With the release of AFT Arrow 6 last month, this month I am going to depart from my usual monthly high level focus and instead get more detailed technically on compressible pipe flow. I am going to revive a topic from 1996 where we built a "Triple Choke" steam flow model in AFT Arrow 1.0. This model is discussed in our AFT Arrow training seminars, so those of you have attended one of these will have seen it. It also has been part of the AFT Arrow Help system documentation since at least 1999.