Wireless Access

I have been tasked to setup a tunneled network for some equpement that connects to the internet installed by a vendor by ethernet. We won't have any control over this equpement that will be monitoring fluid levels in a tank a 3rd party maintains, so we do not want this touching our network. I thought a good way to do this would be to use a rap-3 has 3 ports on it. Since we are already using the same controller also for raps conencted to the internet facing interface can we also use this rap inside our network. I haven't tested anything in our lab yet wanted to see what you thought about the idea. Another way would be to use a AP-225 and configure the 2nd jack for tunnel mode which is a good option as we can use the AP for wireless corprate traffic as well since the AP in our trusted network we really don't need the IPSEC tunnel the rap uses. Rap-3 cost a lot less then an AP-225. 

You don't need a RAP to do what you are doing.  You can try to convert a RAP3 to a CAP to do this.

Do you have a proceedure to convert the rap-3 to a campus AP I have one which is currenlty a rap but I can factory reset it. 

Factory resetting it changes it back to an IAP.  You can convert it to a CAP from there.  http://community.arubanetworks.com/t5/Controller-less-WLANs/How-do-I-convert-an-Aruba-Instant-AP-to-a-campus-AP/ta-p/178988