Process, design, explosion protection in the inner chamber and safety devices
Figure 1/3: Process diagram and explosion protection
1/PE AC, 230 V
C
A
H
B
M
E
F
I
Mat.
Primary ex. protection
Secondary
ex. protection
I
Ventilation fail-safety device
E - Electr. switchbox
M - Flow monitor
C - Exhaust-air connector I - Inner comp
F - Fresh air
B - Blower
H - Heating register
A - Air duct
The blower (B) draws fresh air (F) in from a neutral area. The fresh air is heated by the heating
register (H) and is passed into the inner chamber of the unit (I) via an air duct (A).
The baffles in the inner chamber distribute the heated fresh air which, together with the vapors
released during the heat treatment, is subsequently discharged from the exhaust-air connector
(C) as vapor/air mixture.
The operating temperature is controlled by an electronic controller (in E).
The controller can be used to set the operating temperature in the inner chamber up to 105 °C (T
3) or 70 °C (T 4), depending on the articles or materials undergoing heat treatment.
A seond temperature controller has provided to prevent overheating of the treated articles
(material protection).
As we can assume that
dangerous, potentially explosive mixtures
may be produced
occasionally during the heat treatment process,
supplementary explosion protection
measures
have been
implemented in the inner chamber
of the unit (also refer to the chapter
on safety devices).
Safety devices
Explosion protection
The unit design rules out potential ignition sources, high surface temperatures and ignition
resulting from arcing.
Prevention of dangerously high surface temperatures:
The heating system is rinsed with fresh air during operation and in the event of a fault and is
therefore neutralized. The unit has been dimensioned in such a way that the surface
temperatures in the inner chamber and the nearest baffles in the labyrinth will
not exceed
the
respective
temperature limit
(80 % of the ignition temperature) for the set solvent temperature
class.
The
heating temperature
and the associated
surface temperatures
are
self-limiting
.
The
power switchover
for the heat treatment of combustible solvents between temperature
class
T 1, T 2, T 3
or
T 4
must be made
consciously
by means of a
key-operated selector
switch
.
3
UNIT SPECIFICATION
50 043 136
15/25
