Want to improve your understanding of filtration? We’re here to help. Here are simple explanations of many common terms you might run across.

A

Additive package

One of the three primary constituents of coolant. An additive package is a mixture of chemicals added during manufacturing to enhance the heat transfer performance of a coolant and protect engine and cooling system components from corrosion, scale and deposits, pitting/cavitation, and foam formation. Additive package formulations are the key distinguishing characteristics among the various coolants on the market. Common types include inorganic acid, organic acid and hybrid formulations. (See also Coolant base.)

Air cleaner

Generally, another term for an air filter housing. Specifically, it is a metal or plastic assembly containing one or more filter elements. It is part of the air intake system and removes contaminants from the air before it goes into the engine. (See Air cleaner, single-stage and Air cleaner, two-stage.)

Air cleaner, single-stage

An air cleaner without a pre-cleaner that contains one filter element, sometimes referred to as the primary element, which removes all the contaminants from the intake air. (Compare with Air cleaner, dual-stage.)

Air cleaner, dual-stage

An air cleaner that includes a pre-cleaner that removes most of the larger contaminants from the air before it reaches the filter element. In this case, the filter element is then the second stage of contaminant removal. (Compare with Air cleaner, single-stage.)

Air restriction indicator

A device used to monitor the service life of an air filter. It indicates when a filter is nearing its terminal restriction and should be changed. It measures the vacuum created when air passes through the filter. A plugged filter will have a higher flow resistance and generate higher pressure loss across the filter at a given flow rate. It is the only reliable means of determining when an air filter should be replaced; visual inspection is not sufficient or reliable. This is important because air filters are least efficient at the beginning of their life, before they have developed a layer of dust cake. Changing an air filter too early or too often can increase maintenance costs in the short term and contribute to engine damage in the long term. Changing them too late can put unnecessary stress on your engine resulting in reduced performance. (See also Dust cake, Restriction and Restriction, terminal.)

Antifreeze

A property of coolant that prevents it from freezing when the engine isn’t in use. This property is imparted by the coolant base. Although this term is often used interchangeably with “coolant” and many products are marketed as “coolant/antifreeze”, “coolant” is the more appropriate term because system cooling is the primary function of the fluid. (Compare with Coolant and Coolant base.)

B

Base or coolant base

One of the three primary constituents of coolant. Its purpose is to lower the freezing point and increase the boiling point of water, one of the other primary constituents. Common bases are ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), glycerin or a mix thereof. (Compare with Coolant, Antifreeze and Additive package.)

Beta ratio (ßn)

A measure of how effectively a filter removes contaminants from a liquid, expressed as a ratio of fractional efficiency at a given particle size. It is the best way of differentiating the performance of today’s high-efficiency filters, particularly those for fuel and hydraulic systems, where protection is most critical. Rather than using a percentage like an absolute rating does, it uses a ratio and is determined by a standardized test (ISO 16889). It is the ratio of “the number of particles upstream of a given size or larger” compared to “the number of downstream particles of the same given size or larger”. The higher the beta ratio, the better the filter performance. Beta ratios are written in a particular way to indicate both the particle size and the ratio. For example, a filter with a beta ratio of 1,000 at 10 microns would be written this way: β10 = 1,000. It means that out of every 1,000 particles 10 microns or larger that enter the system, the filter allows only one to pass downstream of it. This is equivalent to a fractional efficiency of 99.9%. (Compare with Filter rating, absolute and Filter rating, nominal.) Read more about beta ratio here.

Biodiesel blend

A type of fuel composed of a mixture of diesel fuel and biodiesel fuel. Biodiesel blends are designated by a “B” factor, which indicates the percentage of biodiesel in the blend. It takes the form BX, where the X is a numeral that indicates the percentage of biodiesel in the mix. For example, B10 denotes a fuel that contains 10% biodiesel fuel and 90% diesel fuel. B100 fuel is 100% biodiesel fuel. (See also Biodiesel fuel. Compare with Biofuels and Renewable diesel fuel.) Discover how the increased use of biodiesel fuel contributed to premature filter plugging on a new engine platform here.

Biodiesel fuel

A type of fuel created by the transesterification of renewable sources such as vegetable oil or animal fats, which are mainly fatty acid methyl esters (FAME). Strictly speaking, biodiesel is not considered a hydrocarbon because its chemical makeup includes an ester group, which contains an oxygen molecule. Many types of oils are used to produce it. The most common in Europe is rapeseed (canola). In the United States, the most common is soybean oil. Properties of biodiesel fuel are similar to those of diesel fuel, as opposed to gasoline or gaseous fuels. As such, biodiesel fuel is capable of being used in compression ignition engines. Biodiesel fuel typically has a cetane rating between 45 and 60, which indicates it ignites more quickly than conventional diesel fuel. It also burns cleaner than conventional diesel fuel; CO and total hydrocarbon emissions are significantly reduced. Biodiesel is commonly blended with conventional diesel fuel to reduce carbon emissions; these fuels are called biodiesel blends. (Compare with Diesel fuel and Renewable diesel fuel. See also Biodiesel blend, Biofuels and FAME fuel.)

