Hi Derek! Thanks for the input / feedback - will look into the alternate way of demonstrating compliance to the traceability requirements.
Here is the excerpt from TIA 603 D 1.4.5 Standard Atmospheric Conditions The standard atmospheric condition is a temperature of 25 °C at an atmospheric pressure of 1013 hPa (1013 mbar). Measurements, however, may be carried out at any combination of temperature, pressure, and relative humidity within the following limits: Temperature: 20 °C to 35 °C Relative Humidity: 45% to 75% Atmospheric Pressure: 860 hPa to 1060 hPa (860 mbar to 1060 mbar) We are accredited to this standard by A2LA. Think the main problem with the weather station seems to be the rain gage and a few of the other measurement capabilities of the device. Think can live with limited cal to accredited parameters and find a good lab out there. BTW - I get the "lazy" way but my experience has been that defining what it is that you need and developing procurement requirements that are followed by the accredited calibration labs can be somewhat of a challenge! Can't just say you want "accredited cal". I have learned a lot about metrology in the process! Good to hear from you and I hope that you and yours have a great Holiday Season! Best regards, Mac Elliott [ ] General Public -----Original Message----- From: Derek Walton [mailto:[email protected]] Sent: Monday, December 19, 2011 6:39 PM To: [email protected] Subject: Re: [PSES] Lab Needed for 17025 Accredited Calibration for Davis Weather Station Hi Mac, NVLAP requires that you follow Annex B of NIST HB-150. An accredited calibration is not the only way, just the "lazy" way. Are you sure you need to record these parameters? If your standard has no limits, then quite possibly you could argue out of recording them. I'm not a fan of doing things "just cos'" Cheers, Derek. On 12/19/2011 12:39 PM, Pettit, Ghery wrote: > Agreed that the instrument needs to be calibrated, but the degree of accuracy > doesn't need to be NWS grade (IMHO). What you are demonstrating is that the > environmental conditions are within the range specified for the test. And if > you have enough control you shouldn't be pushing the edges, so it become less > critical. Just don't try ESD out in the open on a hot, humid day in the > south. Nor try it in the foothills above Denver at any time. The > atmospheric pressure will be too low. Remember, the barometer must be > calibrated to read "absolute" pressure, not pressure corrected to sea level > like the weather guessers will give you. > > Ghery S. Pettit > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of Brian Oconnell > Sent: Monday, December 19, 2011 10:00 AM > To: [email protected] > Subject: RE: Lab Needed for 17025 Accredited Calibration for Davis Weather > Station > > Transcat will cal stuff that does these parameters and does 17025. RH, temp, > and atm pressure xdcrs are common stuff. What is wrong with these cal-lab > people? > > Possible to remove transducers/sensors and send to cal lab to do tables? > Most Davis systems are not NWS-grade, and the rated accuracies could allow a > company verification process where altitude and temp correction is applied > to local METAR data, temp sensor is verified with your recently calibrated > instrument used in Type Tests, and the RH sensor can be verified using the > chemical kits or calc using dry/wet bulb readings. > > Do not have a weather station at place of employment, but have several > similar sensors connected to data logger to monitor lab conditions during > all tests, and have never had any problem submitting this data to auditors. > > Brian > > -----Original Message----- >> On 12/19/11, Elliott Mac-FME001<[email protected]> wrote: >>> All >>> Our cal guys are telling me that they are having a hard time finding a >>> lab that can do 17025 accredited calibrations for our Davis Weather >>> Monitor that we use on our OATS to measure temp / humidity / and >>> barometric pressure during our testing. >>> >>> Any suggestions? >>> >>> Best regards, >>> Mac Elliott > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail > to<[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.org/ > 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]> > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail > to<[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used > formats), large files, etc. > > Website: http://www.ieee-pses.org/ > 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]> > - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ 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]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ 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]>
