In general, most air filters should be changed every 90 days or 3 months. However, this can vary depending on the location of your home, if you have pets, and the age of your system and equipment. If you have pets in the house, you should consider changing the filter every 60 days or 2 months. For homes with multiple pets or people with allergies or respiratory conditions, we recommend changing the filter every 20 to 45 days.
Vacation homes or vacant homes that don't get much use can wait to change the filters every 9 to 12 months. This guide covers portable air purifiers and boiler or HVAC filters used in the home. It includes tips for selecting a portable air filter, oven filter, or HVAC filter. If chemical disinfectants are used, they should only be applied with the air conditioning system turned off.
In addition, disinfectants should not be applied to ventilation filters before continuing to use filters within ventilation systems. The effects of disinfectants on filter performance are unknown. Filters should only be treated with disinfectants if they are going to be removed from service and discarded. UV systems are quite effective at maintaining the cleanliness of HVAC coils, drain trays, and other damp surfaces.
Properly designed systems can be very effective at inactivating microorganisms in moving air currents on the fly. These systems generally require more lamps so that they can provide significant doses of UV in a short period of time. A typical single-pass inactivation efficiency is 85%, much like that of a good particulate filter, but systems can also be designed for inactivation greater than 99.9%. In addition, a well-designed UV air disinfection system within an HVAC system and located next to the cooling coils can also provide surface disinfecting benefits. Another way to install UV is in an “aerial” configuration.
Specially designed wall-mounted accessories create an irradiated area above the occupant and disinfect the air in the space as the air circulates naturally, mechanically or through the HVAC system. The CDC has approved this type of system for use in TB control for nearly 20 years, and there is guidance from the NIOSH on how to design them. Mobile UV systems are frequently used for cleaning terminals and disinfecting surfaces in health centers and other spaces. Systems like these are normally used in unoccupied spaces due to concerns about occupant exposure. Designing and sizing effective ultraviolet disinfection systems can be a complex process due to the need to determine the dose administered to a moving air stream or to an irradiated region of a room.
Inlet systems are further complicated by the configuration of the air handling unit and ducts and reflections from surfaces, which can help achieve higher irradiance levels. Superior air systems require an adequate air mix to function properly, while paying close attention to reflective surfaces that could cause room occupants to be overexposed to UV energy. Accredited manufacturers and system designers can help by making the necessary calculations and designing specific systems for individual spaces. When the final pressure drop of the operating air filter is approximately twice as large as the initial pressure drop (if twice is too low, another relationship can be established), or when the efficiency is less than 85% of the initial efficiency, the weight of the dust deposited on the air filter is called the standard dust holding capacity of this air filter, which is called dust holding capacity for short. Portable air purifiers typically achieve a high CADR by using a high-efficiency particulate air (HEPA) filter. The strongest filters are reusable, usually with metal frames, and can be cleaned according to the manufacturer's instructions.
The EPA does not certify or recommend particular brands of air filters or household air cleaning devices, including purifiers or portable air purifiers. For example, both the pressure drop and the dust holding capacity are different when the same filter medium is used to make a panel filter, a bag filter, or a wedge filter. The other case is to replace the separator plate with another separator, such as the strip formed by thermosol on filter paper, fireproof silk thread that is submerged, fiberglass thread or filter strip stuck on filter paper. Multimedia filters are very easy to maintain and are great for filtering bacteria and other small airborne contaminants. Before delivery or during characterization, HEPA filters are evaluated with monodisperse particles with a diameter of 0.3 μm which were introduced in previous chapters.
This number is intended to help consumers select an air filter based on size of area it will be placed in. To obtain maximum effective filtration area comprehensively consider several factors including filter thickness, ridge distance, ridge angle and filter material thickness. Common range of metal component content in glass fibrous filter paper (atomic extinction analysis). At end of 20th century problem of boron pollution was raised since approximately 11% component of filter medium is B2O3.
