Flow tube(s) inside the sensor vibrate at their resonant frequency, much like a spring with a weight attached to one end. The resonant frequency is a function of the mass of the fluid inside the tubes, which is a function of tube volume and fluid density. Thus, the resonant frequency is related to the fluid density inside. Therefore, for a given sensor, density of the fluid can be determined by measuring the resonant frequency of the sensor flow tubes. -----Original Message----- From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On Behalf Of Balmer, Robert D. Sent: Wednesday, August 08, 2007 9:08 AM To: Foxboro DCS Mail List Subject: [foxboro] General Instrument Question Content-Type: text/plain; charset=3Dus-ascii Content-Transfer-Encoding: quoted-printable I am involved on a project in China and there is a control engineer over there saying they can use a mass flow meter to measure density. I have never heard of such a thing, has anyone out there in control world seen such an application. If so could you point me to some literature on how it is accomplished? Regards, =3D20 Robert Balmer =3D20 Senior Applications Analyst/Programmer ISA CCST 319 463 2206 Robert_Balmer@xxxxxxx =3D20 -- No attachments (even text) are allowed -- -- Type: image/jpeg -- File: image001.jpg -- Desc: image001.jpg =20 =20 _______________________________________________________________________ This mailing list is neither sponsored nor endorsed by Invensys Process Systems (formerly The Foxboro Company). Use the info you obtain here at your own risks. Read http://www.thecassandraproject.org/disclaimer.html =20 foxboro mailing list: //www.freelists.org/list/foxboro to subscribe: = mailto:foxboro-request@xxxxxxxxxxxxx?subject=3Djoin to unsubscribe: = mailto:foxboro-request@xxxxxxxxxxxxx?subject=3Dleave =20 _______________________________________________________________________ This mailing list is neither sponsored nor endorsed by Invensys Process Systems (formerly The Foxboro Company). Use the info you obtain here at your own risks. Read http://www.thecassandraproject.org/disclaimer.html foxboro mailing list: //www.freelists.org/list/foxboro to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave