Level Switch - Buhler Multiterminal Guía Rápida

Multiterminal
5.2 Sampling
To ensure the fluid still has its original performance charac-
teristics and is still suitable for all workloads, regularly
sampling the fluid for analysis is advisable. The location of the
sample in the circuit does not affect the composition of the
fluid. The multiterminal therefore has two sampling loca-
tions: In addition to sampling from the tank, the fluid can also
be sampled from the return flow.
Both sampling locations have at least two connecting bores.
The sampling ports must be selected to always be easy to ac-
cess. Please refer to the drawing in chapter "Product descrip-
tion" for the location of the sampling ports.
5.2.1 Sampling From the Tank
When sampling from the oil tank, it can empirically be as-
sumed the sample will be the representative average oil qual-
ity.
Depending on the configuration, the sampling port will be
equipped with quick-release couplers or Minimess couplers. A
hand pump with the corresponding mating component for
coupling is required for sampling.
When using the Minimess coupler, we recommend modifying
the coupler on the pump with a transverse slot. This increases
the suction cross-section to make pumping down consider-
ably easier.
The sampling point is fixed based on the immersion depth of
the terminal, ruling out any depth-related measuring errors.
Be sure the instruments and the sample bottle are clean to en-
sure reliable sampling.
5.2.2 Sampling From The Return Filter
To obtain additional information about the condition of the
oil it can be helpful to also analyse the unmixed oil from the
return flow. The return filter housing has two bores for this
purpose for attaching a Minimess coupler.
Since the return line is in part pressurised, a hand pump is not
required for sampling. In this case the Minimess tube can be
used to directly draw into the sample bottle.
5.3 Return Filter
The purpose of filters in a hydraulic system is to reduce fluid
contamination due to particles to the necessary level and keep
it at a low level long-term during operation. The filtration sys-
tem cleans the oil to a level of purity which permits continu-
ing to use the oil. The contamination indicators are used to
monitor the filter capacity in oil circuits.
We recommend fixing a tag to the filter housing. This ensures
the warning "no element installed" is clearly visible to the
user. Accidentally using the system without filter can then be
avoided.
5.3.1 Contamination Indicator VSA 24-S
A microprocessor-controlled pressure sensor monitors the dy-
namic pressure upstream from the filter element which in-
creases as the filter contamination increases, or the pressure
drop above the filter element. The contamination indicator
sends an alert when the remaining filter capacity is about
25%. When the filter is fully depleted, the device will emit an-
other alarm so the system can be switched off.
8 Bühler Technologies GmbH
For more information about the function of the VSA 24 con-
tamination indicator, please refer to the separate operating
and installation instructions included.
5.3.2 Contamination Indicator PIS 3085
This indicator responds to the back pressure upstream from
the filter element. Back pressure can increase due to the oil
viscosity (cold start) or a dirty filter element and can only be
measured when oil flows back into the tank. When a certain
pressure level is exceeded, a red button pops out and the elec-
trical switching signal is activated. When this signal deactiv-
ates again with oil flowing and the red button can be pushed
in again, the alert was caused by cold oil or excessive volume.
If the switching signal persists and the red button straight
away pops out again after being pushed in, the filter element
needs to be changed at the end of the shift.
5.3.3 Without Contamination Indicator
During normal use, the alert "Filter element installed on..."
along with the date indicates the ordinary state. This prevents
changing an element before the installed filter element is de-
pleted
5.4 Filling
5.4.1 Manual Filling
There are two types of connections for filling:
A Stäubli receptacle and a Walther coupler. Oil can be added
manually via these ports.
82
64.5
14
Stäubli SBA 11/CN (receptacle)
5.4.2 Filling Control Via 2/2-Way Pilot Valve
The filling control is used for automatic tank filling.
If the level switch indicates a low liquid level, the valve opens
and oil is added. If the level switch indicates the operating
level is reached, the valve closes and filling stops.
If the liquid level continues to drop due to automatic filler fail-
ure, the level switch with emits an alarm at the minimum
level. The system can then be switched off to prevent damage.
For more information about the 2/2-way pilot valve, please
refer to the Flutec documentation.

5.5 Level Switch

The following level switches are available for the multiter-
minal:
• NV 77 / NV 77D
• NV 74 / NV 74D
• NV 73
• NV 71
For more information about the installed level switch, please
refer to the included operating and installation information
for the level switch.
82 20
Walther MD-012 (coupler)
BX100012 ◦ 06/2021