Air vents work by providing a way to release this trapped air or gas, allowing the pump to function correctly.
e.g. Chlorine pumps need air vents because air is incompressible, meaning trapped air or gas (often from chlorine off-gassing or low suction pressure) can cause air locking or vapor locking. When this happens, the pump can't effectively move liquid, leading to a loss of pumping action. Air leaks in the suction line can also introduce air into the system.
