Chlorine Residual

[clane902]

Recently stated to me, "that (rail) car transports chlorine, it's "empty" and only has residual amounts left in it". How much is "residual"? Is there a minimum/maximum that constitutes residual in regards to rail cars. I know we treat Hazmats as all being worst case. Im looking for numbers here, not a lecture. Any specialist here?

[DeputyMarshal]

It's only "empty" if it's empty and has been purged/cleaned. Otherwise it's got chlorine in it and should be placarded. The placard may be marked "residual" if the tank has been emptied but it still contains chlorine and should be treated accordingly.

[TNFF319]

I was under the impression that residual did NOT have to be placarded. This could include a full tank that had been turned around from its original destination.

[clane902]

Found out this from a Norfolk Southern Railway rep. "Residual" in tank cars may be vapors to several hundred gallons of product. The railway does not measure or weigh tanks returning to the chemical manufacturer. If the consumer of the tank product removes 1 gallon or the entire contents, it remains placarded and the return manifest reflects "residual". This is important info to public safety personnel. I would encourage you to seek out a railway rep in your area to compare info.

[cfdballz]

The DOT ERG explains that the "residual" placard can be used when the tank is not "Empty" but has less than 3% of volume remaining, i.e 10,000 tank = 300 gallons remaining.