Appendix G

Micro Oxymax respirometer

 

Student Instruction Manual for Micro-Oxymax

Micro-Oxymax software and calibration:

microOxyMax

 

The instrument is composed of four modules. An expansion interface that has the inlet and outle ports for each chamber on its front pannel. The OxyMax can not determine the oxygen and carbondioxide content of all of the chambers simultaneously. The unit is multiplexed and samples each chamber in turn. The primary function of this unit is to keep track of all 20 valves required to accomplish this. Lots of clicking sounds indicate that it is switching sample bottels. The expansion module also contains the gas dryer units and the electronic valves required to switch them in and out of the gas stream. The oxygen sensor can not tolerate any water and these units remove water with out removing carbon dioxide. Do not use the unit if the dryers look wet and nasty. They will ned to be recharged. The green power indicator should indicate that it is powered and it should not be turned off

 

 

The oxygen and and carbon dioxide sensor modules house the electronic transducers that convert gas concentration into digital signals. Oxygen is quantified by passing a portion of the gas stream through a zinc/oxygen fuel cell. A voltage porportional to the oxygen concentration is generated, digitized and sent on to the computer. Carbon dioxide is quantified by injecting a portion of the gas stream into a miniature gas chromatograph and measuring the CO2 with an infrared detector. Prior to the lab, the Micro-Oxymax was calibrated using gas tanks with pure gases ( N 2, O 2 and CO 2 ) at specific concentrations and left on to equillibrate. These calibrations proceedures are complex and require training that is beyond the scope of this course. This instrument is mainained and calibrated by Tom Brewer.

Operating instructions:

animal chamberBoth the instrument and the water bath should set up and turned on the previous.   The water bath should be set close to the operating temperature and monitored until it equikibrates at the set point. Low temps, in particular, require hours to equilibrate and may require the addition of an antifreeze compound.

 

 

Hardware/software check

shuntsThe expansion module should have bits of tubing sohrting out the input and outlet connectors for each chanel as shown in the photo to the right. The initial software/hardware checks are performed in this configuration.

Connection is accomplished by simply inserting the tubing into the quickloc connectors. Disconection is accomplished by firmly pushing the locking ring in while firmly pulling the tubing out.

It is a good idea to connect all of the chambers and place them in the water bath at this point. This provides equilibration time while you are setting up the software.

Running the system setup software

Running the chamber tests

After 24 hours stop the experiment, cleanup, and save data to the shared drive. 

At this point you should copy the data file to your own drive so that you can work on it. Do not perform calculationms on the shared file on stushare.


 

 

 

 

 

 

 

 

 

 

Walter I. Hatch
wihatch@smcm.edu

August 12, 2012