A high-resolution weighing solution for potentially explosive areas
After expanding its range of products, to include basic chemicals, intermediates, polymers, polycarbonates, fertilizers and metals, SABIC reached out to possible suppliers seeking two specific solutions: a weighing system for a batching hopper used to produce polyethylene granulate additives, and the replacement of a competitor’s defective weighing components in twelve granule hoppers.
Minebea Intec was chosen for the accuracy, reliability and safety standards of its devices.
In the first instance, the new hopper was to be installed in an outside area that required the use of Group II and Category 2G equipment according to the ATEX directive.
On top of compliance with mandatory standards, the customer required a readability of 100 g, and the placement of the weighing electronics (transmitter) at a distance of 500 m from the hopper.
The hopper weighed 523 kg in total with a net capacity of 60 kg. To achieve the desired resolution with such an unfavourable ratio of dead load to weighing capacity, the system had to register a change in signal of 1.3 μV.
Minebea Intec therefore selected three PR 6241compression S-type load cells PR 6241, which combine a high sensitivity to compression with the capability of being tilted and counterbalancing this movement when the hopper undergoes thermal expansion. To respect the distance of 500 m, the signal of the load cells is transferred through a 6-wire connection to the transmitter and then back to the remote display.
For each of the defective hoppers, Minebea Intec supplied four PR 6201 precision compression load cells PR 6201, and PR 6143 compact mounting kits PR 6143. The components were ATEX-certified for Zone 2 and linked over an analogue interface to a PLC system.
Thanks to its wide range of load cells and mechanical and electronic accessories, Minebea Intec met and exceeded the customer’s requirements, and successfully registered with them as an official supplier. This entitles a supplier to automatically submit price quotations and/or bid offers for listed products and to receive orders.