The 0823005009 check valve is a non-return valve that was commonly used on several different Atlas Copco and Chicago Pneumatic rotary screw air compressors. This valve typically is installed underneat the airend assembly.
This is an OEM part from Atlas Copco / Chicago Pneumatic. 0823005009 may be displayed in your parts manual as 0823-0050-09 or 0823 0050 09
Part #: 6215714800
Part #: 2204133150
Part #: 2901000201
Part #: 2200900961
Part #: 1622175580