Hoping there are some more experienced vacuum engineers around this list who can
help advise regarding some antique hardware.

I'm working on an old NRC 3114 evaporator, which uses an oil diffusion pump with
an LN2 cryo trap between the diff stack and the belljar.  My problem is that the
cryo trap is being a truly monstrous consumer of LN2 - a single fill isn't
lasting more than about 30-45 minutes at most.  Does anyone have any thoughts on
1) is this "normal" behavior, and 2) what might I consider doing to increase the
run time on a single LN2 fill?

Thanks,
Mike