A potential health risk?

[DAISY BOYKIN]

Odor Fade | Bruce Goldfarb

The web site above explains about the smell of propane in NEW and OLD tanks.

[Herk7769]

I learned something new again today.
Thank You

[dnaraG_1M]

[QUOTE=DAISY BOYKIN;187606]

This Post: LP-GAS ODORIZATION INFORMATION FOR PROPANE (C3H8) TRADE NAME:LIQUIFIED PETROLEUM GAS, LP GAS, LPG, HD5, PROPANE.

Maybe this will answer your question about the smell in propane. Listed below is a web site that goes into detail about the safety of propane and the odor smell of "ROTTEN EGGS" of "ETHYL MERCAPTAN" that is added for
YOUR safety in using propane and listed like gasses.


LP-Gas Odorization Information[

Your next Post: More information about the Propane Smell-----
Odor Fade | Bruce Goldfarb

The web site above explains about the smell of propane in NEW and OLD tanks.
/QUOTE]

No. Actually neither of these links address the essential
issue of stratification - MORE smell when the tank is
near empty or of the smell surviving combustion and
NOT triggering a propane detector.

The issue the OP brought up was "bad smell" when
pilot light was burning and you said that was caused
by the tank being near empty. Neither of your links
address that issue. The first is a very detailed
explaination of how and why "smell gas" is added -
something most of us have known for ages. The
second discuses the reasons for the FADING - not
INCREASING - of the smell in certain cases. Again,
no mention of stratification or smell surviving
combustion and NOT triggering a propane
detector.........

Please think about this for a moment: if the smell
chemical stratifies - congregates at the bottom of
your tank - it will certainly do the same in any
tank. Including the tank at the propane refill
station. That means that if you get your tank
refilled when their tank is almost empty, you
will get a huge dose of the smell gas and would
smell it from the git-go, rather than just when
your tank is almost empty. The opposite if you get
the refill when their tank was just topped off - ie
little smell. THIS JUST DOESN'T HAPPEN.
It doesn't pass the "Smell Test"! [Excuse the bad
pun.]

Add to that the question about lack of regulatory
prevention of a situation that would cause false
positives, with *bad* results and your claim just
doesn't make sense. Again I ask if you have links
to scientific literature that addresses the dual issues
of "Smell surviving combustion" and "Smell
congregating at the bottom of the tank".

Ready to be proven wrong.....by REAL DATA.....
In the absence of such, we must rely on what we
have always experienced - the smell is detectable
only in the presence of unburned propane gas.
And when we smell it, there is NO question of a
dangerous situation..............

cheers,
johnd

[Herk7769]

I was fascinated by the link on Mercaptan Fade.
I had never heard of it.

I too also would like to see something on the full tank/low tank phenomenon.

I would think that the partial pressure of gasses law or the law of solutions would apply.

A solution of gasses is not all that different than a solution of liquids.
When liquids are "in solution" the distribution stays equal throughout the solution. I would think that the only way the Mercaptan will "drop out" of solution is if the conditions that keep it into solution change or it is not in solution.

IF Mercaptan is not "In Solution" but suspended in the Propane, then it would precipitate over time if "heavier" than Propane and collect on the bottom of the tank (giving you the effect you propose) OR If "lighter" than Propane and suspended would rise to the top of the tank and be used first resulting (I think) in the "Fade" phenomenon.

Having said all that, the propane in the tank IS NOT A GAS. It is a liquid because it is under pressure.

I need to do some reading about the reaction of those two gasses with each other because that is where the answer lies.

[Herk7769]

If you inject the smelling agent Ethyl Mercaptan into propane will it be toxic and adhere itself to the metal tank

Is the reason for "Fade" and not related to separation at all.

[Herk7769]

Matters of degree | Bruce Goldfarb

Partial pressure of gases IS the answer.
Sid is correct and I learn another new thing.

Ethyl Mercaptan and propane have different boiling points and vapor pressures. Mercaptan has a boiling point of 95° F (35° C) and is less volatile than propane, which boils at -44° F (-42° C).

When a tank is filled or refilled, propane vaporizes much more readily than mercaptan. The first gas drawn off the gas will have the least odorant, and the concentration of mercaptan in the liquid portion of propane gradually increases as the fuel is consumed. There can be more than a 30-fold difference in the concentration of mercaptan in a full and nearly empty tank of propane.

(Oh, if you take the time to read the article, olfaction means if you can smell it or not. Had to look that up too. Learned another thing)

[dnaraG_1M]

Originally Posted by herk7769

I was fascinated by the link on Mercaptan Fade.
I had never heard of it.

I too also would like to see something on the full tank/low tank phenomenon.

I would think that the partial pressure of gasses law or the law of solutions would apply.

A solution of gasses is not all that different than a solution of liquids.
When liquids are "in solution" the distribution stays equal throughout the solution. I would think that the only way the Mercaptan will "drop out" of solution is if the conditions that keep it into solution change or it is not in solution.

IF Mercaptan is not "In Solution" but suspended in the Propane, then it would precipitate over time if "heavier" than Propane and collect on the bottom of the tank (giving you the effect you propose) OR If "lighter" than Propane and suspended would rise to the top of the tank and be used first resulting (I think) in the "Fade" phenomenon.

Having said all that, the propane in the tank IS NOT A GAS. It is a liquid because it is under pressure.

I need to do some reading about the reaction of those two gasses with each other because that is where the answer lies.

Correct, they are a liquid in the tank. And it's pretty clear that
they HAVE to be in solution. Put yourself in the shoes of the
chemical design engr tasked with the selecting a tracer
agent that would:

++++++++++++++++++++++
Allow the user to smell UNBURNED propane, trigger
propane detectors (electronic noses), and NOT be
detectable when the propane is combusted, consumed,
burned.
++++++++++++++++++++++

Would s/he choose a tracer that is immiscible in the primary
medium??? Only if s/he wants to be fired!
Would s/he choose a tracer that could be smelled whether
the propane was raw or consumed? Only if s/he wants to
be fired!

To achieve the primary goals, the tracer could NOT be
immiscible or detectable when the propane was consumed.
That would defeat the purpose of the tracer.......

cheers,
johnd

[OffPavement]

What the OP described sounds a lot to me like the odor put off by a vent free propane heater.

You guys sure have made this thread interesting though!

[Herk7769]

Originally Posted by OffPavement

What the OP described sounds a lot to me like the odor put off by a vent free propane heater.

You guys sure have made this thread interesting though!

We Live To Serve

[dnaraG_1M]

Originally Posted by herk7769

We Live To Serve

And as wise Husbands know:
We Serve to keep on Living!


cheers,
johnd

[VinceU]

Originally Posted by OffPavement

What the OP described sounds a lot to me like the odor put off by a vent free propane heater.

You guys sure have made this thread interesting though!

Here's a confirming spin on Off Pavement: Every year when I first light off my zero vent fireplace/heater in the basement it puts off a horrible stench and sets off the smoke alarms for about 2-3 minutes, then things clear up. It smells like half burnt gas due poor combustion. I've had in happen in motorhomes, stored off sight when the oven pilot is left on. Once discovered and vents/doors are open it clears. Appears the pilot in these stoves is not the best combustion, exhaust gases left to collect you'll detect it! Great science lessons on unburned propane however.