Ya know, I just may have made an error.
The Dist 1 does something like that and I found it curious but it didn't
click.
I'll have to recheck.
B'golly you be correct
199.9 it is.
I stand redfaced before all and my horse considerably lowered.
Perceptions are indeed a funny thang.
Still don't mind doing some looking into how they do in the field on CS
though.
I'd actually be glad if they were right on.
If I get two labs tests that are nearly the same, I'd be glad for that too.
A least that would put the cow pie somewere where 'I' can toss it or toast
it 'stead of just standing under the cow.
Ken
At 10:21 AM 10/31/02 -0800, you wrote:
>Hi Ken,
>
>I've been too busy to follow the PWT accuracy thread with anything more than
>casual interest. However, the Hanna technicians assure me the stated range
>is what their accuracy is based on.
>
>Today I took 3 PWT meters and put them into distilled water. I then began
>to add tap water very slowly and watched the readings rise over 99.9 without
>going off scale. However when the reading got to 199.9 it then jumped to
>1--.- So, if for sake of argument the accuracy is 2% of full scale, then
>the most they would be off is 4 uS. But I think the factory is correct in
>saying the accuracy is set by the range they specify rather than the total
>reading the meter is capable of indicating. I believe it was Ivan who said
>they are just using the most linear portion of the scale to use and the
>over-reading capability is not to be considered at the same accuracy.
>
>Unless your meter is different than the three I tried, how can you get a
>reading of 999.0 before it goes off scale? Perhaps your meter is not
>working properly. Or should I try a few more meters to see if they all act
>the same?
>
>I really don't see any problem since we're not trying to measure anything
>near the upper limits. We're talking about the range of 5-20 uS in most
>cases and an occasional foray into the 30-40 uS area. I think they work
>just fine. And the ones I use are always in agreement. I always use 3
>meters when calibrating our SG7's to make sure we get them properly
>adjusted.
>
>This seems like beating a dead horse to me.
>
>Trem
>
>
>----- Original Message -----
>From: "Ode Coyote" <coyote...@earthlink.net>
>To: <silver-list@eskimo.com>
>Sent: Thursday, October 31, 2002 10:49 AM
>Subject: RE: CS>TDS/PWT meters
>
>
>> I'm willing, out of curiosity, to 'determine some idea' of how far off
>> reality is from various stated views of it. [something within a range in
>an
>> infinite scale]
>> I've got an odd feeling that no one can say anything that's true about
>> anything. [Nothing that is, except, perhaps, that statement.]
>>
>> So, maybe an average standard will do? [along with an illustration that
>> that's all we ever had anyway?]
>>
>>
>> The PWT actually has a 4 digit display and pegs out at 999.x uS just
>> before it shows a 1 in the far left saying it can't read that high or any
>> higher.
>> The DIST 1 [much similar to the TDS1 I presume] will read up to 1999 PPM
>> before the last 3 places vanish leaving a 1 in the far left place to
>> indicate it's beyond capabilities. Range is stated as 1990 PPM
>>
>> [all regardless of accuracy issues or what or how anything is written,
>> these are the actual facts based on doing and seeing it.]
>>
>> My problem with all this is that accuracy is based on full scale without
>> any clear indication of what full scale 'is' even if [especially if] full
>> scale is not "as high as it will read". Nor are there any indications
>that
>> there is more than one scale.
>> If they had based accuracy on the intended range within any scale or
>> numbers of scales, I'd not even have a question. Who cares what it reads
>> beyond it's intended range? But when you base accuracy on scale and then
>> don't say what the scale is, leaving you to assume it's something like the
>> stated range, but turns out not to be even close and they don't make any
>> attempt at all to qualify the possible differences in perceptions and go
>on
>> to write a specification based on an undefined quantity...I tend to wonder
>> what the heck they said or if anything was. It smacks of double speak fit
>> for a politician. [or salesman...same motive of persuasion]
>>
>> Have you seen the negative political ad where the written words say "...
>> took $40,000 from sons college fund to buy a new car" [implying that she
>> ripped her son off] and the vocals say "..Took $40,000 out of sons
>> college fund because 'he' wanted a new car..and slurred the 'he' part just
>> a little to sound a little like s-he" ?
>> Double speak and misdirection. Manipulation towards a point of view
>that's
>> not true but done without actually lying.
>> The FDA reports on colloidal silver are chock FULL of that sort of thing.
>> Why?
>> For instance..."not proven safe or effective" does not mean "proven
>> unsafe and ineffective", but that's the impression that one gets from the
>> reading and phrasing of a collection of studies that have the title
>> "Colloidal Silver"...when not one single study within the report even
>> mentions colloidal silver.
>> One may as well compare a Volvo to rust because they both contain iron,
>> then say whatever you want to about Volvos because iron is strong or rust
>> is stable. Is it a true statement that rust can't rust, so it's rust
>proof?
