The Use Of Softenend Water For The Operation Of The Nordmann At4 D - Nordmann AT4 D Service Manual

5.2

The use of softenend water for the operation of the Nordmann AT4 D

SC pump system from Nordmann Engineering
The SC system prevents the deposit of lime at solid surfaces and supports
the formation of fine-grained particles by the following effects:
– enrichment of the water with carbon dioxide by supply of air into the
steam cylinder. The increased portion of carbonic acid permits an im-
proved solution of calcium ions.
– the swirling of water leads to increased molecular mobility. Lime pre-
cipitated during the warming up process is kept floating thus reducing
the lime accumulation on surfaces.
– the agitation of the water favours the formation of small lime particles
and prevents the deposits of lime wafers.
During operation the lime particles are flushed out of the steam cylinder
with the regular draining cycles. Therefore, the water drain line should be
generously dimensioned when using the SC system to prevent clogging.
The siphon in the drain line should be freely accessible to facilitate cleaning
since increased lime deposits could occur.
The use of softened water is not recommended for Nordmann AT4 D. Instead
of the expected cylinder service interval increase, most likely functioning
problems will appear.
By the softening process, the Calcium and Magnesium ions representing the
hardness of the water are replaced by sodium ions. Due to the evaporation of
the water, the content of the sodium ions increases and the sodium chloride
will be dissolved at the boiling temperature of 100 °C in form of sludge. The
sludge at the bottom of the cylinder clogs the outlet of the cylinder and stops
the automatic drainage of the water. Finally, foam and sparks will appear in
the cylinder. The result will be completely defective electrodes.
Instruction for the use of softened water
1. The hardness of the raw tap water must be below 500 ppm per litre.
2. The conductivity must be below 800 μS/cm.
3. Never use completely softened water! The softened water must be mixed
with raw tap water to get either a hardness above 150 ppm per litre or
not less than 1/3 of the raw tap water hardness.
4. Sodium salt concentration may be very high during start up or recreation
cycle of a water softener. Therefore a constant flow of softened water
is required and this may not be possible if the water softener is only
designed for the steam generator.
5. Resulting pH-value must be between 7.0 and 8.0. Higher pH-value may
be the reason for foam.
6. Water softener salt must be from good quality. Low cost products will
have a negative impact of the work performance.
7. Check correct cylinder (see operating instructions Nordmann AT4 D)
settings.
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