What is spit valve on trumpet?

A spit valve is a small valve on a trumpet that allows the player to release any accumulated saliva or moisture that may have collected while playing. It is located on the underside of the third valve slide tubing and is typically made of metal or plastic. When the valve is opened, the moisture can be expelled by blowing sharply into the trumpet. The spit valve needs to be cleaned regularly to prevent blockages and ensure efficient functioning. It is also important to use a cloth or napkin to catch the expelled moisture to avoid damaging the instrument or creating a mess.