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Operating Manual

ORPTestr

®

 30 Pocket Tester

Keypad Functions 
Short press

 = <2 seconds      

Long press 

= >2 seconds

1. Short press to turn on the tester and long press to turn 

    off the tester. 

2. When turned off, long press to enter parameter setting 

    mode. 

3. In measurement mode, short press to turn on backlight. 

1. In calibration mode, short press to change calibration 

    value (unidirectional). 

2. In mode setting, short press to change parameter 

    (unidirectional). 
1. Long press to enter calibration mode. 

2. In calibration mode, short press to confirm calibration. 

3. When measured value is locked (HOLD icon), short 

    press to unlock. 

CAL

<

MEAS

Thank you for purchasing the Oakton

®

 ORPTestr

®

 30 Pocket Tester. 

Please carefully read this operating manual before using the 

product to obtain an accurate and reliable test result and avoid 

unnecessary damage to the tester or probe. 

Features 

• Large easy-to-read LCD with 3-color backlight 

• Replaceable double-junction sensor saves you money 

• Stability and battery status icons 

• Auto power-off function conserves battery life 

• IP67 waterproof rating 

Preparation Before Use 

1. Pour certain amount of storage solution (KCl) into the probe cap, 

soak the probe for 3 to 5 minutes to activate the sensor (if frequently 

used, there is no need to soak). 

2. The soaking solution is 3M KCl solution; preferably Oakton 

Electrode Storage Solution (SKU 00653-04). Users can also 

make it themselves by dissolving 25 g KCl in 100 ml of distilled 

water. 

ORP Calibration 

1. Clean electrode in distilled water and dry it. 
2. Pour a small amount of 222 mV ORP 

standard solution (SKU 80055-90, 500-mL 

bottle) into the calibration bottle. 
3. Short press    /MEAS key to turn the meter 

on. Long press CAL/    key to enter calibration 

mode. If you need to exit calibration mode, 

short press    /MEAS key. 
4. Dip electrode in the ORP standard solution 

(Zobell’s solution), stir gently, and allow it to 

stand still in the calibration solution until a 

stable reading is reached. When measurement stability icon ( ) 

appears and remains on the screen (see Fig. 1), press MODE/

△ 

key to 

adjust the calibration value according to the table below (also on the 

buffer bottle’s label). 

  

Temperature (ºC)

10
15
20
25

  

Temperature (ºC) 

30 
35 
38 
40 

mV 

215 
209 
205 
201 

mV

 

242 
235 
227 
222 

For example, if the temperature is around 25ºC, then adjust the 

calibration value to 222 mV. If the temperature is around 20ºC, then 

adjust the calibration value to 227 mV. Short press CAL/   key to 

complete the calibration.

ORP Measurement 

Press    /MEAS key to power on, clean the probe in distilled water, 

and gently dry it. Place the probe in the tested solution and stir 

gently and let it stand still. Read the measurement after the stability 

icon ( ) appears and remains on.

Notes 

Usually there’s no need to calibrate for ORP testing. When not used 

for a long time, users can test the unit in 222 mV ORP standard 

buffer. If the error is large, recalibrate according to the steps above.

Cleaning and Activating the ORP Probes 

After long-time use, the surface of the platinum sensor can be 

contaminated and cause inaccuracy and slow response time. If that 

happens, the followed methods can be adopted to clean and 

activate: 

A. For contamination caused by inorganic substances, dip the 

probe into 0.1 mol/L dilute hydrochloric acid for 30 minutes. 

Clean it with distilled water, soak in KCL storage solution (SKU 

00653-04) for 6 hours, and then it will be ready for use. 

B. For contamination caused by organic substances and oiliness, 

clean the platinum surface with dishwashing liquid and wash 

with distilled water. Soak for 6 hours in storage solution (SKU 

00653-04) and then it will be ready for use. 

C. If the platinum surface is so severely contaminated that an 

oxide film forms, use toothpaste to clean the platinum surface, 

and then wash it with distilled water. The probe will be ready for 

use again after 6 hours of soaking in the storage solution (SKU 

00653-04). 

Setting the Parameters 

When tester is off, long press    /MEAS key to enter parameter 

settingmode. Short press MODE/

 key to switch from P1 to 

P2…P6. Short press CAL/   key and parameter will flash, then short 

press MODE/

key to choose desired parameter. Short press 

CAL/   key to confirm selection. Long press    /MEAS key to exit 

parameter setting mode. 

ORP Standard Buffer Solution Calibration Reference Table

  Symbol 

  Selection

°C

Menu setting

Restore to

factory default  

Set low

measurement alarm 

Set high

measurement alarm 

Select Automatic

Lock (HOLD) 

Select backlight 

Select temperature

unit 

No – Yes

–1000 to +1000 mV

–1000 to +1000 mV

Off – On

Off – 1 – On

°C – °F

P1 

P2 

P3 
P4 
P5 

P6 

Factory default

–1000

1000

Off

1 (1-min auto-off)

No

A. High and Low Measurement Heads-Up Examples (P1 and P2)

Preset low value = 

mV (stability icon ( ) displays on LCD) the red backlight appears 

on display.

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