AMMRL: Dry air -- supplies + solids summary

Dave Scott (scott@iastate.edu)
Tue, 27 Nov 2007 15:02:48 -0600 (CST) 

>--Original Message--
>From:  Frank Blum 
>new CP-MAS probe and need a source of dry air.
>with two desiccant columns
  We use a Pneumatic Products Corporation Model 60LDE.MEC.  House air
is 85psi in and 80psi out.  The air is used on at least 7 NMRs, an
IR, and an EPR.  Its been trouble free for years, but the physical
plant has a dryer upstream so it probably doesn't have to do much.

>Our house air (80-90 psi)
  I received some good advice from Douglas L, Martine Z,
Timothy C, Ashley B, and David W in 2005 when preparing
to install a 600MHz solids instrument.
  Half used liquid nitrogen with an evaporator and half used air.
Nitrogen is good but expensive for us ($.85/liter). The department
had a surplus membrane nitrogen generator (Air Products PRISM) that
we use for VT gas.  Spinning and eject use dry air.
  It was difficult to spin above 30k with 80 psi air, so we purchased
an air amplifier (Maximator GPLV-2).  It uses 80 psi air to fill a
ballast tank with 120 psi air.  When we want to spin fast, we open one
ball valve and close another.  It seems robust, but not many fast
spinning projects have developed yet.

hth and thanks to Douglas, Martine, Tim, Ashley, and David,

dave scott
iowa state university

Life is not about how fast you run, or
 how high you climb, but how well you bounce.


we use a 3 stage air compressor that supports both our 400 WB and 600
WB and is rated to be able to support an additional horizontal bore
magnet that we would install in the future.  We only do liquids and
microimaging so we probably don't have the same requirements as MAS
would need.

We use nitrogen gas for all our NMR spectrometers. We have a 3000 gallon
liquid nitrogen tank outside the building, equipped with an evaporator that
generates the flow of gas we need at a pressure of 100 psi.
As we are doing a lot of low temperature MAS work, this is a very good
solution for us. If you are planning to do room temperature work mainly, a
compressor is probably a cheaper solution, though I was disappointed that
the one we used to have (an Ingersoll Rand) died after 5 years of
intermittent use. I was told later that Champion makes a much more reliable
compressor.
We used to use gas packs as well (pressurized LN2 dewars), but their
autonomy is only about 8 hours.

Our labs(i.e. 600WB's) are equipped with both air and nitrogen. We have oil-less
scroll compressors which provide ~110PSI air and we use boil-oil(or evaporator)
from a 5,000 gallon liquid nitrogen storage tank to provide 60PSI nitrogen gas.
We use nitrogen when dry gas is required, such as low temps, and air when large
volume of gas is required ,such as MAS solids applications.

We are using the boiloff from a 1500 liter liquid nitrogen dewar.