SQ25 in F entitles you to use the LH Senator lounge upstairs in T-1, next to
B42. It's not unlike the LH business lounges, but it is a bit better. At the time SQ25 is at FRA, it's very crowded -- there's a large bank of LH regional flights leaving between 11 am and 12:30 pm. So, prepare to be underwhelmed.

It's the only lounge you can access, besides the LH business lounge by B45.

Nice view of the runways and apron, though............