Lovibond MD200, Instruction Manual, Page: 45 / 160

45
MD200_8 07/2016
GB
Methods
0.0.0
PH
Zero
Test
RESULT
PH
pH-value with liquid reagent
6.5 – 8.4
Fill a clean vial (24 mm Ø) with
10 ml of the water sample
and
perform zero calibration (see “Operation").
Fill the vial with drops of the same size by holding the bottle vertically
and squeeze slowly:
6 drops of PHENOL RED solution .
Close the vial tightly with the cap and invert several times to mix the
contents.
Place the vial in the sample chamber making sure that the marks
are aligned.
Press the [ZERO/TEST] key.
The method symbol flashes for approx. 3 seconds.
The result is shown in the display as pH-value.
Tolerance:
± 0.2 pH
Notes:
1. When testing chlorinated water the residual chlorine contents can influence the colour
reaction of the liquid reagent. This can be avoided (without interfering with the pH
measurement) by adding a small crystal of Sodiumthiosulfate (Na
2
S
2
O
3
· 5 H
2
O) to the
sample before adding the PHENOL RED solution. PHENOL RED tablets already contain
Thiosulfate.
2. Due to differing drop sizes results can show a discrepancy in accuracy by comparison
with tablets. This can be minimised by using a pipette (0.18 ml PHENOL RED solution is
equivalent to 6 drops).
3. After use replace the bottle cap securely.
4. Store the reagent in a cool, dry place ideally between 6°C and 10°C.
Reagent Form of reagent/Quantity Order-No.
PHENOL RED solution Liquid reagent / 15 ml 471040