Since the 1960's anhydrous ammonia (NH) has become the most widely used source of nitrogen (N) fertilizer in agriculture. In fact over 8.1 billion pounds of NH3 is used in the United States every year (Terry and Kirby, 1997). With the cost and wide spread use of NH3 operators are seeking ways to improve uniformity and reduce rates of application. This is because most NH3 tends to be over-applied due to variability in NH3 equipment. Reducing variability will put more money into producers' pockets and reduce the likelihood of N leaching into water supplies. At a cost of $267/ton of NH3, improved application equipment that reduced use in the United States by 5% would result in direct savings of $65 million annually for crop producers (Hanna et al., 2002). A key component of NH3 application equipment that affects uniformity is the distribution manifold. Tests have shown that some outlets on manifolds release two to four times as much NH3 as other outlets. Some knives could be putting on two to four times the desired rate while other knives could be putting on very little NH3 (Fee, 1999). This means that some plants may be getting more N than they can use and others are not getting enough N due to poor distribution by application equipment. In recent years, new manifolds have been tested and produced that improve uniformity among distribution ports.