ASTM D4865-09(2014)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D4865 − 09 (Reapproved 2014) An American National Standard
Standard Guide for
Generation and Dissipation of Static Electricity in Petroleum
Fuel Systems
This standard is issued under the fixed designation D4865; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Every year a number of fires and explosions in petroleum product systems are attributed to spark
ignition from accumulated static electricity. Such fires require a flammable hydrocarbon/air mixture
and an ignition source. Safety practices can concentrate on the elimination of either factor, but this
guide provides a general background on how electrostatic charges are formed and how they may be
prevented or dissipated.
A subtle and often misunderstood feature of these incidents is the possible accumulation of
hazardous electrostatic charges in systems which are properly bonded and grounded. This can occur
because refined hydrocarbon fuels have low electrical conductivities and electrostatic charges may be
retained within the fuel and on its surfaces.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This guide describes how static electricity may be
generated in petroleum fuel systems, the types of equipment D56Test Method for Flash Point by Tag Closed Cup Tester
D93Test Methods for Flash Point by Pensky-Martens
conducive to charge generation, and methods for the safe
dissipation of such charges. This guide is intended to increase Closed Cup Tester
D323TestMethodforVaporPressureofPetroleumProducts
awareness of potential operating problems and hazards result-
ing from electrostatic charge accumulation. (Reid Method)
D396Specification for Fuel Oils
1.2 This guide is not intended to provide specific solutions
D910Specification for Leaded Aviation Gasolines
but indicates available techniques the user may wish to
D975Specification for Diesel Fuel Oils
investigate to alleviate electrostatic charges. This guide does
D1655Specification for Aviation Turbine Fuels
not cover the effects of stray currents or of lightning, either of
D2276Test Method for Particulate Contaminant inAviation
which can also produce sparks leading to fires or explosions.
Fuel by Line Sampling
1.3 This guide is not intended to address detailed safety
D2624Test Methods for Electrical Conductivity ofAviation
practicesassociatedwithstaticelectricityinpetroleumproduct
and Distillate Fuels
systems.
D2880Specification for Gas Turbine Fuel Oils
D3699Specification for Kerosine
1.4 ThevaluesinSIunitsaretoberegardedasthestandard.
D3948TestMethodforDeterminingWaterSeparationChar-
The values in parentheses are for information only.
acteristicsofAviationTurbineFuelsbyPortableSeparom-
1.5 This standard does not purport to address all of the
eter
safety concerns, if any, associated with its use. It is the
D4306Practice for Aviation Fuel Sample Containers for
responsibility of the user of this standard to establish appro-
Tests Affected by Trace Contamination
priate safety and health practices and determine the applica-
D4308Test Method for Electrical Conductivity of Liquid
bility of regulatory limitations prior to use.
Hydrocarbons by Precision Meter
D5191Test Method for Vapor Pressure of Petroleum Prod-
ucts (Mini Method)
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
mittee D02.J0.04 on Additives and Electrical Properties. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2014. Published November 2014. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1988. Last previous edition approved in 2009 as D4865–09. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D4865-09R14. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4865 − 09 (2014)
D5452Test Method for Particulate Contamination in Avia- 3.1.9 flammable liquid, n—a liquid having a flash point
tion Fuels by Laboratory Filtration below 38°C (100°F) (see Test Methods D56 and D93) and
D6615Specification for Jet B Wide-Cut Aviation Turbine having vapor pressure (Test Method D323 or D5191) not
Fuel exceeding 276 kPa (40 psia) (see NFPA Standard No. 30).
3.1.9.1 Discussion—The definition of flammable is cur-
2.2 National Fire Protection Association (NFPA) Stan-
rentlyunderdiscussionbytheUNCommitteeofExpertsonthe
dards:
Transportation of Dangerous Goods.
NFPAStandard No. 30Flammable and Combustible Liquid
Code
3.1.10 grounding, v—the practice of providing electrical
NFPAStandardNo.407StandardonAircraftFuelServicing
continuitybetweenafuelhandlingsystemandgroundorearth.
2.3 Canadian General Standard Board (CGSB) Specifica-
3.1.11 high vapor pressure product, n—a product having a
tion: 6
vapor pressure above 31 kPa (4.5 psia) (1).
