static electricity booklet jan10

8/3/2019 Static Electricity Booklet Jan10

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Ron J. Zezulka, TB&S ConsultantsEd Ferguson, AmeriGas Propane, L.P.

Statc Electctyin the Propane Industry


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Propane Education & Research Council

1140 Connecticut Ave. NWSuite 1075Washington, DC 20036

202.452.8975www.propanecouncil.org

Note: This booklet was developed by TB&S Consultants under contract to the Propane Education & ResearchCouncil Docket Number 12457. For urther inormation regarding propane saety and static electricity, visitwww.propanesafety.com .

Ntce and Dsclae Cncenng Lablty

The Propane Education & Research Council (PERC) is anon-prot 501(c) 6 trade organization authorized by thePropane Education and Research Act o 1996 (PERA),Public Law 104-284. PERC was created to enhanceconsumer and employee saety and training, to provide or

research and development o clean and ecient propaneutilization equipment, and to inorm and educate the publicabout saety and other issues associated with the use opropane.

PERC is governed by a 21-member Board o Directors ap-pointed by the National Propane Gas Association (NPGA)and the Gas Processors Association (GPA). PERC programbeneciaries include propane retail marketers, producers,transporters, and agricultural cooperatives, as well as rep-resentatives o allied service and supply industries (industrymembers).

The recommendations, standards, or recommended prac-

tices, as refected in this document, were developed byindependent consultants retained by PERC. While PERCadministers the process o obtaining the inormation, itdoes not independently test or veriy the accuracy o theinormation or methods used to collect the data that sup-port the conclusions or recommendations refected in thisdocument.

PERC, NPGA, GPA, and the industry members disclaim anyliability or any personal injury, property damage, businesslosses, or other damages o any nature whatsoever,whether special, indirect, consequential, or compensatory,directly or indirectly resulting rom the publication, use, orreliance on this document, or any inormation, apparatus,

method, process, or similar item disclosed in this document.This disclaimer o liability shall apply even i such lossor damage results, in whole or in part, rom any acts oromissions o or by any negligence on the part o PERC,

NPGA, GPA, or the industry members or any personswho contributed to the development o the inormationcontained in this document. PERC, NPGA, GPA, and theindustry members make no warranty or guarantee as to theaccuracy or completeness o any inormation published in

this document.

The procedures and inormation in this document areintended to implement the standards set orth in the docu-ments reerenced with capabilities o the personnel andequipment available. It does not create new standards orcriteria or compliance. The order o steps in any proceduremay or may not be o importance. This material is not soldnor is it a product o any consulting or engineering activity.

Users o this document should consult the law o theirindividual jurisdictions or codes, standards, and legalrequirements applicable to them. This document is notintended nor should it be construed to (1) set orth policies

or procedures that are the general custom or practice inthe propane industry; (2) establish the legal standardso care owed by propane distributors to their customers;or (3) prevent the user rom using dierent methodsto implement applicable codes, standards, or legalrequirements.

By disseminating or publishing this document, PERC isnot undertaking to render any proessional or other serviceto or on behal o any person or entity. PERC, NPGA, GPA,and the industry members are not undertaking to perormany duty owed by any person or entity to any third party.Anyone reading or using this document should rely on hisor her own judgment or, as appropriate, seek the advice o

a competent proessional in determining the exercise oreasonable care in any and all circumstances.


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Table Cntents

1. Purpose and Denitions .............................................................................. ............................................................................... .. 1

2. Introduction ..................................................................... ............................................................................... ..........................................2

3. A Lesson Learned ............................................................................. ............................................................................... .................3

4. Static Electricit y ..................................................................... ............................................................................... ...............................4

4.1 What Is Static Electricity and Where Does It Come From? .............................................................. 4

4.2 How Does Static Electricit y Act? .................................................................... ........................................................5

4.3 Did You Know? ......................................................................... ................................................................................ ...............6

4.4 What About Relative Humidity? .......................................................................... ......................................................6

5. Steps to Take to Reduce Static Electricity .......................................................................... ......................................... 7

5.1 Identiy the Static Discharge Control Areas ...................................................................... ............................ 7

5.2 Floors and Work Suraces .......................................................................... ................................................................... 7

5.3 Footwear ........................................................................... ................................................................................ ............................8

5.4 Saety Clothing and PPE ............................................................................. ...................................................................8

5.5 Ground the Equipment ..................................................................... ................................................................................ .8

5.6 Remove Field Sources ...................................................................... ................................................................................95.7 Friction Creates Static Electricity............................................................................................................................9

5.8 Temperature and Relative Humidity .............................................................................. ........................................9

5.9 Training ................................................................... ............................................................................... ..................................... 10

5.10 Interviews and Anecdotal Evidence ............................................................................. ..................................... 10

