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Re: [APD] UV Sizing -- or - Why is There Air and other aquatic problems

Proximity, duration of exposure, intensity of the UV light,
those are the factors in play alright.

The book is Aquatic Systems Engineering, P.R. Escobal,
Dimension Engineering Press, 2nd Edition, Copr 1996, 2n
printing 2000. The work has it's faults -- mainly a lot of
simplifying assumptions in the formulas (ironically, he
quotes Alfred North Whitehead: "Seek simplicity and
distrust it") and a tendency to boost products his company
sells. But aside from that, it's nice in that it takes an
analytical approach to aquarium devices. Understanding the
simplifying assumptions and why he makes them, the books is
a good primer on how the devices work. I think it's up
there with Walstad's for being a book that puts science
ahead of postcards.  Chapter 5 is Analytic Theory of
UltraViolet Sterilizers-Flowrate, Power & Diameter.

You can find it, here, among other places:


Re isolation transformers -- You lose your GFCI protection
on the load side of the transformer. That's more isolation
than I'd feel safe with -- an unfavorable tradeoff, imo.
And yes, there is still the possibilty both coils being
shorted to the common core, althought that's probably a
less likely thing to happen than a current leak to the
water -- eel-lectrictrified gardener!

Scott H.
--- Steven Pituch <spituch at ev1_net> wrote:
> . . .  I would certainly like to
> study that information.
> I read the opposite into all the info (advertising hype)
> I could access on
> all the commercially available aquarium UV sterilizers. 
> They boast about
> getting all the water as close to the quart tube or
> sleeve as is physically
> possible.  It fact with most of these, they say you must
> run them at reduced
> flow rates in order to kill parasites, because of the
> small cross-sectional
> area.
> Yes, with a  larger diameter the water velocity will be
> less.  But much of
> it will be further away from the tube.  I choose the ID
> to give me a small
> space around most of the tube.  I also put it on the
> Eheim 2217 that pushes
> water into my 3 inch diameter CO2 reactor because the
> flow is less than from
> my other 2217 which has no auxiliary gear hooked up to
> it.
> I have another UV tube I purchased for my other tank so I
> can build the
> other sump differently.
> Anyone have any suggestions on making it safer by using
> something like a 1:1
> isolation transformer?  Somehow I think it would still be
> a danger since a
> short is a short.

S. Hieber

-  -   -   -   -   -   -   -
Amano Returns
to the AGA Annual Convention
Nov 2004 -- Baltimore

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