Ozone (O3)

What is Ozone?

Ozone  (O₃) is a gas – the same ozone gas that is generated constantly in the Earth’s stratosphere when the Sun’s high-energy ultraviolet rays first encounter oxygen that makes up our atmosphere.  Some oxygen molecules (O₂) are ruptured, forming single oxygen species that are quite reactive.  When such active oxygen species encounter other oxygen molecules, the two species combine to form the very strongly reactive ozone molecule, O₃. 

The molecule itself is a very strong oxidizing agent, and this oxidizing power makes it a very strong disinfectant. Ozone can be applied either as a gas or in aqueous solution.  Microbial oxidation and subsequently disinfection can occur in both phases.  Reactions of all types occur much more slowly in the gas phase, particularly when the air to which ozone gas is applied is dry.  As the relative humidity increases, reaction rates of ozone increase rapidly. 

What is the Commercial Availability of Ozone?

Commercial ozone gas must be generated on site. It is not available in a cylinder because of its unstable nature. Two types of ozone generators are available – corona discharge and ultraviolet radiation (185nm). Corona discharge is a process by which electrical energy is passed between two closely positioned electrodes, thus creating a continuous silent electrical discharge – which generates ozone in the gas phase. For UV radiation, high energy UV rays pass through surrounding air, generating ozone, but in much smaller amounts and concentrations than can be generated by corona discharge.

Ozone Sensor Technology

There are several commercially available sensor technologies for ozone detection:

• UV photometry is very accurate (+/-1ppb), employs active sampling, is stable and operates over a wide range but this technology is expensive.
• Electrochemical sensors are lower cost than UV, however, they lack some sensitivity at lower levels of ozone (<0.5ppm) and are better suited to measuring higher ozone levels.
• Heated Metal Oxide (HMOS) sensors are inexpensive but are susceptible to drift and are also affected by cross sensitivities and relative humidity.
• Gas Sensitive Semiconductor (GSS) sensors are proprietary to Aeroqual. They have been developed to overcome many of the disadvantages of Electrochemical and HMOS sensors by providing a high level of accuracy and faster response times.

Aeroqual Ozone Sensor Specifications

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