Main water line part identification

[TheShape]

Does anyone know the purpose of this part? It's on the lower right in the 2nd photo. I just noticed today that it is dripping. (We moved in a few months ago.)

There is what feels like a piece inside the end that is dripping that is shaped like an X. I was able to turn it with a screwdriver and it let water out. Would it be OK to cap it?

Thank you!

 

[havasu]

Since this is a speciality, I reached out to a former admin here. Chris works on and rebuilds these systems all over California and Idaho.
He said "Thats a typical RPDA device (reduced pressure detection assembly) different from a backflow device, this will bleed off pressure if the private side is higher than the supply side. That chingadera on the lower right must be a thingamajig because I have no idea what it is"

 

[Geofd]

This is back flow preventer it's either on your water main feeding your house or your lawn irrigation,there are 2 check valves( they look like they are at a 45° angle the part that's dripping is the relief valve,

 

[Geofd]

This is back flow preventer it's either on your water main feeding your house or your lawn irrigation,there are 2 check valves( they look like they are at a 45° angle the part that's dripping is the relief valve,

Sorry got called away so that device seperates drinking water and water from another source like lawn irrigation,chemical feeds for boilers or cooling tower the house or street side is drinkable water and after the device it is used for non consumable applications.
They are tested (if registered a couple of times a year,a licenced plumber had to make repairs . After looking at the pics again the close up looks like a pressure
Relief valve above that is the backflow device

 

[breplum]

for clarity, that top picture is an old "pressure relief valve".
Geofd's sentence made it hard even for me to get.

 

[TheShape]

Thank you all for the responses!

I would imagine it's normal for the old pressure relief valve to drip? It hasn't stopped since I noticed it. It's maybe a drop per minute.

My sprinkler system valves are on the side with the old pressure relief valve.

 

[Geofd]

My fault though the releif valve on the backflow device was leaking, but it was the old pressure relief

 

[HWSleuth]

Put a gage on and take a pressure reading. Is there a pressure rating on the valve? If so compare pressure to valve’s relief point. Maybe valve is functioning to relieve pressure as designed. Maybe simply a leaking valve, replace it.

 

[TheShape]

I don't have a gauge and don't see a pressure rating. Just the CII, Cll, or C11 on the one side and USA on the other. I'd replace it, but I don't know what it should be replaced with because I couldn't find another valve that looked exactly like it online.