Filtration technology is a great way to separate and concentrate fluids like water, chemicals and gasses. This can help ensure that a product is free of contaminants and meets hygienic standards.
There are several different factors to consider when selecting the best filtration system for your needs. Some of the most important considerations include: Micron rating, Chemical compatibility, and Pressure capacity.
Filtration Media
Filtration media is a powdery substance that is the unsung hero of water filtration systems. This material is used to remove specific contaminants and it is the key to ensuring that you get the best water possible.
Most filtration media is made from sand, organics, natural stone fibres, and other natural materials that are able to effectively separate solids, organic matter, and soluble substances. These media are designed to act as a filter through a combination of physical capture and chemical and molecular action. Depending on the type of contaminant, it will either be trapped in the pore structure of the filter medium or it will be adsorbed onto the surface.
Activated carbon is another commonly found filter medium. It is created by heating organic material such as coal, wood, coconut shells, and more, which results in a char that binds to certain toxins, removing them from the water. It’s important to note that not all activated carbon is created equal, so it is vital to research your options before purchasing this type of filter.
Reverse osmosis is another popular type of filtration that pushes water through a semi-permeable membrane that allows water molecules to pass while capturing water-soluble toxins. This process is also able to reduce the amount of chlorine, heavy metals, and hydrogen sulfide that is in drinking water.
Micron Rating
A filter’s micron rating describes how small of a particle it can trap. A micron is one-millionth of a millimeter or around 0.000039 inches. To put that in perspective, a human hair is about 70 microns in diameter and bacteria are even smaller. A micron rating can also help you determine what type of particles your filter is designed to trap. For example, a higher micron rating may be more effective at eliminating sediment that can make ice cubes cloudy and cause commercial ice equipment to fail. A lower micron rating, however, is better for removing bacteria and other microscopic organisms that can cause health problems when ingested over time.
There are two main types of micron ratings: absolute and nominal. Absolute filters prevent all of the particles that match their micron rating, while nominal filters provide an indication rather than a guarantee of how many contaminants they’ll eliminate. Nominal ratings are often found in carbon filters and can vary depending on the manufacturer, water chemistry and concentration of the contaminant being tested for.
When shopping for a filter, it’s important to consider what type of impurities you’re trying to remove. The higher the micron rating, the more contaminants a filter will remove but it’s worth noting that this can sometimes result in a loss of flow rate and require more frequent replacement.
Chemical Compatibility
Chemical compatibility is a measure of how well two substances mix together without any sort of chemical reaction. If they react, it means the materials are incompatible and could cause damage or degradation to the device. This is why it is important to consider the chemical compatibility of the components in a system.
This includes the material of the housing and the filtration media. It is also important to think about the pore size. The smaller the pore size, the finer the filtration. This is particularly important if you are filtering out microbes or other small particles.
The strength and durability of a filter are other factors to consider. Nylon monofilaments have the highest tensile strength and felts (POG & PES) are the most abrasion resistant. However, abrasion resistance is affected by chemical exposure so it is important to keep this in mind when selecting a filter.
In addition, it is important to consider the temperature and concentration of the chemicals being used. There are some chemicals that require very low concentrations and other chemicals need to be injected at high pressures. This information should be kept in mind when selecting a system and when changing the chemicals. Any change in chemicals should include chemical, material and performance compatibility testing as part of a specified management of changes process.
Pressure Capacity
Filtration is used in a wide variety of chemical engineering processes for off-gas treatment and to provide high purity gases/compressed air for equipment use. One of the key characteristics that needs to be understood is differential pressure (DP). This is the difference in fluid force (psi) between the clean side of the filter element and the dirty side.
Differential pressure monitoring devices provide real time readings of DP and allow the operator to monitor element condition. These devices usually display a digital readout, often with a graduated scale and color coded segments to indicate “Working within Parameters” or “Service Needed.”
As mentioned above, differential pressure plays an important role in determining the filter’s capability and life span. However, it is also important to understand that the average pressure drop across the filter element can be influenced by factors such as:
The overall membrane design, porosity, pore structure and fleece thickness all impact the filter’s flow rate performance. Flow rates are critical in establishing equipment scheduling and capacity available in a production facility. A 0.2-um rated filter with a low flow rate may require 48 hours to filter a 2,000 L volume whereas a high-flow filter with a similar micron rating might take 20 minutes to perform the same task. This can substantially reduce the amount of time a filter is required to spend in service, dramatically cutting operating costs.