The drain valve on a paint sprayer is also called the bleeder valve and the prime valve. This is the valve that switches the sprayer from the "spray" position to the "prime" position.
For use with the following airless paint sprayers:
Part #: 114659
Part #: 245798
Part #: 193709
Part #: 193710
Part #: 235014
Part #: 235198
Part #: 239914
Part #: 15G563