Can a common brass air vent be used to release air in a plumbing application, or a domestic/heating hybrid system? No! All devices installed in plumbing systems, since January 14, 2014, need to meet the requirements of the Safe Drinking Water Act. This means low lead brass, and NSF 372 (or NSF 61, depending on the Authority having Jurisdiction). The Caleffi NA5026 Series PLUMBVENT is the answer; it is designed for plumbing applications and has a hygroscopic vent cap which prevents potential dripping.
The PLUMBVENT is perfect for releasing air from domestic hot water storage tanks or water heaters, any high point in the piping system, and near the suction side of a domestic hot water recirculation pump to prevent air lock.
Check it out, at this web page: https://www.caleffi.com/usa/en-us/catalogue/plumbventtm-na502640a