SPRAY NOZZLES FOR CLEANING

When selecting the appropriate spray system, the primary consideration is the level of cleaning required, which can be classified into several categories:

1. Sterilization: The elimination of residue through washing or flushing, followed by the application of chemicals and/or heat to kill all forms of life.

2. Disinfection: The removal of residue (either by washing or flushing) and the addition of a disinfecting substance that eliminates or reduces toxins or bacteria to an acceptable level.

3. Sanitation: The removal of residue through washing or flushing, and the application of heat and/or chemicals to kill 100% of bacteria, but not necessarily spores.

4. Cleaning: The removal of residue through a combination of dissolving in cleaning solution and direct pressure.

After determining the required level of cleaning, consideration can be given to the impact, volume, and timing of the spray required to achieve it.

In order to achieve any of the 5 levels of cleaning discussed in designing consideration 1, there are three basic types of cleaning processes that correspond to three levels of spray impact. The three processes require different nozzles, as the properties of the required spray vary.

1. For rinse applications, a low impact and high coverage spray design is necessary since rinsing does not rely on the kinetic energy of the liquid to remove residue. Therefore, full cone spray nozzles are the ideal choice.

2. For wash applications, the impact of the spray helps to remove residue. Full cone spray design nozzles disperse the kinetic energy of the liquid over a large area, reducing the impact. To achieve the necessary impact, other spray designs such as flat fan spray patterns are required. However, this only cleans a narrow line, and some form of relative motion is required to clean a target area. This motion can be provided by a conveyor moving the product under a cleaning spray bar or by a moving spray bar.

3. High impact washing is used to remove stubborn residue. For these applications, only a solid stream spray design is suitable as it delivers the most kinetic energy per unit area (i.e., has the most impact). However, now only a small spot is cleaned, so more refined motion is required. An example of such motion would be an oscillating spray bar targeting a conveyor.