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Author Topic: Relative Permittivity of Water  (Read 233985 times)

Torana

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Relative Permittivity of Water
« on: October 14, 2010, 10:35:01 AM »
There are text books in every corner of the globe with permittivity figures ranging from 78.54 to 81 for water but unfortunately none of them reference the Laboratory source or any experiment to support the figures.
A simple test measuring 12 volts and amps reveals the resistance the water has to DC.
The theoretical resistivity of water is 182k ohms but in the real world of DC its a alot closer to
100 ohms for 1/16 inch gap.
Can anyone find info that shows tests that confirm non conductance of water ?
Trying to prove that the text books are correct is as hard as proving them wrong.

fritznien

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Re: Relative Permittivity of Water
« Reply #1 on: October 15, 2010, 01:33:17 AM »
pure water is non conductive. normal water is full of ions which carry charge.
easy to measure the increase in conduction as you desolve salt in water.

TinselKoala

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Re: Relative Permittivity of Water
« Reply #2 on: October 15, 2010, 01:41:36 AM »
The problem is that only very very pure water has high resistivity. The presence of ANY trace of ions in the water ... like from dissolved salts or even contaminated containers or measuring electrodes ... will make the water conductive and screw up your measurements.
In fact, resistivity testing is how ultra-pure water is characterized. If the resistivity is more than 10 MegOhms per centimeter, you can be assured that your distillation/purification process is working well.
There are lots of references listed on Google for resistivity testing and dielectric testing of water. For example,
http://www.astm.org/Standards/D1125.htm
Too bad it's not a free publication.

Torana

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Re: Relative Permittivity of Water
« Reply #3 on: October 15, 2010, 10:08:35 AM »
The text books refer to "pure" water which is irrelevant in the real world where there is no ultra pure highly filtered deionised water in nature.
Water left to itself is self ionising /auto ionisation / auto dissociation ,a solvent and pretty much everything else but PURE !!
The relative permittivity list should high lite the fact that water rated at 80 is such an isolated case that it shouldnt even be there for practical reasons.
Permittivity is part of electrostatics while electrolysis is in the same book under organic chemistry.

That said ..check out    http://www.powerlabs.org/waterarc.htm

Torana

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Re: Relative Permittivity of Water
« Reply #4 on: October 16, 2010, 10:19:37 PM »
What I shouldve said is : theres no Lab/text book example of a water capacitor for student replication.
Theres calculations etc for ceramic caps and problem solutions for students but nothing about water or pure water because they are obviously 2 different things.
That simple fact divides people.
It should state that Natural water has no relative permittivity simply because DC goes straight thru it .

exnihiloest

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Re: Relative Permittivity of Water
« Reply #5 on: October 17, 2010, 01:41:33 PM »
The text books refer to "pure" water which is irrelevant in the real world where there is no ultra pure highly filtered deionised water in nature.
...

"Pure" water is not irrelevant in the real word. Scientists know how to purify water, and use it.
See:
http://en.wikipedia.org/wiki/Purified_water



Torana

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Re: Relative Permittivity of Water
« Reply #6 on: October 18, 2010, 04:02:35 AM »
Nature doesnt produce pure water is what I meant .
As a commercial product it could be produced on a grand scale but it still hasnt got Natures stamp on it.   
PURE water is clearly a processed product .

Again the relative permittivity scale should note that natural water has NO dielectric qualitiy at all.


fritznien

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Re: Relative Permittivity of Water
« Reply #7 on: October 18, 2010, 07:33:59 AM »
Nature doesnt produce pure water is what I meant .
As a commercial product it could be produced on a grand scale but it still hasnt got Natures stamp on it.   
PURE water is clearly a processed product .

Again the relative permittivity scale should note that natural water has NO dielectric qualitiy at all.
who said ordinary water has no dielectric quality?
its the same stuff just with mobile charge carriers.
put a capacitance meter on an air cap and then flood it, c should go up 80 times.
please note water has a non linear respone to voltage so at low voltage tap water should work well enough.
as for natural just what tech has natures stamp on it?
more important what are you trying to do? you know lots about the subject so just what are you looking for?
fritznien

Torana

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Re: Relative Permittivity of Water
« Reply #8 on: October 18, 2010, 10:05:16 AM »
Ordinary water is clearly not listed on the scale .
A capacitance meter should go up 80 times compared to using air as the initial dielectric but it doesnt ,it goes everywhere,no matter how many times its tested.
In fact using air is the closest it ever gets to being a relable functional cap.
There are thousands of people trying to use water in a capacitor based on what Stan Meyers said but there is no example of ordinary water as a dielectric .
If there were then thered be a place for ordinary water on the scale . There isnt even a repeatable experiment to confirm pure water at 80.
 

Torana

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Re: Relative Permittivity of Water
« Reply #9 on: October 18, 2010, 10:24:59 AM »
I missed a bit there,  Nature is the bench mark for all technology ,we specialise in below unity and consumption, thats where the money is.
Obviously there is a segment of society who seek more , thats why theyre here .

exnihiloest

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Re: Relative Permittivity of Water
« Reply #10 on: October 18, 2010, 01:24:19 PM »
Nature doesnt produce pure water is what I meant .
As a commercial product it could be produced on a grand scale but it still hasnt got Natures stamp on it.   
PURE water is clearly a processed product .
...

