WPI EVOM3 - Tips and Advice for EVOM3 Usage

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
t e  g a t a ntl ell eitane hen  ae finihed
NOTE he K Range an ead  e t K 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 oset
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.)
• Flid leel ( t maintain the ame lme  ee inet  aiatin  
an hae a lage eet in a mall inet)
• Changing CO
2
levels and temperature drift can account for large changes in the
eitane eading he e  a aming late an ede thi eet
• e emmend that th id leel ae at the ame height  that  d
nt hae an ee dieential and the aial ell i filled fit  that 
d nt dildge the memane m the filte  hdtati ee  the
memane detahe itel, then it a nt adheing t the inet filte  mall
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.