What side of the feed does the vent go on a sweat valve with this feature?

Could you post a picture of this "sweat valve with a vent"? What's the valve shutting off? Why a vent? What does it vent anyhow? Please explain in mnore detail. Thanks, Tom

I think he is talking about valves with a small cap that is used to drain the fixture. It has a small knerled nut and a hole to direct the spray.

In general, it's not a vent, but a drain.

If so, the drain is installed on the fixture side (or the side that you need to drain). The "vent" becomes the fixture itself.

In reality, though whether it functions as a vent or drain depends on what's lower, the fixture or the shutoff.

Nonetheless, the port usually goes on the side of the fixture.

Thanks KISS,

The "vent" through me off. The correct name for this valve is a "stop and waste" (see image)..
These valves are used in colder climates, ( we don't use them down here.) to winterize and drain outside hose bibs. The drain's always located on the same side the hose bib is on, there should be a arrow pointing towards the flow In winter time you shut the valve off, open up the hose bib to relieve air lock and open the waste to drain the water back from the hoise bib. Back in Wisconsin when we piped for a hose bib we always gave the line a little slope back so all the water would drain out of the hose bib when we shut off the valve and opened the waste and the outside hose bib. Haven't seen one of those for over 50 years. Regards, Tom
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I tend to install them everywhere because, it gets rid of the "mess" when trying to replace things.

For one outside hose bib, I installed a valve on the drain doing some fancy brazing that runs into the laundry sink.

Now on the bathroom, I have two shutoffs. One fancy stop under the sink and one with the drain in the basement. So, I could drain the entire line before working on the bathroom sink fixture. Did the same with the toilet supply.

No basements, No exposed piping here in the Tampa Bay Area. Most of our piping's under the slab and brought in the walls for a manifold. Regards, Tom