Thinking about it some more, the moisture in the salt that is.... I am wondering
if the chemical composition is fairly constant in the area we race on or if it
might vary from year to tear. If it does i would think it would make a
electrical based measurement such as resistance a little futile as the
conductivity of the base material might change. I was looking at it another way
too. If we assume that what the salt is made of and water added to it, don't you
have a pretty good electrolyte? I mean with two dissimilar metals couldn't you
make a battery and measure the voltage? Or the pH ??? I will ask one of my local
scientist buddies that might have some experience with these measurements how
they might do it on the cheap. I am not looking for absolute readings just
relative ones that can be repeated year to year or day to day.
Dave Dahlgren ( who still believes it all comes down to where the rubber meets
the road.)
rtmack wrote:
>
> Dave:
> I can't tell from my mail whether my last note reached you-- about using
>either neutron
> backscatter or electrical resistance to measure salt moisture. Since then I
>realized that
> the "dielectric test" you referred to is probably similar to another
>technology that was
> being used in the 80's to find moisture in roofs. It was advertised as a
>"capacitance
> device". (Like the neutron backscatter device), it looked like an upright
>vacuum cleaner.
> I never talked with anyone who could explain the technical workings, but I
>know that the
> response was proportional to the amount of water present. I assumed that the
>device
> produced an electrical potential, and in someway "read" the residual charge
>that it
> produced in the subject. (These fell out of favor-- can't remember why--
>before I found
> out much about them. I have no idea whether they are still available.
>Priced a bit less
> than the neutron backscatter device, if I remember correctly.)
>
> What about spatial variation in moisture on the salt? If we knew how the
>moisture varies
> from place-to-place on the course, could we take advantage of it? This could
>be explored
> very easily (need an airplane, pilot, and $400/day equipment rental fee)-- by
>overflying
> the salt after a hot day, and mapping the heat variation with a thermal
>imager. Wetter
> salt has a higher heat capacity, and will show-up after sundown as "hotter"
>spots in the
> thermal images, since it holds the sun's heat longer than the drier salt.
>
> Incidently, the agricultural moisture meters mentioned by "Kvach" seem to be a
> manifestation of the electrical conductivity meter (ohmmeter) that a couple
>of us have
> suggested. It would sure be handy to have one already configured for
>measuring moisture.
> I have been trying to find such a thing without success (probably because I
>know almost
> nothing about agriculture). Can someone tell me where to get one? (I made
>one out of a
> cheap ohmmeter, but have not been very satisfied with it.)
> Russ Mack
>
> Dave Dahlgren wrote:
>
> > I would think there ought to be a way to measure moisture content
> > electronically. Similar to a dielectric test i would think. How do they do
>it
> > with wood i don't think they weight them and burn them do they?? Plus i
>don't
> > want to do an excavating job to get the measurement or take hours to do it.
> > I would use it to compare to either wheel slip or accelerometer readings.
>See if
> > there is a correlation to it all. or to see if it really changes very much
>at
> > all during the day. If it does not change then the experiment proved that
> > whatever it is that changes the times in the am for many cars is not the
>salt.
> > personally I think there s a lot to it but it will remain to be seen.
> > I know I have heard a lot about good and bad salt conditions, i would just
>like
> > to quantify them and relate those conditions to the performance of a car or
> > motorcycle. What may be good for one type car may be bad for another.
> >
> > Dave Dahlgren
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