[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Aquatic Plants Digest V4 #817

------------------------------
>
> Date: Thu, 1 Feb 2001 13:11:52 -0800 (PST)
> From: Adele and Davis Gailitis <adele_davis at yahoo_com>
> Subject: Measures
>
> Ok so call me a little slow BUT........what the !$@!
> is meq/l ???????????? this has been used extensivly in
> the thread: "Equilibrium, Ca and Mg levels" is this
> suposed to be mg/l ??????
>
Hello Davis,
up to somes days I was confused too. Now it's clear. First, meq/l is equal
to mval/l.
Let me explain it by an example:
My water has a content of 91 mg/l Calzium (Ca++) and 2,5 mg/l Natrium (Na+),
of course, other Ions too. The atomic weight of Ca is 40,1 g and of Na is 23
g. Ca, as an ion, has two positive charges, therefore Ca++. Na, as an ion,
has only one positive charge, therefore Na+. If you devide the atomic weight
by the charge, you get the dimension "meq". In my case for Ca++ it means,
40,1 g / 2 = 20,05 g = 1 meq and for Na+ it means 23 g / 1 = 23 g = 1 meq.
Back to the "mg/l". For Ca++ : If 20,05 g (equal to 20.050 mg) are equal to
1 meq, then 91 mg/l Ca++ are equal to 4,5 mmeq/l. For Na+ : If 23 g (23.000
mg) are equal to 1 meq, then 2,5 mg/l Na+ are equal to 0,11 mmeq/l.
The "meq resp. mval" was created, because it was found, that chemical
connections will function only in the relationship of there "quivalenzen".
(Sorry for incorrect language, but english is not my motherlanguage).
The calculation with meq is importent when designing a
KATI/ANI-ion-exchanger to get low hardness in the water. My tapewater has in
_summery_ a total content of kations of 6,6 meq. If one liter of resin has a
capacity of about 1250 meq/l (usible), does it mean, you get 1250 meq/l /
6,6 meq= 189 l water, then you have to regenerate the resin. And now it is
to understand, that an exchanger can exchange the double quantity of
one-charge-kations than of two-charge-kations. Mostly, the capacity of
ion-exchangers are calculated by "Hardness*Liter". That means, does an
exchanger has a capacity of 9000 HL (_H_ardness*_L_iter) and the tape water
has total hardness about 18 dH, you get 9000/18=500 liter of water before
regeneration. This is valid **only**, if the tapewater consists of
one-charge-ions, f.e. Natrium, Kalium a.s.o. In all other cases, that means
practical always, you have to design an exchanger by the meq-method.

I hope it was helpful to you, best regards, Klaus.







> Dazed and Confused
> Davis:)
>
>
> __________________________________________________
> Get personalized email addresses from Yahoo! Mail - only $35
> a year!  http://personal.mail.yahoo.com/
>
>