Cleaning flamable liquid container

Date 02-05-2005 21:34

The army manual TC 9-237 has a procedure for cleaning flamable liquid containers useing automotive exhaust.It consists of the following.
1)drain tank
2)fill 1/4 full with water mixed with soda or detergent,shake and empty.
3)rinse with clean water.
4)open all outlets and flush with automotive exhaust for 30 minutes.
5)blow all exhaust fumes out with compressed air.
6)seal container for 15 minutes.
7)open and check with explosion meter.
Popular belief is that the exhaust gas just displaces the oxygen,but since it is followed by compressed air it leads me to believe the exhaust gas does something more.
Can someone clearify this?Thank you.

By MBSims

Date 02-06-2005 01:04

I would guess the warm exhaust dries the tank and displaces any remaining fumes.

By burninbriar (*)

Date 02-06-2005 01:53

What is driveing me crazy is that the risk of a hot spark or unburned fuel entering the tank would by far out way the benefit of displaceing O2 or fuel vapors when certainly the millitary can aford to use inert gas for this purpose.The drying efect makes sense but still the risk of pumping exhaust into an uncleaned cotainer?Some one mentioned emergency field operation but this training manual is general welding and cutting proceedures as opposed to combat procedure.I cant help thinking that some chemical or molecular change takes place but dont know what it could possibly be.This will drive me nuts till I find out for sure.
Pete

By Northweldor (***)

Date 02-06-2005 12:16

I don't think any reputable source would call this procedure safe, but it might possibly be used out of necessity in combat. Even if detonation doesn't occur through carbon sparks, there would still be residual fuel in seams,and in sediment, that would be released by heating to provide a later explosive environment. Also, why go to all this trouble if steaming or inert gas purging is available?

By Sand Man (**)

Date 02-07-2005 01:29

When I worked as a heavy equipment mechanic and weldor in the 80's
We used exhaust from the welders to stabilize diesel and hydraulic tanks for welding cracks and other leaks.
We carried a lengh of flexible exhaust tubing for this purpose. I have welded many tanks with fluid still in them.
Not saying it is safe, but it was common practice and never blew anything up,although it was somewhat stressful.
Jeff

By MBSims

Date 02-06-2005 15:07

Not sure what you mean by "uncleaned container". You said it requires cleaning with soda or detergent, followed by rinsing with water. I would guess the detergent is enough to break up and remove any residual fuel. How much more does it need?

By burninbriar (*)

Date 02-06-2005 23:09

What I mean by uncleaned is at this point the process is not compleat.Most importantly it has not yet been tested with the explosion meter.This is a quote from the manual concerning cleaning methods "the automotive exhaust and steam cleaning methods are concidered by military personel to be the safest and easyest methods of purging these containers." The steam cleaning is another chapter and is not part of the automotive exhaust process.