Traps for 2 pipe steam-Broomell

I have a 2 pipe Broomell steam system that had 2 of the original rads replaced years ago. There are two Burnham baserays (one about 4 foot, and one about 2 foot) that don't seem to have any traps. It was piped with 3/4" copper and the returns (and main dry returns near by) really heat up. I am sure steam is getting into the main dry returns thru these. Can I add traps on the individual returns before they empty into the common main return (There is not much room up by the baseboards)? If so, what type and size? I contacted Burnham but have not gotten a reply.