🔎 UNIDENTIFIED No idea? we may never know

[TreasureLord KC]

 

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[searcher]

Reminds me of the top half of a carbide lamp.

One of these.

Edit- Probably not... I don't see a way to fill it.
The bottom doesn't look correct for a dripper either.

 

[Back-of-the-boat]

Is the knurled piece hollow like a pipe would thread in it or be inserted?

 

[creskol]

It looks like part of an old sprayer regulator.

 

[Blackfoot58]

A carbide lamp? I’m guessing it had a lens over the large hole: clear, red or green.

Just a guess.

 

[ticndig]

air release valve for hot water heat.

 

[releventchair]

Boiler system relief valve for air?

 

[Blackfoot58]

air release valve for hot water heat.

What is the purpose of the large, side hole? Any gauge would be threaded for a pressure line.

 

[ticndig]

here's another image to show how one would be piped. the relic is missing some parts. but you can clearly see the rubber check valve in one of the pics. the small knurled port is for manual bleeding the side hole is the drain