Retrofitting The Transducer Tube; Initial Operation - Buhler NS Serie Guía Rápida

NS xx/xx-AM, HD-NS xx-AM
Contact protective circuits for reed switches
For direct current voltage a recovery diode per figure A must
be connected parallel to the contact.
For alternating current voltage an RC circuit per Figure B and
Table 1 must be connected parallel to the contact.
A
Contact
Load
Recovery diode
Load in VA 10
Voltage at R/Ohm C/µF
contact V
24 22 0.022
60 120 0.0047
110 470 0.001
230 470 0.001
Please note the max. voltage/load ratings of the respective
level contacts!
Voltages and currents
All Bühler level contacts with reed switch can switch minimal
Switching voltages of 10 µV and minimal switching currents
of 1 µA.
The maximum values specified for the respective contact
types apply.
Level contact with reed switches can therefore be used for SPS
applications as well as for high loads (within the maximum
limits) without hesitation.
Contact material
All reed switches in Bühler level contacts use rhodium as the
contact material for the actual contact areas.
Magnetic fields
Avoid external magnetic fields, including from electric mo-
tors. These can interfere with the function of the reed
switches.
Mechanical loads
Do not expose the level switch to strong blows or bending.
4.4 Level Switch With Transducer Tube (4 – 20 mA
Output or IO-Link)
If the level switch is equipped with BLT transducer tube for
continuous liquid level monitoring, the solenoid switches can
only be installed on the left side of the indicator scale. The
transducer is factory set (4 mA = tank empty; 20 mA = tank
full) and must not be changed.

4.5 Retrofitting the transducer tube

The BLT transducer tube can be retrofit. In this case the solen-
oid contacts must be installed left of the indicator scale.
8 Bühler Technologies GmbH
B
Contact
RC circuit
25 50
R/Ohm C/µF R/Ohm C/µF
1 0.1 1
22 0.022 1
120 0.0047 22 0.022
470 0.001 120 0.0047
The transducer tube contains a reed chain with 5 or 10 mm
resolution and clips to the right side of the indicator. The con-
nector must be at the bottom. The transducer tube must
touch the level switch along the entire length.
Please refer to the appendix for the connector wiring dia-
gram.
Load
0.47
0.1
Transducer tube
5 Operation and control
NOTICE
The device must not be operated beyond its specifications.

5.1 Initial operation

For initial operation level switch operation on a pressurised
tank:
• ALWAYS FIRST SLOWLY open the top valve.
• Wait for the pressure to equalise.
• Now open the bottom valve.
This will prevent the float from shooting up to the top of the
tube at a high speed and under high pressure and from being
damaged.
5.2 Bleeding
If the level switch has a bleeder valve, proceed as follows to
bleed:
• Loosen the bleeder screw approx. 1 turn.
NOTICE
Never unscrew the bleeder screw all the way. Forcing the
bleeder screw to turn can damage it and pieces from it may
render the level switch inoperable.
• Allow air to bleed until liquid comes out. Collect the liquid
and dispose according to local regulations.
• Tighten the screw.
6 Maintenance
Always observe the applicable safety- and operating regula-
tions when performing any type of maintenance. Please refer
to the original operator's manual on the included CD or online
at www.buehler-technologies.com for maintenance informa-
tion.
M12 connector
BX200001 ◦ 08/2020