle sells
for $11.50" to go along with the pwt. Is this useful and/or
necessary? Money is not the problem, I just want to stop buying things I
don't use/need.
Thanks again.
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