The faucets on my laundry tub need to be replaced. I'm trying to figure out how to shut of the water supply to the hot and cold lines. There are two valves(maybe?) inline on each of the water lines right above the tub (shown in the attached picture). Are these shut-off valves? If not, what is the purpose of these? I don't see any other shut-offs on these water lines between the tub and the main pipes that go along the ceiling.