Glossary of Common Filtration and Fueling Terms

Absolute Filter Rating
The size of the largest spherical glass particle which will pass the filter under laboratory conditions. This rating is often misunderstood and misused in the filter industry and by its customers. It is widely believed that the absolute rating is an indication of the largest particles which will be found downstream of the filter. THIS IS NOT SO. The absolute rating simply determines the size of the largest glass bead a filter will pass under very low pressure differentials and non-pulsating flow conditions. It does not bear any relationship to the so-called absolute rating of the filter.

Alcohol Blends
Motor fuels that consist of a mixture of gasoline and alcohol, typically methyl alcohol or ethyl alcohol. Alcohol blends can operate in essentially the same type of internal combustion engine as gasoline. (High-speed racing cars burn pure alcohol.) Each fuel, however, has its own advantages and disadvantages. Alcohol creates less air pollution than gasoline, but alcohol-powered vehicles get fewer miles per gallon. In an effort to reduce crude oil consumption and simultaneously lower pollution and improve engine performance, refiners have developed various blends of gasoline and alcohol. The original blend marketed under the name of Gasohol consists of 90 percent gasoline and 10 percent ethanol (grain alcohol). Another blend, M-85 consists of 85 percent methanol (methyl alcohol) and 15 percent unleaded gasoline.

Beta Value
This value may also be referred to as a Beta Ratio or Filtration Ratio. It is simply a ratio showing the relationship between upstream and ownstream particle counts of a Ratio formula is used for calculating the efficiency of a filter media at removing particles, using base data from multi-pass testing. Example: A filter has 1000 particles, 10 micron or greater in the upstream going in, and 500 particles, 10 micron or greater downstream going out. 1000/500 = Beta (10) 2 =50% efficiency.

Biocide
TA chemical additive, poisonous substance that can kill living organisms in fuel systems.

Biodiesel Blend
Biodiesel Nontoxic, biodegradable replacement for petroleum diesel. Bio-diesel is made from vegetable oil, recycled cooking oil and tallow. Pure or 100 percent bio-diesel is referred to as B100 or “neat” bio-diesel. A bio-diesel blend is pure bio-diesel blended with petro-diesel. Bio-diesel blends are referred to as Bxx. The xx indicates the amount of bio-diesel in the blend (i.e. a B20 blend is 20 percent by volume bio-diesel and 80 percent by volume petro-diesel).

Breather Vent
Storage tanks containing volatile liquids, such as gasoline, need to "breathe." All space in the tank is filled with either liquid or vapor. Because the volatile liquid in the tank tends to increase and decrease in volume as the temperature of the product changes, and as product is added or withdrawn, the vapor space above the liquid level (the ullage) does not remain constant. These changes in the volume liquid, as well as the volume of vapors in the tank, must be accommodated. If they were not, a variation in vapor volume caused by temperature change would result in increased or decreased pressure on the walls of the tank. That's why atmospheric storage tanks must not be made air tight. Instead, air must get in.

BPT
British Pipe Thread. A tapered self sealing metric thread.

Buna-N
A synthetic rubber sometimes used in the seals and gaskets of petroleum nozzles, valves, swivels, and meters.

Capacity
The amount of contaminant a filter will hold before flow starts to slow, leading to excessive pressure.

Capacity-Water
There are no accepted and approved water capacity testing or reporting standards. Consequently, there is virtually no way to compare one lement’s capacity with another. It is also difficult to simulate a specific application in testing, making it hard to predict field performance. The discrepancies with water sensing media capacity are the result of the interplay among three main variables: flow rate, viscosity and the media itself.

Capacity-Water
There are no accepted and approved water capacity testing or reporting standards. Consequently, there is virtually no way to compare one lement’s capacity with another. It is also difficult to simulate a specific application in testing, making it hard to predict field performance. The discrepancies with water sensing media capacity are the result of the interplay among three main variables: flow rate, viscosity and the media itself.
EXAMPLE 1
(Effect of flow rate change): two identical elements, testing the same fluid, varying only the flow rate. Element 1A: 3 gpm = 425 ml, Element 2A: 10 gpm = 360 ml (This 15% reduction in capacity is caused by changing on the flow rate.)
EXAMPLE 2
(Effect of viscosity change): two identical elements, maintaining the same flow, varying only the viscosity. Element 1 B: 20 gpm, 200 SUS=250 ml, Element 2B, 20 gpm, 75 SUS = 550 ml. (Per ASTM Standard Viscosity - Temperature Charts, Diesel Fuel is approx. 40 SUS @ 55° F and 200 SUS @ - 10° F.)

