GOK GWS 904 Instructions De Montage Et De D'utilisation page 38

The controller on the road tanker or another signalling unit must be outside the potentially
explosive area.
The measuring circuit for the
positive temperature coefficient
(PTC) thermistor is designed as
ignition protection type intrinsically
safe and may only be connected to
a certified intrinsically safe electric
circuit with the maximum values
specified here:
In a fixed installation of the connection line, the intrinsically safe electric circuit must be kept
separate from other electric circuits. Regarding tanks designed for storing inflammable liquids,
the connection lines must be inserted into the dome shaft in a gastight manner (see
"Assembly for dome shafts").
Since part of the intrinsically safe electric circuit is installed in zone 0, the intrinsically safe
electric circuit must be connected to the potential equalization system using the earthing lugs
of the safety barrier with the shortest possible route. This requirement also holds true for the
limit indicator design with connector, wall fitting 905. This requirement generally is complied
with regarding limit indicator designs with pipe fitting in connection with the controller on the
road tanker.
Within the scope of testing before initial start-up and recurring tests by qualified persons
according to the German Ordinance on Industrial Safety and Health (BetrSichV), the limit
indicator must be subjected to a FUNCTION CHECK.
Attention is drawn to the joint requirements for a system requiring supervision according to
Section 3 BetrSichV for inflammable category 1 to 3 liquids. Within the framework of the
recurring pressure tests, the limit indicator must not be connected to the controller on the road
tanker.
Installation of the limit indicator to the tank
The following must be observed when installing the limit indicator
• The probe tube of the limit indicator may not be cut to length or bent in any case. The cable
inside the probe tube may be damaged otherwise.
 Install the limit indicator with a suitable probe length.
• The limit indicator, the probe tube or the sensor may not be covered inside the tank, i.e.
installation in a protective or calibration tube not admissible.
 At level L , contact between medium and sensor could be impossible.
1
• The sensor may not make contact with the operating medium splashing from the filling tube,
which would cause the filler valve on the road tanker to be closed prematurely. If the filling
tube is arranged in the lower third of the tank, the sensor being wetted prematurely can be
ruled out.
• Always install the limit indicator in a perpendicular position.
• The operating medium may not have any corrosive or chemical effect on the sensor, the
sensor cover and the probe tube.
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Limit indicator GWG - type GWS -issue 2
nominal voltage U
o
nominal current I
K
nominal power P
effective inner capacity C
effective inner inductance L
maximum value with no risk for
intrinsic safety U
m
max. 19.4VDC
max. DC 150mA
max. 600mW
negligible
i
negligible
i
max. 24V
Part No. 15 382 65