Design guidelines for indoor corona devices to meet ozone regulations

Ozone Generator Hazards - InterNACHI

design guidelines for indoor corona devices to meet ozone regulations

Whenever an electrical spark or corona occurs in air, some ozone is formed. .. See "Health Hazards of Ozone-generating Air Cleaning Devices", [PDF] . standards in protecting public health because the indoor secondary particles can vary . Based on the model, optimized ozone photoreactor designs for ambient air, dry. Ground-level ozone emitted from indoor corona devices poses serious Federal regulations call for effective techniques to minimize the indoor. and operation of positive wire-to-plate corona discharges in indoor air. See all ›. 10 Citations. See all ›. 20 References. Download citation in the design/ operation of a photocopier to follow the federal regulations of ozone emission. . A tris(8-hydroxyquinoline) aluminum-based organic bistable device.

It often appears as tufts of corona at sharp edges, the number of tufts altering with the strength of the field.

Ozone - Wikipedia

The form of negative coronas is a result of its source of secondary avalanche electrons see below. It appears a little larger than the corresponding positive corona, as electrons are allowed to drift out of the ionising region, and so the plasma continues some distance beyond it. The total number of electrons, and electron density is much greater than in the corresponding positive corona.

However, they are of a predominantly lower energy, owing to being in a region of lower potential-gradient.

design guidelines for indoor corona devices to meet ozone regulations

Therefore, whilst for many reactions the increased electron density will increase the reaction rate, the lower energy of the electrons will mean that reactions which require a higher electron energy may take place at a lower rate.

Mechanism[ edit ] Negative coronas are more complex than positive coronas in construction.

design guidelines for indoor corona devices to meet ozone regulations

As with positive coronas, the establishing of a corona begins with an exogenous ionization event generating a primary electron, followed by an electron avalanche. Electrons ionized from the neutral gas are not useful in sustaining the negative corona process by generating secondary electrons for further avalanches, as the general movement of electrons in a negative corona is outward from the curved electrode.

For negative corona, instead, the dominant process generating secondary electrons is the photoelectric effectfrom the surface of the electrode itself. The work function of the electrons the energy required to liberate the electrons from the surface is considerably lower than the ionization energy of air at standard temperatures and pressures, making it a more liberal source of secondary electrons under these conditions.

Again, the source of energy for the electron-liberation is a high-energy photon from an atom within the plasma body relaxing after excitation from an earlier collision. The use of ionized neutral gas as a source of ionization is further diminished in a negative corona by the high-concentration of positive ions clustering around the curved electrode.

Under other conditions, the collision of the positive species with the curved electrode can also cause electron liberation. The difference, then, between positive and negative coronas, in the matter of the generation of secondary electron avalanches, is that in a positive corona they are generated by the gas surrounding the plasma region, the new secondary electrons travelling inward, whereas in a negative corona they are generated by the curved electrode itself, the new secondary electrons travelling outward.

A further feature of the structure of negative coronas is that as the electrons drift outwards, they encounter neutral molecules and, with electronegative molecules such as oxygen and water vaporcombine to produce negative ions. These negative ions are then attracted to the positive uncurved electrode, completing the 'circuit'.

Corona discharge on a Wartenberg wheel Ionized gases produced in a corona discharge are accelerated by the electric field, producing a movement of gas or electrical wind. A pinwheel, with radial metal spokes and pointed tips bent to point along the circumference of a circle, can be made to rotate if energized by a corona discharge; the rotation is due to differential electric attraction between the metal spokes and the space charge shield region that surrounds the tips.

The quality of outdoor air to be used for dilution and control of indoor air pollution has been defined, not only in terms of the EPA primary standards, but also in terms of other recognized guidelines and professional judgment. Values for minimal and recommended ventilation rates have been replaced with required values for smoking and nonsmoking areas. Nonsmoking areas have proposed values similar to the existing minimal values, and those for smoking areas are similar to or greater than the values currently recommended.

A method has been specified that will determine the amount of recirculation air required to compensate for allowable reductions in outdoor air. The amount is determined as a function of air-cleaner efficiency. The operation of mechanical ventilation systems during periods of occupancy is specified as a function of the source of indoor pollutants. An alternative method specifies both objective and subjective criteria for indoor air-quality, but the method of achieving control is left to the discretion of the operator.

design guidelines for indoor corona devices to meet ozone regulations

With the advent of performance criteria for indoor pollutant control, conflicts between various codes and standards could become more intensive. As a result, the designer or operator of a system has the responsibility of reviewing the relevant documents and then deciding which of them apply.

