Environmental Sciences Fair Project
Compare the Effectiveness of Furnace Air Filters


Projects by Grade Level
1st 2nd 3rd 4th 5th 6th
7th 8th 9th 10th 11th 12th
Home Advanced Award Winning Warning!
Project Information
Title: Comparing the Effectiveness of Three Types of Furnace Air Filters
Subject: Environmental Sciences
Grade level: Middle School - Grades 7-9
Academic Level: Ordinary
Project Type: Experimental
Cost: Low
Awards: None
Affiliation: Selah Intermediate School
Year: 2006
Description: Three different types of air filters used in home furnaces were examined. A triple beam balance was used to weigh the unused filters before using them and again after 3 weeks of use. The difference was the amount of particulate collected.
Link: www.selah.k12.wa.us...
Background

An air purifier is a device which removes contaminants from the air. Air purifiers for residential use are commonly marketed as being particularly beneficial to allergy sufferers and asthmatics, and at reducing or eliminating second-hand tobacco smoke.Commercial grade air purifiers are manufactured as both a small stand-alone unit, and as larger units that can be affixed to an air handler unit (AHU) or to an HVAC unit found in the medical, industrial, and commercial industries.

Dust, pollen, pet dander, mold spores, and dust mite feces can act as allergens, triggering allergies in sensitive people. Smoke particles and volatile organic compounds (VOCs) can pose a risk to health. Exposure to various components such as VOCs increases the likelihood of experiencing symptoms of sick building syndrome. Additionally, with the advancement in technology, air purifiers are becoming increasingly capable of capturing a greater number of bacterial, virus, and DNA particulates. Air purifiers are used to reduce the concentration of these airborne contaminants and though very useful for people who suffer from allergies and asthma, technological and scientific studies are finding that poor air quality is more a contributing factor of some forms of cancer, respiratory illnesses, COPD, and other pulmonary infections and illnesses. They also reduce the need for frequent room and area cleaning. Air purifiers use a small amount of electrical energy, causing a small amount of expense and environmental effect.

Several different processes of varying effectiveness can be used to purify air. Different processes may remove different contaminants, so there is advantage in using more than one process in a purifier.

Ultraviolet germicidal irradiation- UVGI can be used to sterilize air that passes UV lamps via forced air. Air purification UVGI systems can be freestanding units with shielded UV lamps that use a fan to force air past the UV light. Other systems are installed in forced air systems so that the circulation for the premises moves micro-organisms past the lamps. Key to this form of sterilization is placement of the UV lamps and a good filtration system to remove the dead micro-organisms. For example, forced air systems by design impede line-of-sight, thus creating areas of the environment that will be shaded from the UV light. However, a UV lamp placed at the coils and drainpan of cooling system will keep micro-organisms from forming in these naturally damp places. The most effective method for treating the air rather than the coils is in-line duct systems, these systems are placed in the center of the duct and parallel to the air flow.

Filter-based purification traps airborne particles by size exclusion. Air is forced through a filter and particles are physically captured by the filter.

HEPA filters can, by definition, remove at least 99.97% of 0.3-micrometer particles, and are usually more effective for particles which are larger or slightly smaller. They are effective down to 0.01 micrometers in many cases, but become very ineffective for particles smaller than 0.01 micrometer. HEPA purifiers which filter all the air going into a clean room must be arranged so that no air bypasses the HEPA filter. In dusty environments, a HEPA filter may follow an easily cleaned conventional filter (prefilter) which removes coarser impurities so that the HEPA filter does not need to be changed or cleaned frequently. HEPA filters do not generate ozone or other harmful byproducts.

Filter for HVAC at MERV 13 or above can remove airborne particles of 0.3 micrometers or larger. A medium efficiency MERV 13 has a capture rate of 75% for particles between 0.3 to 1.0 micrometers. Although the capture rate of a MERV filter is lower than that of a HEPA filter, a central air system can move significantly more air in the same period of time. Using a high-grade MERV filter can be more effective than using a high-powered HEPA machine at a fraction of the initial capital expenditure. Unfortunately, most furnace filters are slid in place without an airtight seal, which allows air to pass around the filters. This problem is worse for the higher-efficiency MERV filters because of the increase in air resistance. Higher-efficiency MERV filters are usually denser and increase air resistance in the central system, requiring a greater air pressure drop and consequently increasing energy costs.

