Hi Arne.
The dampers are not good. I really think you need to have these back so you can assess with your team. These defiantly have not been tested Arne. I can pack up for you, advise weight & cube an you can have collected.
I think the problem is the two sections are pressed together too tight when assembled and riveted. This causes jamming. Also Arne we have asked several times not too have any Nordfab labels on ducting to Airtight. All the pneumatic & manual slide dampers turned up with labels.
I am short these manual dampers now due to the faults so please can you send me replacements as soon as possible.