Cenvat credit on custom duty paid

My Client is a Manufacture of some heat measurement Item and also does trading of some imported items. It acquires some raw material from Import purchase by paying custom duty. 1. It purchases Material(importd from Belgium) for Reasearch & devlopmet purpose and utilised solely for inhouse R&D. 2. It purchases Materia(imported from Belgium)l for Trading. 3. It purchases material (imported from Belgium)for manufacturing and utilised in the process of manufacturing to make finished product (ie., heat measurement item). My query is that in which of the above three cases the client can get cenvat credit for custom duty paid. Can it avail Cenvat credit in all the three cases for Custom duty paid. Thanks Nayan Dey