20
Figure 1 (extract from the EN 12953-10 standard)
Maximum acceptable direct boiler water conductivity based on the pressure, direct feed water conductivity > 30
m
S/cm
1
Direct conductivity mS/cm
2
Operating pressure in bar
Parameters
Unit
Conductivity of the feed water
> 30 mS/cm
Conductivity of the
feed water
< 30 mS/cm
Operating pressure
bar
0.5 - 20
> 20
> 0.5
Appearance
Clear, free from solid suspensions without persistent foam
Conductivity
mS/cm
< 6000
b
See Figure 1
< 1500
pH
10.5 - 12.0
10.5 - 11.8
10.0 - 11.0
c
P alkalinity
ppm CaCO
3
50 - 750
50 - 500
10 - 100
M alkalinity
ppm CaCO
3
100 - 1000
100 - 750
10 - 250
Iron
ppm Fe
< 0.1
< 0.1
< 0.1
Copper
ppm CU
< 0.1
< 0.1
< 0.1
Silica
ppm SiO
2
See Figure 2
Phosphate
ppm PO
4
10 - 30
10 - 30
6 - 15
Deoxygenating agent
ppm
Excessive deoxygenating additive according to supplier’s specifications
Organic substances
Not enough to cause traces, foams or other problems
Table 2
OPERATING WATER FOR STEAM GENERATORS
a. excluding contribution of chemical conditioning treatments
b. with a superheater the limit is 3000 pS/cm
c. use alkalinisers only if the pH is less than 10; in any case, use of Na
or K hydroxides is allowed only if the recommended pH range cannot
be obtained with the exclusive use of sodium phosphate.
1000
2000
4000
8000
10000
1
0
10
20
30
40
2
Summary of Contents for BAHR'UNO
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