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Unknown contaminant in propane line

Unknown contaminant in propane line

Unknown contaminant in propane line

(OP)
I am sticking this in here , because I do not know which forum it should go in.
One of my Hobby jobs is chief of maintenance for a sailing club. About 2 years ago I bought 3 propane powered 5 hp. motors for the club, because I was having problems with fuel contamination with gasoline powered motors, mostly related to water in the fuel.
This week I had one of the propane powered motors, start, run for about a minute then quit, thinking the burst hose valve had tripped I turned the tank off, slowly opened the line, to have the same result.
At this point I turned off the tank, got a wrench and disconnected the fuel line, as the line released its seal, I got a mixture of something out of the line I had never seen before, it looked like spray grease , it was a foam that bubbled out of the fitting like something from " Ghostbusters". After about a minute , it settled down to something that looked like an amber colored heavy weight oil with what appeared to be tiny wax flakes in it.
It would appear that I am going to have to replace the gas line and clean the carb on the motor, that's a given, but I would like to know what I am dealing with here, is it bad gas, or a known contaminant for propane , compressor oil , or What?
B.E.

You are judged not by what you know, but by what you can do.

RE: Unknown contaminant in propane line


As you describe that you have had water containment in the gasoline, the first question is if some of the pipelines and tanks you are using now is the same as before. Second is variation in surroundig/climatic conditions. Third is if all of the equipment you are using is properly cleaned and free of grease, corrosion etc.

It is likely that you have condensation inside your system by moist air condensing. Perhaps in the part of the system that is not filled by propane all the time. If you have had rests of gasoline in your system this might have dissolved newer parts in your system if materials are incompatible.

Read up on pipeline layout and drainage (water will run down and assemble on all lowpoints) and propane handling in general.

In my long experience with solenoid valves for air and gas all persons sending in non-function valves have claimed that they have proper layot and clean lines. Almost all causes for non-functioning have however been impurities and water inside the lines.....

Good luck!

RE: Unknown contaminant in propane line

"a foam that bubbled out of the fitting" sounds like a water/organic emulsion with the organic being a low boiler.

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

RE: Unknown contaminant in propane line

Not all propane is created equal. In the US, the highest spec (cleanest) propane is know as HD-5, this is the only grade recommended for engines. Lots of propane is lower grade. I've read some anecdotal reports that claim even HD-5 can be problematic.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Unknown contaminant in propane line

Propane is never absolutely pure. It seems your contaminant is just high boiling hydrocarbons. If you draw only vapor from your tank, these will tend to stay and accumulate in the tank. If you are draw liquid, it may accumulate where ever the propane gets vaporized, depending on the design of the piping or vaporizer. Water is the most common contaminant, and also has a much higher boiling point, so it too tends to accumulate over time.

RE: Unknown contaminant in propane line

(OP)
The mixture that came out of the fuel line appeared to be an oil /wax based material that was foamed by the escaping residual propane gas in the fuel line. These propane tanks are now about 3 years old and have been filled and have been filled about 70 times each. I have one tank at my local propane gas distributor now, they are going to depressurize the tank, remove the fill valve, and inspect the inside of the tank.
They say they will be looking for contaminants or material that has condensed out of the propane.
Gerhardl
The propane system is a medium pressure system which is sealed, this was the whole purpose of adopting this fuel. In theory the fuel is delivered un contaminated in a sealed tank and the engine burns the fuel in a vapor state. At no time except when changing cylinders/tanks is air even able to enter the system, since the engine will not run on air the line is purged through the demand valve before starting the motor.
B.E.

You are judged not by what you know, but by what you can do.

RE: Unknown contaminant in propane line

(OP)
Composite pro,
These small motors can run off gas or liquid propane, they have a heat exchanger run off the cooling water to vaporize any liquid that comes down the line, my tank setups are vapor draw only. Would I be better of going to liquid fuel burn with a different tank setup?
B.E.

You are judged not by what you know, but by what you can do.

RE: Unknown contaminant in propane line

Perhaps. Drawing a lot of vapor from a tank will cause it to freeze-up and loose supply pressure. Drawing liquid will allow you to supply more lbs/hr, and high boiling components will pass through the system rather than accumulate in the tanks.

RE: Unknown contaminant in propane line

(OP)
This morning I took the hose and one of the cylinders to the gas supply house. They slit open the hose lengthwise, it had clumps of waxy material clinging to the side walls, these were about 1/4" to 3/8" in diameter and about 1/8" high, spaced about every 2 to 3" up the hose.
I do not have the results on the cylinder yet, they had to flare the gas off, that was in the tank, before they could remove the valve.
That was taking longer than I could wait around for.
B.E.

You are judged not by what you know, but by what you can do.

RE: Unknown contaminant in propane line

(OP)
Well, researching this problem I am finding out more than I ever wanted to know about this. It would appear that the supply hoses can produce contaminants from the plasticizers used, and can cause the kinds of trouble I am having, if not replaced on a regular basis. Both the fill hoses at the bulk storage station, and my own fuel hoses from the tank to the motor can leach plasticizers into the fuel. These can then coke the boiler in the motor, and cause more trouble. I had not thought about stripping down the boiler next to the carb, I guess I am going to have to see what's in there now.
B.E.

You are judged not by what you know, but by what you can do.

RE: Unknown contaminant in propane line

Very interesting document, thanks.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Unknown contaminant in propane line

(OP)
Thanks for all of the helpful suggestions.
It would appear that an inline fuel filter is needed on the propane fueled systems just like Gasoline powered systems.
I am going that route with an IMPCO A3-514 line filter.
B.E.

You are judged not by what you know, but by what you can do.

