Glossary of Terms
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Absolute Filter Rating [top]
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 [top]
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 [top]
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 specific size of particle for a filter. The Beta
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 [top]
A chemical additive, poisonous substance that can kill
living organisms in fuel systems.
Biodiesel Blend [top]
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 [top]
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 [top]
British Pipe Thread. A tapered self sealing metric thread.
Buna-N [top]
A synthetic rubber sometimes used in the seals
and gaskets of petroleum nozzles, valves, swivels,
and meters.
Capacity [top]
The amount of contaminant a filter will hold before flow
starts to slow, leading to excessive pressure.
Capacity-Water [top]
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 [top]
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 [top]
Structural failure of a filter element which can occur due
to abnormally high pressure drop or resistance to flow.
Colloidal [top]
Slime in a liquid; the mucus-like substance created by
bacteria.
Contaminant [top]
Any foreign or unwanted substance which can have a
negative effect on system operation, longevity
or reliability.
Contaminant Failure [top]
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 [top]
Migration occurs when the restriction is so great that
the pressure pushes contaminant deeper in the media
and eventually through the media and downstream.
Differential Pressure [top]
(See pressure drop) Also referred to a Delta P (p).
Dissolved Water [top]
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.
There 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 [top]
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 [top]
Occurs when the restriction becomes so high that
the element collapses or the media ruptures to relieve
the upstream pressure.
Emulsified Water [top]
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 [top]
(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 [top]
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 [top]
Method of expressing a filter's ability to trap and retain
contaminants of a given size. Usually given as a percent.
Filter Bypass [top]
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 [top]
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 [top]
A mechanical means of removing and retaining
insoluble contaminants.
Free Water [top]
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 [top]
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 [top]
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 [top]
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 [top]
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 [top]
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 [top]
(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 [top]
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 [top]
(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 [top]
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 [top]
National Pipe Thread. A tapered self sealing thread.
OEM [top]
Original Equipment Manufacturer
Oxygenated Gasoline [top]
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 [top]
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 [top]
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 [top]
Force per unit area, usually expressed in pounds
per square inch.
Pressure Drop [top]
(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 [top]
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 [top]
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 [top]
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 [top]
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 [top]
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 [top]
Water that may collect on the bottom of motor fuel
storage tanks.
ULSD (Ultra-Low Sulfur Diesel) [top]
This is diesel fuel with a sulfur content of 15 ppm (parts
per million) or less.
Underwriters Laboratories (UL) [top]
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 [top]
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).
