Pressure measurement in the production of PBAT, a biodegradable plastic, faces a particular challenge: Temperatures of up to 330 �C prevail along the way. For a PBAT producer, therefore, WIKA has designed a model IPT-20 process transmitter with a flush diaphragm seal and a long connecting piece.
Hopeful , PBAT for short, is a copolymer from the polyester group. The plastic can replace polyethylene and is totally biodegradable. PBAT thus contributes to greater sustainability. Among other activities, it could be used to make protective sheeting for agriculture and gardening, compost bags, shopping bags and medical disposables.
Pressure monitoring during esterification and melt polymerisation
The procedure steps in production include esterification and melt polymerisation. In these two processes, WIKA?s customer, a petrochemical company, uses the IPT-20 transmitter for pressure monitoring.
Corresponding to the task, WIKA supplied the instruments with three basic measuring ranges: 0 ? 16 bar, 0 ? 40 bar and 0 ? 250 bar. The precise measuring ranges can be set for this kind of transmitter utilizing the turndown function. Because of this the output signal is distributed only on the scaled range. Thus, the measured values can be more precisely determined.
Handles temperatures around 330 �C: Measuring unit with IPT-20 process transmitter.
Connecting element as a cooling element
Pressure measurement in plastics production regarding PBAT is subject to process temperatures between 100 �C and 330 �C. For this reason, WIKA has designed a measuring unit comprising an IPT-20, a flush diaphragm seal and a 200 mm long connecting piece. Because of its length, the connecting element acts as a cooling element. Thus, the measuring instrument remains protected against undesireable effects caused by the high process temperatures. The complete design can be minimised in volume to reduce any temperature error effects during measurement to the very least and thus achieve the perfect accuracy.
Plastic is highly viscous at the pressure measurement points
At the measuring points of the IPT-20, the plastic is in a highly viscous form. The diaphragm seal, combined with the transmitter, is therefore implemented with a flush diaphragm. Due to this fact, it enables pressure measurement minus the risk of media entrapment.
Note
Technical information on the model IPT-20 process transmitter can be found on the WIKA website. There additionally, you will find an overview of other products and solutions for the chemical industry and petrochemical industry sectors, in addition to a brochure to download. For those who have any questions, your contact will gladly assist you to.
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There are also out more about the turndown function of WIKA process transmitters in the next video: