Nordmann AT4 Operating Instructions Manual page 12

Upon reaching the requested steam capacity, the inlet valve closes. If the
steam generation decreases below a certain percentage of the required
capacity, due to lowering of the water level (e.g. because of the evapora­
tion process or drainage), the inlet valve opens until the required capacity
is available again.
If the required steam capacity is lower than the actual output, the inlet valve
is closed until the desired capacity is achieved by lowering of the water level
(evaporation process).
Level monitoring
A sensor provided in the steam cylinder cover detects when the water level
gets too high. The moment the sensor comes in contact with water, the
inlet valve closes.
Drainage
As a result of the evaporation process, the conductivity of the water increases
due to an escalating mineral concentration. Eventually, an inadmissibly high
current consumption would take place if this concentration process were
permitted to continue. To prevent this concentration from reaching a value,
unsuitably high for the operation, a certain amount of water is perio dically
drained from the cylinder and replaced by fresh water.
Lime management
The interval controlled SC pump blows air into the steam cylinder. Thus
keeping the solved minerals in the water in motion as a result they are
discharged with the automatic drain cycles.
Control
The steam production can be controlled with the internal or an external
continuous controller or an external humidistat (24 VDC On/Off control).
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