MBH Engineering Systems Design ServicesMBH Engineering Systems: pH meters, pH probes and more

 Home Products Services Shopping Cart Tech  Info About Us Contents Search

                           "pH meters, pH probes, pH controllers and much more"

C                                          781-334-2600 (Office)            sales@mbhes.com

                                                 

Back

 

TIPS

  • How to determine if a pH probe is defective or at the end of it's life: 
  • First, immerse the electrode in a pH 7.01 buffer and use the mV (range key) to change the meter display to milli-volts. 
  • Next compare the reading to +/- 30.00mV.  If the reading exceeds this value, the electrode should be cleaned or replaced as it will be unstable.  An electrode in this condition will not be able to be reliably calibrated.

 

  • How to "calibrate" an ORP probe: 
    • NO Calibration of the instrument should be attempted
    • Instead the ORP probe should be checked for usability
    • First, immerse the electrode in an ORP standard such as 230mV or 470mV. 
    • Next observe the ORP reading.  If the reading is within 50mV of the standard, it is a usable electrode. 
    • If the reading is outside those limits, the probe should be replaced or cleaned
    • Trying to calibrate the controller without a milli-volt simulator is a bad idea. ORP is very different from pH.
    • We do sell pH/ORP "calibrators".  These essentially are milli-volt simulators with displays showing pH or ORP units directly.  A knob control allows the user to output any value to the BNC connected instrument.

     

  • Decrease in slope of pH electrode:
    • Usually caused by problems associated with the glass.  Oil, dirt, or salts which have built up on the surface need to be cleaned.  A "Cal-Check" Meter or controller will indicate this condition.  A value of 58.16mV is equal to a slope of 100%.  Slopes above 90% are normally considered acceptable. 

     

  • Increase in offset of the pH electrode:
    • Typically caused by a clogged reference junction or aging of the electrode. 
    • Cleaning of the electrode can partially restore the electrode's offset closer to zero.
    • Eventually, if the offset is too great, the reading becomes unstable (see Tip #1)

     

  • Reset of pH500 controller back to factory default settings:
    • Pressing the following key in sequence will reset the controller.  Remember to make note of how your controller is setup prior to making this step.
    • Press the four keys simultaneously (use two hands):
    • CFM key, SETUP key,  → and CAL DATA.
    • The controller is now reset and ready to be reprogrammed for your application.  Use the notes of your configuration to reprogram the unit.

 

                   

 

                 

     

 

Home Products Services Shopping Cart Tech  Info About Us Contents Search

 

Send questions or comments to webmaster@mbhes.com
MBH Engineering Systems 2008
Last modified: 29-Oct-2008