WPI EVOM3, Инструкция по эксплуатации

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6 World Precision Instruments
Tips and Advice
Out of Range Error
If you see –––– (5 dashes) on the main resistance display, then the resistance reading
is out of range. Check the ohms range setting to see if it can be increased to display a
higher resistance or set it to Auto . If the display still shows ––––, then go to the Blank
Handling screen and check the settings and the reading. A saved reading will show a
space (“ “) in the grid if the display shows out of range. Do not forget to reset the blank
to zero or go back to a control well resistance when you are finished.
NOTE : The 100K Range can read 5% over to 105K Ω.
Zeroing the blank handling value
1. Select Setup .
2. Then, press Short Electrodes .
3. Press the Blank Handling button.
4. Set the reading to zero.
5. Return to the
Setup page and open the electrodes to remove the short.
Zeroing the probe null offset
1. Select Setup .
2. Then, press Short Electrodes .
3. Press the Probe Null button.
4. Set the reading to zero.
5. Return to the
Setup page and open the electrodes to remove the short.
Resistance levels that are unexpectedly lower or higher can be attributed to a number
of things besides an incompletely grown membrane. Any of these items can change
the resistance reading:
NOTE : Many of these conditions are eliminated with the STX2-PLUS electrodes.
• Electrode resistance (Keep the electrodes clean and chlorided.)
• Fluid levels (Try to maintain the same volume for every insert. A variation of 50 µL
can have a large effect in a small insert.)
• Changing CO
2
levels and temperature drift can account for large changes in the
resistance reading. The use of a warming plate can reduce this effect.
• We recommend that both fluid levels are at the same height so that you do
not have any pressure differentials and the apical well is filled first so that you
do not dislodge the membrane from the filter by hydrostatic pressures. If the
membrane detaches itself, then it was not adhering to the inserts filter. A small
gap from dislodged tissue at the edge of the membrane can open a clear path for
the EVOM3 to read a lower resistance. Instead of the current going through the
membrane, the electricity is going around the membrane. Electricity will take the
path of least resistance and the EVOM3 will measure that as a lower resistance.