Thanks for your reply Greg. One reason I posted what I am using was to get comments on it. I may be wrong, but I think what I have is better than the old pneumatic totalizer that we had. At least I don't have to oil the calc block every couple of months! Loyd Greer Great Lakes Chemical >>> hurwitg@xxxxxxxxxxxxx 04/20/05 09:44AM >>> Loyd, your example implements the typical P/T compensation based on the ideal gas law. Again, while this is better than no compensation at all, it is not very accurate for steam. Greg Hurwitt BASF Freeport |---------+------------------------+----------------------------> | | |"Loyd Greer" | | | |<LGREER@xxxxxxxx> | | | |Sent by: | | | |foxboro-bounce@xxxxxxxxxxxxx| | | | | | | | | | | |04/20/05 09:32 AM | | | |Please respond to foxboro | | | | | |---------+------------------------+----------------------------> >---------------------------------------------------------------------------------------------------------------| | To: foxboro | | cc: | | Subject: Re: [foxboro] Steam FLow Calc | >---------------------------------------------------------------------------------------------------------------| |---------+------------------------+----------------------------> | | | | |---------+------------------------+----------------------------> >---------------------------------------------------------------------------------------------------------------| | | >---------------------------------------------------------------------------------------------------------------| Brian, I don't know if this will help or not but here is a copy of a block that I got from Foxboro. It Compensates for temp and press. [snip] >>> blong@xxxxxxx 04/20/05 09:28AM >>> yes, I should have mentioned I need compensation. Using CHAR blocks is a good thought and I may try that. It will most likely be better than what I'm doing now. Not sure Foxboro offers, Alex? Thanks,Brian -----Original Message----- From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]On Behalf Of Gregory A Hurwitt Sent: Wednesday, April 20, 2005 8:18 AM To: foxboro@xxxxxxxxxxxxx Subject: Re: [foxboro] Steam FLow Calc Are you doing mass flow compensation? If so, are you doing it with the standard compensation term: sqrt ((P/P0)*(T0/T))? This compensation equation is based on the ideal gas law, and steam does not make a good ideal gas. For steam mass flow compensation we have on occasion done a "two-way" characterization where we set up two CHARC blocks to give separate compensation factors for pressure and temperature over a range of interest. It's cumbersome, and it's only accurate over a limited range, but it's better than ideal gas compensation for steam. Does Invensys still offer a physical properties package for I/A? Does it include compensation factors for steam? This might be a good solution. Greg Hurwitt BASF Freeport |---------+------------------------+----------------------------> | | |"BrianLong" <blong@xxxxxxx> | | | |Sent by: | | | |foxboro-bounce@xxxxxxxxxxxxx| | | | | | | | | | | |04/19/05 04:56 PM | | | |Please respond to foxboro | | | | | |---------+------------------------+----------------------------> >--------------------------------------------------------------------------- ------------------------------------| | To: "Foxboro" | | cc: | | Subject: [foxboro] Steam FLow Calc | >--------------------------------------------------------------------------- ------------------------------------| |---------+------------------------+----------------------------> | | | | |---------+------------------------+----------------------------> >--------------------------------------------------------------------------- ------------------------------------| | | >--------------------------------------------------------------------------- ------------------------------------| We are using a CALC block to calculate steam flow. The calculation is not as accurate as I'd like. Does anyone have an accurate "standard" way to calculate steam flow in K# / HR. Thanks, Brian Long Arkansas Kraft _______________________________________________________________________ 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 _______________________________________________________________________ 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 _______________________________________________________________________ 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 _______________________________________________________________________ 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 _______________________________________________________________________ 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