We have recently been posting a discussion on the major components for a ozone water treatment system. In this posting we will discuss some considerations for instrumentation for such a system. You can also find additional detail on this type of instrumentation at www.spartanwatertreatment.com/ozone-water-treatment-system-instrumentation.html.
As we noted in our posting regarding gas preparation systems, the gas feed to an ozone generator must be dry, > -70 degrees C dew point. Dew point monitors are available for this application and are a very good idea to be included in a system. For small systems where the cost of the monitor might not be justified, the use of a pressure switch may be an alternative. In PSA type dryers, pressure is a major factor in their proper operation. If the pressure drops below a certain level, the dryer will not work properly and dew point may become out of specification. So the pressure switch will shut down the system before this occurs.
Measurement of the amount of ozone produced can be achieved by a high concentration monitor and mass flow meter. These components can be relatively expensive, but for large systems they are easily justified. Smaller systems will often rely on the production curves from the ozone generator manufacturers and standard flow meters. This will be back-up by measurements of the dissolved ozone in solution. If the dissolved ozone concentration is at the design level at the appropriate point of the production curve, it can reasonably be assumed that the unit is working properly. The situation becomes difficult to analyze if the dissolved ozone values do not meet expectation. Then it is more difficult to determine where the problem lies.
Ozone generators often come with controls that allow the power output to be varied with an input signal (4-20 mA) from another device. For example, a dissolved ozone monitor can send such a signal as can an ORP monitor. Both provide a measure of the amount of ozone in the water. This process can also be handled manually by measuring ozone residual with a test kit. These kits rely on the Indigo Blue method and the use of a color wheel or colorimeter.
The last piece of instrumentation that should be employed is an ambient ozone monitor. This device measures the amount of ozone that is found the environment around the ozone water treatment system. This is an important safety device especially for ozone systems that are located in a building. These units can be integrated with the ozone generator should a leak be detected above a safe level.
Spartan Environmental Technologies can provide complete ozone water treatment systems including the necessary instrumentation for a variety of applications.