I have a single pipe steam heat system with radiators. To use this system I use the Maid-o-Mist brand valves. These valves come in different sizes. The website provides a nice diagram about what should go where:
And it seems that the difference in the size is just about the little piece that screws into top of the valve.
Now here is the part I don't understand. Because this part screws in, does it have to be tight? It never says anywhere on the website and it feels like loosening it is an adjustment. But maybe it just loosens because it was easier to make it that way.
Question >> How tight should the top piece be for normal operation?
Link of interest: Product web page