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4.2 Operational sequence
The steam humidifier is switched on by
pressing the control switch on the front panel
to the „I“ position. When a demand for humid-
ification is signalled by a hygrostat, a humid-
ity sensor or an external controller
(depending on the implementation), the inlet
solenoid valve (25)
*
opens and water is fed
into the steam cylinder.
Filling level in the cylinder is controlled by a
level control device (27)
*)
. In a plastic cylin-
der, connected to the steam cylinder via
hoses in the way communicating tubes are
connected, a sensor for continous propor-
tional water level survey is located.
The cylinder water is periodically blown
down. For usage of the unit with fully desain-
ated water, the blow-down function may be
blocked.
Water blow-down is achieved by means of
the blow-down pump (32)
*)
that is continously
monitored during unit operation. In case of
pump disruption, the HygroMatik steam
humidifier is shut off.
With normal water quality, blow-down loss is
in the range of 7 to 15% of the steam amount
produced. Depending on water quality, a full
steam cylinder blow-down is run every 3 to 8
days.
Mineral deposits settle in the open area
below the heater element(s) and are
removed through periodic maintenance. The
blow-down pump itself has wide openings
and can flush out smaller pieces of mineral
deposit. This extends the service life of the
unit and reduces the required maintenance
interval.
On blow-down, water flows from the pump
into the drain hose system.
For maintainence purposes, the cylinder
water may be pumped out by pressing and
holding the control switch in the „II“ position.
*)
numbers indicated correspond with those
in the exploded view in the „Exploded view“
chapter.
4.3 Internal Output Setting
4.3.1 Continous control
for units with 1...3 heater elements
Continuous control is achieved by propor-
tional driving (pulse width modulation) of the
heater elements. In this way the humidifier
can be proportionally operated across the
entire output range of 5% - 100% of the nomi-
nal capacity.
4.3.2 Combination of 1-step swit-
ching and continous control
for units with 6 heater elements
If the humidifier features more than 3 heater
elements, service provision is accomplished
in 2 steps. As long as a certain threshold is
not reached, the heating power demanded is
delivered exclusively via the solid state relay
and 3 heater elements by using continous
control (stage 1). If the output power demand
exceeds the power available in stage 1, 3
more heater elements are additionally
switched on in a 1-step mode (stage 2). The
power demand beyond what is available in
stage 2 is then covered in stage 1 by the
solid state relay driven in proportional mode.
4.4 Mechanical Construction
The StandardLine heater steam humidifiers
are designed for wall mounting.
