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2 Description
At the Preamplifier Online Monitor 97211 the amplification factor has to be adjusted to
get an optimum signal for correct interpretation at the Loctite controller. Before each new
start of a dispensing cycle, the controller generates a ready signal or fault signal. This
happens at the end of each dispensing cycle.
In case of failure of the sensor, no measuring signal corresponding to the reference
measurement can be generated. For this reason, whenever a failure occurs, the system
will always generate a fault signal at the end of the dispensing cycle. Therefore the
complete system is fail-safe if linked to a Loctite controller, i.e. even in case of partial or
complete failure no dispensing cycle will pass unchecked.
The type sensors used in the system are absolute pressure sensors. Variations in
atmospheric pressure such as they may result from weather conditions will affect
measurements in a slight but negligible degree. Temperature fluctuations have an effect
on viscosity and consequently on product dispensing where pressure reservoir/valve
systems are used.
The integrated flow monitor of the Loctite controller recognizes the consequences of
these influencing factors, such as changes in the quantity of material dispensed.
To achieve absolutely constant dispensing results would actually require adapting the
dispense pressure to the temperature and thus to the viscosity. In the field, these
variations in quantity due to temperature fluctuations can mostly be tolerated.
However, if the dispensing result deviates too much from the desired bead configuration
due to major temperature variations, the displayed error rate will increase, and the
dispensing pressure will have to be adapted by authorized personnel. In this case a new
reference measurement has to be made.
Therefore, a seasonal check and, if required, adaptation of settings may be advisable.
In summary it should be noted that a new system reference measurement is only
required, if error rates are too high to be accepted and after dispensing has been
checked and readjusted by authorized personnel. The fail-safe design ensures that no
inspection of the system at regular intervals has to be done.
Interpretation specifications:
– The sample rate is 1 kHz, (1000 measuring points per second).
– The minimum and maximum time of measurement are 0,03 and 15 seconds.