Tanks are made from mild steel & not rust protected. Condensation turns to water in the tank and very soon rust is what you get out of the seldom used manual drain valve. Fit the Electronic Autodump valve before the steel in the tank begins to rust.

If you want to install an Automatic Purge valve to an existing rusty tank then an in-line filter is fitted & manually cleaned until the rust level is minimized and unlikely to block the dump valve.

The Automatic Purge valve will open every 30 minutes and expel the condensation from the tank and prevent build up of water and rust that will eventually cause failure in any compressed air system.

Purge Valve PDF