Fisher Scientific Benchtop Meter AB250

Turn meter on and select appropriate mode using MODE button

Soak conductivity electrode in alcohol or clean water if stored dry for some time

Rinse the electrode with clean water

Submerse electrode in first conductivity standard and press STD to enter standardization mode

Is 'Stable' displayed on the meter?

Adjust cell constant manually or keep nominal value?

Adjust upper display to match desired value using ▲/▼ keys

Select the appropriate pH calibration buffer group

Attach the automatic temperature compensation (ATC) probe

Was the pH electrode stored dry?

Soak the pH electrode in storage solution for 10 minutes if it was stored dry

Standard Calibration with Preset Buffers

Turn meter on and set to pH measurement mode

Rinse the pH and ATC electrodes with clean water

Submerse electrodes in the first pH standard buffer

Prepare ion standards that bracket your measurement range

Follow the ion selective electrode instruction manual for ionic strength adjustment and sample preparation

Press MODE for concentration mode

Dip the ISE into the lowest calibration standard and stir

Connect the temperature probe and place into a solution with a known accurate temperature

Press STD from any measurement mode

Observe the active temperature on the upper display

Observe the factory default temperature on the lower display

Adjust the upper display using ▲/▼ keys

Turn meter on and connect a combination ORP electrode

Press MODE if needed for mV (or R.mV) measurement

Dip the ORP electrode into a solution with a known mV value

Press STD to begin standardization

Adjust the value using ▲/▼ keys

Press STD when the reading is stable to accept the calibration offset