Cellulose Media
A filter material made from plant fibers. Because cellulose is a natural material, its fibers are rough in texture and vary in size and shape. These characteristics create a higher restriction to the flow of fluids. See synthetic media for a comparison.

Collapse
Structural failure of a filter element which can occur due to abnormally high pressure drop or resistance to flow.

Colloidal
Slime in a liquid; the mucus-like substance created by bacteria.

Contaminant
Any foreign or unwanted substance which can have a negative effect on system operation, longevity or reliability.

Contaminant Failure
Any loss of performance due to the presence of contamination. Two basic types of contamination failure are: Perceptible - gradual loss of efficiency of performance and Catastrophic - Dramatic, unexpected failure. As contaminant becomes caught in the media it begins to build up and fills the pore openings. As the pore openings shrink, the differential pressure (pressure drop) increases. Too much contaminant in the media can cause contaminant migration or element failure if the elements are not removed promptly.

Contaminant Migration
Migration occurs when the restriction is so great that the pressure pushes contaminant deeper in the media and eventually through the media and downstream.

Contaminant Migration
Any loss of performance due to the presence of contamination. Two basic types of contamination failure are: Perceptible - gradual loss of efficiency of performance and Catastrophic - Dramatic, unexpected failure. As contaminant becomes caught in the media it begins to build up and fills the pore openings. As the pore openings shrink, the differential pressure (pressure drop) increases. Too much contaminant in the media can cause contaminant migration or element failure if the elements are not removed promptly.

Differential Pressure
(See pressure drop) Also referred to a Delta P (p).

Dissolved Water
Small quantities of water will mix into solution with hydrocarbons. This is called "dissolved water" (sometimes referred to as soluble water, miscible water or bound water). You can relate dissolved water in hydrocarbons as you would moisture in air. Like the weather, if the relative humidity is 50% you know there is water vapor present in the air; however, you cannot see the water or feel it. The same relationship applies to hydrocarbons.

here is a definite limit to how much dissolved water can be held in a hydrocarbon. This limit is referred to as the saturation level (same as 100% relative humidity). The saturation level decreases as the temperature drops and increases as the temperature rises. When the hydrocarbon is exposed to the atmosphere, the hydrocarbon will absorb moisture from the air or release dissolved water to the air until equilibrium is obtained.

E-85
This is the term for motor fuel blends of 85 percent ethanol and 15 percent gasoline. Ethanol blends are referred to as Exx. The xx indicates the amount of ethanol in the blend, i.e., E15 (standard blended ethanol fuel) is 15% ethanol and 85% gasoline.

Element Failure
Occurs when the restriction becomes so high that the element collapses or the media ruptures to relieve the upstream pressure.

Emulsified Water
It is still "free water" but in the form of finely dispersed droplets suspended within the hydrocarbon. Causes a slight haze or milky appearance to the hydrocarbon.

Ethanol
(Ethyl) grain alcohol. Typically fermented from grain (corn, sugar cane, etc.). When used as a motor fuel, it is usually an ingredient in a gasoline/alcohol blend as an octane enhancer added at a rate of up to 10% in gasoline. Ethanol is a fuel oxygenate. In the U.S., Ethanol used in gasoline blends is principally derived from corn. In other countries, e.g., Brazil, ethanol used in motor fuels is derived from sugar cane. It is also produced synthetically from petroleum base stocks.

Filter, Pump
A filtering element located inside a gasoline station dispenser which removes impurities that might be present in the motor fuel, just before the fuel enters the dispenser hose on its way to the customer's vehicle tank.

Filter Efficiency
Method of expressing a filter's ability to trap and retain contaminants of a given size. Usually given as a percent.

Filter Bypass
Occurs when the fluid upstream of a filter can pass to the outlet of the filter without going through the filter media, allowing contaminant to pass downstream. Fluid flowing through a filter can bypass the filter media for many reasons, such as improperly sealed media seams and endcaps, element ruptures and damaged and misaligned gaskets.

Flow Rate
A term used to describe the speed at which a liquid moves through a system. In the U.S. petroleum operations, the flow rate is usually identified in terms of GPM (Gallons Per Minute). A particular type of gasoline nozzle, for example, might be described as having a flow rate of 10 gpm.