Biofuels

A category of fuels produced from renewable resources. Examples include biodiesel and renewable diesel. Many emissions conscious areas of the world are either incentivizing or mandating the use of biofuels by truck fleets and equipment operators since they burn cleaner than diesel fuel. (See also Biodiesel fuel and Renewable diesel fuel.)

Blow-by

A mixture of pressurized air, fuel and other gases that escapes from the combustion chamber of an engine into the crankcase. In a diesel engine, blow-by typically occurs when worn piston rings or cylinders can’t contain the pressure during power stroke. Some amount of blow-by is normal, but too much can result in loss of power, increased oil consumption and decreased fuel efficiency.

Breather

A breather is a device that allows air to enter and exit a closed system (such as a tank, reservoir, or gearbox) so as to safely equalize the pressure within that system. Though not all breathers filter the incoming air, some Fleetguard breathers do. Some Fleetguard breathers employ desiccants to absorb moisture from the incoming air. They may also include a layer of synthetic media to prevent dust and other particulate matter from entering the system via the incoming air. Those units maintain pressure equalization within the system while preventing the ingress of contaminants that can degrade system fluids and accelerate component failure.

Breather, desiccant

A type of filtered breather that uses hygroscopic materials to remove moisture from a system such as a bulk fuel storage tank, hydraulic fluid reservoir, lubricant drum, or gearbox. Some Fleetguard desiccant breathers also include a layer of synthetic media to prevent fine particulate contaminants from entering the system. Those units maintain pressure equalization within the system while preventing the ingress of contaminants that can degrade system fluids and accelerate component failure.

C

Cake

See Dust cake.

Capacity (aka dust holding capacity)

Generally: the total mass of particulate matter a filter can hold before becoming restricted or “plugged”, thus rendering the filter ineffective. Technically: The quantity of test dust removed by the air cleaner under test conditions with a terminal restriction of 25 in H2O (6.23 kPa). This is an industry standard test measurement. Refer to ISO 5011 for more information.

Carboxylates

Soft, gel-like contaminants that can form in fuels. They are more prevalent in biodiesel fuel but also occur in diesel blends. They are also known as carboxylic acid salts, metal carboxylates or carboxylate soaps. Chemically, they are not very different from natural lye soaps. They are formed by a chemical reaction with different substances in fuel, such as fatty acids, in the presence of metals (like sodium or calcium). Biodiesel typically contains large amounts of fatty acids as they are a natural byproduct of the production method. Other sources of reactive substances may include fuel additives such as corrosion inhibitors or lubricity improvers, which may be added by the refiner during manufacturing and at distribution or by an end-user utilizing commercial fuel additives. Metals may be introduced into the fuel as part of the refining process in the case of diesel fuel or via contaminants such as road salt. Learn how carboxylates contributed to premature filter plugging on a new engine platform here.

Cartridge filter

A type of filter wherein the filter element is replaceable. The filter is composed of two primary parts: the shell or housing and a separate filter element (also called a “filter cartridge”), which is fitted inside the shell or housing. The shell is installed onto a filter head. The housing is mounted to the engine/system and is not replaced during regular maintenance (unless damaged). The filter element, on the other hand, is replaced as maintenance requires. Cartridge filters require care during reassembly so as to not damage associated gaskets and/or O-rings. (Compare with Spin-on filter. See also Filter element.)

Cavitation

The formation and rapid collapse of gas bubbles within the coolant system. In the context of engine coolants, this occurs when dissolved gases in the coolant come out of solution and form bubbles when passing through a localized low pressure area of the coolant system. When the gas bubbles then travel back through a higher-pressure area of the system, they collapse or implode. The implosions can impart sufficient force to create small craters or pits in the cooling system components, including cylinder liners. Contaminated or degraded coolants are more prone to this. Proper coolant selection and maintenance will help reduce the potential for cavitation. (See also Pitting)

Cetane number (CN) or cetane rating

A widely accepted measure of the ignition quality of diesel fuels, including biodiesel and renewable diesel. It is to diesel fuel what the octane rating is for gasoline. The cetane number scale ranges from 0 to 100. The higher the cetane number, the faster the fuel ignites. Fuels with higher cetane numbers often provide better fuel economy with fewer emissions.

Check valve

In the context of Fleetguard and filters, a check valve is a one-way valve used in desiccant breathers to reduce desiccant exposure during periods when the associated system is not operating. Some check valve designs accomplish this by venting moisture-ladened system air directly to atmosphere instead of passing it back through the desiccant before venting to atmosphere. Using check valves in this way helps to extend desiccant life, thereby increasing the breather’s service interval.

