Air Filters – Everything You Need To Know
There are two methods of air filtration in use: adsorption and diffusion. The former relies on the inertial impaction of particles in a fast fluid. Distribution creates a permanent state of Brownian motion within the filter, where a given contaminant will repeatedly circle a filter until a vent is removed. Diffusion is the more complex of the two processes. This article will explain how each method works and why it’s essential. You can also learn more about this personally from the distributors in your area, like air filter supplier Richmond for example.
MERV Rating
To make the best choice for your HVAC system, consider the MERV rating of an air filter. An air filter with an eight or lower MERV rating is adequate for residential use, but a filter with a higher MERV rating will be more effective. Higher MERV ratings scrub out more air contaminants, including pet dander and bacteria. Higher MERV ratings are better for people with allergies and asthma, and those with lower MERV ratings can save money on their energy bills.
MERV ratings indicate the effectiveness of an air filter’s ability to capture large particles. The largest particles in the air are between one and 10 microns in size. The smaller particles sized below one micron make up the majority of indoor air pollutants. Therefore, the MERV rating is divided into three ranges based on the size of these particles. For example, E1 filters are designed to capture particles that are 0.3 to 1.0 microns in size, while E2 filters are designed to capture particles between one and three microns.
Dust Spot Efficiency
The ASHRAE 52.1-1992(153) standard aims to provide a relatively rapid test procedure for evaluating the performance of ventilation filters. The test involves the comparison of two target filter sheets that are rated according to their efficiency in capturing atmospheric dust. The upstream and downstream target filter sheets will discolor at different rates. The result is the “ASHRAE atmospheric dust spot efficiency.”
The MERV ratings are determined by introducing a variety of particles into a standardized test environment. A laser particle counter samples the air before and after the filter. Then the numbers are compared, and the filter’s Particle Size Efficiency (PSE) is calculated. The difference in performance between the two samples is presented on the MERV Rating Chart. If you’re unsure which filter is best for your needs, you can always refer to the MERV Parameters chart.
Most Penetrating Particle Size
The most penetrating particle size of air filters is 0.3 micron. Therefore, if the filter is effective at this size, the efficiency will translate to the other particle sizes. In general, particles larger than 0.3 microns are filtered more efficiently than those smaller. A typical atmospheric air sample comprises hundreds of thousands of particles that are 0.3 microns in size.
To determine the most penetrating particle size of an air filtration device, it is best to find a product with a 0.3-micrometer rating. This will give you a better idea of whether the size range of your filter is adequate. Furthermore, this criterion will help you decide which product to purchase based on the size range. If the size of the particles is smaller than 0.3 microns, you should buy a filter with a higher filtration efficiency.
HEPA Filter
A HEPA air filter traps dust particles in three ways: high-speed advection, interception, and diffusion. High-speed advection traps larger contaminants directly into the fibers, while low-speed advection traps particles randomly. All three mechanisms work together to trap dust and pollutants. Combined, these three methods can trap up to 97 percent of airborne particles. Ultimately, this results in cleaner air and a reduced risk of sickness.
A typical HEPA filter is made of white paper-like fiber material wrapped around an orange plastic case. This allows the filter to fold up to increase the surface area in contact with the airstream without reducing airflow. HEPA air filters also feature a gradient composition of synthetic fibers. These filters also work silently. They are effective in both offices and classrooms, as they are virtually inaudible.
Ionizer Air Filters
Ionizer air filters work by producing an ionization field. You should avoid buying an ionizer that produces a corona discharge, as this will cause high ozone levels. Ozone is a very reactive gas, and it will disinfect unoccupied spaces. A corona discharge is the opposite of ionization. The ions produced by an ionizer filter are negative charges.
The ionization process can leave dust on surfaces, making it harder for humans to breathe. Electrostatic air filters have a significantly poorer performance than HEPA filters. Electrostatic air cleaners also make the surrounding area dusty, and people may re-release the particles they collect. Moreover, the charged particles can stick to surfaces and end up in their lungs. Ask a doctor if you are unsure whether an ionizer air filter is right for you.
