11
Table 4
Feedwater Quality Requirements for best UNI-MATIC UM operation and preservation
(a)
with copper alloys in the system the pH value shall be maintained in the range be from 8.7 to 9.2
(b)
with softened water pH value
>
7.0 - see the manual of the boiler
(c)
If the operating pressure is
<
1 bar, the max total acceptable hardness should be 0.05 mmol / l
(d)
Instead of observing this value at intermitted operation or operation without deareator if forming agents and/or excess
of oxygen scavenger shall be used.
(e)
Organic substances are generally a mixture of several different compounds. The composition of such mixtures and
behaviour of their individual components under the conditions of boiler operation are difficul to predict.
Organic substances may be decomposed to form carbonic acid or other acidic decomposition products which increase the
acid conductivity and cause corrosion or deposits. They also may lead to foaming and/or priming which shall be kept as
low as possible.
PARAMETERS
UNIT
FEED WATER PROPERTIES
ACCORDING TO EN 12953
OPERATING PRESSURE (X)
bar (= 0,1 MPa)
0,5
<
X
<
20
X
>
20
APPEARANCE
/
Clean, free from suspended solids
DIRECT CONDUCTIVITY AT 25°C
μS/cm
Not specified
pH VALUE AT 25 °C (a)
/
>
9,2 (b)
>
9,2 (b)
TOTAL HARDNESS (Ca + Mg)
mmol/l
<
0,01 (c)
<
0,01
IRON (Fe) CONCENTRATION
mg/l
<
0,3
<
0,1
COPPER (Cu) CONCENTRATION
mg/l
<
0,05
<
0,03
SILICA (SiO
2
) CONCENTRATION
mg/l
Not specified
OXYGEN (O
2
) CONCENTRATION
mg/l
<
0,05 (d)
<
0,02
OIL/GREASE CONCENTRATION
(see EN 12953-6)
mg/l
<
1
<
1
ORGANIC SUBSTANCES CONCENTRATION
/
See footnote (e)
