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No propane oil

Recent discussions warned about propane oil accumulation.  So we removed the flexible rubber hose from our propane tank to drain any accumulations.  Happy to report hose and fittings were clear and no evidence of any oil accumulations were found.


Re: No propane oil

Reply #1 –
 ^.^d

see ya
ken

Re: No propane oil

Reply #2 –
Barry & Cindy, on your checks did you open the bottom fitting on the cast iron Tees forming the outlets for copper pipes to units? that is where I got some a couple of years back when making a BBQ outlet valve. There may be a "drop" at the bottom of them acting as a clean out .
JohnH

Re: No propane oil

Reply #3 –
After reading this thread, and having just done some work on my propane system, I became curious: what is the source of this "oil", and why is it (sometimes) found in the propane lines?  Did a quick Google search on "propane oil" and "oil in propane".  I got quite a few hits, and found very little consensus on the subject.  The opinions (everybody has one) on the subject varied from "I've never encountered this problem in XX number of years owning RVs" to "This is a very common problem - the oil is contained/added/dissolved in propane due to XXX reasons".  In other words, many varied opinions, but (so far, at least) no verifiable facts.

One commonly held opinion is that the "oil" is actually a residual component of the stuff added to propane to give it a "odor" (ethyl mercaptan).  However, given the minuscule amount of this chemical normally present in the fuel (1.5 lbs. per 10,000 gals, according to the report linked below), it seems it would require decades of accumulation in a tank, before it would or could ever become a problem.  And even if it did accumulate in measurable quantities in a tank, it would be on the bottom of the tank.  The propane we use for most RV appliances is drawn off the TOP of the tank in vapor form.  How would the "oil" in the bottom of the tank ever make its way through the layer of liquid propane, then into the vapor layer, and then be carried through the regulator to be finally trapped at the low point in the hose?  Given the extremely low flow rate of the gas, this sounds like a pretty remote possibility to me, but I'm certainly no expert.

If "oil accumulation" in propane lines was really a common problem, wouldn't the RV manufacturers provide some sort of drain valve in the gas line?  Surly this would be better than dealing with complaints of fouled regulators, malfunctioning water heaters/stoves/furnaces, and other problems due to "oil" in the lines.  I find it hard to believe there would be NO mention of this potential problem in the owner's manuals for RV's, propane appliances, portable gas stoves, etc.

During my cursory search on this subject, I did come across a copy of a government report titled "Information On LP-Gas (Propane) Odorant".  I did not have time to completely read the report, but I did see some references to the "oily residue" left behind in old used propane storage tanks.  You may find it interesting...

http://www.cpsc.gov//PageFiles/101141/propanept1.PDF

So what say you, Expert Forum Members - is "propane oil" a real problem, or just a Urban Myth?  Any "opinions" that are backed up by actual scientific proof or published documentation would be most welcome.

Re: No propane oil

Reply #4 –
In an earlier post I mentioned how the regulator on our new Weber Q100 failed after using a new long hose from the coach's propane tank and how the yellow fluid ran out when I set the regulator down on the floor. The regulator was full of the fluid, but not much odor. Our coach came with a "tap" so I don't know if the fluid accumulated over 25 years. The "tap is on the main supply line with everything else so a bottom outlet is not part of the problem.

It will be very interesting to find out where this fluid is coming from and what it is. Possibly a chemical reaction between the propane, the sulpher "stuff", The tank itself, and/or the hose?

Re: No propane oil

Reply #5 –
THIS JUST IN!  I found another document that may be pertinent to this discussion, and especially to members such as Nitehawk (who made a EXCELLENT guess in post above).  The report deals with potential problems when using a long flexible hose to transport LP Gas to propane devices.  On page 9 of the report (link below), there is this paragraph:

"It is interesting to note that after each static test was complete, and the LP Gas had been flared, an oily, golden-yellow liquid (shown in Figure 7) was recovered from the hose. The amount of liquid varied from test to test, from less than a teaspoonful to several tablespoonfuls for a 2-foot hose. By analogy, for a 125 ft hose typically used on a bobtail, the amount of residue would be in the cupfuls! An analysis of the liquid showed that it consisted mainly of plasticizers and heavy hydrocarbons. It is also interesting to speculate what happens to such liquids in the LP Gas distribution system. If the residue segregates in tanks, the level of residues probably continues to rise as the tank ages, unless the tank is cleaned out. If the residue is transported to the converter/vaporizer, it may remain there depending on the temperature and other conditions in the vaporizer. This could lead to additional maintenance requirements or operational problems."