5.11 Limit Access to Static Discharge Control Areas ......................................................................... ........... 10

Static Discharge Prevention Quick Tips .......................................................................................................................11

Glossary ...................................................................................................................................................................................................12

Reerences and Acknowledgments ................................................................................................................................14

Field Evaluation Guide: Static Discharge Hazards .............................................................................................15

Static Discharge Control Quiz ..............................................................................................................................................21

DVD ......................................................................................................................................................................Inside Back Cover

Static Discharge Control Quiz Answers ................................................................................Inside Back Cover


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CommoN TErmS USED iN ThiS BookLET

static electricity

an electrical charge on the surace o a material created by an excess or

a deciency o electrons; electricity at rest

static discharge

the rapid equalization o static electricity; electricity in motion

conductive

the property o a material that allows or the fow o electrons

conductor

a material that allows the fow o electrons; common examples include most metals

and the human body

non-conductive

the property o a material that resists the fow o electrons

non-conductor

a material that resists the fow o electrons; common examples include plastics,

vinyls, and dry abrics

(See Glossary on page 12 or additional terms used in this booklet.)

1. Pupse and Defntns

The purpose o this booklet is to inorm propaneindustry proessionals, acility managers, companysaety ocials, and other responsible employees olessons learned and inormation gained rom researchon the ignition hazards o static electricity and theresulting static discharge in the propane industry.The approach is a practical one, citing science andtechnology where necessary.

The objective is to equip readers with the knowledgeand tools to:

Evaluate their facility for static electricity and staticdischarge hazards;

Implement remediation or mitigation actions; and

Facilitate appropriate training/instruction forall applicable employees.

This booklet provides a basic understandingo static electricity, its sources, commonexposures, and strategies that can/should beused to reduce the risk o unwanted ignition.The sources and causes o static electricityare varied. This booklet identies commonstatic threats that may be present at propanehandling acilities.

Te llwng tanng tls ae aalable:

1. An instructional printed manual.2. A companion DVD to be used as a visual aid.


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2. intductn

Static electricity is electricity at rest, or simplynot moving. Other than an attraction to other materials,it is relatively harmless. However, i a conductive pathis prov ided or the stat ic electricity, the resulting staticdischarge or spark may cause the ignition o propanevapor. When propane mixes with air (2.15 to 9.60% byvolume), the resulting mixture can be ignited easily by astatic discharge. Static discharge is sometimes cited asthe possible cause o res or explosions.

Advances in chemistry and technology have broughtus new polymers and synthetics that have increased thelikely presence and generation o static electricity. Forexample:

Wood and steel are being replaced with polymericmaterials such as high-density polyethylene (HDPE)

Polyvinyl chloride (PVC) and stretch wrapsare used to cover and secure loads

Figure 1. Static discharge can cause ignitions.

PVC pipes are replacing metal pipes in low-pressuresystems

Natural fabrics are being replaced by synthetics

Automation has brought faster production speeds

The study o static electricity has grown exponen-tiallyover the past decade. However, there is still a vastmisunderstanding about how it works where propane istranserred and handled.

This guide oers a practical view o static electricity asan ignition source and provides general suggestionsto reduce associated risks. It must be noted, we cannever completely eliminate static electricity. However,by understanding what static electricity is, where itcomes rom, and how it behaves, we can more eec-

tively control it.


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3. A Lessn Leaned

Te eent:

In July 2006, an employee at a northern Caliorniacylinder processing acility reported to his managerwhat he believed to be a re during the transer

process. An immediate investigation did not show anysigns o ignition or re.

1NFPA 58,Establishes a maximum ugitive emissions standard or certain product transer operations. Low-emission transer specifcations might be employed to comply with environmental

regulations or to determine certain minimum distance requirements, 2008 Edition,

Section 3.3.37.5 Low-Emission Transer.

Copyright AmeriGas Propane, L.P., February 23, 2007.All rights reserved.

Te nestgatn and dscey:

The nature o the employee report promptedmanagement to install surveillance cameras in an eortto determine the source. A video camera captured

the event (see Figure 2), which was the ignition o the24 cc release o propane at the precise moment thepropane/air mixture was perfect for ignition (2.15 to9.60% by volume).

The ignition source was determined to be a static sparkgiven o by the employees clothing while lling thecylinders. Static electricit y had been produced andthen transerred to the employee by contact with HDPEcylinder storage trays.

The employee was wearing ootwear and standing ona mat that isolated the employee rom ground, makingthe employee a charged carrier looking or a place todischarge the energy! Later, several employees reportedthey had been hearing a pop sound, similar to thesound o an old-style fash bulb. Others reported seeingfashes, which were at rst thought to be light refectingrom nearby trac. This had been happening or sometime!