Chemical coolant filter

A type of coolant filter that delivers supplemental cooling additives (SCAs) into the cooling system in addition to filtering contaminants out of the coolant. The purpose of the SCAs is to improve performance and extend coolant life. Standard service chemical water filters immediately release SCAs at standard intervals, while extended service versions replenish additives with a slow-release mechanism over time. (Compare with Coolant filter.)

Contaminants

In the context of Fleetguard and filters, contaminants are undesirable particles and/or substances that make their way into fuel, air, lubrication, hydraulic, and cooling systems on vehicles and equipment and degrade the quality of the affected fluid and/or cause damage to system components. Common contaminants found in diesel fuel can include water, microorganisms, dust, dirt, salt, sand, and other sediments as well as soft substances such as waxes and carboxylates. Even fuel additives meant to enhance performance can contribute to contamination. Contaminants found in engine air intake systems can include dust, dirt and debris. The tolerances of modern engine and system components are often extremely small and susceptible to wear, corrosion or other types of damage from contaminants that can result in reduced performance and service life. (See also Carboxylates; Contaminants, hard and Contaminants, soft.) Explore the various contaminants that can affect fuel, lube, hydraulic, and coolant systems here.

Contaminants, hard

In the context of Fleetguard and filters, hard contaminants are undesirable particles that make their way into fuel, air, lube and hydraulic systems and are characterized by their hard, often abrasive nature. Examples include natural items like dirt, dust, and sand as well as man-made items like paint chips and rust particles, all of which can scratch or wear components. Due to the tight tolerances found in today’s equipment, particularly hydraulic systems and high-pressure common rail (HPCR) injection systems, hard particles as small as 4 microns can inflict damage that is sufficient to degrade equipment performance, cause unplanned downtime or even result in catastrophic failure. (Compare with Contaminants, soft.)

Contaminants, soft

In the context of Fleetguard and filters, soft contaminants are undesirable substances found primarily in diesel fuels that are characterized by their soft, sticky and organic nature. Examples of soft contaminants common in fuels include microbes (bacteria, fungi and molds), paraffin waxes, and carboxylates. Some of these contaminants are naturally occurring solutes in fuels (like paraffin waxes) and only cause issues when they precipitate out of solution due to a change in temperature. Others make their way into the fuel during transportation (like microbes) or are the result of a chemical reaction within the fuel injection system (like carboxylates). Because of their sticky nature, these substances are known to coat the exterior surfaces of filter media and plug filters prematurely. Premature filter plugging caused by soft contaminants has become more common due to several factors including the increased use of biodiesel blends, which typically contain more of the fatty acids that can contribute to carboxylate formation. (Compare with Contaminants, hard. See also Carboxylates.)

Coolant

The thermal fluid used in an engine cooling system. Typically, it is composed of nearly equal parts of a base (glycol or glycerin) and water, plus an additive package. Its primary purpose is to transfer heat away from the engine. It also protects the engine from cold temperatures when it is not in use. Both protect the engine. Overheating can cause engine components to warp and freezing fluids can cause engine components to crack. Various chemical additives are used to prevent corrosion, scaling, and cylinder liner pitting. There are many types of coolants, each formulated with different chemical additives that provide particular performance and protective characteristics. (See also Additive package; Base; Coolant concentrate; Coolant, conventional; Coolant, OAT; Coolant, HOAT; and Coolant, NOAT. Compare with Antifreeze.)

Coolant concentrate

Coolant supplied without its water component and therefore must be diluted prior to use. Although concentrates require less packaging and storage space, performance loss and damage can result if they’re diluted to the wrong proportion or with poor quality water (e.g., hard water, wrong pH, etc.). Fleetguard recommends premix coolant to ensure best performance. Failing that, concentrates should always be diluted with either distilled or reverse osmosis (RO)-treated water. (Compare with Premix coolant.)

Coolant, conventional

A type of coolant formulated using inorganic acid chemical additives (such as borate, molybdate, nitrite, nitrate, phosphate, and silicate) to protect cooling system components from corrosion, pitting/cavitation, scale/deposits, and other forms of damage. Because they use inorganic acid chemicals, they are also known as inorganic additive technology (IAT) coolants. Of the coolant technologies currently available, conventional coolants have the lowest service interval and life. They also require the most maintenance. The additives used in them degrade over time and must be recharged with supplemental coolant additives (SCAs) to ensure adequate system protection. Chemical coolant filters that introduce SCAs into the system — either gradually or at timed intervals — are available. (Compare with Coolant, hybrid and Coolant, OAT.)

Coolant, extended life (ELC)

See Coolant, hybrid.

