Viessmann Vitomax HS M73 Operating And Service Instructions page 20

Water quality
Saline boiler feedwater requirements
Permissible operating pressure
General requirements
pH value at 25 °C
Conductivity at 25 °C
2+
Total alkaline earths (Ca
Oxygen (O )
2
Bound carbon dioxide (CO
Iron (Fe), total
Copper (Cu), total
Oxidability (Mn VII Mn II) as
→
KMnO
4
Oil, grease
Tab. 17
Organic substances
In general, organic substances are mixtures of differ-
ent compounds. The constitution of such mixtures and
the characteristics of their components when subjected
to boiler operating conditions are hard to predict.
Organic substances may break down into carbonic
acid or other acid products. These increase conductiv-
ity and cause corrosion and deposits.
Boiler water requirements
Feedwater conductivity
Permissible operating pressure
General requirements
pH value at 25 °C
Acid capacity (K )
S 8.2
Conductivity at 25 °C
Phosphate (PO )
4
Silicic acid (SiO ) *4
4
Tab. 18
Detailed information
EN 12953-10
*2 Demineralised water with mixed bed quality (conductivity < 0.2
alternative, AVT operation may be applied. Conditioning with volatile alkalising agents: pH value of feedwater pH
pH value of boiler water pH
be < 5 S/cm.
µ
*3 Standard pH value setting: Injection of Na
*4 If allowance is made for all other values, higher PO
for example, to compensated or coordinated phosphate treatment (see section "Conditioning").
20
bar
S/cm
µ
mmol/ l
2+
+ Mg )
mg/l
) mg/l
2
mg/l
mg/l
mg/l
mg/l
bar
mmol/l
S/cm
µ
mg/l
mg/l
8.0. In such cases, the conductivity downstream of a severely acidic cation exchanger must
≥
PO , additional injection of Na OH (if the pH value < 10)
3 4
concentrations are permissible when using phosphate. This applies,
4
0.5 PS 20
≤ ≤
Colourless, clear, free of undissolved substances
>
Only standard values applicable to boiler water
< 0.01
< 0.05
< 25
< 0.2
< 0.05
< 10
< 1
They can also lead to the formation of foam and
deposits, which must be kept to a minimum. The TOC
content (Total Organic Carbon) should also be kept to
a minimum.
30 S/cm
> µ
0.5 PS 20 PS
≤ ≤
Colourless, clear, free of undissolved substances
10.5 to 12 10.5 to 11.8
1 to 12 1 to 10
< 6000 See Fig. 2
10 to 20
Pressure-dependent, see Fig. 2 & 3
S/cm) may be used without a phosphate injection. As an
µ
PS 20
>
9
< 0.02
< 0.1
< 0.01
30 S/cm
≤ µ
20 PS 0.5
> >
10 to 11 *2*3
0.1 to 1.0 *2
< 1500
6 to 15
9.2 and
≥