Flowserve NRG 21-11 - Manual (Page 7)

7
English
Purpose
Used in conjunction with GESTRA
electronic control units for continuous level
monitoring of vessels containing liquids or
granular products not prone to form
deposits.
Avoid subjecting level probe to shocks as
these might cause damage to the electrode
seal. The PTFE tubing of the electrode
must not be damaged.
Design
Screwed connection 1½" BSP (to DIN 228),
PN 6
Installation (see Fig. 1 and 2)
The level probe must be installed vertically.
Make sure not to insulate the probe body
above the hexagonal part.
NRG 21-11
From a length
> 300 mm, the probe has to
be installed vertically.
Use ring joint supplied with the probe and
screw probe with ring joint into the vessel
and tighten. Tapped hole acc. to DIN 3825,
part 2, screwed 1½" BSP (DIN 228),
form X, standard version (
∅ of hole for
probe: 44 mm)
NRG 21-51
Guiding of weight in axial direction
In strongly agitated products an additional
guidance of measuring probe and weight in
axial direction is necessary. This can for
instance be effected with a protection tube
provided with vent holes.
If the product is only slightly agitated, it is
sufficient to attach the weight at the vessel
bottom.
Wiring and Adjustment
(see Fig. 3 and 4)
The probe is not ready for operation
unless the preamplifier housed in the
terminal box has been adjusted to suit
the operating conditions of your
installation. Before commissioning the
probe ascertain the control range for the
application in question and the electrical
conductivity of the medium to be
monitored.
Step 1
Undo screw of terminal box and
unplug terminal box from level probe
(fig. 3). Unscrew PG cable gland and
open the transparent lid of the terminal
box. The terminal strip and the
preamplifier PCB with code switch are
now accessible. Effect wiring in accordance
with wiring diagram, fig. 4, and re-attach
PG cable gland . Note that screened
four-conductor cable is required for wiring
to the probe, e. g. I-Y(St)Y 2 x 2 x 0.8 or
LIYCY 4 x 0.5 mm
2 . The position of the
cable entry can be modified by max. 270 °.
Proceed as follows: Insert a screwdriver
with a 3 mm blade into the opening
and lever out plug plate . Select the
required direction, and reinsert plate.
Step 2
Plug terminal box onto level probe. The
individual switches 1 to 6 of the code
switch are set at our works so that the
control range (fig. 1 and 2) for water
(conductivity
> 20 µS/cm) is activated.
The control range corresponds to
dimension H (fig. 1 + 2). Before
commissioning, determine the utilized
measuring range, e. g. from min. level (LW)
to max. level (HW). Measure the distance
between the highest measuring point
(e. g. HW) and the lower limit of the control
range H . Determine the type of fluid to
be monitored and refer to charts 1, 2 or 3
for the required setting of the code
switches.
5
H
D
J
I
F
H
G
E D
D
Note
F
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