We use 3/8" air line & blow out 50' of 3" hose OK.

We have check valves to protect the air tank. Our air supply is 100% remoted from truck air supply. We use an electric 12V compressor to blow out the lines. That also prevents draw down on truck air which means you don't have to sit there for 2 minutes building air when it's time to go. Unless your tractor/trailer is a "leaker", you 'll be able to move ASAP. Also, if you have an air line failure in the blow out system going down the road, it will have 0 influence on the semi operation.

Works great here. Use an old 100# LP bottle as a storage tank. Very small footprint.