Hi, measuring conductance, the inverse of resistance, is a little tougher than one might think; it depends on the size of the electrodes and their spacing, and some other parameters, too. Short form, two electrodes, each of 1 centimeter area, separated by 1 centimeter (cm). But you can't just plop some arrangement into a glass of water, conductivity will occur all over the place - out to the side and back in again, the water will be drifting through the test area, etc., etc. Also, temperature can play a big part in 'correcting' the reading to a standard.
You're probably right to expect some residual contamination from your used machine. First, it has been used, and the water where it was used may have plated out some 'scale' inside the boiler or condenser, second, the stainless steel may be giving up some metal ions to the distilled water - surely not many, but perhaps enough to affect the conductivity. One component of almost all commercial stainless steels is nickel - which is not good for you. I don't know that such a thing is happening, but the lab grade stills all are made of Pyrex or similar glass and have no metal in contact with the water being distilled; there's probably a reason. Take care, Malcolm herx wrote: > Hello list, I need advice on measuring the conductivity of water. > > I recently bought a used water distiller, and the starting current for CS > is 20%-50% higher than it was previously with store-bought distilled > water, with all other factors being equal. The logical conclusion is > that my Kenmore (mfg by Ecowater) distilled water is of lesser quality > than the DW I get from the grocery store. Current is still MUCH lower > than with tap water, so I know the distiller is doing something. But is > it enough? > > I ran one gallon through the distiller twice to see if there was a > difference, but it resulted in roughly the same initial current as a > gallon that had been distilled only once. Ill have to repeat this > experiment a few times to see if any pattern develops. > > I'd like to measure the conductivity of water from both sources to > compare quality. Ive read on this list that conductivity should be 2uS > or less to be suitable for making CS. Is there a way I can calculate > conductivity using my simple 7-function digital multimeter? I dont want > to blow $50-$100 on a PWT tester. > > I have enough trouble getting a simple resistance reading of my circuit > through the DW the readout never holds still and jumps over a wide > range of values; maybe Im doing it wrong. But I can still calculate > resistance by dividing voltage by current (is that right? I think I saw > Ivan post to that effect a few weeks ago). Any advice will be appreciated > > __________________________________________________ > Do You Yahoo!? > Try FREE Yahoo! Mail - the world's greatest free email! > http://mail.yahoo.com/ > > -- > The silver-list is a moderated forum for discussion of colloidal silver. > > To join or quit silver-list or silver-digest send an e-mail message to: > [email protected] -or- [email protected] > with the word subscribe or unsubscribe in the SUBJECT line. > > To post, address your message to: [email protected] > Silver-list archive: http://escribe.com/health/thesilverlist/index.html > List maintainer: Mike Devour <[email protected]>