Coolant filter

A filter designed to remove contaminants from coolant. Also known as water filters, coolant filters reduce wear on cooling system components. (Compare with Chemical coolant filter.)

Coolant, fully formulated

See Coolant, heavy-duty.

Coolant, heavy-duty

Coolant formulated for the needs of heavy-duty diesel engines used in many industrial vehicles, as opposed to light-duty engines used in automobiles. They include additives that help stabilize pH, provide corrosion, erosion and liner pitting protection, as well as foam, scale, and deposit control. (Compare with Coolant, light-duty.)

Coolant, hybrid

Coolant that uses both conventional inorganic additive technology (IAT) and organic additive technology (OAT) to provide superior liner protection and extended service intervals. Although this combination isn’t as efficient as pure OAT, it significantly extends coolant life and requires less maintenance than purely conventional coolants. Hybrid coolants must still be recharged periodically with SCAs, but don’t need to be tested or serviced as often as conventional coolants. (Compare with Coolant, OAT and Coolant, conventional.)

Coolant, HOAT

Acronym for “hybrid organic acid technology”. See Coolant, hybrid.

Coolant, light-duty

A type of coolant that is formulated to provide pH stabilization, corrosion protection, and foam control. Designed primarily for automotive-grade applications, light-duty coolants do not include adequate amounts of additives to prevent liner pitting and/or scale/deposit formation in heavy-duty equipment. (Compare with Coolant, heavy-duty.)

Coolant, NOAT

Short for nitrated organic acid technology, NOAT coolants are variants of OAT coolants that include nitrites to provide additional corrosion protection for systems that require them. Although the life of NOAT coolants is comparable to that of OAT coolants, they require extenders at approximately 600,000 mi (965,600 km).

Coolant, OAT

Short for organic acid technology, OAT coolants utilize organic carboxylic acids as their primary corrosion inhibitors. A higher concentration of additives — typically 20,000 to 30,000 ppm — enables them to deliver more efficient corrosion protection than conventional alternatives. OAT coolants are preferred by most OEMs because they offer the longest service intervals and usable life with the least maintenance. No SCAs or extenders are needed because additives are depleted at a much slower rate: end users can simply top off with more of the same OAT coolant as needed. OAT coolants can be used in diesel, gasoline, natural gas, and battery electric vehicles, making it ideal for mixed fleets.

Coolant, POAT

Short for phosphate organic acid technology, POAT coolants are variants of OAT coolants that primarily use phosphates as their corrosion inhibitors. Some OEMs are attempting to use POAT to achieve even longer coolant or water pump life; but as of this writing, no publicly available data has been released to support these claims. Phosphates are more stable than nitrites and offer better protection for aluminum, but are more likely to form scale if mixed with hard water.

Coolant, precharged

A light-duty coolant mixed with SCAs to make it acceptable for heavy-duty service. This practice is now seldom used because of the wide availability of fully formulated heavy-duty coolants.

Coolant, premixed

Coolant that is packaged in its “read-to-use” form (i.e., already diluted with water). The water content of premix coolant is generally 40% to 60% depending on climate and altitude. Premix coolant is preferable to coolant concentrate because it ensures correct proportions and water purity. (Compare with Coolant, concentrate.)

Coolant, Si-OAT

Short for silicate-enhanced organic acid technology, Si-OAT coolants are another variant of OAT which uses silicate-based formulations to inhibit corrosion. Si-OAT coolants are primarily recommended or required by European OEMs and engines from other manufacturers that are marketed in Europe. Si-OAT coolants provide good protection for aluminum components and are less likely to form scale in hard water (common in Europe) than POAT coolants. The primary tradeoff is that Si-OAT coolants can form a filter-clogging silicate gel if pH levels fall too low.

D

Desiccant

A hygroscopic material that absorbs moisture from the atmosphere. Common desiccants are silica gel and activated alumina. In filtration, desiccants are used to remove moisture from an environment or an air/gas stream.

Desiccant saturation

The point at which a desiccant cannot absorb or hold any more moisture. This is usually visually indicated by the desiccant changing color.

Diesel coolant additives (DCAs)

Fleetguard term for SCAs. See Supplemental coolant additives (SCAs).

Diesel fuel (aka petroleum diesel, or petrodiesel, ultra-low sulfur diesel, or distillate diesel)

A fuel derived from the fractional distillation of crude oil and used in diesel engines, which use compression to combust the fuel instead of a spark like in gasoline engines. Since 1999 in Europe and 2006 in North America, almost all petroleum diesel fuel is ultra-low sulfur diesel (ULSD), which produces substantially lower harmful emissions when used with advanced emissions control technologies. Many other countries also have adopted ULSD fuel, though limits vary by country. (NOTE: unless otherwise specified, references to diesel, petroleum diesel, petrodiesel, or conventional diesel in this glossary refer to this form of ULSD fuel.) Diesel fuel typically has a cetane rating between 40 and 45. It is not uncommon for diesel fuels to contain some percentage of biodiesel fuel as well; these are called biodiesel blends. Diesel fuel must meet certain cleanliness standards before leaving the refinery. Unfortunately, there are many opportunities and ways contaminants can get into diesel fuel during transportation from the refinery to the point of use. (Compare with Biodiesel fuel and Renewable diesel fuel.)

