Mechanical Patternator

The use of a mechanical patternator offers a very direct and accurate method for assessing the liquid volume distribution across a spray plume. The ease of operating and simplicity of the data allow for fast collection times and clear comparisons between setups. However, it is critical that the spray material that enters a collection region is properly captured and not allowed to migrate to other spray areas / collection bins.

The mechanical patternation method provides a direct, fast and accurate liquid volume distribution characterization. Below are two examples.

• Full Cone Spray Distribution Assessment for Product Coating
  A customer was using a full cone spray to coat their product. It was necessary to have a somewhat uniform coverage that spanned a circular target. In order to assess the center-to-edge distribution of various candidate full-cone sprays, a series of 1" x 1" square collection bins were used across the spray centerline. An axisymmetric spray pattern was assumed and was checked at one operating condition. Using the patternator results, the nozzle with the most uniform distribution was selected. 

• Flat Spray Overlap Analysis for Uniform Coverage
  Applications that spray on to a conveyor or moving target typically use a series of flat sprays, which, when properly overlapped, provide uniform coverage over a wide area. A paper manufacturing company required a very wide and uniform spray. By using a mechanical patternator with many collection troughs, the flat spray nozzle operating conditions, spray height, overlap and number of nozzles were optimized.

To collect the liquid volume distribution using a mechanical patternator, the nozzle is operated overtop an array of collection tubes ranging in size from a half-inch to multiple inches across, and the liquid is collected over time. Once sufficient material is collected, the level in each bin is recorded. In conveyorized applications, the liquid distribution is most appropriately evaluated by spraying into troughs, which then drain into collection bins (i.e., a 1D distribution). Typically, water is used as the spray material during mechanical patternation, simply for ease in emptying / cleaning the collection bins. 

The recording of the liquid volume distribution information may be done with a simple ruler, or by reading the volume on a graduated cylinder. Alternative methods include ultrasonic water-level assessment and image-processing techniques, both of which are employed at Spraying Systems Co. to provide fast and accurate measurements.