Ozonation

What is Ozone

• Ozone (O3), or Trioxygen is a color less odorless gas made of oxygen. It is sometimes called the activated oxygen. It contains three atoms of oxygen rather than the two atoms we normally breathe. Ozone is the second most powerful sterility in the world and its function is to destroy bacteria, viruses, and odors.

• We are probably most familiar with ozone from reading about the 'ozone layer' that circles the planet above the earths atmosphere. Here the ozone is created by ultra-violet rays from the sun and subsequently helps to protect from the damaging ultra-violet radiation.

• Ozone occurs quite readily in nature. In fact that fresh smell after a thunderstorm is actually the smell of ozone, most often as a result of lightning strikes. Ozone is also created by waterfalls.

Introduction Ozone

Stratospheric ozone
is formed naturally through the interaction of solar ultraviolet (UV) radiation with molecular oxygen (O2). The stratospheric "ozone layer" extends from approximately six to thirty miles above the earth's surface and reduces the amount of harmful UV radiation reaching the Earth's surface.

Tropospheric, or ground-level, ozone
forms primarily from reactions between two major classes of air pollutants: volatile organic compounds (VOCs) and nitrogen oxides (NOx). These reactions depend on the presence of heat and sunlight, meaning more ozone forms in the summer months.

Ground-level ozone
is not emitted directly into the air, but it is formed by chemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOC) in the atmosphere.

Is ozone Harmful

There has been some debate over the safety of ozone and humans, however The EPA, USDA and OSHA have approved the use of ozone at concentrations of 0.1 Parts Per Million, for an exposure period of eight hours, without any side effects. Note that this permissible level is for continuous exposure throughout an entire 8 hour day for 5 days a week. The temporary affects of such a low exposure would range from headaches, to sore throats, irritation in the eyes, and nose. No long term effects have ever been documented from ozone exposure.

Permissible Ozone Concentration

Maximum Permissible Concentration in Occupied space:
• OSHA : 0.1 ppm ( 100 PPB)
• Exposure of : 8 Hr /day, 5 days a week
• ASHRAE : 0.05 ppm (50 ppb)
• FDA :0.05 ppm ( 50 ppb)
Continuous exposure 24 hr/day 365 Days a year
ASHRAE Ventilation Code No.. 62-1999 –
• 15CFM per person (Min.),
• 30 CFM per Person if smoking is permitted.

Why do we need fresh air?

• To Reduce the Volatile Organic Compounts(VOC)
• To make-up oxygen content.
• To remove foul odours.

Hence, Fresh air is required to improve the Indoor Air Quality. But Fresh air is not cheap!

Hot and humid air needs to be cooled down to room temperature
Hidden cost of fresh air
60% to cool moisture ….. waste of energy
28% to cool nitrogen ….. waste of energy
12% to cool oxygen ….. the only useful component in fresh air

Energy Consumed by Fresh Air.
• 150 CFM of fresh air will required 1 Ton of Cooling Load (approx.)
• 1KW for Water Cooled system & 1.3KW for Air Cooled system.

Why use of Ozone for environmental Control?

Improved Environment Quality
• Reduction of VOC, Smoke and foul odour.
• Drastic reduction of bacteria, viruses and pathogens.
• An healthy and fresh environment.

By oxidation of contaminants and odorous molecules
• Economy of Operation & reduction in HVAC plat size attainable
• 20 to 30% IS POSSIBLE(Depends on Application, country of operation and other variables)
• Reduction in Capital Cost of HVAC is often Less Than total investment in Ozone System, Controls and Monitors.