Dust cake (aka cake)

The layer of contaminants that builds up on the surface of the filter media of an air filter. It makes the filter more efficient by reducing the number of paths that a particle could take to pass through the filter media and thereby capturing more of them. Air filters are more effective with a layer of dust cake on them than when brand new; that is why it is recommended you not change an air filter before it reaches terminal restriction.

Dust holding capacity

See Capacity.

E

Efficiency

In the context of filters, efficiency is a measure of how effectively a filter removes contaminants from fluid at a given contaminant size. Efficiency can be calculated in two ways: fractionally (by particle count) or gravimetrically (by weight). Generally, liquid filter ratings use fractional efficiencies and air filter ratings use gravimetric efficiencies. (See also Efficiency, fractional and Efficiency, gravimetric.)

Efficiency, fractional

Filter efficiency expressed as a percentage by particle count. Ratings for liquid (fuel, oil, etc.) filters generally use fractional efficiencies. (Compare with Efficiency, gravimetric. See also Beta ratio.)

Efficiency, gravimetric

Filter efficiency expressed as a percentage by weight. The efficiency ratings of air filters for engines and compressors are determined by testing in accordance with ISO 5011 requirements, which calculates efficiency gravimetrically. (Compare with Efficiency, fractional.)

Extenders

Additives used to replenish the nitrites in NOAT coolants. (See also: Coolant, NOAT).

F

FAME fuel

A particular type of biodiesel fuel made from feedstocks composed of animal fats, which are mostly fatty acid methyl esters. All FAME fuels are biodiesels, but not all biodiesels are FAME fuels. FAME fuel typically has a cetane rating between 50 and 65. (See also biodiesel fuel.)

Filter cartridge

See Filter element.

Filter element

The part of a filter that includes the filter media and is responsible for capturing and retaining contaminants. Depending on the purpose of the filter, the filter element may be made from one or multiple media types and include design features — such as the number, depth and spacing of pleats — to optimize performance. (See also Cartridge element and Primary element.)

Filter head

A component on an engine that contains the fluid (oil or fuel) flow path and includes a connection point where the filter is attached.

Filter rating

A measure of how well a filter removes contaminants from fluid. They are used by filter manufacturers to compare the relative performance of filters and by equipment manufacturers to ensure filters provide adequate protection for maintaining equipment longevity and performance. Ratings for air filters and liquid (fuel, oil, etc.) filters are calculated and expressed differently. Filter ratings are determined by testing per applicable industry standards, including:

Fuel filters – SAE J1985 (single-pass) or ISO 19438 (multi-pass)
Fuel water separators – SAE J1488, ISO 16339
Hydraulic filters – ISO 16889 (multi-pass) and ISO 23369 (new alpha ratio rating)
Lube filters – ISO 4548-12 (multi-pass)

(See also Filter rating, air; Filter rating, liquid; Filter rating, absolute; Filter rating, nominal; and Beta ratio.) Learn more about the different types of filter ratings here.

Filter rating, absolute

A measure of how effectively a filter removes contaminants from a liquid (such as fuel, oil, hydraulic fluid, etc.), expressed as a percentage of fractional efficiency at a given particle size. Absolute ratings are still fairly commonly used but the meaning has evolved so there is some confusion with them. Historically, an absolute rating indicated a filter would capture 74 out of 75 particles of a given size, which correlates to an efficiency of 98.7%. Today, it can mean the filter is 99.9% efficient at capturing particles of a given size. If you see one of these and you aren’t sure, ask for clarification. (Compare with Beta ratio and Filter rating, nominal.)

Filter rating, air

A measure of how effectively an air filter removes contaminants from an air intake system. Ratings for air filters used with engines and compressors are determined in accordance with ISO 5011 test requirements and expressed as a percentage of gravimetric efficiency only. During testing, a known weight of standardized test dust is fed into a test rig upstream of the filter. The weight of dust that passes downstream of the filter is measured. The filter efficiency is expressed as the percentage of the dust it captures (efficiency = (upstream dust - downstream dust / upstream dust). The higher the value, the better the filter performance. (Compare with Filter rating, liquid.)

