What Types of Supplemental Filters Are Available?

What Are Types of Supplemental Filters Are Available?

There are three types of devices:

  • Gravity-Feed designs In Gravity-Return designs, the oil flows downward out of the device by the force of gravity. Gravity-feed designs must be mounted above the engine’s return port to assure that the oil returns to the engine. Gravity-Return devices must be mounted vertically. The two major types of gravity feed are the centrifuges and the Multi-Component “oil refinery” devices, which include an oil heater and a chemical pack.
  • Pressure-Return designs In a Pressure-Return device, the oil exits the device under pressure and is pumped back to the engine. Pressure-Return devices can be mounted either above or below the engine’s return port or below the return port. Many Pressure-Return devices may be mounted either vertically or horizontally. Most canister designs are Pressure-Return devices.
  • Combo Full-Flow/By-Pass designs In a Combo Full-Flow/By-Pass Filter, the space in the canister is divided between full-flow, low density media, and high density media. While this design offers convenience, it compromises both the amount of media usually found in a full-flow filter and compromises the amount of media found in a microfilter installed in a bypass mode. Most combo units are enclosed in throw-away metal containers, usually with synthetic media, which wastes resources compared with a device made with a life-time metal container and renewable resource media.


What is Gravity-Feed Centrifuge?

The centrifuge uses a gravity-feed to return the oil to the crankcase. Technically, the centrifuge is not a filter. It is a mechanical particle separator, which separates out certain particles by rotating (“spinning”) at high speeds to produce a centrifuge action. In large commercial centrifuges, an electric motor and control mechanism maintains the centrifuge speed at a consistent, optimum rotation speed. In the typical centrifuge installed in truck, bus, and automobiles, there is no electric motor or speed control to maintain a consistent optimum spin rate. Instead, the speed varies with the engine oil pressure and the volume of oil from the engine. One problem is that many vehicles, such as transit buses, garbage trucks, or mid-and smaller size trucks used for deliveries in urban environments, do not have consistent engine pressure. A transit bus, for example, will go from idle to major acceleration several times an hour. The oil is sprayed onto a rotating outer bowl, where oil particles are pressed against the bowl. The bowl must be cleaned to remove the particle accumulation. In addition, the device must be removed and partially disassembled to clean the bowl, using a cleaning solution, a process requiring extra time and labor.

Centrifuges have three disadvantages: Filtering efficiency is not constant, installation is difficult, and centrifuges require more maintenance than other devices. Filtration efficiency is lower when vehicles operate in stop-and-go traffic, when the strain on the engine is higher and particle contamination is high. Filtration efficiency is higher when vehicles operate at relatively constant highway speeds, where engine strain is lower and particle contamination is lower. The lower cleaning power during idling and stop and go traffic is a problem for vehicles operated in city traffic, such as city transit buses, with frequent low-speed idling during passenger stops. It is especially problematic in hot weather on transit buses, due to the increased parasitic demands from the air conditioning compressor and generators to cool the bus and usually higher passenger loads. At this time when the engine is under its greatest strain, the centrifuge’s cleaning power is at its lower efficiency. Second, centrifuges are Gravity-Return devices, which are more difficult to install than a canister device. The centrifuge must be installed vertically and most designs require a vacuum connection to the vehicle’s air supply system for the centrifuge’s control mechanism. Third, cleaning a centrifuge device is the most time consuming of all devices, which increases labor costs. A mechanic must remove and clean the centrifuge bowl in special solvents to remove the caked up particles and eventually, the centrifuge’s moving parts also need to be serviced. This adds time, labor costs and creates a new form of contaminated waste in the cleaning solvent. In addition, centrifuges are mechanical devices, which require more maintenance than passive devices.

What is a Canister Filter?

Canister devices are Pressure-Return devices. Some canisters are one-piece designs, similar to a full-flow filter, enclosed in a thin metal housing, designed to be thrown away after one use. Other canister designs consist of a permanent canister and a disposable cartridge. Canisters are passive, non-mechanical devices, where particles are trapped in a disposable cartridge. Canisters vary in size, filter efficiency, and cartridge retention capacity. Canisters are easier to install and less expensive to maintain. Inside the metal canister housing, there is a removable filter cartridge. The early canisters were not very efficient. These early canisters often used paper towels for media, had limited cleaning power in the CLP range and media structural integrity problems. In addition, the early paper-towel canisters were very large, some retaining up to two gallons of oil. The major difference among the canister microfilters can be found in the design of the cartridge. ECO MicroFilters use 16-gauge steel exterior canister housing. Inside the canister there is a removable, patented, ultra-high efficiency cartridge.

