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ST Series PH Pen Meter

ST Series PH Pen Meter

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Product Manual

Precision is now available in a line of portable electrochemistry products that provide accurate measurement of pH, ORP, conductivity, TDS and salinity. ST series pen meters are the economical option when you are simply looking for meters that are easy to use and provide accurate measurements.

Water Proof Pen Meters ST20
Cond. range 0.00 – 14.00 pH
Resolution 0.01pH
Accuracy ± 0.05 pH
Battery 4 x 1.5V
Dimension 185 x 42 x 37mm
Weight 105g
Auto-off After 6 min no operation
Ambient temperature 0~50 °C (32-122°F)
Materials ABS


First Usage
Condition the pH electrodes by immersing it in pH electrode protection solution for 1 hour before using. If the pH electrode protection cap is dry (may cause white crystals), add storage solution in the cap and soak the pH electrode for 1 hour.

ST20 is 0.01pH resolution and 0.05pH accuracy pen meter. Each ST20 pen meter is factory calibrated. You may need to calibrate the ST20 regularly to ensure accuracy.

pH Measurement
Remove the protection cap, rinse the pH electrode glass bulb with pure water (distilled water), and wipe clean. (Glass bulb is fragile, be careful, do not scratch it.)

  • Press button-On/Off turn on the meter.
  • Dip the electrode about 2 to 3cm into the test solution(at least 20ml). Stir and wait until the reading stabilized.
  • Clean the electrode with pure water after measurement.
  • When measurement, you can press button-Hold to freeze the reading, press button-Hold again to release measurement again.
  • Press and hold button-On/Off to turn off the meter
  • Press the button-ON/OFF to switch the pen on, dip the electrode into pH 7.0 buffer
  • Press the button-CAL to enter into calibration mode, The “CAL 7.00 pH” will be shown, “CAL” is blinking. the meter will judge if the signal is stable automatically, it will take a few seconds, then the meter display “CAL 4.01 pH”.
  • When display “CAL 4.01 pH”, “CAL” is blinking, means pH7.00 calibration has been finished, Rinse the electrode with pure water and dip it into pH 4.01 buffer.
  • The meter will judge if the signal is stable automatically; it will take a few seconds, then the meter display “CAL 10.00 pH”. If the number, such as “4.01” is blinking, means the calibration point can not pass. You may need to check if the buffer is right.
  • When display “CAL 10.00 pH” , means pH4.01 calibration has been finished, Rinse the electrode with pure water and dip it into pH 10.00 buffer.
  • The “CAL” will disappear after finishing 3-point calibration and go back measurement mode

Clean the electrode after test and cover the protection cap, be sure storage solution is not dry in the cap. Harsh samples may short the pen meter life time, such as sticky, dirty or oily liquids. The meter use button battery 1.5V (AA)*4 , replace all the batteries when the display fade or not turn on.

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