CAN/CGSB 3.6 Regular Sulphur Diesel Fuel
3.1.12 intermediate vapor pressure product, n—a product
CAN/CGSB 3.517Automotive Low Sulphur Diesel Fuel
withavaporpressurebelow31kPa(4.5psia)andaflashpoint
2.4 British Standards Institute (BSI) Standard:
below 38°C (100°F) (1).
BS 5958 (Part 2)Recommendations for Particular Industrial
3.1.13 lowvaporpressureproduct,n—aproductwithaflash
Situations
point above 38°C (100°F) (1).
3. Terminology
3.1.14 relaxation time, n—the time required for a charge to
dissipate to 36.8% of the original value (2).
3.1 Definitions of Terms Specific to This Standard:
3.1.1 bonding, v—the practice of providing electrical con-
3.1.15 residence time, n—thelengthoftimeafterachargeis
nections between conductive parts of a fuel system to preclude
generated that a product remains in piping or a closed vessel.
voltage differences between the parts.
3.1.16 splash filling, v—the practice of allowing fuel to
3.1.2 bottom loading, v—the practice of filling transport
free-fall or to impinge at high velocity on a tank wall while
compartments by pumping fuel through a bottom inlet.
loading a compartment.
3.1.3 charge accumulation, n—the increase of electrostatic
3.1.17 static discharge, v—thereleaseofelectricalenergyin
charges in a tank, compartment, or liquid resulting from a rate
the form of a spark or corona discharge across a gap between
dissipation slower than the rate of charge delivery by the
surfaces of differing voltage.
incoming product.
3.1.18 switch loading, v—thepracticeofloadingonetypeof
3.1.4 charge generation, v—the creation of electrostatic
productintoatankorcompartmentwhichpreviouslycontained
chargesinaliquidduetotheseparationofionicspeciesduring
a different type of product.
liquid flow.
3.1.18.1 Discussion—When involving handling safety,
switch loading often refers to loading a low vapor pressure
3.1.5 charge relaxation, n—the decrease of electrostatic
product into a tank or compartment previously containing a
charges with time.
high vapor pressure product. A flammable vapor in the ullage
3.1.6 combustible liquid, n—a liquid having a flash point at
space is likely to result.
or above 38°C (100°F) (See Test Methods D56 and D93).
3.1.19 top loading, v—the practice of filling transport com-
3.1.6.1 Discussion—Subdivisions of this classification will
partments through an open dome at the top of the transport.
be found in NFPA Standard No. 30.
3.1.20 ullage (vapor) space, n—the space between the
3.1.7 conductivity, n—the reciprocal of electrical resistivity,
liquid surface and the top of the tank or compartment contain-
the capability to transmit electrostatic charges normally ex-
ing the liquid.
pressed in picoSiemens per metre (pS/m) for petroleum prod-
ucts.
3.1.21 unbonded charge collector or accumulator,
3.1.7.1 Discussion—Conductivity has also been expressed
n—unbonded, conductive objects which concentrate electrical
−12
inconductivityunits(C.U.)whereI.C.U.=1pS/m=1×10
charges.
−1 −1
Ω m .
3.1.21.1 Discussion—These unbonded charge collectors
may be objects floating on the surface of the charged liquid or
3.1.8 conductivity improver additive, n— a material added
objects such as gaging tapes lowered toward the charged
to a fuel in very small amounts to increase its electrical
surface. The high conductivity of metallic charge collectors
conductivity and thereby reduce relaxation time.
permits the rapid discharge of accumulated charges.
3.1.8.1 Discussion—Conductivity improver additives are
also known as static dissipator additives (SDAs) or antistatic
4. Significance and Use
additives.
4.1 Pumping, filtering, and tank filling of petroleum
products, particularly refined distillates, can cause the genera-
Available from National Fire Protection Association (NFPA), 1 Batterymarch
tionandaccumulationofelectrostaticchargesandcanresultin
Park, Quincy, MA 02269-9101.
Available from Canadian General Standard Board, Ottawa, Canada.
Part 2 of British Standard Code of Practice for Control of Undesirable Static
Electricity, available from British Standards Institute, 2 Park St., London, England The boldface numbers in parentheses refer to the references at the end of this
WIA2B5. standard.