What is an “Oil Refinery” Bypass Filter?

The “Oil Refinery” designs are Gravity-Feed devices. Some manufacturers add one or two components to their filter media and label the multi-function devices as “oil refineries.” Marketing a bypass device as an “oil refinery” overstates the device’s abilities, as one can see by examining the process in an actual oil re-refinery facility.

How does an Actual Oil Refinery Facility Operate?

An oil re-refinery plant is a large processing facility. Re-refining oil is a sophisticated process involving chemical pre-treatment, dehydration, vacuum distillation, hydro treating, fractionation, and hydro finishing. This process creates the lubricating “base oil”, which makes up approximately 80% of the lubricating oil. Next, the re-refined base oil must receive the other 20%, which consists of a mixture of chemical additives designed for the various oil specifications. These additives can not simply be poured into the base oil. Another process, called a blender operation, is required to produce the final product of re-refined lubrication oil.

What Add-On Features do “Oil Refineries” Provide?

These devices usually add a heating element and a chemical pack. The three components in the “oil refinery” are: (a) a canister portion with a filter element. This can provide adequate filtration, depending on the specific characteristics of the media used, which varies from one manufacturer to another, (b) an add-on heating device. A separate electrical connection is required to provide electrical power to the device, and (c) an add-on chemical pack, which adds chemicals to the oil as the oil circulates.

Why do “Oil Refineries” Heat the Oil?

The purpose of heating the oil is to flash off water vapor . This feature provides limited value. The moisture in cold engine oil quickly evaporates when the engine reaches operating temperature, vaporizing the moisture, allowing it to be vented from the engine. After the engine warms up, lubricating oil even is briefly exposed to temperatures in excess of 300F degrees when it circulates around the combustion areas.

Can Adding Heat Harm the Lubricating Oil?

Yes. High lubrication oil temperature causes oxidation, which degrades the oil. When the engine temperature is raised by 10 degree C, the rate of oxidation approximately doubles. Due to the negative effects of high oil temperature, engine manufactures seek to reduce oil temperature, not to raise it. Most heavy-duty equipment and performance automobiles use oil coolers to cool the oil. It is important to make sure that the oil refinery heating element is not adding heat to the oil when the engine reaches operating temperature.

What Precautions are Needed Before Adding Chemicals to Lubricating Oils?

Oil sampling and testing are required to determine the characteristics and condition of engine oil before pouring any chemicals into the oil. There are many different types of lubrication oil, each with its own complex additive formulations. Adding the wrong chemicals may cause a serious negative reaction, such as creating non-conforming viscosity, chemical degradation and the destabilization of the lubrication oil. It is important to determine if the chemicals added by the various “oil refinery” devices are compatible with the fleet’s engine oil.

What Type of Supplemental Filter is Easiest to Install?

The compact canister-type designs, such as ECO MicroFilters are easiest to install. Large canister designs are heavy, and do not fit within many engine compartment, such as in the popular diesel work trucks. Also, the large canisters often require a gallon or more of make-up oil each time the large, rolled paper towel-like cartridges are changed.

The canister designs are easier to install. Both the oil refinery and the centrifuge must be installed vertically. In both designs, the oil flows back to the engine by gravity. This means that the centrifuges and oil refineries must be installed above the height of the engine’s oil return port. It sometimes is not possible to find a location in a cramped engine compartment. Canisters, on the other hand, have pressure oil returns and can be installed below the return port. ECO MicroFilters can be installed either vertically or horizontally, above or below the return port because the oil returns under pressure, not by the draw of gravity.

Many centrifuge designs require a vacuum pressure connection. Oil refineries require an electrical connection. Among the devices on the market, the ECO MicroFilters compact canisters (various sizes depending on the size of the engine) are the easiest to install.

What is the Ideal Microfilter Cartridge?

The ideal cartridge must have three essential characteristics: (1) High Beta Ratios at the target micron sizes, such as the CLP range (1-10 microns), (2) High retention, the ability to hold a large amount of contaminants, and (3) High structural integrity to prevent media distortion, such as caking, surface build-up, or particles circumventing the filtering media, such as channeling and rupturing.

