For the first time in many years, I asked a man out (a coworker, at that). And it worked out just fine. We went out and had a lovely time. Both of us agreed to not tell ANYone. Your superiors don't have to know unless you tell them or others that you work with. Believe me, it gets around. My advice is to not tell any of your work friends that you want to ask him out and just do it!! He probably likes you too, but is scared.
Once you go out (and you will - women have great intuition) you can talk about keeping it on the "down low". Even if it doesn't work out, hopefully both of you are mature enough to keep it quiet. If you don't think that he is, don't ask him out. You don't want to risk your professional career. Just do it! good luck.