Sanitizer level control is required in many systems where sanitizers are used to control microbiological growth, avoid cross-contamination, or sanitize as part of a HACCP plan. These systems include dump tanks, water conveyors, wash systems with flumes or float tanks, and some spray systems where water is recycled. Chlorine is the most common sanitizer and the one with the most developed control. As such, chlorine is frequently used in the following example; however, the concepts discussed here have application to other sanitizers, as well.
The system requirement is the first question when considering control. The tighter the control window, the greater the required precision and accuracy. Controlling chlorine between 2 ppm and 5 ppm is much more challenging than controlling its level between 7 ppm and 15 ppm. Knowing the minimum acceptable level is an important input for assessing the ability of a monitoring system or other measurement system to control the wash chemistry. The minimum acceptable level is specific to each application.