This paragraph is accompanied by a photo of the "Oily residue recovered from hose after static testing".  See the full report for additional details:

http://www.propanecouncil.org/uploadedFiles/Council/Research_and_Development/REP_11297%20Hose%20Conditioning%20vol1.pdf

Re: No propane oil

Reply #6 –
@Chuck Thanks again. Excellent work. I was planning on researching this today too. You just saved me the work! :)

So the answer seems to be check your propane hose. You may or may not find oil in your line. It's easy enough to do that anyone with propane should check for it at least once. The articles you site mentions they found a couple of tablespoons for oil in the line but that was under their controlled conditions. I found at least 1/2 a cup in mine. I'm pretty sure mine was a 22 year accumulation.

I have to wonder if the oil came from the rubber propane line on my coach or from rubber hose at the fill station. Probably both.

Would be interested in results from anybody else that does this check. Hopefully it's a small percentage of owners that find oil in the line. I've included a pic of where to disconnect the hose to check. Be sure to have a container handy to catch anything that comes out.

see ya
ken

Re: No propane oil

Reply #7 –
Not to try to highjack the thread.  The photo also shows the old style solenoid 12 volt valve that was once installed and controlled by the gas detector inside.  The solenoid valves have been know to fail, and then you don't get any gas into the propane system.  The valve can be either taken apart and the plunger removed and thrown away, or the whole assembly can be removed and the hose connected directly.

If you still want a new valve solenoid assemble they can be found in the marine store.  They are used in boats where you can fill the hull with propane gas, when you leave the stove burner open.

Re: No propane oil

Reply #8 –
Put me in the line following "if it ain't broke, I'm not loosing any sleep".  pc

Re: No propane oil

Reply #9 –
@Dave I've never had any trouble with the propane solenoid. If/when I do I'll be removing it. Since I'm talking out loud about it and if history is any kind of teacher I'm pretty sure it will fail in the next 24 hours. :(

see ya
ken

Re: No propane oil

Reply #10 –
When I took the gas drop off at bottom of manifold where the copper pipes to various heating/frige pipes are connected I found about a tablespoon of it drain out. Did not disconnect the hose so will try that at some time.
There is always some oily residue in gas lines which is one of the reasons when you have a line you put a 'drop" (short nipple in the end of piping just before the take off point.)
Not just propane but any gas.
JohnH

Re: No propane oil

Reply #11 –
Quote
Barry & Cindy, on your checks did you open the bottom fitting on the cast iron Tees forming the outlets for copper pipes to units? that is where I got some a couple of years back when making a BBQ outlet valve. There may be a "drop" at the bottom of them acting as a clean out . JohnH

Our flexible rubber propane hose connects the regulator to the BOTTOM of the tee-manifold, so we do not have 'drop' and bottom plug.

We removed the hose at the regulator flare fitting, not at the pipe thread manifold end, and straightened the hose down to drain. I also do not like to remove and replace pipe thread fittings (NPT). Even though we use Teflon sealer sometimes threads have small leaks. The flare end was more fun.

Re: No propane oil

Reply #12 –
Probably comes from worn out seals in the pumps & compressors at the plant. It SHOULD all be dropped out at the bulk facility, but they don't take the propane to the gas phase so it stays in suspension.??

Re: No propane oil

Reply #13 –
Quote from: cajk –

.............................So what say you, Expert Forum Members - is "propane oil" a real problem, or just a Urban Myth?  Any "opinions" that are backed up by actual scientific proof or published documentation would be most welcome...................................


Chuck,

A real problem, although some owners may go years without accumulating enough contamination to be bothered by Propane oil residues/contaminants.  The longer it has been since a coach's propane service tank was flushed and cleaned, the smaller the service tank, the more heavily the on-board propane systems are used, the longer and the smaller the flexible BBQ hose is, the more often the on-board tank has been overfilled, the longer the time since the outlet lines were drained, the more likely it is that the propane contaminant oils will cause a problem.

The residue may come from many places in the supply chain; refinery, pipelines, ships containers, intermediate transit storage tanks, pumps compressors, delivery trucks, supplier storage tanks and from our own on-board storage tanks that we seldom if ever drain entirely and clean.  Repeated overfilling of on-board tanks and long small diameter delivery hoses (like to BBQ grills) exacerbate the symptoms.  If we use supply filters at the outlet of our tanks, it would eliminate the concern but create additional preventative maintenance service tasks.  Once I experienced the issue, I started separating and draining the propane tank outlet hose low point and the BBQ hose annually.  Seems to take care of it for me.

