This manual introduces the use of OHAUS ST20M pH and conductivity pen electrodes, including preparation before use and precautions during use, as well as how to calibrate.
This manual provides instructions for the Ohaus ST20M series of waterproof pen meters, which measure pH, ORP, conductivity, TDS, and salinity. The ST20M-B measures up to 1999 μS/cm, while the ST20M-C measures up to 19.99 mS/cm. Both models feature a 0.01 pH resolution and require weekly calibration for accuracy.
| pH Range | 0.00 – 14.00 pH |
|---|---|
| Conductivity Range (ST20M-B) | 0-1999 μS/cm |
| pH Resolution | 0.01 pH |
| pH Accuracy | ± 0.05 pH |
| Conductivity Accuracy | ± 2% FS |
| Battery | 4 x 1.5V AA |
| Dimensions | 185 x 42 x 37 mm |
| Weight | 105 g |
| Auto-off | After 6 min no operation |
The ST20M pen meter is factory calibrated but requires calibration every week for both pH and conductivity.
The pH electrode should be conditioned by immersing it in pH electrode storage solution (3M KCl solution) for 1 hour before use.
If the cap is dry, white crystals may form; you must add storage solution to the cap and soak the electrode for 1 hour.
Press and hold the On/Off button to turn off the meter.