Is a trap necessary for a urinal

All plumbing fixtures need traps. https://www.google.com/search?q=urinal+traps&hl=en&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=ZAC9T6y-IoSQiALOvvTVDQ&sqi=2&ved=0CKUBELAE&biw=1272&bih=684 Toilet traps are built into them, everything else needs an exterior trap.

Here's a link that might help. How to Install an American Standard Urinal | eHow.com (http://www.ehow.com/how_7828020_install-american-standard-urinal.html) Good luck, Tom