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Viscosity Process Analyzer VISC-4
Safety
2.5.2
Control box (Ex p)
Figure 2.2: Control box (front view)
Figure 2.3: Control box key switch
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The control box (Ex p) contains operating equipment without its own igni-
tion protection type and therefore contains potential ignition sources.
Explosion protection is provided for the control box by the pressurization type
of protection (Ex p).
To prevent potentially explosive atmospheres from entering, overpressure is
created with the aid of instrument air in the interior of the control box. The
overpressure is monitored by a pressure monitor. The housing protects
against contact and foreign bodies as well as against splash water.
Even after switching off the voltage supply, components on the
inside can still have electrical charges or high temperatures which form po-
tential ignition sources.
The key switch is used to switch pressure monitoring in the control box on and
off.
To switch on the pressure monitor on:
Close the door of the control box.
Turn the key anticlockwise to its stop limit (see figure). Pull the key out.
The control box pressure monitor is switched on. This provides explosion pro-
tection only in this operating mode.
If the pressure inside the control box drops below a specified threshold value,
the pressure monitor switches off the voltage supply for the analyzer.
You will find more information on the pressure monitoring in
i
the manual for the APEX pressurization system.
Make sure that only responsible persons have access to the key.
NOTICE
04/2016
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