Filter rating, liquid

A measure of how effectively a filter removes contaminants from a liquid (such as fuel, oil, hydraulic fluid, etc.). A liquid filter rating denotes the fractional efficiency (expressed as a beta ratio or percentage) with which the filter removes particles of a particular size (also called the micron rating). Both the particle size and the efficiency value are necessary components; one is meaningless without the other. For example: Beta 2,000 at 6 microns (β6 = 2,000), or 99.9% efficient at 4 microns. (Compare with Filter rating, air.)

Filter rating, nominal

A not-so-accurate means of expressing how effectively a filter removes contaminants from a liquid (such as fuel, oil, hydraulic fluid, etc.). Though not widely used anymore, a nominal filter rating signifies only that the filter will remove the majority (generally 50 to 90%, which is equivalent to a beta ratio of 2 to 10) of particles of a given size. For example, a nominal rating of 10 microns means only that a majority of particles 10 microns or larger will be captured. Be wary of filters with nominal ratings; they are no match for the conditions in which today’s high-performance equipment operates. (Compare with Beta ratio and Filter rating, absolute.)

Fluid

Generally, a term that refers to both liquids and gases. Technically, fluid is a state of matter. It describes substances that do not have fixed shapes and so conform to the shapes of the containers they are in. Liquids are non-compressible fluids, meaning their densities do not change with pressure. Gases are compressible fluids, meaning their densities do change with pressure.

Fractional efficiency

See Efficiency, fractional.

Fuel water separator (aka primary fuel filter, stage 1 fuel filter)

The first line of defense in the diesel fuel injection system. Also referred to as the primary fuel filter, the main purpose of the fuel water separator is to remove free and/or emulsified water from the fuel. (Fleetguard also refers to it as the stage 1 fuel filter.) The fuel water separator is usually located between the fuel tank and the fuel pump. In addition to removing water, it captures contaminants before the diesel fuel goes into the fuel pump to be sent up the line to the injectors. It protects the fuel pump, fuel lines and fuel injectors from abrasive contaminants and corrosion from water. Fleetguard fuel water separators utilize advanced medias which are unaffected by “slugs” of water that may be present in the fuel system. (Compare with Secondary fuel filter.)

G

Gravimetric efficiency

See Efficiency, gravimetric.

H

Housing

In the context of Fleetguard and filters, a housing is a component mounted on the engine that contains the filter element. (Compare with Shell.)

HVO fuel

A form of renewable diesel fuel specifically created from hydrogenated vegetable oil. All HVO fuels are renewable diesel fuels, but not all renewable diesel fuels are HVO fuels. (See Renewable diesel fuel.)

Hygroscopic

The ability of a material to absorb or attract water from its surroundings, typically air or other gas. Hygroscopic materials are often used as desiccants in filtration systems.

I

Inorganic additive technology (IAT)

See Coolant, conventional.

L

Liner pitting

See pitting.

M

Media

The material used in a filter that captures and retains contaminants. Filter media may be made from natural or synthetic materials. Examples include cellulose, micro-glass, and nanofiber. The types and sizes of contaminants to be captured determine which type of media is used in a filter. Some filters use multiple types of media. Fleetguard knows the diameter of a single strand of the filter media needs to be approximately 1/10 the size of the particles to be captured. (See also Media, activated carbon; Media, Cellulose; Media, micro-glass; Media, nanofiber; Media, NanoNet; Media, StrataPore; and Media, synthetic.)

Media, activated carbon (aka activated charcoal)

A form of carbon used to filter contaminants out of fluids. It is composed of small charcoal granules that have been processed (activated) to significantly increase the number of pores on each granule. The effect is to greatly increase the surface area of the granules and, consequently, their capacity for adsorption. Adsorption refers to the adhesion of atoms, ions, and molecules to a surface, in this case the charcoal granules. Activated carbon is often used in cabin air filters. (Compare with Media, cellulose; Media, micro-glass; Media, nanofiber; and Media, synthetic.)

Media, cellulose

A traditional, filter media that is used to capture larger contaminants. It is made from natural cellulose fibers, most often derived from wood pulp like paper. (That is why it is sometimes referred to as paper media.) Cellulose media is generally made using a wet-laid process that results in a non-woven structure. It is widely used in air filters but not limited to them. With larger fibers, it’s less efficient than micro-glass media and modern synthetic media. However, cellulose can be combined as a base layer with other media types to improve overall filter performance, particularly in applications wherein both hard and soft contaminants are present or the contaminants range widely in size. (Compare with Media, activated carbon; Media, micro-glass; Media, nanofiber; and Media, synthetic.)

Media, micro-glass

Filter media made from borosilicate glass microfibers formed into an unwoven fabric. It’s smaller, more uniform fibers (generally 1-5 microns in diameter) make it more efficient than cellulose and a few other types of media and give it greater holding capacity. It also is compatible with more fluids than cellulose and a few other types of media and is not susceptible to swelling. (Compare with Media, activated carbon; Media, cellulose; Media, nanofiber; and Media, synthetic.)

