Re: compress your own air?

Bruce D. Ray (bray@iupui.edu)
Tue, 6 Apr 1999 12:50:31 -0500

>I am interested in hearing from any members who compress their own air for
>SOLIDS NMR use. Specifically we have problems on our Doty 4mm/15kHz probe
>on the ASX300 using house air: when the AMX500 user (on same air circuit)
>ejects his/her/its sample the pressure drops enough to cause spinning to
>droop and thence become unstable. As we have tried all the measures
>which would up our flow and pressure using building air, we are having
>to look at buying our own compressor. I would like to know manufacturers,
>costss, models, capacity and experiences.

We use a direct drive Atlas Copco LE-7 compressor
mounted on a horizontal 80 gallon tank which the
vendor's literature terms an Atlas Copco model
D5-80H. Atlas Copco Airpower n.v. is a Belgium
firm which has designed a very nice low oil in
air entrainment compressor. Our compressor is
set to run between 90 and 120 PSI, and requires
almost no maintenance.

This model costs around $2200.

In addition, in our air system, we placed a Balston
"D" series coalescing filter {model 92-812 holder
with the 100-12-DX filter} in line before an Arrow
A25 refrigerated air dryer and a Balston "B" series
coalescing filter {Model A915A-BX with 100-18-BX
filter} after the air dryer. With three spectrometers
simultaneously ejecting, we have not noticed a pressure
droop.

The refrigerated air dryer, and two Balston filter
units combine to add about another $1200 to the total
cost.

I hope this helps.

Bruce D. Ray
IUPUI Physics Dept.
NMR Center