Dear Wei,
We just moved to a new facility that contains two spectrometers which require compressed air. These are both supplied by a Powerex model SET1507HP rotary scroll compressor system located in a utility room on the floor below the NMR lab. The compressor package itself contains three 5 HP units, each of which can deliver 12.5 standard cubic feet per minute (SCFM) at 115 psi. The microprocessor in the compressor package monitors the demand and turns on and off the three units in order to equally distribute wear and tear between the units. The system also includes two Hankison HPR35 refrigerated air dryers and two Parker desiccant air dryers. At any one time, only one refrigerated dryer and one desiccant air dryer are in use; this allows redundancy and lets us perform preventive maintenance without interrupting experiments. After the compressor package and after the desiccant dryers, there are receiver tanks which buffer any pulsations, protect the probes against any sudden loss of pressure and collect residual condensed water vapor. The final tank is a FDA-certified stainless steel tank with a special lining to prevent rusting. Everything is connected using 1" copper pipes and there are in-line monitors for dew point, carbon monoxide and pressure at various points in the system. These are connected to our building management system, which sends a text to me in case of any failure.
The rotary scroll compressors are ideal for providing compressed air to NMR spectrometers since they are very quiet, relatively free of pulsation and use no oil. Like any compressor, they need to be drained regularly to avoid accumulation of condensed water and thereby prevent rust from forming and blowing into the magnet. We protect against this by using automatic, motor-actuated timed ball valves at the drain port of each air tank and at the sump of each dryer as well as particulate filters at various points in the system. Please let me know if you would like additional information on our compressed air system.
Best regards,
Ken Fishbein
Kenneth W. Fishbein, Ph.D.
Facility Manager, MRI Section
National Institute on Aging
National Institutes of Health
251 Bayview Boulevard
Suite 100, Room 04B120
Baltimore, MD 21224
(410) 558-8512
FAX: (410) 558-8376
Kf31x_at_nih.gov<mailto:Kf31x_at_nih.gov>
From: Wycoff, Wei G. [mailto:WycoffW_at_missouri.edu]
Sent: Friday, November 08, 2013 12:31 PM
To: 'ammrl_at_ammrl.org'
Subject: AMMRL: air compressors for solid NMR operation
Dear AMMRL,
I would like your experience on a reliable air compressor that would support solid state NMR's operation. Our current 7mm CPMAS probe requires 8 cu.ft./min at 80 psi. We are barely operating with the air supply we got from campus, which has recently reduced the pressure to save maintenance cost. If we are to get faster sample spinning probes in the future the air flow would need to be doubled at least. We are considering buying a compressor just for the NMR facility. If you are using a dedicated compressor for your NMR facility with solid NMR operation, could you let me know the model of the compressor, the specifications such as pressure, flow rate, pipe size from compressor to NMR lab, etc.? Info on location of the compressor (inside or outside of the NMR facility) and how many NMR instrument the compressor supports are also important. Actually any suggestions would be very useful to me.
Thanks in advance.
Wei
Wei Wycoff
NMR Core Facility
125 Chemistry Building
601 S. College Ave.
University of Missouri-Columbia
Columbia, MO 65211
Phone: (573) 884-7807 (office), (573) 882-3291 (lab)
Fax: (573) 882-2754
Email: WycoffW_at_missouri.edu<mailto:WycoffW_at_missouri.edu>
Received on Fri Nov 08 2013 - 08:50:21 MST