Note: The size o the reball was limited to the24 ccs o propane released, the only available uel.

Te utce:

Once we understood what and why this washappening, it was an issue easy to resolve. A

ew simple process changes were implementedto keep HDPE trays and other HDPE items outsidethe transer area. The employees now wear approvedanti-static ootwear or heel grounders, and the matshave been changed to anti-static conductive types.Employees were educated on static electricity, staticdischarge, and their role in controlling static electricity.

obseatn:

The only time we notice or pay any attention to staticsparks is when they are painul or they ignite uel. Statcspas t sall t be seen elt can gnte ppane!

This cylinder processing acility was relling 20-pound cylinders, lling by weight using

a low-emission transer process.1 The low-emission transer releases between 2

and 4 cubic centime ters (ccs) o propane a t the end o each ll cycle as the ll nozzle is

released rom the c ylinder.

Figure 2. Ignition o propane at a nor thern Caliornia cylinder processing acility.


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4. Statc Electcty

4.1 Wat is Statc Electcty and Wee Des

it Ce F?

We have all seen examples o static electricity. Theway our hair fies around when we brush it, the way

some garments cling together when they come out oa clothes dryer, or the annoying little zap you eel whenyou reach or a light switch. Static cling andstatic sparks are common everyday events.

Figure 3. Paper strips react to an electric eld.

Static electricity is simply that static: its electricitythats standing still! A material with either too many ortoo ew electrons in its atomic structure has a staticelectrical charge.

Static electricity can come rom a number o sources.Atmospheric lightning is the largest and most violentorm.

Most o the static electricity we experience inour daily lives is not as dramatic. In act, weusually dont notice it at all, or i we do, we dontpay it much attention. This is the static electricitycreated or generated by riction, scientically calledtribogeneration. Walking across a loading dock withrubber-soled boots, removing a wool sweater, andwind blowing over stretch wrap are all examples oriction generating static electricity.

Figure 4. Stretch wrap in the wind may generateand induce static on cylinders.

When any two materials touch and separate, onematerial rips electrons away rom the other material

creating an imbalance or charge. It happens with allmaterials. The material that receives the electrons hasa negative charge, and the material that gave them hasa positive charge.

Dierent combinations o materials will developdierent levels o static charge or voltages. Relativehumidity, speed o movement, the materials size,and the materials electrical properties are all actors indetermining how much static will be generated and howits going to behave.

When we walk across a carpet, the soles o our shoes

separate rom the carpet, there is riction inside ourshoes and socks, and our clothes rub against ourbodies. These sources o ric tion generate a staticcharge. Then, i we reach out to touch a light switch orother conductive material, a spark is emitted.

Other examples include uel fowing at high velocitythrough a small opening, which can generate enoughstatic electricity in the uel vapors to ignite them. Also,the riction o a dry wind blowing over cellophane orstretch wrap may energize the wrap. The wrap, in turn,may induce a charge into nearby conductors. A con-ductor can be any material that an electric current can

pass through. Non-conducting materials resist the fowo electric currents.


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2 Within the eect s o the electric eld surrounding the charged object.

When a person walks across a non-conductiveoor, his/her body picks up a static charge fromthe riction o the shoes and clothing layers. The human

body is electrically conductive, which means when youreach out to a light switch (also electrically conductive),all that extra electrical energy your body has pickedup is ree to jump to the light switch or any otherconductive object you get close to.

Charged conductors such as people can easily throwstatic sparks. Non-conductors such as most polymericmaterials, plastic lms, and dry abrics usually dontthrow sparks, unless the voltages are very high ormovements like removing a sweater are involved.

Even though they dont readily throw sparks,

non-conductors can transer their electrical energyto something or someone which can spark. Thischarge transer results rom a conductor being veryclose2 to the charged non-conductor. The static eldrom the charged material will orce the conductor tobecome charged i the conductor is briefy grounded.Scientically, this is known as induction.

A typical example could be an employee carryinga charged plastic trash barrel. I the employee ismomentarily grounded, his/her body will becomestatically charged because o the charge on the barrel.After the employee puts the barrel down and if he/

she is not wearing static discharge control ootwear orgrounded any other way the employee may carry theinduced charge into a control area and then throw aspark.

4.2 hw Des Statc Electcty Act?

Most o us have elt a static spark when we havereached out to a light switch or the door handlein our car. This is the way static electricity acts

with conductors.

A common childrens party trick involves rubbingan ordinary balloon on your hair and then havingthe balloon cling to a wall, sometimes or hours.The static charge on the balloon is attracted tothe wall, but the electricity cant fow becausethe balloon and the wall are non-conductors.

The balloon was held to the wall because o itsstatic charge and its attraction to the electricallyneutral wall. To lose its static charge, the balloon mustattract oppositely charged particles rom the air. This

process (ionization) takes time, but eventually thecharge on the balloon decreases to a point where theballoon alls. We can quickly regenerate the staticcharge and put it back on the wall.

