Need help identifying 2 pipe system style and trap type .

Murf201

Top of 4 story 12 apt building in bathroom and living room are both loops like in picture shown . I was assuming the trap discharged into smaller line . But then ive never seen that kind of trap where the disc is vertical , i was assuming all angle traps discs sat horizontal . And if you know whag kind of trap whats the name as all the hoffmans and mepcos i have used in past are set up different .  

Murf201

Bump

DanHolohan

Is this one-pipe steam? 

EBEBRATT-Ed

Looks like some sort of vent or crossover trap.

Just repace it with another trap or scrape all the paint off the cover to find out what it is

Murf201

This is two pipe steam , the traps are a shiny high polish brass or metalic not simmilar to the newer products im familiar with . Each one are the same on top of disc is a cap , And the two j replaced already on the radiators which are the same at the risers have two different names . 

One is Walter Gross
The othere is E.W Mandeville . 

DanHolohan

They’re being used as main vents to speed steam distribution to all the radiators on the riser. They handle air and steam, but not condensate. Check with Tunstall for repair parts. 

JUGHNE

Should each riser have their own vent?
The faster riser would close the vent and the slower one not be vented as well.

DanHolohan

@JUGHNE Yes