If you have 2 or more identical meters, place one in any solution that makes it read 20 uS or 10 PPM. Use that same meter to make a solution that reads half that and see if any of the other meters calibrated to read the same in the 20 uS solution agree within a full digit.
Good luck. [Some do and some don't] The specifications seem to be written in doublespeak to 'not' reveal the actual limitations. The temperature factors in the calibration instructions are totally absent..took me a MONTH to figure out what was going on and what the temp compensation did, on what, so the reading didn't wander all over the place while trying to calibrate the meter. Hanna tech was no help at all. Clue: The temp compensation compensates for the temp of the meter...not the solution. BUT, the DIFFERENCE in temperatures affects both as the one heats or cools the other. [DON'T hold the little sachet in your hand or the reading will appear to never stop rising as your hand warms it up] Asking a Hanna techie a relevent question will get you a whole lot of silence...if they don't just imply that you are an idiot not qualified to ask questions. ..and Hanna meters are the 'good' ones. None of the meters are "useless" any more than actual exact PPM matters when final absortion, distribution and dilution factors are total unknowables. It simply doesn't matter how much shot is in the air when it only takes one pellet to get dinner. Putting a lot of shot up there just increases the odds that one will get the bird and all the misses fall out of the sky harmlessly. A meter tells you the gun is loaded...not where and how to aim or exactly how many shells are in it beyond what it takes to know the difference between making a little bit of noise and insisting that the cops show up to check your hunting license. Some people just glance into the magazine tube to see if the gun will fire at all...blaze away and reload when they hear it go "click" till they run out of birds in the sky. [Taste it..shine a laser through it etc. "It is a shot shell or a cluster bomb?"] Ammo is dirt cheap and they get just as stuffed at dinner time as the person who weighs every pellet. Ode At 09:53 PM 10/17/2004 -0500, you wrote: >Ode and Mike, > >As you indicate, the range that we would use the PWT is at the lower end of the >meter's range. The accuracy, when calibrated at full scale, along with the >linearity of the response, makes the error large when compared to the smaller >readings at the low end of the scale. > >I would suggest, then, that we increase the accuracy of the readings in the >range that we will be using them. The way to do this is to calibrate the meter > at the maximum uS reading that we are likely to encounter, say, between 25 to >30 uS. This will throw off the accuracy at readings substantially above this >level, but will increase the accuracy between 0 and 30 uS. So, unless the >linearity of the meter's response between 0 and 30 uS is particularly bad, we >would approach an accuracy of near +/- 2% of full scale, with full scale being >20 or 30 uS (our new "full scale" value). If the linearity between 0 and 30 uS >is particularly bad, then we will not achieve this accuracy, and the accuracy of >the meter with normal calibration will also be bad; in short the meter would be >useless for our purposes... > >Dan > > >> Re: CS>Hanna Meter Model Number >> >> * From: Mike Monett (view other messages by this author) >> * Date: Sat, 16 Oct 2004 06:48:15 >> >> Ken, thanks for the good info, especially on controlling >> temperature! >> >> As far as getting two units to agree, the spec is +/-2% of full >> scale. This means +/-2ppm, which means one unit could read 4 ppm >> higher or lower than another and they would still be in spec. A >> slight difference in temperature would increase the discrepancy. >> >> The problem is the units are design for higher conductivity than we >> typically get in cs, so our readings are at the bottom 20% of the >> range. This is the least accurate portion. Here's the specs from >> Hanna's site: >> >> Range : 0.1 to 99.9 uS/cm >> Resolution : 0.1 uS/cm >> Accuracy (@20C/68F) : +/-2% Full Scale >> >> http://www.hannainst.com/products/testers/pwt.htm >> >> >> Although individual units may differ by more than we would like, one >> would hope they would be consistent and repeatable. As far as I can >> determine from searching the archives, most people seem to feel the >> units are repeatable. I know you have posted seeing different >> results, but it is not clear what caused them. >> >> Best Wishes, >> >> Mike Monett >> >> >> -- > > > >-- >The Silver List is a moderated forum for discussing Colloidal Silver. > >Instructions for unsubscribing are posted at: http://silverlist.org > >To post, address your message to: silver-list@eskimo.com >Silver List archive: http://escribe.com/health/thesilverlist/index.html > >Address Off-Topic messages to: silver-off-topic-l...@eskimo.com >OT Archive: http://escribe.com/health/silverofftopiclist/index.html > >List maintainer: Mike Devour <mdev...@eskimo.com> > >
