Mechanical Patternation is the most direct method to evaluate the liquid distribution provided by a nozzle, or array of nozzles. Typical mechanical patternators (sometimes referred to as Patternation Tables) collect the sprayed material at many locations across the spray plume and the level of each collection bin is recorded. These instruments are very useful for quickly and accurately assessing the spray distribution change with different nozzle types/capacities, operating conditions, spray distances, and nozzle spacings.
Spraying Systems Co. uses many custom manufactured mechanical patternators, which can assess the spray centerline cross-sectional distribution, or the collapsed 1D distribution of a spray; both manual, automated, and image-based systems are used to record the distribution data.
To collected the liquid volume distribution using a mechanical patternator, the nozzle is operated overtop an array of collection tubes (which range in size from a half-inch to multiple inches across) and the liquid is collected over time. Once sufficient material is collection, the level in each collection 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.
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.
There a few drawbacks to mechanical patternation, 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 provide a direct, fast, and accurate liquid volume distribution characterization. Below are two examples of here this type of distribution information was found valuable to Spraying Systems Co. customers.
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-come sprays, a series of 1” x 1” square collection bins were used across the spray centerline; an axisymmetric spray pattern was assumed, and checked at one operating condition. Using the pattenator results, the nozzle with 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 a 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 trough, the flat spray nozzle operating conditions, spray height, overlap, and number of nozzles was optimized.