This discussion is getting interesting. Given that the limits for pressure in 61000-4-2 will only be approached in a few special situations (high altitude labs, or labs in the very few places on earth below sea level), this becomes the old “measure with a micrometer, mark with chalk and cut with an axe” game. Yes, I can measure the height of the column of mercury (a more common type of manometer) with great precision, but the question to ask is “why?” While atmospheric pressure can impact ESD (air discharge) results, is it that critical? Somehow I doubt it.
Ghery _____ From: Cortland Richmond [mailto:[email protected]] Sent: Thursday, April 03, 2008 7:45 AM To: Garnier, David S (GE Healthcare); Pettit, Ghery; EMC-PSTC Subject: RE: Looking for Barometric pressure meter This is an *interesting* discussion. Yes, of course (I should have know, too) the reading at the airport is normalized to sea level. But one could without too much trouble apply it to the known (surveyed) altitude and derive the actual pressure. I have however a metal picture of a Rube-Goldberg/Heath Robinson plumbing setup making up a water barometer. Since the height of the column of water is constant over any practical tubing diameter, one might proudly display a calibration document applying only to the Meter Stick used. Of course, one now needs to know the temperature. Is it sufficient to calibrate a thermometer at only the the melting point of ice and the boiling point of water? How about the latter alone -- since the boiling point varies with pressure, if we _have_ a calibrated thermometer, do we need a barometer? Cortland KA5S ----- Original Message ----- From: <mailto:[email protected]> Garnier, David S (GE Healthcare) To: <mailto:[email protected]> Pettit, Ghery; <mailto:[email protected]> [email protected] Sent: 3/31/2008 8:27:16 AM Subject: RE: Looking for Barometric pressure meter Hi Gary, Thank you for the important point... I too am one of those people that would have said, "What?" ;-) In the past we have used the local Airport online readings for our Baro readings. http://weather.noaa.gov/weather/current/KUES.html Recently, our quality people have been having fits about the lab doing this. Questions such as: "When was it last calibrated?" " Was it an accredited Cal? "Do we have access to the data?" Reguardless that GEHC & Airport are at the same elevation and that our facilities are approximately 1 mile a apart does not cut slack with them. BTW, I am not exactly neutral in this controversity, I wrote the original SPR (software complaint report) complaining concerning this practice. Anyhow, I appreciate your prespective as an "PP-ASEL" person, being up front that is. Regards, Dave Garnier PS: I have gotten 4 recommendations for the Vaisala PTB330 instrument. Have you any experiance with this device? David Garnier e GE HealthCare ___________________________________________ David S. Garnier Quality Assurance Technician Quality-DI RA-EMC 3000 N. Grandview Ave - M/S W-1250 Waukesha, Wi. 53188 Tel: 262.312.7246 Cel: 414.899.7580 <http://weather.noaa.gov/weather/current/KUES.html> _____ From: Pettit, Ghery [mailto:[email protected]] Sent: Saturday, March 29, 2008 6:58 PM To: [email protected]; Garnier, David S (GE Healthcare); [email protected] Subject: RE: Looking for Barometric pressure meter The information provided by the FAA and weather guessers is pressure corrected to sea level. It is not the actual pressure. I can get an altimeter setting in Denver (mile high) or Olympia (206 ft MSL) and it will be in the same range, even though the actual pressure in Denver is about 5 inches of mercury lower. This is one of my favorite questions when auditing a lab when they have a barometer on the wall is that absolute pressure, or corrected to sea level? And I usually get blank looks. And you want to report absolute pressure. Ghery Pettit PP-ASEL _____ From: [email protected] [mailto:[email protected]] On Behalf Of Cortland Richmond Sent: Saturday, March 29, 2008 2:44 PM To: Garnier, David S (GE Healthcare); [email protected] Subject: RE: Looking for Barometric pressure meter Why not get the air pressure from the nearest FAA control tower by radio? Critesfield Airport in Waukesha broadcasts airfield information that includes updated barometric pressure http://www.critesfield.com/facilities/ Cortland KAS/6 ----- Original Message ----- From: Garnier, <mailto:[email protected]> David S (GE Healthcare) To: [email protected] Sent: 3/28/2008 10:25:25 AM Subject: Looking for Barometric pressure meter Hello, I am looking for advice or suggestions for the purchase of a Barometric pressure meter for our EMC lab... - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
