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Re: [APD] Aquatic-Plants Digest, Vol 35, Issue 9

I don't know what they do in India. To my knowledge, in the US, there is no additive routinely put in CO2 for odor or anything else. The CO2 I worked with had a very slight "rotten egg" smell due to the presence of trace amounts (2 to 5 ppm) of H2S remaining in the fluid.
  Your "cooking gas" is probably methane, with small amounts of ethane, butane, and possibly propane). The additive used to impart the charateristic odor is probably either ethyl mercaptan or methyl mercaptan, a sulfur based compound. This is a requirement in the US, possible all of North America. I don't know if it is an international standard or not.
  A very small amount of this stuff goes a very long way. At a chemical plant where I once worked, about 4 ounces was added to a 10,000 gallon rail car to odorize the entire contents.

Madan Subramanian <madans at hathway_com> wrote:
  On reading your post I disconnected the tubing after the open needle 
valve and checked for the smell, it's still there. My nose still tingles.
The smell is not as pungent as acetylene gas but something similar.
My supplier gives me Medical Grade CO2, do they add an odorous compound 
to the gas so that leakages are quickly detected? Just wondering. They 
do add a compound that gives out a characteristic smell to cooking gas 
here in India, to quickly detect a leak.

Madan Subramanian
Bangalore, India.

Re: [APD] Aquatic-Plants Digest, Vol 35, Issue 8
Douglas Guynn 
Thu, 6 Jul 2006 03:10:25 -0700 (PDT)

aquatic plants digest 

I'm not sure why you experienced the effects you did when your tubing burst. I worked in a plant that extracted CO2 from a natural gas stream as part of a CO2 flood system in the Permian Basin oil fields in Texas. We shipped out over 600 gallons of liquid CO2 A MINUTE for re-injection into the Seminole-San Andreas formation. I was on shift one morning when a 3/8-inch fitting under 2000 psig of pressure (140 kg/cm2 for those on the metric system) broke loose and released a visible cloud of CO2 you could not see through. I experienced no ill effects of being directly in the cloud ( about 10' in diameter) and working to close some 24-inch (39 cm) valves to isloate the pump.

I realize the cloud I saw was not the CO2, but the moisture in the air condensing to a visible state (like fog on a cool morning) due to the cooling effect of the expanding liquid.

By the way, for those of you with OCD, the material in the bottom of your CO2 cylinder is TECHNICALLY not a liquid. It is a supercritical fluid (look that one up in your Funken-Wagnals). Just a little bit of information I learned a long time ago. Not really anything to get in a pissing contest about, just some little known trivia.

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  Douglas Guynn
       PointForward, Inc.       5030 East University, Suite B-101
       Odessa, Texas 79762
       432.550.3331 (office)
       432.366.1879 (fax)
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