Thales 421 - Mixing Sulphuric Acid

LLZ 421
Maintenance Operation and Maintenance
ILS 420
6−16 Ed. 01.10SOAC
cording to which no components which may be harmful to the plates may be used, must be con-
formed with.
Particularly harmful substances are chlorine, which is present both in the water and in the acid, and
iron which is sometimes contained in the acid. These impurities can however easily be evidenced.
Only specially purified water, i.e. water which has been distilled or fully desalted, may be used. It must
moreover be clear, colorless and odorless
CAUTION
Boiled water, rainwater, well water, river water, tap water or condensation from machines,
heating systems etc. are unsuitable.
The sulphuric acid and the water should be kept in glass or plastic containers, which must be sealed
and covered carefully. Dust and vapors which penetrate may contaminate originally pure liquids.
6.4.1.2.2 Mixing sulphuric Acid
If the accumulator acid does not have a specified density, specially purified water should be mixed
with a high−density acid (mixed acid) in order to obtain the values shown in the chart (Fig. 6−3).
WARNING
When mixing high−density acid with water the acid must be added to the water in a thin
stream whilst stirring with a clean wooden rod. If the water is added to the acid, the latter
will splash dangerously.
Litres
density of mixed acid (kg/l) *
values at 20 °C (68 °F)
nominal density of accumulator acid (kg/l)
* mixed acid: available high−density acid
100
90
80
70
60
50
40
30
20
10
100
90
80
70
60
50
40
30
20
10
quantity of mixed acid
special purified water
0
1,200 1,250 1,300
1,350
1,400
1,500
1,600
1,710
1,800
1,180 1,220 1,260 1,300 1,340
A
0
Fig. 6−3 Accumulator acid chart
Example for mixing accumulator acid:
100 l accumulator acid with a density of 1.24 kg/l is required. The mixing acid available has a density
of 1.71 kg/l. The intersection A on the right−hand side of chart Fig. 6−3 is obtained as follows:
The slope 1.71 (density of mixed acid) intersects the vertical 1.24 (nominal density of accumulator
acid). The horizontal through point A intersects the slope at 72 l (specified purified water) and the verti-
cal at 31 l (quantity of mixed acid) in the left−hand section of the chart. The two quantities must then
be mixed in order to obtain 100 l acid with a density of 1.24 kg/l. This chart is only valid for tempera-
tures of +20 °C. For other operating temperatures see 6.4.1.2.3 .