Is Filter Retention a Serious Problem?

Yes. Some cartridges claim high Beta Ratios but can not deliver high retention. As a result, they operate at reduced flow rates under real-world conditions and will not deliver the specified efficiency over the full oil drain interval.

What Factors Effect Structural Integrity?

The microfilter operates with oil flowing though it at a temperature of 180F degrees or higher, and an operating pressure of 55 PSI and higher when the engine accelerates. In addition, vehicles are subjected to bumps and jolts, which can jar the filtering media, causing channeling and rupturing. The ECO MicroFilters cartridge uses a wound cord design, which has more structural integrity than pressed cotton or rolled paper designs.

What is Filter Caking?

Filter caking is the build-up of contaminates around the surface of the media. One challenge in filter design is with high efficiency media will provide efficient cleaning but it also will clog more quickly due to caking around the circumference. If the media is a fine 4-micron media, then particulates will build up around the exterior surface, which will quickly choke off the flow of oil. This causes a short filter life. Using a 15-micron media will provide longer life but reduce cleaning of the smaller particles. In addition, under real-world conditions, cartridges prone to filter caking frequently have other structural weaknesses, which allow the particles to re-contaminate the oil. When a bus or a truck hits a pothole or other sudden jolting event, the cartridge is jolted. When jolted, often the contaminants caked around the circumference of the cartridge are dislodged. If the cartridge is also subject to channeling or rupturing, then the oil will be re-contaminated.

What is Channeling?

Channeling occurs when the oil entering the device creates a path through the cartridge back to the oil return, avoiding going through the filter media. When channeling occurs, filter capacity drops dramatically because most of the oil is not being filtered at all. It is simply starting at the surface, following a stream down to the return port on the device and returning to the engine unfiltered. Cartridge designs most prone to channeling are the compressed media designs.

What is Rupturing?

“Rupturing” is one of the most serious challenges. Rupturing occurs when the filter media collapses or the media tears. This can occur when the media design lacks structural strength, sufficient to withstand not only the 45-PSI usual operating pressure but also the high start-up pressure that can exceed 80 PSI. A ruptured media is broken open and does not provide filtration.

ECO MicroFilters cartridges prevent channeling and rupturing with an overlapping, criss-cross winding pattern, which prevents the formation of open spaces that allow channeling. The oil cannot avoid passing through the media. The winding design also prevents rupturing by providing greater structural integrity to the media.

How often is the ECO MicroFilters Cartridge Changed?

ECO MicroFilters are changed at the oil drain interval. For some fleets, the normal oil interval is based upon the number of hours of engine operation, for example, 150 hours of engine operation. In other fleets the oil drain interval is based on mileage, for example, 6,000 miles.

At the vehicle first oil drain interval after an oil change (for example, 150 hours or 6,000 miles), only the ECO MicroFilters cartridge is changed. At the second interval, (300 hours or 12,000 miles), a full oil change is performed. Using this process will reduce the number of oil changes. If currently there are ten oil changes per year, the number of oil changes will be reduces to five.

Why is Oil Analysis Important?

To assure oil quality, ECO MicroFilters recommends regular oil sampling and analysis. Regular oil sampling assures a scientific, condition-based oil change program. Based upon oil analysis, the oil should be changed if anything abnormal is indicated, such as coolant contaminating the oil. On the other hand, if the oil remains viable, the oil drain interval can be extended. Some garages now are equipped with oil analysis machines to provide quick feed-back.

What Type of Microfilter is Easiest to Maintain?

Canister-type designs are the easiest to maintain. ECO MicroFilters products only require unscrewing the cartridge and installing a new cartridge. The used high efficiency cartridge can be crushed in the fleet’s filter crusher, which squeezes out the used oil and creates a smaller form factor. The used cartridges can be disposed of in the same way as a full-flow filter.

Will Using ECO MicroFilters Void My Warranty?

No. Installing a microfilter does not void the warranty.

Will ECO MicroFilters Work in Most Engines?

Yes. ECO MicroFilters provides devices to fit virtually any engine, from a small automobile engine to a large commercial diesel. Our products are used in transit buses, cement mixers, construction equipment, police cars, commercial boats, small and large electrical generators, and ambulances.


What can I do?

See ECO Microfilters Bypass Oil Filtration Systems