The seems no systematic/designed solution ,to stop smoke passing through most fire-rated door hinges: between the leaves; through the spaces between the leafs and the knuckle (see white wire in .jpg below); around the knuckle. I can't find a fire-rated smoke seal for hinges and can only imagine a fire-rated adhesive foam - similar to a window draught excluder strip.

BTW please, how far should the knuckle or its pin best be positioned from the jambs?   
 

Edited May 7, 20251 yr by Hugh Riddle
to maximise clarity

The Standards for restricted spread of ambient temperature smoke, BS 476 part 31.1 and BS EN 1634-3, do permit leakage to a defined limit in the pressure test. Therefore smoke protection around doors should not be viewed in absolute terms. For more on smoke seals visit https://www.ifsa.org.uk

The knuckle of the hinge should be positioned up to the door frame jamb and door leaf face so as to avoid 'door growth' in operation of the door.  Refer to the ASDMA best practice guidance at https://asdma.com/

Very many thanks, Neil, for your precise and comprehensive response and troubling to indicate the standards concerned. BTW, I've spotted an approved intumescent tape with an edge smoke brush. Might laying a strip downward across one leaf of each hinge be worthwhile, to minimise smoke and fire passage?
https://www.amazon.co.uk/Intumescent-Self-Adhesive-Draught-Excluder-Approved/dp/B0DRFQH49T?th=1

You mean, in order to exceed the required Standards?  There are already continuous smoke seals that reamain uninterrupted by hinges and locks because they fit to the edge of the rebate stop. https://www.lorientuk.com/products/batwing   Also, ones for retrofit like this:

 

Yes, forgive my toying with unbroken smoke and fire protection using the existing 10mm wide rebate, beyond the already met proportional requirement. The batwing strip seems to need a wider, deeper rebate. I've added the link I forgot to give to my last reply.

Thanks. Interesting, if used in place of intumescent edge seals it would be unsuitable for some fire resisting doors that specifically state a specification for the intumescent seals required. Couldn't see any link for the product certification?