I the air in the room is humid (above 50% relativehumidity), rubbing the balloon may not put enoughcharge on it or it to stick to a wall. This is becausehumid air has more ree charged particles positiveand negative that can be attracted to the balloonto neutralize it. Additionally, humid air will moistensuraces. The moisture is electrically conductiveand thus quickly coats both suraces.

Wen electcal cnducts ub tgete, tey d ntgeneate statc.

Cn mateals

Cnducts Nn-Cnducts

Most metals Plastic lm

Human body High-density plastics

Wet abrics Most dry abrics

Wet concrete Dry concrete


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3 It is the s uperheated air that ignites propane or other uels. 4NFPA 77,Recommended Practices on Static Electricity, 2007 Edition, Section 7.4.2.3.

4.3 Dd Yu knw?

Most o us have elt a static spark, perhaps whenexiting a car, turning o a light, or even pulling oa sweater. These may be annoying, but are seldom

painul. Perhaps that is why some o us dontassociate a static spark with signicant energy and,specically, ignition energy.

Scence as taugt us tat te sallest statc spa an aeagepesn can eel, see, ea s easued at abut 3,000 lts.It sounds lethal, but it isnt. The actual static dischargeevent lasts only 300 billionths o a second. It s overbeore it can hurt the human body. The fash o lightseen with the static spark is actually the superheatedair that continues to glow ater the electrons havestopped moving.3

Even though the static spark is very ast, it gives oenergy in the orm o heat and light. At 3,000 volts, astatic spark rom your ngertip will deliver about .50millijoules (mJ) o energy. This may not sound like muchuntil we learn that propane mixed with air at 2.15 to9.60% requires about .25 to .30 mJ o energy orignition.

Te sallest statc spa we can see eel as duble teenegy equed t gnte ppane!

A piece o ordinary plastic the size o a binder or poly-styrene coee cup can generate and transer morethan enough energy to generate an incendiary spark.

Figure 5. Normally innocuous items may generateand retain incendiary levels o static electricity.

4.4 Wat Abut relate hudty?

How much static electricity can be generated and howlong it lasts are aected by relative humidity (RH).There are more ree charged particles in humid air than

dry. By supplying charged particles o opposite polarity,humid air will neutralize static charges aster than dryair.

Higher relative humidity reduces static generation

and reduces decay time.

Eects mstue n Statc Geneatn(typcal alues)

Figure 6. Plastic lm remains dry on the inner surace, even when t he outer suraceis wet.

Suce Belw 25% rh Abe 50% rh

Walking on a carpet 30,000 volts 1,500 volts

Walking on concrete 8,000 volts 500 volts

Rubbing a plastic bag 20,000 volts 1,200 volts

Brushing hair Dry 25,000 volts Wet 0 volts

Humid air also reduces the ability to generate staticby depositing a microscopic moisture layer on thematerials surace. The moisture is conductive, therebymaking the suraces temporarily conductive.

Polymeric materials such as HDPEs, PVCs,and plastic lms do not absorb moisture andcan charge to extreme voltages, even at 100%relative humidity.4 While one side o the plasticmay be wet, the inner surace is dry.


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5. Steps t Tae t reduce Statc Electcty

Static electricity is all around us. It is not possibleto eliminate it completely, but we can control itsgeneration and provide sae discharge paths. Toreduce the risk o ignition, we must rst identiywhere the Static Discharge Control Areas are andwhere the static electricity may be coming rom.A Static Discharge Control Area may be denedas any area where there is a reasonable possibilityo the presence o propane vapor.

5.1 identy te Statc Dscage Cntl Aeas

Clearly identiying Static Discharge Control Areasinorms visitors and reminds employees o the risk ostatic discharge.

Typical Static Discharge Control Areas may include,but are not limited to:

Transer areas. This includes lling docks, purge,recovery, reurbishing, or any other area wherepropane may be present.

Bulk transer connections. The areas immediatelysurrounding domes, hatches, covers, and othertranser hose connections. These areas maybecome temporary Static Discharge ControlAreas at the end o the uel transer operationwhen the connections are decoupled and somevapor is released.

Retail delivery to vehicles such as motor homes and catering t rucks.

Signage or foor markings are common methodso identiying Static Discharge Control Areas.

Clearly identiying Static Discharge Control Areasreminds employees o the static discharge hazardand deines where static discharge ootwearand other personal protective equipment (PPE) arerequired.

Some propane transer locations are mobile.Examples include ork lit cylinders, which maybe exchanged in the eld, and bulk delivery bytruck or rail. The Static Discharge Control Areasor mobile units should include the immediatearea where there is the likelihood o the presenceo propane vapor.