Fluid Filtration
A mechanical means of removing and retaining insoluble contaminants.

Free Waterr
That water within the hydrocarbon which is not dissolved - generally referring to large droplets which are visible and accumulate below the hydrocarbon at the bottom of the reservoir. Free water can vary in concentration from a few ppm (parts per million) to several percent. However, you can have fuel with a 0 ppm of freewater (visually crystal clear) and yet have 35 to 50 ppm of dissolved water. Free water is described in many different ways such as: "entrained water" or "slugs of water". "Emulsified" water normally refers to the tightly dispersed droplets, and "suspended" water has a milky haze. The combination of both free and dissolved water is called total water.

PetroClear water sensing products, (Type "W"), remove only free water and not dissolved water. Type "A" will sense suspended water in gasohols.

Testing methods for detection of free water are visual, aqua-glo, centrifuges and turbidity monitors. Total water content is usually determined by the "Karl Fisher Method" (ASTM D 1533).

Gasohol
In the United States the term gasohol refers to a blend of gasoline and (usually) 10% ethanol. This term was used in the late 1970s and early 1980s but has been replaced by terms at the pump such as Super Unleaded Plus Ethanol or Unleaded Plus.

Gravimetric Filtration Efficiency Rating
The percentage of contaminants removed by weight. If 100 grams of contaminant are in the stream flow and 80 grams are stopped by the filter being tested, the filter has an efficiency rating of 80%.

Gravity Flow
The movement of liquid caused by the force of gravity. Gravity flow provides the primary method of delivering product to underground storage tanks. Liquid in a hose or pipe that is tilted in a "downhill" direction will, of course, move in that direction, even without any external power source. The pressure that gravity imposes on liquid in a pipe is referred to as the static head.

Hydrocarbon
Any class of compounds consisting of hydrogen and carbon atoms. Gasoline, fuel oil, and other petroleum products are referred to as ydrocarbons, although they usually also contain additives from other chemical groups.

M-85
This is the term for motor fuel blends of 85 percent methanol and 15 percent gasoline. Methanol blends are referred to as Mxx. The xx indicates the amount of ethanol in the blend, i.e., E15 (standard blended ethanol fuel) is 15% ethanol and 85% gasoline.

Methanol
(methyl alcohol, wood alcohol) Typically manufactured from natural gas. In the 1980s methanol was used in combination with heavier co-solvent alcohols as an octane enhancer for addition to gasoline. Methanol is not typically blended into today's gasoline.

Micron
A unit of length. The commonly used shortened form for micrometer. One micron = 39.4 millionths of an inch (.0000394"). Contaminant size is usually described in microns. Relatively speaking, a grain of salt is about 100 microns, human hair about 70 microns, white blood cell 25 microns, talcum powder 10 microns, red blood cell 8 microns and bacteria is about 2 microns. The smallest an eye can see is about 40 microns.

MTBE
(methyl tertiary butyl ether) An ether manufactured by reacting methanol and isobutylene. The resulting ether is high octane and of low volatility. MTBE is a fuel oxygenate.

Multi-Pass Test
A test sanctioned by the International Standards Organization (ISO) for use in determining a filter's efficiency and capacity at a specific flow rate. Nominal Filter Rating An arbitrary value assigned to the filter by the manufacturer. This value has no meaning whatsoever. It does not signify any characteristic of the filter which can be determined and measured against an accepted standard. The nominal rating sometimes is represented as a value loosely relating to the removal efficiency of the filter. The origins of the term can be traced to an outdated military specification. In defining filter performance, any reference to the so-called nominal rating is strongly discouraged.

NPT
National Pipe Thread. A tapered self sealing thread.

OEM
Original Equipment Manufacturer

Oxygenated Gasoline
Gasoline that has been formulated in a way that is designed to reduce carbon monoxide from automotive exhausts. Oxygenates are either alcohols or ether compound, added to gasoline. A number of U.S. communities with severe air pollution problems now mandate use of oxygenated fuels. The regulations generally require that oxygenated gasoline contain 2.7% oxygen by weight (2.0% in California), equivalent to 15% of MTBE (methyl tertiary butyl ether) by volume, or 7.4% of fuel ethanol by volume. Oxygenated gasoline is particularly in demand during the winter months in areas where weather conditions cause increased air-pollution levels. Oxygenates increase the oxygen-to fuel ratio in an internal combustion engine. This results in a more complete burning of the fuel, and hence reduces the amount of harmful pollutants released into the air.

