I agree with the above advice. But really, you should never put yourself in a position to be stung in the first place. Volitans will never intentionally sting you, they are just curious. So when they see a limb submerged into there domain they will probably come to check it out. Most stings occur when aquarists brush past a Volitan! This is why divers find them so easy to catch, instead of them swimming away, they swim towards the diver to investigate.
So If you have to place your arms in your system for whatever reason, use a simple partition to trap the volitan at the other end. Ive kept volitans since the early seventies, and this method has never failed me.