Viessmann VITOMAX 200-HS Operating And Service Instructions page 23

Water quality for steam boiler systems
Permiss. operating
pressure
Total alkaline earths
(Ca 2+ + Mg 2+ )
Oxygen (O )
2
Bound carbon dioxide
(CO )
2
Iron, total (Fe)
Copper, total (Cu)
Oxidability (Mn VII →
Mn II) as KMnO
4
Oil, grease
Organic substances
Table 2: Boiler water requirements
Permiss. oper- bar
ating pressure
General require-
ments
pH value at
25 °C
Acid capacity mmol/litre
(K )
S 8.2
Conductivity at µS/cm
25 °C
*1 In general, organic substances are mixtures of different compounds. The consti-
tution of such mixtures and the characteristics of their components when subjected
to boiler operating conditions are hard to predict. Organic substances can decom-
pose into carbon dioxide and other acidic products that would increase the con-
ductivity and result in corrosion and deposits. They can also lead to the formation
of foam and/or coatings that must be kept to the minimum levels possible. The
TOC content (Total Organic Carbon) should also be kept to a minimum.
When using demineralised water with a mixed bed quality (LF < 0.2 µS/cm) phos-
*2
phate injection is not required; alternatively the AVT method (conditioning with
volatile alkalization agents, pH value of the feedwater
≥ 8.0) can be applied. In such cases, the conductivity downstream of
boiler water
a severely acidic cation exchanger must be < 5 µS/cm.
*3 Standard adjustment of the pH value through injection of Na
injection only if the pH value is < 10.
bar > 0.5 < 20
mmol/litre
mg/l
mg/l
mg/l
mg/l
mg/l
mg/l
—
Feedwater conductivity >
30 µS/cm
> 0.5 to 20
Colourless, clear and free of undissolved substan-
10.5 to 12
1 to 12
< 6000
(cont.)
< 0.01
0.05
< 25
< 0.2
< 0.05
< 10
< 1
*1
See comment
Feedwater conduc-
tivity ≤ 30 µS/cm
> 20
ces
10.5 to 11.8
1 to 10
See Fig. 1,
page 25
≥ 9.2 and pH value of the
PO ; additional NaOH
3 4
Water quality
> 20
< 0.01
< 0.02
< 25
< 0.1
< 0.01
< 10
< 1
> 0.5
*2*3
10 to 11
0.1 to 1.0 *2
< 1500
23