Activated carbon is a highly porous material that can adsorb volatile chemicals on a molecular basis, but does not remove larger particles. It is important to note that the adsorption process when using activated carbon must reach equilibrium thus it may be difficult to completely remove contaminants. Activated carbon is merely a process of changing contaminants from a gaseous phase to a solid phase, when aggravated or disturbed contaminants can be regenerated in indoor air sources. Activated carbon can be used at room temperature and has a long history of commercial use. It is normally used in conjunction with other filter technology, especially with HEPA. Other materials can also absorb chemicals, but at higher cost.

Photocatalytic Oxidation (PCO) is an emerging technology in the HVAC industry that has great potential for application toward improvement of indoor air quality. In addition to the prospect of IAQ benefits, it has the added potential for limiting the introduction of unconditioned air to the building space, thereby presenting an opportunity to achieve energy savings over classical prescriptive designs. As of February 2007 there was disputable concern raised by Lawrence Berkeley National Laboratory that PCO may increase the amount of formaldehyde in real indoor environments. As with other advanced technologies, sound engineering principles and practices should be employed by the HVAC designer to ensure proper application of the technology. Photocatalytic oxidation systems are able to completely oxidize and degrade organic contaminants. For example, Volatile Organic Compounds found low concentrations within a few hundred ppmv or less are the most likely to be completely oxidized. (PCO) uses short-wave ultraviolet light (UVC), commonly used for sterilization, to kill 99.9% of bacteria and viruses. UVC in-duct units can be mounted to an existing forced-air HVAC system. PCO is not a filtering technology, as it does not trap or remove particles. It is sometimes coupled with other filtering technologies for air purification. UV sterilization bulbs must be replaced about once a year; manufacturers may require periodic replacement as a condition of warranty. Photocatalytic Oxidation systems often have high commercial costs.

Ionizer purifiers use charged electrical surfaces or needles to generate electrically charged air or gas ions. These Ions attach to airborne particles which are then electrostatically attracted to a charged collector plate. This mechanism produces trace amounts of ozone and other oxidants as by-products. Most ionizers produce less than 0.05 ppm of ozone, an industrial safety standard. There are two major subdivisions: the fanless ionizer and fan-based ionizer. Fanless ionizers are noiseless and use little power, but are less efficient at air purification. Fan-based ionizers clean and distribute air much faster. Permanently mounted home and industrial ionizer purifiers are called electrostatic precipitators

Liquid Ioniser purifiers use a capillary to feed liquid into an ionisation field that creates electrically charged liquid ions. Liquid ions only retain a small enough charge so that they are able to float on the wind whilst still effectively purifying the air. Liquid ions attach themselves to airborne particles in a similar way to air ionizer purifiers. However as liquid is charged rather than air/gas they absorb the pollutants in the air. In the process of creating Liquid ions there are no by-products produced such as ozone or oxidants.

Ozone generators produce ozone, and are sometimes sold as whole house air cleaners. Unlike ionizers, ozone generators are designed to produce significant amounts of ozone, a strong oxidant gas which can oxidize many other chemicals. The only safe use of ozone generators is in unoccupied rooms, utilising "shock treatment" commercial ozone generators that produce over 3000 mg of ozone per hour. Restoration contractors use these types of ozone generators to remove smoke odors after fire damage, musty smells after flooding, mold (including toxic molds), and the stench caused by decaying flesh which cannot be removed by bleach or anything else except for ozone. However, it is not healthy to breathe ozone gas, and one should use extreme caution when buying a room air purifier that also produces ozone.

For more information (background, pictures, experiments and references): Air Purifier

Source: Wikipedia (All text is available under the terms of the Creative Commons Attribution-ShareAlike License)

Useful Links
Science Fair Projects Resources
Citation Guides, Style Manuals, Reference
General Safety Resources
Electrical Safety FAQ
Environmental Sciences Fair Projects

Ecology Science Fair Projects

Environmental Sciences Experiments
Books

         



Projects Home
Primary School
Elementary School
Middle School
High School
Advanced
Easy Projects
Award Winning
Popular Ideas
Branches of Science
Experiments

Science Fair Project Guide
Home
Science Fair Project Types
The Scientific Method - How to Experiment
The Display Board
Topics, Ideas, Sample Projects

Repeat Famous Experiments and Inventions
Science Jokes Science Trivia
Scientists & Inventors

Read for Free
The Science Fair
A Juvenile Science Adventure Novel
by Julian T. Rubin

Human Abridged Wikipedia Articles



My Dog Kelly

Follow Us On:
     

Privacy Policy - Site Map - About Us - Letters to the Editor

Comments and inquiries:
webmaster@julianTrubin.com


Last updated: January 2018
Copyright 2003-2018 Julian Rubin