Bedienungsanleitung Analysekoffer Chemie / Wasser - Winterhalter

GB
Instruction manual for Chemistry /
Water Analysis Kit (30 000 320)
1. Determining detergent residues on dishes
Appearance: white/colourless streaks
Required reagents: phenolphthalein (20 000 185)
1. Put a few drops of phenolphthalein on the wet dishes.
2. Alkaline residues, e.g. due to over-concentration of detergents or insufficient
rinsing, show a purple-red colour. Residues of neutral products (e.g.
rinse aids) do not show this reaction.
Warning! Hot, softened water causes a purple-red colour change in association
with phenolphthalein as well, which can simulate detergent residues.
This effect does not occur when letting the dishes cool down to room
temperature before the test. When it comes to dry plates that have
cooled down, it is recommended to drop a few drops of water on
them and add phenolphthalein afterwards. The purple-red colour may
also appear after a few minutes, as the dried detergent residues need
to dissolve in order to show a reaction.
2. pH value measurement
Required reagent: duotest indicator (3202001)
Definition: The pH value measures the concentration of hydrogen ions in
solutions and can be determined by a special ph paper.
1. A pH test swab is dipped in the solution to be tested, and the moistened
area will change its colour. Compare the resulting colours with the colour
scale and the corresponding pH value.
This measurement does not simply determine the concentration of alkaline or
acid products, but it reveals whether a medium is slightly or strongly acidic,
slightly or strongly alkaline or neutral, respectively. Moreover, using the pH test
strip provides information about the type of product which has, for example,
been used into the machine‘s integral chemical containers.
Classification of pH values
1 – 3 strongly acid
4 – 5 slightly acid
6 – 8 neutral
9 – 11 slightly alkaline
12 – 14 strongly alkaline
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
acid neutral alkaline
pH 7 means: no detergent left inside the machine tank
pH 8 means: not enough detergent inside the machine tank
Determining the pH value does not provide any further information. Titration is
necessary in order to determine the exact detergent concentration inside the
rinse tank!
3. Checking for white and grey coating on dishes
White and grey coating on dishes can be both limescale as well as starch.
3.1 Determining limescale on dishes
Appearance: white/white and grey coating
Required reagent: hydrochloric acid (limestone test solution 20 000 181)
1. Drip several drops of 1 N hydrochloric acid on the coating and observe:
In case of a thick coating, small gas bubbles will emerge, and the quantity
of these bubbles makes the test spot appear white. Upon rinsing the spot
with water, the shining porcelain surface or the white-metal surface of the
steel parts will reappear.
3.2 Determining starch on dishes
Appearance: white/white and grey coating
Required reagent: starch test solution (20 000 184)
1. Drop some of the starch test solution onto a piece of crockery and disperse
the liquid by rocking it. This can also be achieved by further dilution with
water.
2. If the solution changes its colour to deep blue this indicates starch residues.
If the solution changes its colour to yellow, this indicates protein residues.
The reaction is very sensitive. Consequently, a single starch grain in a glaze
scratch can result in a blue spot on the crockery.
Please note that starch grains often stick to calcified surfaces (rough surface).
4. Determining water hardness
Required reagent: water hardness test set (GH: 20 000 187, KH: 20 000 188)
The TH (total hardness) water hardness test set is used for determining the total
water hardness. The CH (carbonate hardness) water hardness test set is used for
determining carbonate hardness.
1. Prior to each water hardness test, the titration cylinder must be carefully
rinsed.
2. Fill up the titration cylinder with the water sample to the 5 ml mark.
3. To measure total hardness, add TH reagent drop by drop until the colour
changes from red to green. Move the titration cylinder slightly after each
drop so that the reagent properly mixes with the water sample. A single
drop of TH reagent corresponds to 1ºdH*.
4. Repeat step 1 and 2 for measuring carbonate hardness.
5. Add drops of CH reagent until the colour changes from blue to green and
lemon yellow. Move the titration cylinder slightly after each drop so that
the reagent properly mixes with the water sample. A single drop of CH reagent
corresponds to 1ºdH*.
Warning! Always keep the flask in a vertical position. Make sure the drops are a
consistent size – only use gentle pressure on the flask.
The carbonate hardness can be as high as the total hardness at most. In the case
of softened water, higher carbonate hardness can be simulated for determination
(e.g. identification of sodium carbonate).
Note:
Determination of hardness does not reveal the total salt
content of the water.
Total salt content: The total salt content of water is determined with the conductometer:
take water sample, remove protective cap, and
place conductometer in the water. The result is displayed in
µSiemens. TH and CH cannot be determined, and have to be
obtained using the water hardness test set.
Conversion: conductivity in µS / 30 = total salt content in °dH*
Using Winterhalter‘s water treatments
Items: Water quality Type of water
treatment
Dishes,
devices
Glasses,
dark dishes
Glasses, cutlery
Total hardness (TH)
above 3° dH*
If difference of
total salt content –
CH < 5° dH*
With cutlery rinsing
machines and in if
difference of total salt
content – CH > 5° dH*
ist (for glasses)
Recommendations: glasses: ≤ 150 µS/cm
cutlery: 80 µS/cm
* 1 °dH = 1,78 °fH = 1,25 °e
Softening
Device
Partial demineralisation TE 15
TE 20
Full demineralisation
or reverse osmosis
MonoMatik
DuoMatik
Integrated softener
VE 15
VE 20
RoMatik 150, 160, 210,
420