From:
http://www.propanecouncil.org/uploadedFiles/REP_11352%20Good%20Practices%20Care%20and%20Custody%20of%20Propane.pdf

Oil Residues and Heavy Hydrocarbons
Description: This type of potential contamination can vary from very light oil to a very viscous tar-like
substance. Sometimes it is a waxy material like paraffin, or it may be similar in consistency to axel
grease. Sometimes it is transparent (no apparent color) while at other times it is light brown, dark brown,
or even black. It usually has a strong odorant smell, as the ethyl mercaptan used as an odorant in propane
appears to concentrate in the oily residues.
Source: The oils in propane can come from many sources; from processing, pipelines, pumps or
compressors, piping systems, and flexible hoses. Heavy-ends usually appear when the liquid propane is
vaporized for end-use applications (engines as in vehicles, forklifts, etc.). When external heat is used to vaporize propane, like in a propane
powered vehicle vaporizer or industrial water-bath vaporizer, heavy-ends tend to deposit in greater
volumes.
Potential Problems: Oils and heavy-end contaminants can cause operational problems with many types of end-use equipment, such as internal combustion engine fuel systems, microturbines, (burners, furnaces, stoves, grills) and fuel cells.Dissolved oils and heavy ends can also accumulate in vapor service tanks (customer tanks, on-board RV propane service tanks) and eventually cause an odor problem (oily smell) with propane heating and cooking appliances.
Testing Methods: The laboratory test is Residues in Liquefied Petroleum (LP) Gases (ASTM-2158).
Field test methods include the Weathering Test (NPGA #151, 1991, Suggested Field Tests for
Contamination in Propane) and the Stain Tube Test for Oil Mist.
Prevention: The following steps may prevent or reduce the occurrence of oily residues and heavy-ends in
propane:
· Investigate and develop processes and procedures to help identify and eliminate the sources
of oil.
· Use filters in the propane liquid or vapor lines (such as a coalescing filter) to remove oil prior to the end-use equipment.
· Use inspection and remediation procedures to ensure that empty storage tanks and piping are
free of oils and heavy-end contaminants before being filled with liquid propane.
· Use oil traps to collect and remove any oils downstream of all externally heated vaporizers.
 Neal

Re: No propane oil

Reply #14 –
Quote from: pocketchange –
Put me in the line following "if it ain't broke, I'm not loosing any sleep".  pc
I'm not either, years ago we ran a good number of trucks on propane which draw liquid from the bottom of the tank , over time with the large volume of fuel they use (some as much as 100 gal per week) they would get oily residue and just plane black gunk in the regulators, vaporizers, and throttle body. My gas supplier at the time I was doing all the conversions told me propane and natural gas are not as clean as you may think, we did try some filters on the high pressure side of the fuel feed line but as I remember that did not work to well. That was over 30 years ago, I'm sure technology has improved since then. I fill the propane tank about once a year in the F/T so not to much of a concern for me. I am sure there is gunk in the bottom of the tank but we draw vapor only from the top of the tank.

Re: No propane oil

Reply #15 –
Quote from: bbeane –
I am sure there is gunk in the bottom of the tank but we draw vapor only from the top of the tank.

This was one of my BIG questions in my first post.  Neal's post (above) documents the problem of contamination being introduced into the propane product at various points in the commercial supply process.  Assume it is possible that this contamination could be transferred into a RV propane tank, either by sloppy filling procedures or poor maintenance of bulk storage equipment.  Once in the RV tank, would it not either settle to the bottom, or remain in solution in the liquid phase of the fuel?  Given the minuscule quantity of fuel required by RV appliances, the low rate of flow out of the tank, and the fact that we only draw the VAPOR from the top of the tank - how is it possible for reported large quantities (a "cup or more") of this oily substance to accumulate in the low point (rubber hose) just past the gas regulator?

I linked a document (above) referring to oily liquid accumulating in rubber propane hoses.  I can understand how this might be a problem in the LONG flexible hoses used to supply portable propane devices, as mentioned above by nitehawk.  As I understand it, this would be more likely to occur with cheap imported rubber hoses, and would mainly be a function of age.  New hose = more likely to have a problem.  The condition can (reportedly) be avoided by using high quality synthetic "oil free" supply hoses, and small accessory filters designed to catch these oils.

To my knowledge, in our coaches we only have the one short piece of rubber hose that goes from the gas regulator to the gas distribution manifold.  Even assuming this hose was brand new and of "Low" quality, the quantity of oil leeched out of the rubber should not exceed a teaspoonful (or less).  The hoses on most of our coaches are "well seasoned" (mine is over 20 years old), and were probably of excellent quality when new.  How could this short hose possibly produce the large quantity of oil being reported by some RV owners?

It remains a mystery (to me)...

Re: No propane oil

Reply #17 –
Just thought I'd add that while we were in Quartzite this year we checked Kent Speer's LP line. We extracted about a 1/4 cup of oil on his beautiful 93' U300. Not sure why my 92' had almost 3 times that amount.

Anyway if you have an older coach CHECK YOUR LP LINE! :) (sorry for the shouting)

see ya
ken
 

Re: No propane oil

Reply #18 –
I found a little bit of oil in the solenoid valve for the gas detector, but none in the rubber hose. It was probably less than a teaspoon. I wouldn't have given it a thought except for this discussion. It certainly wasn't enough oil to catch my attention. LP gas is literally "Liquified Petroleum Gas" so it seems reasonable to me that it would contain oil, since that's where it came from after all, just saying.