"PURE water" is H2O molecules. A H2O molecule is pure and there are many in nature, even in intergalactic space.
By "not pure", you are refering to a certain quantity of water without any other molecule, that the nature could provide on earth and that it doesn't. Your viewpoint is anthropic, I don't see its interest in the frame of this thread.

You asked first "Can anyone find info that shows tests that confirm non conductance of water ?"
The reply I gave confirms that the scientists can purify water and have measured its permittivity. You can produce water with megohms of resistance, just follow their methods. Pure water is a reality.

« Last Edit: October 18, 2010, 02:50:14 PM by exnihiloest »

Torana

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Re: Relative Permittivity of Water
« Reply #11 on: October 19, 2010, 12:12:31 AM »
Hi exnihiloest,
deionisation and purifying is a process that nature doesnt follow, its a commercial manufacturing process from a natural resource.
My initial question "Can anyone find info that shows tests that confirm non conductance of water?" 
The Permittivity scale shows water at 80 , the more you delve into it ,every response youll ever find refers to pure water . But no actual experiment to support it.
Natural unprocessed water is not on the permittivity scale , simply because it conducts just as good as a copper wire , its the exact opposite of pure water.
I encourage anyone to try and stop DC passing thru water, the breakdown voltage is just over 1 volt ,Ive got 10 cent capacitors that can hold more than that .
A capacitance is calculated by Physical dimension = area ,distance and permittivity or the INSULATOR between the plates.
If anyone can find a replicable experiment (natural water)let me know because that means a theoretical capacitor can be used as a substitute capacitor in any electrical circuit WITHOUT short circuiting.
With an insulator , Current is the result of failure .
Pure water is a reality ,scientists have measured its permittivity ,its a commercial product with a manufacturers name ,trade mark and no doubt copy right.
Where does that leave rain water ,sea water ,tap water ? If they have permitttivity does that mean they too can be utilised as a dielectric? 

TinselKoala

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Re: Relative Permittivity of Water
« Reply #12 on: October 19, 2010, 02:01:55 AM »
http://www.flickr.com/photos/ruudvankoten/4235278134/

See that bank of big jugs in the middle rear, with all the conductors going down to them?

Water capacitors, high voltage DC kind, otherwise known as Leyden jars. Ultrapure water isn't required, just enough current supplied to allow voltage to build in spite of the resistivity of the water being relatively low.

Torana

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Re: Relative Permittivity of Water
« Reply #13 on: October 19, 2010, 09:33:04 AM »
hi t-koala ,   Leyden jar is a good example ,Ive made and used them and also had them at school,
but the GLASS is the dielectric which has a rating of 7 in alot of text books and some rate 5-10.
The water is a conductor and that is its purpose ,mercury can be used but hasnt been used for a long time being poisonous. Water is the next BEST conductor.
The leyden jar has an external plate of foil or it can be sitting in a larger body of water which again is conductive. therefore being 2 conductive water plates.
Resistance is the reciprocal of conductance ,  R = 1 / G
A Resistor has conductance and Water in this case is the conductor with very little resistance ,thats why it is chosen for the job.
A dry leyden jar has 2 foil plates ,the top of the jar is sealed to avoid arc over.

People will have a hard time trying to find info to support the non condutance theory, theres nothing out there. Pure water does not represent ALL types of water especially tap water.
A water capacitor is not going to happen any time soon.

Torana

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Re: Relative Permittivity of Water
« Reply #14 on: October 20, 2010, 11:59:11 PM »
Any claim that uses a water cap surely has to supply that claim with a relevant cap measurement and construction details.
Capacitance is determined by physical dimension, C = er x e0 x A / d   ,and permittivity.
Air =1 and has a breakdown Voltage of 3kv per mm
Pure water = 80 , theoretically a breakdown Voltage 80 x that of air =240 KV per mm.

1st problem= a functional cap is an open circuit to DC and will not pass DC (test for yourself)
2nd problem =any voltage less than breakdown V will not break down the dielectric which is the sole intention.
3rd problem= Natural water breaks down at just over 1 volt. (test for yourself)
It all leads back to the permittivity scale ,  either you use pure water with an assumed rating of 80 which means the text book breakdown voltage = 240 KV per mm , which also means the electrical circuit HAS to reach at least 240 kv and if it doesnt , where is the copious amounts of hydrogen going to come from??? dielectric breakdown???
Tf you use rain, tap ,sea or puddle water , what is the permittivity of that water ???
The general assumption is to go back and quote the permittivity scale which says ..80 .

Use 12 vDC + measure conductance of the water to determine if the water is a conductor or an insulator. (test for yourself)
Fundamental requirements for construction of a cap is 2 conductors separated by a NON conductor, NOT 3 conductors in a row , thats called a resistor.
For anyone to accept water permittivity as 80 , HAS to accept what goes with it, which is the breakdown Voltage of 240 000 volts per mm .