Steve,
Dry air at the level you require is definitely possible.  The other messages detailed most of
the equipment you might need.  We run a dryer that does not cost a fortune in maintenance.
For critical areas we have desiccant traps in the lines that we change 2x a year.  Balston has
lots of stuff for this purpose.  Check on air dryers with the supplier or service agent for
the compressors.

Chuck Brummer (whose water traps are dry)
Acuson


Stephen R. Gregory wrote:

> So Brian,
>
> You're saying that it isn't possible to put a air compressed air system in
> place, that will provide one with air that doesn't contain the kind of
> moisture, that requires you to drain from traps every day...so my plant
> engineer is right, we'll always have water in our lines no matter what kind
> of air drier we have...that is, unless we want to spend the money that you
> say we have to spend to acheive that...
>
> Seems pretty discouraging to me...and to all the vendors that make air driers
> that claim they can provide their customers with clean, dry, shop air...they
> are lying to us.
>
> Brian, I'm not talking about clean-room air, just air that is free enough
> from moisture that you don't have to drain traps everyday...I don't think
> that's too much to ask...
>
> -Steve Gregory-
>
> << Steve
>
>  What you are saying is half true. A lot depends on the humidity of the
>  air being compressed. It is clear that if you have, say, 20 g/m3 of
>  water vapour in air (c. 80% RH) at 25°C, adiabatic compression to, say,
>  10 bars will give you 200 g/m3 as a first approximation. As the
>  temperature will rise during compression, the RH will not change a great
>  deal. As the air cools again down to ambient, condensation will occur
>  and roughly 150 g of water will condense out per m3 of compressed air. A
>  lot of this will occur in the reservoir, which needs regular purging,
>  but the reservoir is usually at an elevated temperature, so a lot will
>  occur in the lines and will find its way into your filters.
>  Notwithstanding, ALL the air you are using will be quasi-saturated.
>
>  So, what to do? Let it be said, the only way to have cleanish air is to
>  eliminate the impurities, such as moisture, oil, dirt, etc. This usually
>  requires a total re-installation, especially if you have iron pipes for
>  distributing the air. These will have rusted to hell. The compressor
>  should be an oil-less type (e.g. a Roots blower), to prevent an oil mist
>  from entering everywhere, the reservoir should have an automatic water
>  purge, the outlet of the reservoir should be fitted with a 5 micrometre
>  filter, followed by alternating cryogenic condensers, operating at -25°C
>  (one defrosting off circuit while the other is working on circuit),
>  followed by a large, properly maintained, silica gel filter. That way,
>  you will get reasonably clean, dry air. If you want better, you will
>  have to resort to a liquid air reservoir. For the air lines themselves,
>  I recommend certified high-pressure non-halogenated plastic pipe.
>
>  Now all this costs money, especially in maintenance. Most compressed air
>  systems receive minimal maintenance, if any at all. Big mistake! Your
>  problem, Steve, will be persuading the powers-that-be that something
>  that cost a few thousand 25 years ago and nothing since, except a a few
>  kWH of electricity/day and a few litres of oil per year is suddenly
>  going to cost a small fortune in incremental capital costs and a
>  quasi-infinite increase in incremental operating costs... Ball in your
>  court :-(
>
>  Brian
>
>
>
>  "Stephen R. Gregory" wrote:
>  >
>  > Hi All,
>  >
>  > I've become involved with our facility compressed air. We seem (in my
>  > opinion) to have an excessive amount of moisture in our air lines. There is
>  > an air dryer installed downstream from the compressor, but the water traps
>  > that are installed at various locations on the production floor need to be
>  > drained regularly (sometimes daily).
>  >
>  > My take on this is that the air drier that we have either isn't functioning
>  > properly, or that it doesn't have the capacity that we need for the demand
> of
>  > air that we require.
>  >
>  > I'm being told by our "Plant Engineer" that there isn't anything out there
>  > that will eliminate the moisture from our compressed air lines, he says
> we're
>  > always going to have water in our compressed air lines...I beg to differ
> with
>  > his opinion.
>  >
>  > Would any of you please post something that says that it is possible to
> have
>  > clean, dry, compressed air on your production floor? This is air that is
>  > supplied for our automation, and everything else.....
>  >
>  > I know that this is possible, I've worked at too many other companies where
>  > one of the last things I had to worry about was the quality of our
> compressed
>  > air, but I have a new challenge now...I see water in the traps throughout
> the
>  > production floor every single day that need to be drained daily (and other
>  > things that I don't want to get into), but yet I'm told our air drier is
>  > functioning properly, and that it just doesn't get any better....that it's
>  > just physics.
>  >
>  > I'm about to go crazy...please help me.
>  >
>  > -Steve Gregory- >>
>
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