Figure 7. Some Static Discharge Control Ar eas are stationary and o thers aremobile.

5.2 Fls and W Suaces

Floors and working suraces can play a signicant role

in the generation and control o static electricity. Con-ductive and static-sae foors provide a grounding pathor static charges developed or carried by personnel(equipped with static discharge ootwear).

Non-conductive or insulating foors prevent the drainingo charges rom personnel and materials and willcontribute to the generation o charges.

Static-sae foors, static-sae foor mats, anddissipative paints should be in the static dissipativerange.5 Conductive fooring or mats may be used i nohazardous voltages are present. The resistanceo foors and work suraces may be measured

with a Surace Resistivit y Meter ollowing themanuacturers directions.

5The static dissipative range is between 1 x 105 and 1 x 1011 ohms per square. Conductive is less than 1 x 106. Dissipative is bet ween 1 x 106 and 1 x 1011. Non-conductive is above 10 11.

Static-sae foor coverings and mats are commercially available.


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6Static Discharge Type I, below 100 Meg ohms and Stat ic Discharge Type II, below 1,000 Meg ohms.

5.3 Ftwea

People generate static charges by movement. Theycan carry the charge a considerable distance beoredischarging. Static-sae ootwear6 or temporary heel

grounders allow the wearer to discharge saely to astatic-sae foor or foor mat beore the charge levelsbecome great enough to spark. Other groundingmethods are available, including conductive wristbands with cords.

Figure 8. Static Discharge Type 1 saety boot and a disposable heel grounder.

5.4 Saety Cltng and PPE

Clothing has proven to be a source o static electricity

and static sparks. Some abrics and combinations oabrics generate more static electricity than others.For example, cotton and cotton blends tend togenerate less static electricity than most synthetics andpolyester materials.

For critical applications, specialized static-saegarments and abric treatments are available.Here are some guidelines:

Cotton and cotton blends generate less static thanmost synthetic materials.

100% nylon, 100% polyester, and wool clothing

should be avoided.

Garments such as sweaters or coats should never beremoved or put on inside a Static Discharge ControlArea.

5.5 Gund te Equpent

Any conductor not grounded is said to be foating.All process and handling equipment must be groundedand bonded in accordance with state and ederalelectrical codes. Ground wires may become looseor disconnected and should be checked periodicallyby a qualied electrician. Non-electrical processequipment, such as roller systems, isolated scales, andother isolated (non-grounded) metal objects, may

become charged and be a spark source. I all spark-producing materials (conductors) are grounded, theyare all at the same voltage potential, and thus no staticsparks are possible.

Figure 9. Process equipment such as conveyers androller systems may develop static i they are not bonded and grounded.

Avoid garments that snap and crackle when put on orremoved.

Flame-retardant, chemical-retardant, and anti-staticgarments may be required.


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7Some polymeric materials may be made anti-static by adding conductive elements in the ormulation process or coating with topical,

anti-static compounds.

5.6 ree Feld Suces

Grounding non-conductors does not drain their staticcharge. Non-conductive materials such as mostpolymeric compounds, HDPEs, and plastic lms rely on

attracting charged particles rom the surrounding air toneutralize their charge. Some even generate a chargein the wind aster than they decay into the atmosphere.

Remove all the non-conductive materials that areunnecessary to the operation in progress. Store largeaccumulations o these materials (e.g., HDPE stackingtrays, trash barrels, plastic wraps, etc.) at least 25eet rom Static Discharge Control Areas. Under idealconditions, a piece o plastic the size o a clipboard cantranser ignition energy.7

5.7 Fctn Ceates Statc Electcty

Many static discharge events are generated byprocesses or activities. Any process that involvesmovement and the separation o materials may

generate static electricity through riction. A typicalexample may be decoupling a bulk hose at the end oa transer ater walking around or returning rom thevehicle cab, or the movement required on a lling dock.

Removing plastic sleeves rom barbecue cylinders in arelling operation is an example o a repetitive motionprocess involving non-conductors.

5.8 Tepeatue and relate hudty

Temperature and RH aect the level o staticelectricity generated and the length o time it lastsbeore decaying. The eect o temperature is clearlyevident in colder climates during winter months.The measured RH outdoors may be almost 100%;however, i the air is heated without adding moisture, itsability to hold moisture increases dramatically, and thecorresponding measured RH drops. This is why indoorstatic shocks are more common during cold wintermonths in northern climates.

Polymeric materials, plastic lms, and many syntheticmaterials do not absorb moisture and dry very quickly.Plastic lm used to wrap cylinders will remain dry onthe inside even when it is raining. Thus, the dry lm willgenerate static even i the outer layer is wet!

Figure 12. Any process that requires movement may generate static electricity.

