KROHNE OPTISENS PAS 2000 EN - Manual (Page 25)

OPERATION
5
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OPTISENS PAS 2000
www.krohne.com 11/2008 • MA PAS 2000 R04 en
The time between calibrations varies with the application, it is usually between one and ten
weeks. It is important that the sensor has been switched on for about 30 minutes prior to the
calibration in order to stabilize.
5.3.1 Calibrating pH
For a pH calibration there are two alternatives: smart or manual. Irrespective of the type of
calibration you chose, you need two pH buffers which both have a common, known temperature.
For a smart calibration you need two different buffer solutions with pH 4.00, 7.00, or 10.00. For a
manual calibration, two different buffer solutions can be used irrespective of the buffer value.
Remove the sensor and, if necessary the electrode as well, but make sure that the electrode is
still connected to the signal amplifier. Make sure that you have at least 2 standard buffers
available with pH 4 00, 7.00 or 10.00 of a known temperature (it is best to pour the buffers into
plastic cups). Now do the steps that follow:
• Enter the sensor menu. The output is frozen when the menu is opened.
• Open the "Calibrate" menu, select "Calibrate", then "Smart" or "Manual" and press ^.
• A window pops up and asks for the buffer temperature. Enter the temperature and press ^.
• MAC 080 will say "Put the electrode in buffer 1". Spray the electrode using clean water, then
immerse it in the first buffer, and press ^.
• The text will say "Waiting for stable signal xxx,x mV" (xxx,x is the millivolt signal from the
electrode). By pressing ^ you can select to abort the calibration or to accept the value shown.
• If smart calibration is used and MAC 080 recognizes the buffer, MAC 080 will suggest a pH
value showing the text "Accept smart calibration pH X.X". You can choose to accept the value
or to change it manually.
• If manual calibration is used MAC 080 will always ask for the value of the buffer, enter the
value and press ^.
• MAC 080 will now tell you "Put the electrode in buffer 2". Spray the electrode using clean
water, then immerse it in the second buffer, and press ^.
• The text will say "Waiting for stable signal xxx,x mV" (xxx,x is the millivolt signal from the
electrode). By pressing ^ you can select to abort the calibration or to accept the value shown.
• If smart calibration is used and MAC 080 recognizes the buffer, MAC 080 will suggest a pH
value showing the text "Accept smart calibration pH X.X". You can choose to accept the value
or to change it manually.
• If manual calibration is used MAC 080 will always ask for the value of the buffer, enter the
value and press ^.
• The second buffer is not accepted if it is less than 1 pH from buffer 1, if so the second
calibration will be repeated.
• When the calibration is finished the slope is shown in the display ("Slope XX%"). This gives an
indication of the shape of the electrode. A good electrode has a slope between 93 and 102 %.
• Press ^ to finish the calibration.
.book Page 25 Friday, November 28, 2008 2:32 PM