Unical BAHR'UNO, Instructions On Installation, Use And Maintenance

19

Installation instructions

3.6 - WATER FEATURES

The generator must be fed with water of 

quality complying with the requirements set 

out in this paragraph.

It must also be ensured that the feed water 

and the system water cannot be polluted 

by harmful substances (e.g. oil, grease, sea 

water).

Standard of reference UNI EN 12953-10 or 

UNI 7550.

Most of the waters are not suitable at source for use as feed 

water of a steam generator. The type of feed water treatment 

depends on the features of the water at source. Its features vary, 

so regular checks of the chemical composition are required.

The water supply pipe, downstream of the chemical treatment, 

must be fitted with a meter in order to detect the flow rate of the 

top-up water added to the return condensate water; this also 

allows direct control of the amount of steam intake.

It is appropriate to recover as much condensate water in the 

supply tank as possible.

The condensate water must eventually be treated so as to meet the 

requirements indicated for the generator feed water (as per table 1).

On the basis of these requirements, including those needed for 

feed water (as per table 2), it is necessary that, depending on the 

features at source and on the top-up flow rate, a water treatment 

system be installed and allow binders to be added for oxygen 

(possibly stabilisers for residue hardness, for alkalinisation or 

phosphates) in the feed water tank or in its flow pipe.

These requirements should be checked by means of suitable 

equipment and, if possible, easy to use every 24 or 72 hours, 

depending on the operating mode, or according to local regulations. 

Record  the  measured  values,  the  top-up  water  flow  rate,  the 

consumption of chemicals and the necessary maintenance 

operations in the instruction manual, in order to be able to 

always go back to the operating conditions.

WARNING

Do not put water with a temperature below 60°C in the generator.

It is recommended to put feed water with an average temperature of 80°C in the generator.

ATTENTION!

Damages caused by external agents (limescale, oxygen, acid attacks, etc.) are not covered 

by the warranty.

Below are the quality requirements for the feed water and for the operating water according 

to the European Standard EN 12953-10 (tables 1-2) and indications on the frequency of the 

analyses (tables 3-4)

Table 1

FEED WATER FOR STEAM GENERATORS

Parameters

Unit

Feed water

Operating pressure

bar

0.5 - 20

> 20

Appearance

Clear, free from solid suspensions without persistent foam

pH

 a,b

8.7 - 9.2

 c

8.7 - 9.2

 c

Total hardness

ppm CaCO

3 

(°F)

< 1 (<1)

< 1 (<1)

Iron

ppm Fe

< 0.1

< 0.05

Copper

ppm CU

< 0.05

< 0.03

Oxygen

ppm O

2

< 0.05

 d

< 0.02

 d

Oils - greases

ppm

< 1

< 1

Organic substances

Not enough to cause traces, foams or other problems

a. for boilers fed with water with conductivity less than 30 pSicm use 

of Na or K hydroxides is allowed only if the recommended pH range 

cannot be obtained with the exclusive use of sodium phosphate;

b. for systems where there is no copper or its alloys, the feed water pH 

must be higher than 9.2 ;

c.  with water softened to pH > 7, it is necessary to respect the pH range 

indicated for boiler waters; when operating without a degasser an ex-

cess of deoxygenating agent must be guaranteed;

d. the excess value to be guaranteed must be indicated by the supplier 

of the additives used for chemical conditioning.