RE: Unknown contaminant in propane line

(OP)
Now it gets even more mysterious . I just got the report from the gas supplier on the tank. They say it is clean and dry inside with no sign of any contaminant, other than what was in the valve.
B.E.

You are judged not by what you know, but by what you can do.

RE: Unknown contaminant in propane line

(OP)
Jay,
I don't know,
I dis- assembled the carb on the motor, and the stainless internal fuel lines, I am even more puzzled. The boiler next to the carb had a dark colored oil in it that ran right out.
The primary pressure regulator had two tablespoons of a light yellow oil like substance that smelled strongly of odorant, The secondary regulator had about a teaspoonful of a slightly darker oily substance, and the demand valve had a trace of this same material. I cleaned all of this out, and flushed the lines with methanol. when I was sure I had the thing clean, I re assembled the carb and the stainless fuel lines. Connected the motor with a new fuel line onto the newly inspected and re filled tank. The engine started on the first pull and ran better than it has in a while. I had to turn the idle screw back a bit, because it was idling too fast.
I cannot see a self destructing 1/4" diameter hose generating that quantity of the oily substance. I can see higher boiling point hydrocarbons being left in the fuel system after the propane had evaporated, like oil being left behind in a 2 stroke fuel mixture.
I am going to add inline fuel filters. Then see how long it goes before the trouble recurs. I am also looking at buying a couple of liquid feed forklift tanks and adopting Composite Pro's suggestion of using liquid feed to see if the contaminants can be flushed through the engine instead of bunging things up.
B.E.

You are judged not by what you know, but by what you can do.

RE: Unknown contaminant in propane line

You found a bunch of junk in your vaporizer and other parts as well. This will be made only worse with liquid feed. You should check the mounting orientation of these parts to make sure that junk can drain out naturally.

RE: Unknown contaminant in propane line

(OP)
Composite pro,
That's not good news, I cannot do anything about the orientation of the components, because this is how the manufacturer laid out the motor. The boiler feeds vertically up the side of the carb into the main pressure regulator, then down a little to the secondary regulator, then back up a little to the demand valve. This is all a one piece pressure die casting, and there is no leeway to change anything. Higher boiling point hydrocarbons will collect in that boiler until they are blown into the engine. The sales people tell me they have not heard of this problem in the USA , but they have heard of it in other countries, where propane quality is not tightly controlled. I asked them if the motor was designed to burn higher level contaminants like tramp oils, and they said " We will get back to you."
B.E.

You are judged not by what you know, but by what you can do.

RE: Unknown contaminant in propane line

I wonder if you may have gotten one or two really dirty tanks.
My first response would be to clean everything and put the motor back into service.
That said, you are the one onsite and have a better feel for the problem.
If onsite factors led me to believe that this may be an ongoing problem with a questionable quality of LPG available I would consider installing a cleanable knock-out tank. Possibly a restriction ahead of the tank will keep it cool and encourage the drop-out of high boiling point fractions in the KO tank. This suggestion is subject to comments from others with more hands on experience with LPG products. I did once experience the oily smelly gunk reminiscent of your description. That seemed to be an issue with a bad fill on one tank only.
I would consider installing a KO tank on one motor only. If inspections show it to be staying clean the job is done. If inspections show a buildup of gunk, then the KO tank is working and it may be well to install tanks on the other motors.
If the tank stays relatively clean, then the contamination may have been a one time thing and the issue is done.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Unknown contaminant in propane line

(OP)
Waross,
I hope you are right. I am going to try the inline filter . Remember I have three of these motors, and this is the only one that has experienced this problem, and all of the propane comes from the same source.
B.E.

You are judged not by what you know, but by what you can do.

RE: Unknown contaminant in propane line

I would agree with the post regarding a propane liquid setup will pick up contaminants in the bottom of the propane tank that is largely lubrication oil from the various compressors upstream in the propane supply chain.

I have a propane liquid feed Miller Bobcat generator/welder and when I drain the high pressure regulator at the recommended intervals, a small amount of fairly heavy lub oil comes out..

Liquid feed tanks of course have a dip tube in them to supply liquid propane and they can will pick up any oil in the bottom of the tank..The engine exhaust also has a characteristic oil burning smell from burning the mixed in lub oil.. This is a new engine so it's not the engine burning its own oil.

btw.. with this being a factory option propane engine, the engine manufacturer (Kohler) recommends using synthetic oil for the following reason. All valve guides and their seals are designed to seep a small amount of oil to keep the valve stems lubricated. In a gasoline engine, the solvents in the gasoline keep the stem and top of the intake valve well cleaned. Otherwise the seeping lubricating oil will coke on top of the valve with deposits building up enough to begin limiting air flow. Propane does not have the solvent cleaning capability so with dino oil, deposits will build up.. Synthetic oil has far better resistance to coking at the temps the intake valve is running at..

RE: Unknown contaminant in propane line

(OP)

DanEE (Electrical)

I have had several conversations with the maker of the motor and the Propane supplier, and the general consensus is, that I was just unlucky in picking up a batch of contaminated Propane. I have put fuel line filters on ,and have not had any problems since the middle of January.
B.E.

You are judged not by what you know, but by what you can do.

RE: Unknown contaminant in propane line

Can you go to all metal lines?
In the past I have problems with compatibility between non-metallic hoses and fuels, I have finally drawn the line and gone all metallic.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Unknown contaminant in propane line

(OP)
Hi Ed,
I could run stainless part way, but these motors are used on boats, and the motors have to swivel and tilt.
B.E.

You are judged not by what you know, but by what you can do.

RE: Unknown contaminant in propane line

Perhaps a rubber hose with a liner in it, HDPE of something similar. There will not be plasticizers in the liner material and it should slow the reactions.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

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