Traps & system

Dave_145

My home is heated by two pipe system having 16 cast iron radiators. The men that installed it in 1925 have been dead twenty years. The individual steam traps on each radiator are 1/2 inch MILVACO with diaphrams. Is there a trick to resurfacing the valve and valve seat or is it best to replace them. If replacement is prudent, what type should I buy?

My system has a large cast iron vessel about 12 inches high and about 9 inches across (it is octagonal)with a vertical pipe teed into the condensate return pipe just upstream from the boiler. The vessel has a sight glass with its bottom limit at what appears to be at the same level from ground as the top of the furnace sight gage. From the top there are two mpipe. One leads to the steam manifold above the boiler. The second one rises vertically and then turns horizontaly into the intake side of a MILVACO 1/2 inch steam trap. The discharge side of the trap flows down into
the condensate return line.

What is that big thing and what is it doing for me?