Static Electricity

[Firechief-47]

We had a fire at a grain elevator involving ground oat hulls and pvc pipe. They were blowing ground oat hulls into a semi trailor using steel pipe to the trailor. The trailor had three pvc pipes installed in it to blow the oat hulls into it. The fire started inside the trailor and spread to the tarp and to a plastic dust curtain they had around the trailor. It then spread to the outside of the structure. My question is, can moving grain through a plastic pipe generate enough static charge to ignite the fine oat dust? The fire was very intense by the pipe outlet and had melted the trailor in a small area by it.

[DD]

My opinion is that it might. Consider PVC collection systems for saw and sanding dust from wood. A copper wire is placed inside of the pipe to conduct the static charge to a ground.

[Jim M.]

There was an article several years back in either Fire-Rescue or Fire Engineering about fires caused by static electricity. Basicly, the moving product builds up quite a bit of charge. The amount is dependent on temperature and air moisture content (I think - article was awhile ago!) So something that works perfectly well for months and months suddenly blows up when conditions are just right. The article included suggestions on how to ground the pipes, tubes, or whatever to reduce the problem.

[Capez]

I would look at a different ignition source.
Static charge may result in a dust Explosion but not just a fire. As with all organic compounds it could have been spontainious combustion due to breakdown of the husks. or even friction from the product being moved at a high rate of speed, Large surface area low mass = low ignition temp and high thermal inertia.

Alex Capezza BS, CFEI, CFII, FF2, EMT-I

[This message has been edited by Capez (edited October 03, 1999).]

[Firechief-47]

Capez, We had the State Fire Marshal investigate and eliminated other ignition sources. I am waiting for the report from him to see what he came up with. The grain elevator has stopped loading trucks this way until we figure out the cause.
Thanks for the help.