Beam size to support a joist hanger

Hi all,
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I have a free-standing, bricked-up pantry in the kitchen which needs removing but it is currently supporting one end of a timber joist hanger. My intent was place a steel beam under the hanger, running perpendicular to it and supported at each end by an internal brick wall.
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There is 3” (thickness of joist) of room under the hanger so the quickest and easiest solution would be to ‘slide’ a beam under it, as is, if the beam could support this weight. Could any please tell me what minimum safe/legal size beam would be needed for this situation?

Specs as follows:
I haven’t measured the hanger but it is close to 10” x 2” and spans just on 6M in the centre of the adjoining room. Joists being supported by the hanger span just under 4M (2M either side) and are also supported at each end by an internal brick wall. Joists are standard 18” or 450mm centre spacing apart. A rough guess would be that the weight being supported at each end of the hanger is only about 200Kg? Spacing between the two internal walls which the proposed steel beam is to rest on is 3800mm, with the hanger resting pretty much in the centre of this beam.
Lastly, the hanger is only supporting joists and of course, the plaster ceiling. IE, there is no roofing structure being supported by the hanger. The ceiling, being 35+ years old, has been screwed to the joists as the old ceiling straps were VERY tired! So it should be able to withstand a little movement during this work.
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Look forward to any suggestions/comments.
Thanks.

Please use the term hanging beam. A joist hanger is a propriety metal bracket that connects joists to beams/bearers.

A 75PFC will work but the deflection is right on the limit. I would consider using 2/75PFC back to back and bolted together.