Controlling the amount of air in a conventional pressure tank is key in providing an efficient and reliable pumped water system. In smaller residential systems, simpler, less expensive air-charging devices are common.
The snifter valve, typically mounted on a tapped check valve between the wellhead and the tank, allows air into the drop pipe so that the water can be released through the bleeder orifice when the pump shuts off. A snifter valve looks like a valve stem on a tire, but it has a very weak spring or no spring at all to function properly in this application.