>> I've had "dependable" Datsuns that ran till there was nothing left to
>> hold the wheels on..in only 10 years. Well, it ran extremely dependably
>and
>> still does, but you can't drive it. Toyota fixed the rust problems but
>> screwed up the motors by replacing a $12 steel part that never fails with
>a
>> plastic one that tears up the entire front of the motor and contaminates
>> the oil which burns up the bearings, rings and cylinder walls when it goes
>> out. I drive a 1985 Toyota with a 1978 motor in it. They both died from
>> different diseases so I did some grafting. We won't even get into Ford,
>> Crysler and GM. {AMC?? Yea, right...no two alike}
>>
>> Never-the-less, we still use automobiles and they serve us adequately.
>The
>> ambiguities can often be worked around to make something that's actually
>> good in all respects. The manufacturers won't tell you what fits what with
>> whatever modification or what's weak. [Just don't asked me what year,
>model
>> or brand my car is 'cause I'll have to ask you which part?]
>>
>> My lastest in progress is a Hondumpharly motorcycle. The Triumaha works
>> good as did the 1968 thru 1990 510610810620720280240z L/z series
>> Subavolksadasun! ;-)
>>
>> "More doctors recommend this drug over all others combined" OK, what
>> doctor would recommend combining all other drugs? The statement is true,
>> but does it say what it says? LOL
>>
>> Maybe, just maybe, we can get doublespeak [our only language] to talk more
>> true than false for a change and in one instance.
>> Ken
>>
>> At 01:31 PM 10/29/02 -5, you wrote:
>> >Ivan and Ken,
>> >
>> >You're exploring the issue of accuracy and precision of the Hanna PWT
>> >and TDS quite thoroughly! But let's see if I'm misinterpreting you
>> >right on a couple of points... <grin>
>> >
>> >Specs for my Hanna TDS-1:
>> >
>> >Range: 0 to 999 ppm
>> >Resolution: 1 ppm
>> >Accuracy: +/- 10 ppm
>> >Typical EMC Deviation: +/- 1% of Full Scale
>> >
>> >If I interpret this right, my TDS meter should read in steps of 1 ppm,
>> >with no decimal point or tenths, etc., which indeed it does.
>> >
>> >That means the smallest increment it can *resolve* is 1 ppm.
>> >
>> >The display, with 3 digits, will show from 0 to 999.
>> >
>> >The accuracy of 10 ppm out of a full scale range of 1000 ppm is, indeed
>> >1%.
>> >
>> >I don't know what "Typical EMC deviation" means. What's EMC?
>> >
>> >It's pretty clear why the TDS-1 isn't the best tool for measuring low
>> >ppm CS. I'm attempting to use ruler where a vernier caliper would be
>> >better. Still, it's been stable and seems more accurate than spec.
>> >
>> >So what are the specs for the PWT?
>> >
>> >From: http://www.hannainst.com/products/testers/pwt.htm
>> >
>> >Specifications:
>> >
>> >Range: 0.1 to 99.9 µS/cm
>> >Resolution: 0.1 µS/cm
>> >Accuracy (@20°C/68°F): ±2% Full Scale
>> >
>> >This suggests that the smallest step this instrument can resolve is one
>> >tenth of a micro-Seimens per centimeter, and it can count up to a
>> >thousand of them, or 99.9 µS/cm. So I presume the display should show
>> >only 3 digits, one to the right of the decimal place.
>> >
>> >However, Ken writes:
>> >> It says "Range is .01 to 99.9 uS" and "Accuracy is +/- 2% Full
>> >> Scale" [but don't mention what full scale is] Now, you'd think that
>> >> range and full scale would be the same thing, BUT, stick the PWT in
>> >> water and add salt to see where the scale ACTUALLY pegs out. That
>> >> would be at 999.9 NOT 99.9. If the meter were accurate to +/- 2% in
>> >> its "range" they would have said it that way.
>> >
>> >It looks like Ken made a small mistake about the low end of the range.
>> >That aside, does the PWT actually have a 4-digit display and behave as
>> >Ken describes here? It *should* have only a 3-digit display and top out
>> >at a reading of 99.9 uS.
>> >
>> >Whatcha say guys?
>> >
>> >Be well,
>> >
>> >Mike D.
>> >
>> >[Mike Devour, Citizen, Patriot, Libertarian]
>> >[mdev...@eskimo.com ]
>> >[Speaking only for myself... ]
>> >
>> >
>> >--
>> >The silver-list is a moderated forum for discussion of colloidal silver.
>> >
>> >Instructions for unsubscribing may be found at: http://silverlist.org
>> >
>> >To post, address your message to: silver-list@eskimo.com
>> >
>> >Silver-list archive: http://escribe.com/health/thesilverlist/index.html
>> >
>> >List maintainer: Mike Devour <mdev...@eskimo.com>
>> >
>> >
>>
>>
>>
>
>
