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Subject: Water purification

Water purification

From: Rhea DeStefano <rdestefano>
Date: Friday, May 11, 2007
Winston Atkins <winston.atkins [at] duke__edu> writes

>Water Filtration for Conservation Lab
>Duke University Libraries is planning a new book and paper
>conservation lab and one of the issues we need to address with our
>architects is how to spec out the water filtration system. I'd
>appreciate advice from you all regarding:
>    *   merits of deionization vs reverse osmosis,
>    *   volume (gals/minute) to request for a large washing sink
>    *   degree of purity (see paragraph below--our architects'
>        consultants tell us that getting 3 megohms resistance will
>        be difficult; RO will give us 0.5 to 1.0 megohm resistance,
>        putting in DI beds will give us up around 18 megohm)
>    *   issues of cost (initial purchase and ongoing maintenance)
>    *   ease of maintenance
>I've scouted the Cons DistList for information and have a 1994
>exchange, which includes a recommendation not to go for greater
>purity than 3 megohms--too corrosive. I've also reviewed Season
>Tse's CCI publication on water quality. Unhappily, it is not
>prescriptive enough for me. So--I'm going public and would
>appreciate any thoughts or guidance you all can provide.

July 06 we moved to our new conservation lab here at the Folger
Shakespeare Library installing a new water filtration system. We
installed DI water (which we also had in our previous lab) using
HYDRO <URL:>, updating certain features.
Kelly Cloman was our sales representative who is very knowledgeable;
she worked with us and the architects to install the system.

We did not choose RO because:

    1.  First all RO is a very expensive system to purchase in
        comparison to deionized water filtration system.

        *   It removes only 98% of the ions out of your water,
            whereas DI lacks of all ions and salts except H3O+
            <>  and

        *   RO requires big storage tanks to store water before use.

        *   If you have big sinks and you use up all your water it
            takes hours for your water supply to be refilled.

    2.  DI water gives you an unlimited amount of water supply, the
        initial cost of installation might be costly (I would have
        to go back and check if you want exact numbers) but running
        cost are around $600/year to exchange the anion cation
        tank.(Depending on how much water you use)

        *   DI water is very reactive at 18.3 megaohm coming out of
            the cation anion tank, but once it goes through a bed of
            oyster shells for recalcification the water reactivity
            drops to 1 megaohm, which is desirable for our work with

        *   We have a UV filter installed in our wet room in close
            proximity to the taps to kill organic impurities that
            might settle in water sitting in the pipes.

        *   The pressure we have out of our tap is comparable to
            what you get out of a standard faucet.

I would encourage you come and visit our set up. We will have an
open day for conservators in the area June 14, 2007 all day.

Rhea DeStefano
Senior Paper Conservator
Folger Shakespeare Library
201 East Capitol Street S.E.
Washington DC 20003
Fax: 202-675-0317

                  Conservation DistList Instance 21:4
                   Distributed: Friday, May 11, 2007
                        Message Id: cdl-21-4-009
Received on Friday, 11 May, 2007

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