8/3/2019 2003 07 Static Electrical Spark

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CCPAn AIChE IndustryTechnology Alliance

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AIChE P P rocess S S afety B BeaconMessages for Manufacturing Personnel

July 2003

Heres What Happened:

By design, plastic beads fall by gravitythrough this sieve. The beads containtrace amounts of pentane, a flammable,volatile material which is liberatedduring processing. The sieve wasdesigned with an air sweep to keep the

pentane fume concentration below theflammable limit. One evening, wheneverything appeared to be operating as itshould, the operators heard a loud BANG! BANG! They quickly investigated andsaw flames coming out of the sieve.Quick action by the fire brigadecontrolled the fire and no one wasinjured, but the plant was down for

repairs.

AIChE 2003. All rights reserved. Reproduction for non-commercial, educational purposes is encouraged. However, reproductionfor the purpose of res ale by anyone other than CCPS is strictly prohibited.

Contact us at ccps@aiche.org or 212-591-7319. http://www.aiche.org/ccps/safetybeacon.htm

Critical Safety Devices come in many forms. Know them and use t Critical Safety Devices come in many forms. Know them and use t hem!hem!

What Can You Do to Prevent

Similar Problems?Regularly check ALL safe guards

to be sure that they are still in placeand working properly. This includesinterlocksare they there, are theyworking? Remember, air purges can

be safeguards too.Be aware that static electricity may

be anywhere. Good design and wellmaintained systems control it.

Some equipment has groundingcables. If they are damaged, replacethem quickly to remove the spark

potential.Make sure that all three components

of the fire triangle do not exist at onetime and in one place.

How Could this have Happened?

Plastic beads falling through air generate anelectrical charge. When this charge is large enough,it discharges.

This is a static electrical spark!!This is a static electrical spark!!These beads contained trace amounts of pentane, avolatile flammable material. As the beads fell, someof the pentane vaporized and made the atmosphereflammable.The air purge that was suppose to sweep theflammables out of the sieve was not workingproperly. This critical safety system failedtoolittle air flow allowed a flammable atmosphere todevelop!The purge air flow system was not interlocked tothe sieve operation so no alarm sounded at low airflow.And, as we all know--a spark in a flammableatmosphere = KABOOM!!! KABOOM!!!

PSID Memberscheck for Static in the free search area.

Static Electricity + Flammables + Air = ??

You Guessed it Explosion & Fire !

SCENTER FOR CEHMICAL PROCESS SAFETY

This is a picture of a sievecovered in soot after staticelectricity sparked anexplosion.

Sieve traysSoot andflame damage

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