Hi Spinlanders,
First, thank you to everyone who replied over the past couple of weeks to my inquiries. There are too many to list individually.
As I expected the single most common way people are drying air in their respective facilities is using a twin tower (DBA) desiccant drier with a –40°C or better dewpoint, possibly with an upstream refrigerated drier. It was suggested that several models have a colorimetric moisture indicator built in, which is potentially useful if you check on the unit regularly – they're noisy and tend to be kept in a mechanical room or closet. The most common models are made by Ballston or Kaiser. Purge valves/autodrains on any compressors are also common additions.
Another trend is that labs using house air as opposed to dedicated compressors and driers tend to have more issues with moisture in the lines and more frequent freeze-ups of their VT chillers.
Finally, the answers to the big question – how are people monitoring the dry air? Some labs essentially are not. Several are using a color indicating system. This could be as simple as Drierite in a trap, or one somewhat fancier version mentioned is a gel-based system that can be had for tens of dollars (
http://www.airdryers.com/products/moisture.html). For those with greater concerns or a larger budget, there are monitors with digital readouts available, some can even be connected to the internet. A while back I looked into these and found them expensive, but they might be easy to budget for if you're doing major renovations or designing a new facility. Several people mentioned Xentaur dew point transmitters, and one mentioned a meter by Shaw (
http://www.shawmeters.com/super.html) as having worked flawlessly for many years.
No matter what system you use, it's important to make sure it can monitor moisture under line pressure.
Cheers,
Andrew
--
C. Andrew Fowler, Ph.D. | University of Iowa
Associate Director | B291 CBRB, 500 Newton Rd.
CCOM NMR Facility | Iowa City, IA 52242
319-384-2937 (office) | 319-335-7273 (fax)
andrew-fowler_at_uiowa.edu
________________________________
Notice: This UI Health Care e-mail (including attachments) is covered by the Electronic Communications Privacy Act, 18 U.S.C. 2510-2521, is confidential and may be legally privileged. If you are not the intended recipient, you are hereby notified that any retention, dissemination, distribution, or copying of this communication is strictly prohibited. Please reply to the sender that you have received the message in error, then delete it. Thank you.
________________________________
Received on Fri Dec 07 2012 - 10:49:45 MST