Figure 11. Packing materials and wraps should be removed and stored away romStatic Discharge Control Areas.

Figure 10. HDPE stacking trays may develop extreme levels o static electricity.Because trays are stacked, air fow cannot neutralize t he charge on the trays inthe center o the stack.


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Take note o the obser vations o people whowork in Static Discharge Control Areas. They are theones who witness static discharge events rst hand

and thus are the rst to be aware o potential ignitionrisks.

5.11 Lt Access t Statc Dscage Cntl Aeas

By limiting access to Static Discharge Control Areasto those individuals necessary to conduct normalbusiness activities, we can limit the number opotential charge carriers. Casual observers and retailcustomers may not be equipped with the appropriatePPE or be aware o static discharge hazards.

5.9 Tanng

There is no single tool or material that can control allstatic electricity. Instead, by understanding what staticelectricity is and where it comes rom, we can apply

simple means to reduce and control it. We shouldexamine our processes and equipment to determine ithey are part o the problem or part o the solution.

5.10 inteews and Anecdtal Edence

People working inside Static Discharge ControlAreas and other personnel oten observe situations andconditions that may indicate the presence o staticelectricity. They are aware o changing conditions andsituations oten beore management or saety ocials.

Figure 13. Static Discharge Control Areas include areas where hoses and connections are coupled and decoupled and there is the potential or the presence o vapors. Itincludes railheads, bulk transers, and cylinder lling areas.


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1. Know the area

Be aware o Static Discharge Control Areas; that is,

any area where propane vapors may be released orpooled. Some areas may be designated as Static

Discharge Control Areas; however, any transer,

storage, or processing location where the odor o

propane is present should be considered a Static

Discharge Control Area where appropriate static

discharge prevention measures should be taken.

Remember, the odor o propane is a warning.

2. Ground your personnel

Are all personnel in the Static Discharge Control

Area properly grounded? People generate

static charge by movement, and they can carry

the charge a considerable distance beore

discharging. Static-sae ootwear or temporary

oot grounders allow the wearer to discharge

saely to a static-sae foor or foor mat beore

the charge levels become great enough to spark.

Other grounding methods are available, including

conductive wrist bands with cords.

3. Ensure proper attire

Cotton and cotton blends will generate less

static electricity than most synthetics and

polyester materials. (Static-sae garments and

abric treatments are available.) Be aware o any

garments or layers o garments that snap and

crackle when put on or removed. Never put on

or remove garments inside a Static Discharge

Control Area.

4. Clean up

Remove all plastics, HDPEs, and other synthetic

materials rom Static Discharge Control Areas.Chargeable materials necessary or operation

may be treated with topical anti-static coatings.

5. Follow the code

Is your equipment properly grounded? Any

electrical equipment inside a Static Discharge

Control Area must be installed in accordance

with NFPA 58 and state electrical codes and

regulations. Metal, non-electrical stationary

equipment, such as rollers, should also be

grounded.

6. Observe your processes

Most static electricity comes rom the riction

between materials. Processes that involve

non-conductive materials will usually generate

static electricity.

7. Limit access

Limit access to Static Discharge Control Areas

to those people necessary to conduct normalbusiness activities.

8. Listen

Take note o the observations o people working in

Static Discharge Control Areas. They are the ones

who witness static discharge events rst hand and

thus are the rst to be aware o a static threat.

STATiC DiSChArGE PrEvENTioN QUiCk TiPS


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GLoSSArY

bond

electrically connect two or more conductive materials

to ensure they are at the same voltage level, not

necessarily earth ground; to achieve equal potential

conductive

the property o a material that allows or the fow o

electrons

conductor

a material that allows the fow o electrons; common

examples include most metals and the human body

ground

the reerence point rom which voltages are measured;

it is the return path or electrical current to earth; adirect physical connection to earth

high-density polyethylene (HDPE)

dense, economical, hydrocarbon-plastic having good

moisture barrier and chemical resistance; commonly

used or bags, bottles, and other household products

induction

the method by which an electrically charged object

can create an electrical charge in a second object

without physical contact between the two objects

insulator

see non-conductor

ionization

the process by which a neutral atom or molecule

loses or gains electrons, thereby acquiring a

negative or positive net electrical charge; when

electrons are gained, it is known as a negative

ion; a positive ion has lost electrons

joules

a unit o heat, energy, or work; there are 4.184 joules

in a calorie, and 1,055 joules in a British thermal unit

(Btu); a watt is a joule/second

millijoules (mJ)

