Charging hose shut off valves are good to prevent refrigerant blowing out to the air while you are servicing an air conditioning unit.
Our hose shut off valve can be anywhere installed in the line. Near at the vacuum pump or close to the AC service connector.
Shut off valves should be twelve inches from the end of the hose to stop venting the refrigerant.
These charging hose shut off valve is a swivel ball valve with 1/4" flare male and 1/4" flare female end.