Lasting accuracy for diaphragm seal systems for vacuum process

A diaphragm seal system in a vacuum process must master a significant challenge ? it must deliver a reliable measuring result, even when the pressure drops and the temperature rises simultaneously. The exemplory case of a chemical company producing phthalic anhydride (PA) shows that it is in no way self-evident that this requirement could be met on a consistent basis.
PA is primarily used as a plasticiser for plastics. However, it is also found in the production of synthetic resins and dyes. The plant operator obtains this compound via the catalytic oxidation of o-xylene in the gas phase, followed by a vacuum distillation process.
Critical phase for pressure measurement
In this technique, the critical phase for pressure measurement occurs in the distillation column. There, the process temperature can rise to a lot more than 230 �C while the pressure drops to 100 mbar abs. With this type of contrary action, the traditional installed measurement technology reaches its performance limit relatively quickly, which the aforementioned manufacturer was forced to find out ? all instrumentation showed a measurement deviation beyond your defined tolerance after only a fortnight.
Diaphragm seal system adapted in every elements to the vacuum process
The diaphragm seal system is tailored exactly to the conditions of the vacuum process and tested under application conditions.
Consequently, the business approached WIKA with the request for a measuring solution that would also fulfil its task with the required accuracy in the long run under the conditions described. WIKA then drew on Billion -depth expertise to create a diaphragm seal system for the vacuum process, consisting of a process transmitter (model IPT-20), a flange-type diaphragm seal with flush diaphragm (model 990.27) and a capillary.
All components of this measuring system were selected designed for the application. Silicone oil KN32 was therefore selected as the fill fluid for pressure transmission. The cleaning and conditioning of the diaphragm seal, the capillary, the connection pieces and also the automated filling process were also matched to each other exactly. With sensitive limit ranges, even one drop of liquid too much or too little can destabilise the quantity balance of the diaphragm seal system and therefore impair its function. Because of this, correct measurement would no longer be guaranteed.
Test under application conditions
After cleaning, all elements of the diaphragm seal system were first fully welded into a single unit as usual, followed by the filling and adjustment of the machine. Before delivery, however, there is another crucial step ? in its laboratory, WIKA simulated vacuum pressure process for the diaphragm seal system relative to the customer?s conditions and subjected it to a thermal ageing process. This test confirmed the process suitability of the measuring system.
Note
More info on the WIKA diaphragm seal systems are available on the WIKA website. Assuming you have any questions, your contact will gladly assist you to.
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How do diaphragm seals work?
Watch the following video to learn more about the functionality, application areas and advantages of diaphragm seals:

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