Boeters Ketel Constructie B.V.


Voor het in bedrijf stellen dient de waterkwaliteit aan de onderstaande norm te voldoen!

The waterquality should meet these standards, noted below, before operating!

Table 5-1: Feedwater for steam boilers (except attemperator spray water) and hot water boilers.

Parameter Unit Feedwater for steam boilers

Make-up water for hot waterboilers

Operating pressure

bar (= 0,1 MPa)

> 0,5 to 20 > 20 total range
Appearance -

clear, free from suspended solids

Direct conductivity at 25° C µS/cm

not specified, only guide values relevant for boiler water see table 5-2

pH value at 25° Ca - > 9.2 b > 9.2 b > 7,0
Total hardness (Ca + Mg) mmol/l < 0,01c < 0,01 < 0,05
Iron (Fe) concentration mg/l < 0,3 < 0,1 < 0,2
Copper (Cu) concentration mg/l < 0,05 < 0,03 < 0,1
Silica (SiO2) concentration mg/l not specified, only guide values for boiler water relevant, see table 5-2 -
Oxygen (O2) concentration mg/l < 0,05 d < 0,02 -
Oil/grease concentration (see EN 12953-6) mg/l < 1 < 1 < 1
Organic substances (as TOC) concentration - See footnote e
a With copper alloys in the system the pH value shall be maintained in the range 8,7 to 9,2.
b With softened water pH value > 7,0 the pH value of boiler water according to table 5-2 should be considered.
c At operating pressure < 1 bar total hardness max. 0,05 mmol/l shall be acceptable.
d Instead of observing this value at intermittent operation or operation without deaerator if film 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 the behaviour of their individual components under the conditions of boiler operation are difficult to predict. Organic substances may be decomposed to form carbonic acid or other acidic decomposition products with 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.
Table 5-2: boiler water for steam boilers and hot water boilers. 
Parameter Unit Boiler water for steam boilers using

Boiler water for hot waterboilers

Feedwater direct conductivity > 30 µS/cm Feedwater direct conductivity ≤ 30 µS/cm
Operating pressure

bar (= 0,1 MPa)

> 0,5 to 20 > 20 > 0,5 total range
Appearance -

Clear, no stable foam

Direct conductivity at 25°C µS/cm < 6 000 a see fig. 5-1a < 1 500 < 1 500
pH value at 25° C - 10,5 to 12,0 10,5 to 11,8 10,0 to 11,0 b, c 9,0 to 11,5 d
Composite alkalinity mmol/l 1 to 15 a 1 to 10 a 0,1 to 1,0 c < 5
Silica (SiO2) concentration mg/l pressure dependent, according to figure 5-2 -
Phosphate (PO4) e mg/l 10 to 30 10 to 30 6 to 15 -
Organic substances - See footnote f
a With superheater consider 50% of the indicated upper value as maximum value.
b Basic pH adjustment by injection NA3PO4, additional NaOH injection only if the pH value is < 10.
c If the acid conductivity of the boiler feedwater is < 0,2 µS/cm, and its Na + K concentration is < 0,010 mg/l., phosphate injection is not necessary. Under the conditions AVT (all volatile treatment, feedwater pH ≥ 9,2 and boiler water pH ≥ 8,0) can be applied, in this case the acid conductivity of the boiler water is < 5 µS/cm.
d If non-ferrous materials are present in the system, e.g. aluminium, they may require lower pH value and direct conductivity, however, the protection of the boiler has priority.
e If coordinated phosphate treatment is used: considering all other values higher PO4 -concentrations are acceptable (see also clause 4).
f Seee in table 5-1.
According NEN/EN12953-10:2003.



We hebben de afgelopen tijd een paar keer problemen gehad met de aangeleverde waterkwaliteit voor het afvullen van onze nieuw geleverde ketels. Vanwege dit probleem, waar nogal eens gemakkelijk over wordt gedacht, zoals is gebleken, hebben wij stickers laten maken met bovenstaande tekst. Hierop staan de NEN-eisen waaraan het water moet voldoen. Wij zullen deze stickers in het vervolg op onze nieuwe ketels plakken. De verantwoording ligt uiteraard bij de waterleverancier. Wij hopen u hiermee voldoende te hebben geďnformeerd, voor verdere vragen kunt u uiteraard altijd bij ons terecht. Hier kunt u eventueel ook de tekst downloaden in PDF.

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