Electricity + Control July 2017

round up FLOW MEASUREMENT + INSTRUMENTATION

Measuring high viscous resins Production processes in manufacturing of abrasives and superabrasives require precise dosage of even high viscous resins (e.g. 1 500 cP). Kob- old Instrumentation, represented locally by Instrotech , was asked to look into, and supply a solution. The application image below shows one dosing skid in such applica- tion. Each skid comprises of the following components: • Main tank • Secondary tank with low level alarm, always ensuring enough prod- ucts and no air in the circuit • Manual valve to close the circuit • Peristaltic pump • Oval Wheel Flowmeter At higher viscosities and depending on temperature fluctuations, the peristaltic pump (positive displacement pump comprising of flexible tube and of roller(s) displacing the medium from one end of the flexible tube to the other) is not able to displace the medium completely. This means that some part of the medium flows back through the flowmeter resulting in error readings. In addition, the operating pressure developed by the small sized peristaltic pump is quite low. Oval wheel flowmeters model DON can be provided with special cut rotors reducing the pressure drop by 50%. Choosing the optional Quad Hall Sensor Dual Pulse Output provides two out of phase pulse outputs ‘A’ and ‘B’, so that net flow rate ‘A-B’ may be computed correctly by the PLC. Net flow rate could also be computed using ZOK-Z3 electronic with a pulse discriminator in between. With these features, Kobold was able to solve all problems associated with this application and conduct very fine dosing of resins, resulting in an improved repeatability and quality of the finished abrasives. Enquiries:Tel. +27 (0) 10 595 1831 or email sales@instrotech.co.za • Pressure Switch (safety against high pressure) • 3-way valve (for manual or automated operation) • Outlet pipes for manual product collection