With the vast array of industrial cartridge filters available on the market today, it can be difficult for an engineer to figure out what shape, size, and type is right for his or her specific filtration need. The fact that most cartridges have complicated, jargon-filled names like “2.5 DOE” and “Type 226 Option G” can add another layer of confusion to the decision making process. In a continual effort to educate our customers and provide them with information that is applicable to their responsibilities, we have created this guide to clarify cartridge filter terminology and hopefully simplify your business’ ordering and re-ordering process.
DOE vs. SOE Cartridge Filters
One of the most common and simple classifications of cartridge filters is as either DOE or SOE. They both have their own advantages and disadvantages:
- DOE – The most common filter cartridges found are DOE, or Double Open Ended. These cartridges have no built in seals on either end, thus the name. Instead the filter cartridge housing is relied upon to seal one side and stop contaminants from bypassing the cartridge.
- SOE – As the name indicates, Single Open Ended cartridges have one end sealed. This seal is usually accomplished by using a polyporpylene cap. By using a cap on one end, filter bypass is impossible, so systems that require higher purity filtration typically implement this type of cartridge filter. The higher cost associated with the end cap prevents this type from being used in general applications.
Cartridge Filter Naming Terminology
In addition to the SOE and DOE divisions, industrial cartridge filters can be named by type, function, or after a component of the filter.
- Type 222 – This type of filter is almost always SOE, utilizing a cap on one end. They contain double gaskets that seal against the cartridge filter housing to provide better bypass protection than a typical DOE cartridge.
- Type 226 – Also known as sanitary cartridge filters, Type 226’s have double gaskets which are similar to the Type 222. Locking fins are included with this type of cartridge, which ensure proper installation of the filter. When installing this type of cartridge into the sanitary cartridge filter housing, it must be properly lined up with the opening and twisted as it is pushed in. This ensures a full lock and proper bypass protection.
- Flat End – Typically used with DOE and Type 222 compatible cartridge filter housings, flat end cartridges are SOE with a flat plastic cap used for the seal.
- Spear – An SOE cartridge with a pointed cap instead of a flat one. It utilizes a bracket to eliminate the ability of the cartridge to sway, allowing it to maintain a seal. Type 226 cartridges may also have this end configuration.
- High Flow Cartridges – Designed for high flow rates, these cartridges have a much larger surface area than standard cartridges. Most are 6.5″ diameter by 40″ long with a maximum flow rate of 350 gpm, whereas standard 2.5″ diameter by 10″ long cartridges have a maximum flow rate of 5 gpm.