*PLUMBERSSTOCK EXPERT* responded:
Hi! Thank you for posting a question regarding the Fresno F035-20000 Air Vent. Air release vents are also known as automatic air valves, small orifice air valves and pressure air valves. These vents continue to discharge air, usually in smaller quantities, after the air vacuum valves close shut as the line is pressurized. It greatly improves the efficiency of centrifugal pumps by releasing entrapped air while ensuring continuous priming by not allowing air intake. Also, it enables siphon build-up by releasing infiltrated and/or trapped air and maintains the siphons by continuously releasing air while not allowing air intake. We hope this helps. Thank you for visiting PlumbersStock.com. Have a great day!