Select the route curve, click on its Details... in the top right corner of the screen and click the Calc button to find the length. Then draw a straight line of similar length. Flow can accommodate a variation in length if need be.

You might try a different (simpler) way of making the hose, because I don't think it will be a trivial thing to join all those pieces into one item, although I haven't tried to do it myself.

Martin.