Paraffin
A wax which is a natural product in crude oil and is dissolved within diesel fuel. Paraffin causes gelling in diesel fuel at low temperatures. When combined with water, it will begin to congeal at higher temperatures.

Phase Separation
The separation of gasoline and alcohol in a storage tank caused by the presence of water or by the addition of warm gasoline to a cold storage tank, particularly in humid coastal areas. Many motor fuels consist of a mixture of gasoline and alcohol. Care must be exercised in the handling of some of these products to ensure that phase separation does not occur.

Pressure
Force per unit area, usually expressed in pounds per square inch.

Pressure Drop
(See differential pressure) The pressure difference between two points, generally at the inlet and outlet. All system components through which there is flow, have a pressure drop. This drop is the net pressure required for the fluid to flow from the inlet to the outlet of the component. (In filters, this includes the pressure from across the housing and filter element.) It varies with flow rate and fluid viscosity. Generally measured in the U.S. in pounds per square inch (psi).

Pressurized System
Pressurized systems at motor fuel dispensing facilities are those in which the pumping unit is located at a position remote from the pump island, typically inside or directly above the tank, and not in the dispenser itself. When one of the dispensers is authorized to dispense fuel, the pump serving that dispenser is turned on. Since the pump may serve several other dispensers, its operation will pressurize all the pipe lines in the system carrying the same product. Leaks in pressurized piping can thus quickly reach a catastrophic level.

Pump, Dispensing
Original gasoline station pumps were truly pumps. By working a hand lever on the side, the operator created a vacuum in the interior pumping unit and this, in turn, "pulled" product up from the storage tank below. Later, electric motors operated suction pumps, with the pumping unit located inside the dispensing device on the island. In most modern gas stations, the actual pumping unit is not located in the dispenser. Rather, it is located in a remote position, within the storage tank. The mechanism located on the pump island, therefore, is not really a pump. It is, rather, a dispenser. It contains a meter, electronic controls, a length of hose with a nozzle on the end, and quite probably a filtering element. Through long usage, however, the piece of equipment on the pump island continues to be referred to by many people as a "pump" or a "gas pump". To accommodate this usage, it has become common, within the industry to speak of the dispenser as a "dispensing pump" although "dispenser" is more accurate.

Strainer
As the name implies, a strainer is a screen - like device fitted into a product line to prevent impurities in a fuel supply from flowing through to the fuel tank of a vehicle or airplane.

Submersible Pump
Also called a submerged turbine pump (STP). A pumping unit located inside a storage tank. Because the pump is positioned near the bottom of the tank, below the liquid level, it is not normally submerged in the fuel - thus, a submersible pump. Installations in which submersible pumps are used are usually referred to as remote systems.

Synthetic Media
Filtration media made up of synthetic fibers that are uniform in size and have a more aerodynamic shape. This creates less resistance to flow and because the synthetic fibers are smaller, more filtration can be done in a given space. This combination of low flow resistance and increased surface area results in improved filtration efficiency and allows contaminants to be trapped throughout the depth of the filter material.

Tank Water Bottoms
Water that may collect on the bottom of motor fuel storage tanks.

ULSD (Ultra-Low Sulfur Diesel)
This is diesel fuel with a sulfur content of 15 ppm (parts per million) or less.

Underwriters Laboratories (UL)
One of the most widely known, nationally-recognized, independent testing services. UL was originally developed by insurance companies for the purpose of establishing the safety and reliability of manufactured products. Hundreds of products - electrical devices, storage tanks, filters, machines, etc. - are said to "bear the UL label." This means these products have been manufactured to standards developed by Underwriters Laboratories. It also means that specimens of the products have, from time to time, been subjected to performance tests conducted by the Laboratories. Having been manufactured to these standards and having passed the tests, the products are authorized to display the UL label. (Note: Underwriters Laboratories of Canada (ULC) is the Canadian counterpart of UL. The services and operations of the two organizations are essentially the same.)

Viscosity
A property of a fluid that has to do with its resistance to flow and hence its rate of improvement. Molasses, for example, is highly viscous fluid - much more viscous than water. Similarly, gasoline is less viscous than diesel fuel. In terms of physics, viscosity is the measure of the extent to which a fluid resists the force tending to cause the fluid to flow. Usually expressed in Centistokes (cSt) or Saybolt Seconds Universal (SSU).