I want to add a washer drain onto and existing plumbing in my kitchen but don't want to run it inside the sink.
On the next side of my kitchen wall is a full bath and the sink inside runs on the same plumbing,but the kitchen sink branches of first.
Should I run the washer off the end where the bath sink forms a 90 degree or sightly above from the main vent pipe.
Hope this is clear enough.

"washer drain " washer or diswasher? Dishwasher connects into the existing down tube above the trap.Is Your Dishwasher Drain Installed Properly? - YouTube (http://www.youtube.com/watch?v=S_0OWuFVLNw)

I'll just assume that it's a cloths washer we're talking about. Correct?
Because if it's a dishwasher you're already set up. However, a washer's a different story. You just can't connect to the kitchen drain and think the job's done. You'll have to open up the bath wall and run a washer station off the lavatory stack vent. It will have to have a standpipe, a trap and be vented. You may revent the washer back into the lavatory vent at least 6" over the flood rim. Good luck, Tom