Grundfos DIT-M, Installation And Operating Instructions Manual

Page: 20 / 36

English (GB)
20
Turbidity can lead to errors
The use of the DPD No. 1 tablet (No 95727747 ) in samples with
high calcium ion contents* and/or high conductivity* can lead to
turbidity of the sample and therefore incorrect measurements. In
this event, the reagent tablet
DPD No. 1 high calcium
(No 95727748 ) should be used as an alternative. Even if turbidity
does occur after the DPD No. 3 tablet (No 95727750 ) has been
added, this can be prevented by using the DPD No. 1 high
calcium tablet.
* It is not possible to give exact values, because the
development of turbidity depends on the nature of the sample.
The precision of our reagent systems (tablets, SPADNS) is
identical to the precision specified in standards literature, such as
American Standards (AWWA), ISO, etc.
Most of the data referred to in these standard methods relates to
standard solutions. Therefore they are not readily applicable to
drinking, boiler or wastewater since various interferences can
have a major influence on the accuracy of the method.
For this reason we don’t state such potentially misleading data.
Due to the fact that each sample is different, the only way to
check the tolerances (‘precision’) is by using the "Standard
Additions Method".
According to this method, first the original sample is tested.
Then further samples (2 to 4) are taken and small amounts of a
standard solution are added, and further results are obtained.
The amounts added range from approximately half, up to double
the amount present in the sample itself. These supplementary
results make it possible to estimate the actual concentration of
the original sample by comparison.
7.3 Acid demand for pH 4.3 / 0.1 - 4 mmol/l
7.3.1 Important notes
1. The terms "total alkalinity", "alkalinity-m",
"m-value" and "acid demand for pH 4.3" are identical.
2. For accurate results, exactly 10 ml of water sample must be
taken for the test.
7.3.2 Measurement
7.4 Aluminium, 0.01 - 0.3 mg/l Al
7.4.1 Important notes
1. Before use, clean the vials and the
measuring beaker with hydrochloric acid (approx. 20 %).
Rinse them thoroughly with deionised water.
2. To get accurate results the sample temperature must be
between 20 °C and 25 °C.
3. A low test result may be given in the presence of fluorides and
polyphosphates. The effect of this is generally insignificant,
unless fluoride has been added artificially to the water.
In this case, the following table should be used:
4. Al
Al
2
O
3
7.4.2 Measurement
1. Fill a clean vial (
∅
24) with 10 ml of the
water sample. Close tightly with the cap.
2. Place the vial correctly in the sample
chamber. See fig. 4 .
3. Press the [Zero] key.
4. Remove the vial from the sample
chamber.
5. Add one Alka-M-photometer tablet
(No 95727763 ) straight from the foil to
the water sample and crush the tablet
using a clean stirring rod.
6. Close the vial tightly with the cap and
swirl several times until the tablet is
dissolved.
7. Place the vial correctly in the sample
chamber. See fig. 4 .
8. Press the [Test] key.
The result is shown in the display as acid
demand to pH 4.3 in mmol/l.
2 0
prepare Zero
press ZERO
Zero accepted
prepare Test
press TEST
∅
24
Fluoride
[mg/l F]
Displayed value: Aluminium [mg/l Al]
0.05 0.10 0.15 0.20 0.25 0.30
0.2 0.05 0.11 0.16 0.21 0.27 0.32
0.4 0.06 0.11 0.17 0.23 0.28 0.34
0.6 0.06 0.12 0.18 0.24 0.30 0.37
0.8 0.06 0.13 0.20 0.26 0.32 0.40
1.0 0.07 0.13 0.21 0.28 0.36 0.45
1.5 0.09 0.20 0.29 0.37 0.48 ---
1. Fill a clean vial (
∅
24) with 10 ml of the
water sample, close tightly with the cap.
2. Place the vial in the sample chamber
correctly. See fig. 4 .
3. Press the [Zero] key.
4. Remove the vial from the sample
chamber.
5. Add one Aluminium No. 1 tablet
(No 95727755 ) straight from the foil to
the water sample and crush the tablet
using a clean stirring rod (dissolve the
tablet).
6. Add one Aluminium No. 2 tablet
(No 95727755 ) straight from the foil to
the same water sample and crush the
tablet using a clean stirring rod.
7. Close the vial tightly with the cap and
swirl gently several times until the tablets
are dissolved.
8. Place the vial in the sample chamber
correctly.See fig. 4 .
9. Press the [Test] key. Wait for a reaction
period of 5 minutes.
When the reaction period is finished, the
measurement starts automatically.
The result is shown in the display in mg/l
aluminium.
4 0
prepare Zero
press ZERO
Zero accepted
prepare Test
press TEST
∅
24
Countdown
5:00