Media, nanofiber

A synthetic filter media that is characterized by long, continuous polymeric fibers of sub-micron diameter. (See also Media, synthetic and Media, NanoNet.)

Media, NanoNet®

A synthetic nanofiber filter media designed and manufactured by Fleetguard. When used in fuel filters and some lube filters, NanoNet™ media can trap 98.7% of particles as small as 4 microns — that’s 12 times smaller than the smallest particle visible to the human eye. It provides superior protection for HPCR fuel injection systems running at pressures at or exceeding 30,000 psi. As a result, engines operate at peak performance. One of the key advantages of NanoNet media is that its efficiency does not degrade over the life of the filter. It provides longer service intervals when compared with legacy filter media. It also has greater holding capacity and lower restriction than legacy filter media and StrataPore. Fibers are bonded at each junction for improved rigidity and do not move apart during vibration and flow surge, meaning contaminants stays put over the life of the filter. (See also Media, synthetic and Media, nanofiber. Compare with Media, StrataPore™.)

Media, paper

A generic term for filter media made from natural fibers such as cellulose or cotton. These media are often created using a wet-laid process that results in a non-woven structure. (See also Media, cellulose.)

Media, StrataPore™

A synthetic filter media made by Fleetguard that offers greater efficiency and longer life than conventional cellulose or micro-glass media. (See also Media, synthetic. Compare with Media, NanoNet®.)

Media, synthetic

Filter media that is made from man-made materials, such as glass and synthetic polymers, instead of natural materials like cellulose. Examples include micro-glass and nanofiber media. Synthetic media are less sensitive to moisture than cellulose media, which means they are less susceptible/prone to swelling. They are typically more efficient and able to remove smaller particles than cellulose media due to their smaller fiber size. They also provide greater capacity to capture small particles that cause premature wear on high-pressure injectors and other components. (See also Media, micro-glass; Media, nanofiber; Media, NanoNet, and Media, StrataPore.)

Micron or micrometer (μm)

A unit of length applied to very small objects. One micron is equal to one-millionth of one meter (m). There are 25,400 microns in 1 inch. Liquid filter ratings include a micron component. Liquid filters are rated based on the efficiency with which they remove particles of a particular size. Both the particle size in microns and the efficiency value (beta ratio or percentage) are necessary for proper filter selection. (See also Micron rating.) Discover more about what a micron is and how it impacts filtration.

Micron rating

One of two values used to express liquid filter ratings. It is the particle size on which the filter efficiency value is based. Liquid filters are rated based on the efficiency with which they remove particles of a particular size. Both the micron rating and the efficiency value (beta ratio or percentage) are necessary components of a liquid filter rating. (See also Beta ratio and Micron or micrometer.) Learn more about micron ratings here.

P

Petrodiesel

See Diesel fuel.

Pitting (aka liner pitting)

In the context of Fleetguard and coolants, pitting refers to the mechanical damage caused by cavitation, wherein the implosions of tiny gas bubbles impart sufficient force to create small craters, or pits, in cooling system components, including cylinder liners. (See also Cavitation.)

PPM (parts per million)

A dimensionless unit of measure for very dilute concentrations of substances. It is a number that indicates how many parts of a particular molecule or compound are present in a solution comprised of one million total parts. One ppm is equivalent to 0.0001%. In the context of Fleetguard and filters, PPM may be relevant to the performance of filtration in removing water particles from diesel fuel.

Pre-cleaner (or air pre-cleaner)

A filtration device installed as the first stage of an air intake system to prevent larger contaminants and water from entering the system and prematurely clogging the primary element. Often mounted upstream of the air cleaner inlet or included in the air cleaner design, it removes up to 95% of incoming dust. As a result, it helps to improve the efficiency of the air intake system and extend the service interval of the primary element. It also reduces unplanned downtime and maintenance costs. It is typically but not exclusively used on heavy-duty and/or high-horsepower equipment operated in extremely dusty environments like those found in mining, agriculture and construction.

Primary air filter

See Primary element.

Primary element

The main filter in the air cleaner. Its purpose is to capture contaminants before they enter the engine. (See also Safety element.)

Primary fuel filter

See Fuel water separator.

R

Refractometer

A device used to determine the freeze point protection of coolant. Refractometers are more accurate in this regard than test strips or float-type hydrometers.

Renewable diesel blend

A fuel comprised of a mixture of two or more of the following fuels: renewable diesel, petroleum diesel, and B100 biodiesel. Similar to biodiesel blends, renewable diesel blends are designated by an “R” factor, which indicates the percentage of renewable diesel fuel in the blend. It takes the form RX, where the X is a numeral that indicates the percentage of renewable diesel fuel in the mix. R100 fuel is 100% renewable diesel fuel. For example, a blend of 20% renewable diesel and 80% petroleum diesel is called R20. A blend of 20% biodiesel and 80% renewable diesel is called B20R80. A blend of 20% biodiesel, 20% renewable diesel, and 60% petroleum diesel is called B20R20. (See also Renewable diesel fuel. Compare with Biodiesel fuel and Biodiesel blend.)

