Hand-Held Applicators - Henkel Content Management System

Process Monitoring
The Loctite ® Flow Monitor, when integrated with an appropriate dispensing system, ensures reliable process monitoring.
This means that the Online Flow Monitor detects and evaluates malfunctions with respect to the quality and quantity of
dispensing. These malfunctions may include air bubbles or pressure changes in the dispensing system, lost or clogged
needles, or accidental needle-to-substrate contact.
Measuring Principle Illustration Item # IDH No.
Pressure based
Preamplifier 97211 215992
Dispensing valve 97138 1147046
Preamplifier 97512 1126901
Calorimetric
Dispensing valve 97830 1122415
Fluorescence Detector 98083E 664169
Theory of operation:
Two different measuring principles are used for online flow monitoring: The pressure based and the calorimetric method.
The pressure based system comprises a pressure sensor (with suitable pressure range), a Preamplifier and a Loctite ® controller. The electronic
evaluation system integrated into Loctite ® controller 97152 or 97153, combined with Preamplifier 97211, measures the pressure profile by means
of a pressure sensor built into the dispensing valve. This parameter is stored in the system and serves as a reference. The controller compares the
pressure profile that has been measured to the previously stored reference pattern, based on four different factors; dispensing time, integral of
pressure profile (equals the amount of product dispensed), length of the envelope curve for the pressure profile, and centre of gravity.
As long as the measured values are within a pre-defined tolerance range, the dispensing cycle is accepted, and the Ready signal is indicated
on the controller. If the deviation is outside the tolerance range, the dispense cycle is rejected and signalled as an error. This message is indicated on
the display of the controller and is made available as a signal to a higher-ranking controller.
Depending on the process environment conditions, appropriate tolerances can be adjusted to determine the optimum between a false alarm and a
reliable error recognition.
The calorimetric system is similar with respect to system integration and signal processing but is based on a different measuring method.
A miniaturised heating element placed in the product flow gets slightly heated, and the temperature difference in the flowing product is analysed.
This system is recommended in particular for flow monitoring of small dispensed amounts at low pressure settings. The signal strength delivered by
the pressure based method is too low for such applications and cannot be reliably processed.
Combined with a Loctite ® controller, both systems are fail safe because no dispensing cycle will pass unchecked.
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