Extra part after cleaning

[Melix]

[IMG][/IMG]

Hello - first time poster here. Glad I found the forum.
I picked up a line cleaning kit for my local AOH hall's kegerator and have been doing OK with an old unit, but now I have an 'extra' part aftere putting everything together. We are pushing Guinness and I suspect this part goes into the coupler somewhere.

Thanks in advance

[Sketch]

It is the check valve for the Co2 line. Place it in the coupler with the duckbill going into the coupler and the washer side facing the Co2 hose.

[Melix]

"extra part'

Thanks...I see it as #10 in the blow-up sketch