Calculating the flow rate knowing Pressure and Diameter

Dear colleagues,

I'm currently coursing my internship as a mechanical engineer in a factory and I'm in charge of restoring a certain machine, for which task I was asked to calculate de flow rate at the outlet of a pipe. This is a compressed air system, which feeds a small tank that finally delivers 6 BAR of pressure at the outlet of a 1/2" pipe. These are pretty much all the parameters known. I'm not supposed to use a flowmeter. I think I could use Bernoulli's principle to calculate the flow rate, but I'd like further assistance on how to solve this problem. I'll be patiently waiting for insight. (Sorry for my English)