User Tips And Faqs - MicroCal VP-ITC User Manual

1.) When powering up the VP-ITC, always follow the sequence listed below:
1. Turn on PC power
2. Turn on VP-ITC power
3. Launch VPViewer
2.) After initial power up of the VP-ITC, the data channels will display incorrect values until the
power LED on the front of the cell unit becomes lit. Once the power indicator light comes
on, all data channel readings will be accurate and the instrument is ready to use.
3.) When the VP-ITC requires cooling to get to a target temperature (thermostat or run
temperature) it uses an algorithm which will do the following:
- Set shield to target minus 10 degrees to help cool jacket/cells via conduction/convection.
- Wait for jacket temperature to be cooler than target minus five degrees.
- Set shield to target minus three degrees to bring jacket and cells closer in temperature.
- Wait for deltaT to be non-saturated (small jacket-cell deltaT).
- Set shield to target minus one degree.
- Heat cells and jacket to target
While this algorithm requires more time than heating, it will cool the VP-ITC to the desired
temperature as fast as possible and the operator should not interrupt the algorithm in efforts to
speed up the cooling process. For very low temperature operation of the VP-ITC (less than
10 degrees), users should call MicroCal for consultation.
4.) When filling the cells it is important to load solution that is colder than the intended run
temperature. The operator must also account for the change in temperature that will occur
during the transfer of solution to the filling syringe and then into the cells. If a solution which
is hotter than the ensuing run temperature is loaded into the cells, the ITC will likely require
cooling in order to get a precise starting temperature for the run. Alternatively, the operator
could check the 'No Check T' option in the ITC setup window. This will tell VPViewer to
allow the jacket to be heated up to the cell temperature and commence with the pre-run
equilibration.
5.) When filling the injection syringe, there are a couple of things that should be avoided in order
to get the optimum performance form the ITC.
- Do not allow the syringe needle or paddle to be flexed when drawing solution into the
syringe during filling. During syringe loading this can sometimes occur if the sample
tube is not straight in the threaded tube holder, or if the threads themselves were not
mated correctly. If you can see that the needle or paddle is hitting the side or bottom of
the sample tube, correct the situation before you actually draw your solution into the
syringe.
- Do not allow the solution level to go below the bottom tip of the paddle when drawing
your titrant into the syringe. Be sure to close off the flow path (close port button) before
the solution level gets too low. The sample tube can be positioned in it's holder to adjust
it's height relative to the bottom of the paddle if necessary.
- Always avoid flexing of the injection syringe needle when inserting and removing it from
the cell.

6.1 User Tips and FAQs

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Section 6: Tips and Troubleshooting