Transport of flammable liquids without inerting ? normal?

[mrtangent]

Dear Sirs,

I have found out that a supply which sends a C7 hydrocarbon to us ocassionally. Does not normally inert tankers the safety case is based on the LEL/UEL C7 is very narrow and the vapour pressure at atm pressure would not be in the flammable range. Talking with the distriubtor this sounds like normal pratice (ie we dont inert petrol/gasoline tankers but I thought that was ok because the have anti static additives which prevent the buildup.). On first glance i was horrified to hear they dont inert but maybe we are a conservative company where we work

So my question is this normal pratice with in the chemical industry or is this distributor abnormal ?

 

[owg]

Commercial heptane has a flammability range of 1.2 - 6.7 mol % in air. The vapour pressure of normal heptane at 70 deg F is 0.8 psia which means the vapour space is 0.8/14.7*100 or 5.4 mol % in air. It looks to me as if the trucks should be inerted. Static is only one source of ignition. I would rather see someone else comment on normal practice in the chemical industry.

HAZOP at

http://www.curryhydrocarbons.ca

 

[Compositepro]

Owg, your calculation is for volume % but your data is for mol %. One or the other is wrong.

 

[mrtangent]

Compositepro,

For owg calc it does not mater as we are dealing with gases. For appoximate idea gas mol % = vol %.

I checked his calcs, it seems to me rather odd pratice to rely on static dissipation.

I am surpised there are not more fires issues...

 

[Compositepro]

Uh... never mind.