Filtration systems go back at least to the time of the ancient Egyptians and the peoples of ancient India. Hieroglyphic depictions from the tombs of both Ramses II and Amenophis II suggest that the Egyptians filtered drinking water using sand. They chose sand for this task because it caught and settled suspended particles in the water. Also, we have found ancient texts written in both Egyptian and Sanskrit, such as the Sushruta Samhita, that describe methods with which they purified water, including heating under the sun, boiling, and running through gravel.
Another important society in the ancient world that practiced filtering (to an extent) was Greece. Around 500 BC, the Classical Greek physician Hippocrates invented the first bag filter or sieve. This filter, which we now call a Hippocratic Sleeve, was a cloth bag through which he poured boiled water. By filtering the water with his filtration device, he was able to remove sediments from the water that would create bad smells or bad tastes. He used filtered water as bathwater for sick patients.
Between Antiquity and the Industrial Revolution, very little changed in filtration on the European continent. However, in the 8th century in the Middle East, an Arabian alchemist named Gerber came up with several new water purification strategies. His methods involved the use of stills connected to wick siphons, which purified water as they drew it from one still to the next.
After the Dark Ages passed, scientists began experimenting with filtration systems again. First, in the 1500s, scientists created the first air filtration systems, which functioned as respirators.
In 1627, an Englishman named Sir Francis Bacon started exploring how he might desalinate, or remove the salt from, saltwater. He tried to do so using sand. Unfortunately for Bacon, his experiments were a failure. However, they did spark further research by others of water and the microscopic organisms that live in it. To that end, in the 1670s Robert Hooke and Antonie van Leeuwenhoek developed the microscope and they were able to see pathogens in the water. This demonstrated to them and others the importance of figuring out how to filter water.
Another important filtration related discovery of this time was the discovery of reverse osmosis. Though Jean-Antoine Nollet first observed this in 1748, scientists wouldn’t put it to use in filtration processes until the mid-1900s.
Throughout the 19th century, many scientists made important breakthroughs in filtration. In 1804, John Gibb, a Scotsman from a town named Paisley, successfully used sand filtration to reclaim water and sell it. Similarly, in the early 1800s, many people used ceramic filters to purify their water. By 1830, London had its first water treatment plant.
While manufacturers did make some rudimentary air filter products in the early days, they did not really become popular until after World War II. In fact, the U.S. Army Chemical Corps and the U.S. Atomic Energy Commission designed the HEPA filter during WWII for protection against radiation while they were working on the Manhattan Project. Once the war ended, the American government allowed access the HEPA filter designs, and manufacturers quickly began manufacturing these products for use in both industrial and home applications.
As time went on, manufacturers and scientists developed better filter medium materials and more efficient filter systems in general. During the 1970s, the prevention and reduction of air pollution and water pollution became a point of interest, and the government issued a number of laws reflecting that. The Clean Water Act of 1972, for example, mandated that industrial manufacturers develop better procedures for capturing waste so that it wouldn’t enter the water source. Since then, air cleaners and industrial water filtration systems have only become more important. They have also become important for high stakes applications like aerospace and aeronautics.
How It Works
Material separation does not occur in the same way in every filtration system. For example, some systems work by suspending solids. Meanwhile, membrane filtration systems use media to trap contaminants as they pass through the filter. Some systems trap contaminants in foam. Other filtration options use centrifugal force, gravity, and even biological filtration agents or electrically charged particles. They may also employ hydrostatic or rotational pressure in order to remove heavier particles.
Vacuum filters work by creating pressure at the outlet of the filter media that is higher than the pressure in the outside atmosphere. In other words, vacuum filters create a vacuum. This causes the outside to push itself into the vacuum, where it encounters the filter media.
Pressure filters do their work by applying pressurized fluid or compressed air to force a fluid stream through their filter media. As the stream moves through the filter media, the media catches and removes any suspended debris and separates out unwanted materials.
Membrane filtration is a popular type of filtering system that makes use of a thin sheet to strain liquids.
In-line filters are filters installed along flow lines. Their job is to catch contaminants and prevent system clogging.
Chemical filters dissolve contaminants by pulling them out of the solution as it flows through the filter.
Biological filters can be used to remove organic compounds, but this function is less common.
Two different types of filtration systems use an electrical charge to cleanse air or fluids: electrodialysis systems and electrolysis reversal systems.
