Weighing Tanning Drums

This project involved fitting 6 x 40 tonne tanning drums with loadstools to weigh the contents of the drum. This application is made difficult as the loadstools need to restrain the 2 metre diameter drum which rotates at up to 6 rpm with an unbalanced load. The weighing equipment also had to be resistant to the corrosive chemicals used in the tanning process. The project was accomplished by fitting a loadstool under one bearing of each drum. The load cells used in the loadstool construction were Vishay Celtron DSR stainless steel versions with laser welded seals.

The transmitter used for each loadstool was a Rinstrum 1203. This is a microprocessor-based load cell transmitter rather than a simple analogue circuit. All calibration and damping variables are stored in non volatile memory. The 1203 also has multiple serial and analogue outputs. We used these to good effect in this project. The 4-20 mA analogue output went to the plant process PLC so the filling of the drum could be controlled. The RS232 serial output went to a Rinstrum 2101 remote display so the operator could view the weight alongside the drum.