<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><br></div><div>I found something in the user guide saying that the flow rate reading accuracy may vary by 5% depending on the GCF. It was not totally clear as to what the 5% was so I queried and below is MKS's answer.</div><div>(The GCF is used to calculate the flow rate for the gas being used, as the meters are calibrated with nitrogen.)</div><div> I also phoned (before Don replied) and spoke to a different person who said that since the GCFs for the gases we are using are fairly close to 1 (they are 1.4 and 0.7) our flow rate inaccuracy should be less than 5%, we should expect error 5% if the GCF was for 0.2.... </div><div><br></div><div>Also I was advised to check the zero reading every 6 months. </div><div><br></div>Naomi.<div><br></div><div><br><div><br><div>Begin forwarded message:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1);"><b>From: </b></span><span style="font-family:'Helvetica'; font-size:medium;"><a href="mailto:Don_Higgins@mksinst.com">Don_Higgins@mksinst.com</a><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1);"><b>Date: </b></span><span style="font-family:'Helvetica'; font-size:medium;">November 8, 2010 9:25:35 AM EST<br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1);"><b>To: </b></span><span style="font-family:'Helvetica'; font-size:medium;"><a href="mailto:nsj@cmu.edu">nsj@cmu.edu</a><br></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;"><span style="font-family:'Helvetica'; font-size:medium; color:rgba(0, 0, 0, 1);"><b>Subject: </b></span><span style="font-family:'Helvetica'; font-size:medium;"><b>Fw: Service Website Contact Form</b><br></span></div><br><div><br>Naomi: The Gas Correction Factor should be within 5% of the reading, since<br>it is applied to the particular flowrate. We would typically charge<br>approximately $500 for a calibration with the specific gas, although CO2 is<br>not a gas we keep inhouse. If you require better accuracy than what is<br>quoted, we do have one line, the piMFC which is function based rather than<br>factor based, that is within 1% reading for all gases that have been<br>"made". "Made" i means that we have analyzed various gas parameters and<br>have developed a function that is actually stored on the MFC. These have<br>been shown to be within 1% reading for all these gases.<br><br>Please let us know if you need to move forward with calibration using the<br>specific gas, or piMFC.<br><br>Sincerely,<br><br>Don Higgins<br>Sr. Applications Engineer<br>MKS Instruments<br>6 Shattuck Road<br>Andover, Ma 01810<br>Phone: 978-738-3089<br>Toll Free: 800-227-8766 ext.3089<br>Fax: 978-687-6215<br>E-mail: <a href="mailto:don_higgins@mksinst.com">don_higgins@mksinst.com</a><br>----- Forwarded by Don Higgins/US/MKS on 11/08/2010 09:20 AM -----<br><br><br>----- Forwarded by Steve Boudreau/US/MKS on 11/04/2010 05:00 PM -----<br><br> <a href="mailto:nsj@cmu.edu">nsj@cmu.edu</a> <br><br> 11/04/2010 04:53 To <br> PM <a href="mailto:webmaster@mksinst.com">webmaster@mksinst.com</a> <br> cc <br><br> Please respond to Subject <br> <a href="mailto:nsj@cmu.edu">nsj@cmu.edu</a> Service Website Contact Form <br><br><br><br><br><br><br><br><br><br><br>Submitted by <a href="mailto:nsj@cmu.edu">nsj@cmu.edu</a><br><br>Form Type: 24 (servicecontact.html)<br><br>Email: <a href="mailto:nsj@cmu.edu">nsj@cmu.edu</a><br>First: Naomi<br>Last: Jarvis<br>Company: CMU<br>Zip: 15213<br>Country: United States<br>Comments: Hello,<br>I have a question about the MKS 1179A Mass-Flo Controller and 179A<br>Mass-Flo Meter instruction manual 116527-P1 Rev E, 3/99<br><br>On page 35 it says that when using the GCF, the flow reading accuracy may<br>vary by 5% but the repeatability will remain within 0.2% of FS... Does<br>this mean that the reading will vary by 5% of the reading, or 5% of full<br>scale?<br><br>Is it possible to avoid this by getting our MFCs calibrated with the gas we<br>will be using? (Ar and CO2). What would you charge for this? Also what<br>would you charge for recalibration, I read that this is recommended every 6<br>months. I have 4 MFCs (but only 2 are in use at present).<br><br>Thanks for your help,<br><br>Dr Naomi Jarvis.<br>Phone: 412268 6949x<br>product_group: Flow Measurement, Control & Verification<br><br><br><br><br><br>********************************************************************************************<br>This message may contain confidential information of MKS Instruments, Inc. or its subsidiaries. If you are not the intended recipient and have received this message in error, then any use or distribution is prohibited. Accordingly, please notify me immediately by e-mail and delete this message. Thank you.<br><br></div></blockquote></div><br></div></body></html>