Electrodialysis systems (ED) have membranes that allow either negatively charged or positively charged ions to flow through. Note: they do not allow both ion types to flow through.
Electrolysis reversal systems (EDR) work in a similar way. However, EDRs periodically reverse the current in order to generate a fresh flow.
Other less common types of filters are reverse osmosis (RO), ultrafication (UF), and electrodeionization (EDI). Although these are all less common than ED or EDR systems, they are just as efficient and come with their own distinct advantages.
Reverse osmosis systems work by pushing pressurized water through a membrane. They block any impurities from coming along with it.
Ultrafication filters are designed to remove particles and organisms sized between 0.003 and 0.1 micrometers. Examples of organisms this size include viruses and bacteria.
Electrodeionization filters use a combination of electricity, membranes, resin, and ion exchange. To purify water, they deionize it and remove the dissolved ions.
Progression filtration systems are a good choice in industries where solid recovery is a priority. This is because these systems sort contaminations based on its size.
Oil filtration systems are filtration systems designed specifically to filter oil. They are staples of equipment that run on oil, like cars, trucks, manufacturing equipment, and agricultural equipment. Oil filtration systems remove particles from all types of oil, including hydraulic oil and motor oil.
Coalescing filters are another specific filter type designed to meet particular specifications. Coalescing filters catch and remove mists, vapors, and oils from process air streams.
Water filters remove contaminants, microorganisms, and particles from tap water, drinking water and wastewater. In systems that produce ice and water, they can also serve as refrigerator water filters.
Pool filters are a type of water filter designed specifically to clean pool water. These water filters are usually designed as small and removable cartridge filters.
HEPA filters, or High Efficiency Particulate Air filters, are filters designed to remove up to 99.999995% of particles they process. They are important for use in airplane cabin ventilation, industrial vacuum systems, respiration, and more. To be considered HEPA filters, they must be certified.
Design and Customization
When designing and customizing filtration systems, manufacturers must consider a wide range of application specifications, such as the stream to be processed, the particles/contaminants to be filtered out, the setting (in the home, in a factory, in a hospital, etc.), and the standard requirements.
Based on what is being processed, what the filter is intended to capture, and the particle size, filtration system manufacturers can decide on the filter pore sizes.
Manufacturers also use these details to consider the best filtration rate, which is the rate at which a stream can move through a filter as it provides maximum particle separation/removal. To reach the best filtration rate, manufacturers may place the filter at the intake, inline, or exhaust of a system. Sometimes, they may place multiple filters at all of these points. By using multiple filters in a flow, particles can be separated and removed several times over. Not only will this improve the quality of the product, but it allows the filters to function with more efficiency, since they are not being regularly clogged with large particles.
Based on the variables such as filter location, filter rate, load capacity, absorption, and so on, manufacturers can decide what filter media is best.
Common materials manufacturers use to manufacture filter housings/filter cartridges include aluminum, plastic, steel, and stainless steel. Common materials manufacturers use to make filter media include carbon, Teflon, resin, nylon, sand, and synthetic fibers. Each offer something different. Carbon, for example, is great at removing chlorine, volatile organic compounds, bad smell, and odors from water.
Safety and Compliance Standards
Different filters must meet different standards based on their location and application. A wide variety of organizations, such as ASTM, ANSI, and the ISO’s Technical Committee 131, put out filtration system standards that some organizations use as a baseline. For example, ANSI partners with the American Society for Healthcare Engineering to put out standards that pertain to filtration systems used in hospitals. Also, HEPA filters must meet the standards of both the U.S. Department of Energy (DOE) and the National Institute for Occupational Safety and Health (NIOSH). To learn about the standards, you should make sure your filters meet, talk to your industry leaders.
Choosing the Right Manufacturer
One of the best ways to prepare yourself before searching for a filtration system manufacturer is to take time to write down all of your specifications. This includes not only the filter use and process stream details, but also the nitty-gritty stuff, like your price point, your project deadline, your standard requirements, your delivery preferences, your installation assistance, and other post-delivery preferences. It’s also a good idea to discuss whether or not the manufacturer issues replacement filters, and how much they cost.
With a list like this, you can quickly eliminate those filter manufacturers that will not work for you and determine those with potential. Of course, even with a list, you may still feel overwhelmed because there are so many suppliers advertising themselves on the internet. To help assuage any anxiety, we have compiled a list of some of the best filtration system manufacturers in the business. Check them out by scrolling up. You will find their profiles wedged in between chunks of information. Good luck!