Renewable diesel fuel

A type of fuel created by hydrotreating plant oils and/or animal fats. HVO fuel is a subset of renewable diesel fuel that is made from feedstocks consisting only of plant oils. Renewable diesel fuel is not the same as biodiesel fuel. They are chemically different: renewable diesel is a hydrocarbon and biodiesel is not. Chemically, renewable diesel fuel is very similar to conventional diesel fuel but it burns cleaner. It emits fewer pollutants than conventional diesel fuel, including carbon dioxide (CO2), nitrogen oxide (NOx), and particulate matter. It can be used in existing diesel engines without modification, including fuel filters. Renewable diesel has a cetane number between 75 and 90 and so is much easier to ignite upon compression than conventional diesel fuel. It may be used as a standalone fuel but is often blended with conventional diesel or biodiesel to improve lubricity. Fleetguard filters are compatible with renewable diesel blends up to 100% that meet EN15940 (Paraffinic Diesel Fuel from Hydrotreatment) and ASTM D975 (Standard Specification for Diesel Fuel).

Restriction

The degree to which fluid flow is reduced across a filter. It applies to air filters as well as filters used with liquids such as fuel, oil, hydraulic fluid, etc. It is the flow resistance created by the filter element itself plus the accumulation of contaminants on it, measured under steady state flow conditions and with a clean element. The balance between restriction and efficiency is a critical part of the design process to ensure optimal filter performance. (See also Air restriction indicator and Restriction, terminal.)

Restriction, terminal

Generally, terminal restriction is the point at which a filter is so full of contaminants that the fluid flow to the engine or system is compromised, and the filter must be replaced to prevent loss of performance and/or damage. For air filters, it technically is the maximum restriction across the air cleaner/filter element(s) recommended by the engine manufacturer, usually 5.0 to 6.2 kPa (20 to 25 in.) water gauge. (See also Air restriction indicator and Restriction.)

S

Safety element

A smaller filter installed on the clean side of the primary element to prevent contaminants from entering the engine if the primary element fails or during service events. (See also Primary element.)

Scale

In the context of Fleetguard and coolants, scale is a chalk-like layer of dissolved minerals, notably calcium and magnesium, commonly found in hard water. Scale can form on hot surfaces inside equipment as it runs, creating an insulating layer that prevents coolant from absorbing engine heat. This can cause worn piston rings, higher oil consumption and, in the worst cases, total engine failure.

Secondary element

See Safety element.

Secondary fuel filter (aka stage 2 or on-engine filter)

The secondary fuel filter is usually located on the engine, right before the diesel fuel enters the injectors. It serves as the last line of defense, working in conjunction with the fuel water separator (if one is installed) to remove contaminants that can wear critical components and compromise engine performance. It is particularly important in protecting the fuel injectors on high-pressure common rail injection systems. The injectors have tight tolerances and are easily damaged by abrasive contaminants. (Compare with Fuel water separator.)

Shell

In the context of Fleetguard and filters, a shell is an outer layer that protects the filter element during use when it is not installed in a housing. (Compare with Housing.)

Silica gel

A hygroscopic material commonly used as a desiccant in filtration. Often used in the form of small, transparent beads, silica gel can absorb up to 40% of its weight in water. It is also non-toxic.

Soaps or soaping

See Carboxylates.

Spin-on filter

A one-piece, disposable filter design in which the filter element is encased in a sealed shell that screws onto a filter head. No part of a spin-on filter is replaceable. Instead, the entire unit must be replaced. (Compare with Cartridge filter. See also Filter element.)

Stage 1 fuel filter

See Fuel water separator.

Stage 2 fuel filter

See Secondary fuel filter.

Supplemental coolant additives (SCAs)

A mixture of inorganic acid chemicals added to conventional coolants to recharge the additive package and extend the coolant’s useful life. SCAs are available in liquid form or as a solid contained within a chemical coolant filter.

T

Terminal restriction

See Restriction, terminal.

U

Ultra-low sulfur diesel (ULSD) fuel (aka diesel fuel)

A type of petroleum diesel fuel that contains very low levels of sulfur and enables the use of advanced emissions control technologies. Upon combustion, ULSD fuel produces substantially lower harmful emissions than legacy diesel formulations. Since 1999 in Europe and 2006 in North America, almost all petroleum diesel fuel is ultra-low sulfur diesel. Many other countries also have adopted ULSD fuel, though sulfur limits vary. (See also Diesel fuel.)

W

Water filter

See Coolant filter. Compare with Chemical coolant filter.