D4865 − 09 (2014)
static discharges capable of causing fires and explosions. This a static discharge. The voltage difference is limited by charge
guide provides an overview of the factors involved in the dissipation/relaxation processes which occur both in the pipe-
generationofsuchelectrostaticcharges.Methodsaredescribed work downstream of strong charge generating elements and in
for the alleviation of the problem, and cited authoritative the tank itself. Relaxation in the pipework reduces the amount
references contain more details.
of charge that reaches the tank while relaxation in the tank
reduces the voltage produced by a given amount of inlet
4.2 Thisguideisnotintendedtoprovideoperatingorsafety
charge. Under most practical loading conditions, the voltage
rules for the handling of petroleum products to avoid electro-
generated by a given inlet charge density is proportional to the
static hazards.
relaxation time of the fuel. This relaxation time is inversely
proportional to the conductivity and is approximately 20 s
5. Background
when the conductivity is 1 pS/m. The conductivity of hydro-
5.1 Ignition Principles:
carbon fuels is highly variable as a result of natural product
5.1.1 Forignitiontooccur,itisnecessarytohaveanignition
differences, commingling, or the use of additives. Products not
source of sufficient energy and a mixture of fuel and air in the
containing additives, including diesel fuels, may have conduc-
flammable range. The boundaries of the flammable range are
tivitiesoflessthan1pS/mbutmanymodernadditivepackages
defined by the lean and rich limits. Below the lean limit there
(not just static dissipator additives) provide considerably in-
is not enough hydrocarbon vapor to sustain combustion,
creased conductivity, possibly up to several hundred pS/m or
whereas above the rich limit there is not enough oxygen. The
more. The relaxation time can therefore be anything form a
mixture temperature and pressure and the fuel characteristics,
fraction of a second to a number of minutes. It has been found
including boiling range and vapor pressure, determine the
that the reduced relaxation time produced by increasing the
amount of a given fuel which is vaporized and therefore
conductivitymorethancompensatesforanyincreaseincharge
establishtheflammabilityofthemixture.Normallytheselimits
generation that may occur. The highest voltages and electro-
are measured under equilibrium conditions with the fuel
static ignition risks are therefore associated with low conduc-
partially or completely vaporized. However, ignitions have
tivities. Unless conductivities are controlled, the possibility of
occurredbelowtheleanignitionlimitwhenthefuelwasinthe
encountering low conductivity product should be allowed for
form of a foam or spray. Also, systems are not normally in
when defining safe loading procedures (3, 4).
equilibrium when there is sufficient fuel flow to generate
electrostaticcharges.Turbulenceinthevaporspacecanleadto
6. Practical Problems
unexpected flammable air-vapor mixtures in localized areas.
6.1 Certain switch loading operations, such as loading of
Equilibrium flammability limits can therefore be used only as
diesel fuel into a truck which previously carried gasoline and
rough guidelines of flammability.
still contains vapors or liquid gasoline, are especially danger-
5.1.2 The second requirement for ignition is a static dis-
ous.The combination of a flammable vapor space and charged
charge of sufficient energy and duration. Discharges occur
diesel fuel presents a potential explosion hazard if an electro-
when the voltage across a gap exceeds the breakdown strength
static discharge occurs. Analyses (5) of past tank truck acci-
of the fluid or air in the gap. Minimum energy requirements
dents reveal that switch loading or splash filling, or both,
vary widely depending on the nature of the spark, the configu-
account for 80% of static-initiated explosions. More informa-
ration of the spark gap and electrodes, nature of materials, and
tion on the hazards of flammable atmospheres formed during
other factors. There is no doubt that sparks due to static
switch loading will be found in 7.6.
electricity in petroleum systems can have sufficient energy to
igniteflammablemixtureswhentheyoccurinthevaporspace.
6.2 Microfilters and filter-separators are prolific generators
Discharges from highly charged fluids are known to penetrate
of electrostatic charges. The type of ionic impurity in the
plastic tubing.
product as well as the type of surface determine the magnitude
and polarity of separated charges that are swept away in the
5.2 Charge Generation—Whenever a hydrocarbon liquid
flowing stream. Many additives in fuel increase the level of
flows with respect to another surface, a charge is generated in
charge generation upon filtration, although in the case of static
the liquid and an equal but opposite charge is imposed on that
dissipatoradditivesthisismorethancompensatedbyenhanced
surface. This charge is attributed to ionic impurities present in
charge dissipation. Most common filter media such as
parts per million or parts per billion quantities. At rest the
fiberglass, paper, and cloth as well as solid adsorbents are
impurities are adsorbed at the interface between the fuel and
potentchargegenerators.Whencarryingoutoperationssuchas
the container walls, with one part of the ionic material having
...