Lovibond CheckitDirect, Instruction Manual

Page: 36 / 104

36 CheckitDirect_Cl-Br-pH-CyA-TA-CaH_2 09/2010
GB
Methods
Hardness, Calcium with Tablet
0 – 500 mg/l
Fill a clean vial (24 mm Ø) with 10 ml of the water sample and
perform zero calibration (see “Operation").
Add one CALCIO H No. 1 tablet straight from the foil to the 10 ml
water sample, crush the tablet using a clean stirring rod and dissolve
the tablet completely.
Add
one CALCIO H No. 2 tablet
straight from the foil to the same
water sample and crush the tablet using a clean stirring rod.
Close the vial tightly with the cap and swirl gently several times until
the tablet is dissolved completely.
Place the vial in the sample chamber making sure that the marks
are aligned.
Wait for a reaction period of 2 minutes.
(Countdown can be activated, see page 27)
The method symbol flashes for approx. 3 seconds.
The result is shown in the display in mg/l CaCO
3
.
Tolerances:
0 – 250 mg/l: ± 5% (full scale)
251 – 500 mg/l: ± 10% (full scale)
0.0.0
RESULT
Notes:
1. Strong alkaline or acidic water samples must be adjusted to a pH-value between
pH 4 and 10 before the tablets are added (use 1 mol/l Hydrochloride acid resp.
1 mol/l Sodium hydroxide).
2. Due to the accuracy of this method the result is rounded (in steps of 10 mg/l CaCO
3
).
3. The tolerance of the method is increasing with higher concentrations. When diluting
samples, this should be taken in account, always measuring in the first third of the
range.
4. Interferences:
• Magnesium hardness up to 200 mg/l CaCO
3
does not interfere.
• Iron concentration above 10 mg/l may cause low results.
• Zinc concentration above 5 mg/l may cause high results.
! Zero
Test
.CaH