1/1000 joule

non-conductive

the property o a material that resists the fow

o electrons

non-conductor

a material that resists the fow o electrons; common

examples include plastics, vinyls, and dry abrics

polymeric materials

popular usage describes materials composed o

molecules with large molecular mass typical o

polypropylene and common plastics; polymers with

covalent chemical bonds

polyvinyl chloride (PVC)

polyvinyl chloride, a polymer o vinyl chloride used

to make a wide range o consumer products such

as stretch wrap and low-pressure pipes; commonly

known as vinyl

PPE

personal protective equipment; personal attire, tools,

and materials designed to protect the user rom the

normal hazards associated with the current activity;

common examples include static-sae saety boots,

ace shields, and gloves

resistance

the quality o a material that resists or impedes

the fow o electricity


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13

resistivity

surace resistivity; the electric resistance o

the surace o an insulator, in ohms per square, as

measured between the opposite sides o a square on

the surace, and whose value in ohms is independent

o the size o the square or the thickness o the

surace lm

static discharge

the rapid equalization o static electricity; electricity

in motion

static discharge footwear

ootwear designed to discharge static electricity

through static dissipative materials in the shoe soles;

static discharge ootwear may be designated asstatic discharge Type 1 (below 1 x 108) and static

discharge Type 2 (below 1 x 109); other common

designations include static sae, static dissipative,

static control, and ESD (electrostatic discharge) sae

static dissipative

the property o a material that reduces the speed o

static discharge; a material with a surace resistivity

between 1 x 105 and 1 x 1011 ohms per square

static electricityan electrical charge on the surace o a material

created by an excess or a deciency o electrons;

electricity at rest

stretch wrap

a thin, plastic, stretchable wrapping material applied

to the outside o a nished load or pallet to protect

against dust and moisture, and to reduce load

shiting during transit

tribogeneration

the generation o static electricity through

the riction o contact and separation o two

dissimilar materials

volts

the unit o electrical pressure required to cause

one ampere o current to fow through one ohm o

resistance


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14

reeences

NFPA 77, Recommended Practices on Static Electricity, 2007 Edition.

NFPA 58, Liquefed Petroleum Gas Code, 2008 Edition.

Jonassen, Niels, Electrostatics, Chapman & Hall, 1998.

PERC, Dispensing Propane Saely, 2005.

S.A.H. Rizvi and P.R. Smy, Characteristics o incendive and non-incendive spark discharges romthe surace o a charged insulator, 27, Journal o Electrostatics , 267282, (1992).

Acnwledgents

The authors o this booklet would like to grateully thank the ollowing people or theirvaluable assistance, contributions, and comments in the preparation o this document:

Mike Walters AmeriGas Propane, L.P.

Jerry Lucas Heritage Propane

Carlton Revere Revere Gas and Appliances

Eric Kuster Fairmount Specialty

Eric Leskinen Grith Energy

Phil Applegate Targa Resources

Randy Warner Ferrellgas

Stuart Flatow PERC

Vincent Sibilia PERC


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15

Feld Ealuatn Gude:Statc Dscage hazads

Date: Report #:

Company: Location: Operation:

instuctns

This static discharge eld evaluation guide may be used as an initial acility evaluation or as part o regularly

scheduled saety or quality management evaluations.

I your company has established procedures regarding static discharge control, please comply with those policies. This eld evaluation guide is intended to help propane

companies identiy and reduce the possibility o static discharge in the workplace.

Observations are to include all deviations rom the recommendations noted in the checklist.

Corrective Actions are to include the remedial actions proposed to reduce the possibility o static discharge.

1. Identication and Access to Static Discharge Control Areas (SDCAs)

SDCAs should be identied clearly. Areas where static discharge presents an ignition r isk should be marked clearly with signage or borders that limit access and inorm

visitors and employees o the risk o static discharge.

SDCAs may be dened as any area where there is a reasonable possibility o the presence o propane vapor. These areas include ll lines, carousels, recovery

areas, bulk transer stations, and any other areas where propane may be present.

Have these areas been identied and marked clearly, limiting access to authorized personnel?

YES NO I NO, please complete the ollowing:

Observations:

Corrective Action Plan:


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16

2. Floors and Work Suraces

Floors and work suraces play a signicant role in the generation and control o static electricit y.

Conductive and static-sae foors provide a grounding path or static charges developed by personnel (equipped with static-control ootwear) and reduce or

eliminate charges developed or carried by personnel.

To determine i a foor or work surace is static-sae, the use o a surace-resistivity meter or megohmeter equipped with ve-pound weights is required.

Prior to testing, the foor should be swept clean but not washed. The weights should be spaced three eet apart.

Perorm a minimum o ve tests per contiguous foor surace, or a minimum o ve tests per 5,000 square eet, whichever is greater. Three o the ve tests

should be conducted in those areas that are subject to wear or that have visible soiling or contamination.

When testing foor mats, perorm a minimum o one t est per 20 square eet . Floor mats should also be tested or their resistance to ground. To test or

resistance to ground, place one ve-pound weight on the mat and connect the second test lead to a known ground.

