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 ORPTestr

®

 5 Pocket Tester       

Features

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

•  Replaceable single-junction sensor saves you money

•  Stability and battery status icons

•  Auto power-off function conserves battery life

•  IP67 waterproof rating

Operating Manual

Thank you for purchasing the Oakton

®

 ORPTestr

®

 5 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.

ORP Calibration

1. Clean electrode in distilled water and dry it.

2. Pour a small amount of 222 mV ORP stan-

dard 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 calibra-

tion 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 measure-

ment 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).

ORP Standard Buffer Solution Calibration Reference Table

Temperature (ºC)

mV

Temperature (ºC)

mV

10

242

30

215

15

235

35

209

20

227

38

205

25

222

40

201

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

bration 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 buf-

fer. 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 con-

taminated and cause inaccuracy and slow response time. If that hap-

pens, 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 setting 

mode. 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.

Symbol

Menu setting

Selection

Factory default

P1

Set low measurement alarm

–1000 to +1000 mV

–1000

P2

Set high measurement alarm –1000 to +1000 mV

1000

P3

Select Automatic Lock (HOLD)

Off – On

Off

P4

Select backlight

Off – 1 – On

1 (1-min auto-off)

P5

Select temperature unit

°C – °F

°C

P6

Restore to factory default

No – Yes

No

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

Heads-up when measured value 

120 mV:

 Preset low value = 120 

mV, highest value = 1000 mV, when measured value is 

120 mV (sta-

bility icon (

) displays on LCD) the red backlight appears on display. 

Heads-up when measured value 

150 mV:

 Preset high value = 150 

mV, lowest value = –1000 mV, when measured value is 

150 mV (sta-

bility icon (

) displays on LCD) the red backlight appears on display. 

Heads-up when measured value in range of 120 mV and 150 mV: 

 

Preset low value = 120 mV, highest value = 150 mV, when the 

measured value is <120 mV or >150 mV (stability icon (

) displays 

on LCD) the red backlight appears on display.

B. Automatic Lock (P3)

Select “On” to activate auto lock function. When reading is stable for 

more than 10 seconds, the tester will lock the value automatically, 

and “

HOLD

” icon will appear on the bottom left of the screen. Press 

CAL/

  key to cancel HOLD on reading.

C. Backlight (P4)

Select “Off” to turn off backlight function, “On” to turn on backlight 

function, or “1” to have backlight last for 1 minute.

D. Temperature Unit (P5)

Select °C or °F; the factory default is °C.

E. Factory Default Setting (P6)

Select “Yes” to recover tester calibration to theoretical value (pH 

value in zero potential is 7.00, slope is 100%), parameter setting 

return to initial value. This function can be used when instrument 

does not work well in calibration or measurement. Calibrate and 

measure again after resetting the unit to factory default status.

220

25.8

mV

ORP

°c

Figure 1

Keypad Functions

Short press

 = <2 seconds         

Long press

 = >2 seconds

MEAS

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.

MODE

1.   In calibration mode, short press to change calibration 

value (unidirectional). 

2.  In mode setting, short press to change parameter 

(unidirectional).

CAL

<

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.

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.

99 Washington Street 
Melrose, MA 02176 

Phone

 781-665-

1400

Toll Free 1-800-517-8431

Visit us at www.T

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