In many cases, the values in these codes and standards will not be consistent. Thus, it can present a challenge to the building designer and operator to select a ventilation rate that will meet the requirements of all relevant codes and standards. Under these circumstances, the usual procedure has been to select the largest value that would satisfy the requirements of all the codes and standards.

Because of recent concerns regarding energy consumption and costs, some regulations have been promulgated or proposed that are in direct conflict with those promulgated to protect the health or comfort of occupants; an example is the Assembly Bill of Wisconsin, Ventilation Requirements for Public Buildings and Places of Employment.

Corona discharge

Bill would have eliminated mandatory minimal ventilation requirements specified in the state building code i. Building owners would have been allowed to close or otherwise regulate outside-air intakes to conserve energy during these periods.

Bill was passed by the General Assembly and vetoed by the governor; the veto was overridden by the Senate and sustained by the House. This legislation was reintroduced as a rider to an appropriations bill in the General Assembly. It was later amended to allow reduced ventilation only through adminstrative action; in that form, it passed.

Corona discharge - Wikipedia

The state Department of Industry, Labor and Human Relations, previously responsible for ventilation requirements, will administer the law. A summary of the most commonly cited ventilation codes and standards is shown in Table IX The ASHRAE standard, in turn, defers to other standards or codes when they have precedence and require higher ventilation rates. The higher rates are for bathrooms and kitchens and are for intermittent operation. The MPS also set intermittent exhaust rates in kitchens and baths at 15 and 8 ach, respectively.

The revisions of the MPS allow ventilation by infiltration rates of 0.

Corona Demonstrator

Although the ventilation rates are specified differently in these voluntary standards, the results are intended to be equivalent. Moreover, the revisions to the MPS and the values in Standard 62— are in close agreement with values recommended internationally.

However, the minimal supply-air rate i. Standard 62— specifies required ventilation rates of 5 cfm 2. Laboratories Specific controls for ventilation in laboratory spaces are required for protection of the health and comfort of laboratory personnel and for the preservation of specimens and critical experimentation conducted in the facilities. A differential in air pressure may be required between laboratory areas and public spaces, such as meeting rooms and reception areas, to protect the general public.

Thus, the nature of ventilation control is more complex in these facilities than in most other indoor environments. Toxic and hazardous materials used in the laboratory must be controlled to within the limits prescribed by OSHA.

The Animal Welfare Act 74 specifies many procedures for the care and handling of the animals, but is vague and nonspecific about environmental control in the laboratory or the cage. These outdoor-air requirements may be reduced by two-thirds for mechanical ventilation systems with adequate particle filtration. Sincethese regulations have allowed recirculation in sensitive areas, such as operating rooms.

design guidelines for indoor corona devices to meet ozone regulations

However, changes have occurred in the specified number of air changes per hour of supply air and the percentage of outside air. Appropriate air-pressure relationships must be maintained with respect to adjacent areas.

When this feature is used, positive provisions, such as an electric interconnect between the ventilation system and room lights, must be included, to ensure that the specified ventilation rates are automatically resumed when the rooms are reoccupied.

Standard 62—73 specifies ventilation rates for hospitals and nursing and convalescent homes in terms of minimal and recommended cubic feet per minute per person and allows reductions in the use of outdoor air to one-third of the specified values when mechanical ventilation is used.

Ozone Generator Hazards

Health Considerations Unfortunately, the same chemical properties that allow ozone to alter organic material in household air also give it the ability to react with organic material inside the human body. Even low levels of ozone exposure can cause the following conditions: People's susceptibility to ozone varies widely. An ozone generator should never be operated in occupied spaces, and the area should be adequately vented before people or animals are allowed to re-enter.

Also, from the toxins with which ozone does react, there is a potential for the creation of new, potentially more dangerous toxins. For example, ozone mixed with chemicals from new carpet can create aldehydes, which can irritate the lungs. Other reactions may create formic acid, another irritant.

design guidelines for indoor corona devices to meet ozone regulations

The potential for chemical reactions in the average house is difficult to predict.