Sorry Trem:
What I meant was what is final formula for the "PWT", not
the TDS-1..
Tks Grant..
Trem wrote:
>
> Hi Grant,
>
> I really don't know since we will not sell them. I bought one years ago
> thinking it might be the unit to use and provide to our customers but soon
> after discovered the PWT meter was the unit of choice.
>
> I just took the average of 3 PWT readings of some CS that measured 20 uS
> (water was 1.6 uS so total PPM was 22) and measured it with the TDS-1. It
> measured 7 so guess I would multiply by 3 to get the same PPM as the PWT.
>
> Of course I have no idea if the TDS is reading correctly but if it is then
> the correction factor would apply to anyone else's TDS meter when measuring
> CS with the same ionic content as our CS.
>
> Hope this helps.
>
> Trem
>
> ----- Original Message -----
> From: "Grant" <[email protected]>
> To: <[email protected]>
> Sent: Wednesday, May 29, 2002 8:20 PM
> Subject: CS>TDS-1 versus PWT for measuring PPM
>
> > Hi Trem:
> > ` So what's the final formula for the TDS 1???
> > `Is it half the pwt reading plus 20%.??
> > Tks.. Grant..
> >
> >
> >
> > ***********************
> > Hi James, I don't mean to jump in when you addressed the post to Dean
> > but the fact is that the PWT reads CS much better than the TDS-1 for
> > several reasons as pointed out on our website. Also, you do NOT divide
> > by half when using the PWT. You ADD to the reading. In the case of our
> > generators you add 20%. Hanna is right in telling you to cut the
> > reading in half IF you're measuring dissolved solids such as minerals in
> > the water. However, we as CS users are interested in measuring the
> > content of CS to determine what silver content we have. In this case
> > the meter only measures the ionic portion of CS. And that reading is
> > always less than the total amount of silver content because the meter
> > will NOT read the colloidal portion. Therefore one has to add to the
> > reading to get the total PPM. The correction factor will be the
> > difference between how much of the mix was colloidal versus ionic. We
> > have had our CS analyzed by atomic absorption spectrophotometry and it
> > is generally always the same ratio. Another thing I forgot to mention is
> > the fact that the TDS-1 has an accuracy tolerance of + - 2% of full
> > scale. Since the TDS-1 reads from 0-999 that's + - 20 PPM. Since the
> > PWT reads from 0-99.9 and has the same percentage of accuracy that's + -
> > 2 PPM. And the PWT gives you a decimal point in the reading while the
> > TDS-1 reads in whole numbers only. I hope this helps clear up some of
> > the controversy about the TDS-1 versus the PWT. The PWT is the best
> > choice hands down for measuring PPM.T
> >
> >
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