CO2 Gas Mixer Fluctuation in Wave Bioreactor

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jscott Participant Join Date: Oct 2012 Location: USA Posts: 2	CO2 Gas Mixer Fluctuation in Wave Bioreactor 10/19/2012 2:04 PM
	I have been battling a CO2 mixer on a Wave/GE bioreactor S200EH. Running it at 5% CO2 it fluctuates up to 8% and down to 4% for short periods. These are calibrated every 6 months, adjusting the zero and span potentiometers while concentrations of 100% N2, 5% CO2 and 10% CO2 cal gas are sampled. Sometimes adjustment is needed but most cals are within tolerance. I've replaced pumps, sensors, hoses, filters, orifices and entire modules. I've checked the gas supply (CO2 and Clean Air), Tested the mass flow controllers. Everything works great except the CO2 mixer. Does anyone know what causes the fluctuations? More to the point, how do I fix it?
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	Pathfinder Tags: bioreactor biotech calibration CO2 GE Metrology wave

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Joshi Guru Join Date: Oct 2007 Location: India Posts: 1246 Good Answers: 34	#1 Re: CO2 Gas Mixer Fluctuation in Wave Bioreactor 10/19/2012 2:39 PM
	Could you give more info. on your Wave Bioreactor? Is it a waste water treatment unit?
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leveles Guru Join Date: Jan 2008 Posts: 1753 Good Answers: 59	#2 Re: CO2 Gas Mixer Fluctuation in Wave Bioreactor 10/19/2012 11:22 PM
	Based on the meager info, the first thing comes to mind, that the CO2 fluctuations are real. The biomass uses up, changes acidity. Activity changes. Then new supplies come in and the cycle repeats. A bioreactor does not have to behave steady state at all.
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jscott Participant Join Date: Oct 2012 Location: USA Posts: 2	#3 Re: CO2 Gas Mixer Fluctuation in Wave Bioreactor 04/15/2013 9:05 AM
	The bipreactor is used for mammelian cell growth. I can't say much more as I'm a Calibration Technician not a Biotechnician. These fluctuations are short staccato like waves. They don't last more than a few seconds but are enough to trigger the alarm set points. So I dont think the cell growth is causing it. I appologize for the length of time between posts. This is still an issue.
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