For surace resistivity and resistance to ground tests, a value below 1E9 (1 x 10 9/square) is considered sae.

Warning: Never perorm these tests in the presence o propane vapors.

Static-sae foors, foor mats, and/or dissipative paints should be used in all SDCAs.

Are all foors and work suraces static-sae?


Observations:



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17

4. Saety Clothing

Clothing has proven to be a source o static electricity and static sparks. Some abrics generate more

static electricity than others.

For critical applications, specialized static-sae clothing and abric treatments are available. Here are

some guidelines:

Cottonandcottonblendsgeneratelessstaticthanmostsyntheticblends. 100%nylon,100%polyester,andwoolclothingshouldbeavoided. GarmentssuchassweatersorcoatsshouldneverberemovedorputoninsideSDCAs. Avoidgarmentsthatsnaporcracklewhenputonorremoved. Flame-retardant,chemical-retardant,andanti-staticgarmentsmayberequired.

Do all personnel who enter SDCAs wear saety clothing that ollow these guidelines?


Observations:


3. Footwear

All personnel who enter SDCAs should be equipped with static-sae ootwear or temporary heel grounders. Ent rance to SDCAs should be limited to authorized

personnel equipped with the required ootwear.

Are all personnel who enter SDCAs equipped with static-sae ootwear or temporary heel grounders?


Observations:



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18

5. Ground the Equipment

All process and handling equipment must be grounded and bonded in accordance with state and ederal electrical codes.

Are all process and handling equipment bonded and grounded?


Observations:


6. Field Sources

Remove all plastics and other synthetic materials rom the SDCA. Store these materials (stacking trays, trash barrels, plastic wraps, etc.) at least 25 eet

away rom SDCAs.

Are all o these types o materials unnecessary to the operation in progress removed rom the area?


Observations:



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19

7. Process Observations

All processes that require movement and the separation o materials are capable o generating a static charge.

Have processes, process changes, and new tools been evaluated or static generation?


Observations:


8. Training

All employees involved with the transer o propane should be aware o the hazards o static discharge.

Have all employees involved in the transer o propane been instructed on the hazards o static discharge and appropriate mitigation measures?


Observations:



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20

Signed: Date:

9. Employee Observations

Employees are the eyes and ears o saety.

Are employees actively encouraged to share their observations and concerns regarding static discharge saety?


Observations:


Additional Observations:


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21

Statc Dscage Cntl Quz

1. Static electricity is electricity at rest, or simply electricity not moving. ___ True

___ False

2. Static discharge is an electrical spark between two objects.

___ True

___ False

3. The human body cannot store electrical energy or throw static sparks.

___ True ___ False

4. People generate static charges by movement.

___ True

___ False

5. A static spark too small to be seen or elt can ignite propane.

___ True

___ False

6. Clothing can generate enough static electricity to cause a spark and ignite propane.

___ True

___ False

7. Clothing made rom cotton and cotton blends generate more static electricity than synthetic and nylon clothing.

___ True

___ False

8. Static-sae ootwear and temporary heel grounders allow the wearer to drain static charges rom his/her body to a static-sae foor.

___ True

___ False

continue

Name: Date:


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22

9. All personnel who enter Static Discharge Control Areas should be grounded properly with static-sae ootwear or temporary heel grounders.

___ True

___ False

10. It is sae to put on or remove clothing inside a Static Discharge Control Area.

___ True

___ False

11. More static electricity is generated on a rainy day than on a dry day.

___ True

___ False

12. Removing plastic sleeves rom cylinders can generate static electricity. ___ True

___ False

13. Which places are NOT usually considered Static Discharge Control Areas?

___ Bulk transer connections

___ Cylinder lling operations

___ Storage and recovery areas

___Generalofce

___ Any area where there is the likelihood o the presence o propane vapor

14. What materials should be removed rom Static Discharge Control Areas to help reduce the threat o static discharge?

___ Plastic stacking trays

___ Trash barrels

___ Plastic wraps

___ All o the above

___ None o the above

15. Who is responsible or static discharge saety?

___ Plant managers

___ Saety managers

___ Bobtail drivers

___ Any employee who is in an area where propane is present

All o the above

Statc Dscage Cntl Quz...cntnued


27/28

Statc Dscage Cntl Quz

ANSWEr kEY

1.True

2.True

3.False

4.True

5.True

6.True

7.False

8.True

9.True

10.False

11.False

12.True

13.Generalofce

14.Alloftheabove

15.Alloftheabove\


28/28

Ppane Educatn & reseac Cuncl

1140 Connecticut Ave. NW, Suite 1075

Washington, DC 20036

(202) 452-8975

www.propanecouncil.org

static electricity booklet jan10

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