Viessmann Vitomax HS M73 Operating And Service Instructions page 17

Shutdown
(cont.)
Sodium sulphite excess
Type of fill water for steam
boilers
Low salt content, fully desali-
nated or condensate
Saline, e.g. softened water or
boiler water
Tab. 15
!
Please note
Film forming amines can cause damage to the
boiler.
Do not use film forming amines.
Preservation through physical-technical measures
The following physical-technical procedures can also
be used for preservation:
■ Maintain a positive steam pressure in the steam or
hot water boiler
■ Flow preservation of steam boilers
Preserving individual areas of a multi boiler sys-
tem
The relevant individual boilers are kept at temperature
by pumping boiler water from the rest of the boiler sys-
tem through them.
Corrosion protection on the entire boiler shell
A fully filled boiler shell is maintained at a pressure of
0.1 to 0.2 bar using nitrogen, specifically nitrogen 5.0.
!
Please note
Frost may cause damage to the boiler.
Do not use wet preservation if there is a risk of
frost!
*1
!
Please note
Do not use layer-forming monoamines.
The use of film-forming polyamines must be
agreed with and approved by the boiler manu-
facturer.
Recommendation
Agree the steps for the preservation of the water side
with the manufacturer of the preserving agent.
See the "Using antifreeze in boilers" chapter in the technical guide
*1
Idle time Sodium sulphite concentra-
tion Na
1 week
1 month
1 month
>
1 week
1 week
>
Shutdown and preservation
Additional sodium sulphite
So in preserving
Desiccated
2 3
solution
mg/l
20 - 50
100 - 200 100 - 200
200 - 500 200 - 500
40 - 100 40 - 100
400 - 1000 400 - 1000
Applicable regulations:
■ For draining preserving solutions:
Observe conditions for draining waste water into
sewer systems or the main discharge system.
For the use of preserving agents:
■
Observe working instructions and safety datasheets
supplied by the product manufacturer.
Applicable regulations
Draining preserving solutions
■ Conditions for draining waste water into sewer sys-
tems or the main discharge system
Use of preserving agents
Working instructions and safety datasheets supplied
■
by the product manufacturer
Treating the flue gas side
1. Clean the heating surfaces on the flue gas side.
Maintain the alkaline balance of the water used for
cleaning at pH 8 to 9, or, in the case of ammonia,
pH 10.
2. Dry the heating surfaces on the flue gas side (allow
normal air flow).
3. Accelerate the ventilation process by means of a
fan heater. If necessary, open the flue gas shut-off
dampers, then close them again.
4. Spray preserving oil, e.g. graphite or varnish, onto
the flame tube walls and hot gas flues, or apply it
with a brush.
5. Keep the boiler door(s) open. Keep the boiler sur-
faces dry during idle periods.
6. Apply a desiccant (silica gel).
7. Use a dryer with a fan.
Crystallised
3 3
g/m g/m
20 - 50 40 - 100
200 - 400
500 - 1000
80 - 100
800 - 2000
17