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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. If the safety chain is
closed, the inlet multiple solenoid valve (twin
solenoid valve (25)
*)
in case of FLPxx-T and
FLPxx-TSPA units, 4-fold solenoid valve
(71)
*)
with FLPxx-TPRO units)
*
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 deselin-
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
Continuous control is achieved by propor-
tional driving (pulse width modulation) of the
heater elements via one or both solid state
relays. In this way the humidifier can be pro-
portionally operated across the entire output
range of 5% - 100% of the nominal capacity.
A power setting of 0% to 5% of the nominal
output is possible, but not technically feasible
due to condensate losses in the steam line.
If the unit is equipped with more than 3
heater elements, the output power provision
is accomplished in 2 stages. As long as a
certain threshold was not reached, the heat-
ing power necessary is solely controlled via
the solid state relays and the 3 heater ele-
ments in a propotional manner (stage 1). If
the output power requested lies beyond what
is available in stage 1, three additional heater
elements are activated via a main contactor
in a one-step operation mode (stage 2). Any
power requirement in excess of the stage 2
rating is then proportionally supplied via the
solid state relays by the stage 1 operational
mode.
4.4 Mechanical Construction
The type of housing is designed for wall
mounting. The steam cylinder is made from
stainless steel. Depending on the power out-
put range, one, three or six heater elements
are encorporated.
4.4.1 FlexLine Plus
Freshwater supply is accomplished by
means of a twin solenoid valve that is also
used for the SuperFlush functionality.
4.4.2 FlexLine Process
The units featuring the TPRO-control allow
the exceedingly precise steam control via a
fourfold solenoid valve. For this to work, the
use of fully demineralized water is manda-
tory.
