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View Full Version : Does gasoline degrade faster in a translucent container?



winchman
08-01-2008, 12:17 PM
Looked, but can't find the answer.

Roger

Tim The Grim
08-01-2008, 12:30 PM
I work in the area of a refinery that takes low octane Naptha and turns it into 99 octane blend stock. When I pull my sample for an octane check it has to be in a brown bottle and we shade it from direct sunlight. Otherwise the sunlight will degrade the octane rating rather quickly. So I would suspect that at least a portion of the multiple blend stocks that go into the make up of pump gasoline would be effected by the light coming through a translucent jug.

Evan
08-01-2008, 12:35 PM
Yep, modern gasoline is an unstable product with a short "shelf" life. I recall reading somewhere that it does degrade pretty quickly in sunlight and even just in warm conditions. Maximum storage life is only a few months unless it is kept cold. That especially applies to winter fuel formulations purchased in cold climates during winter. Summer formulations are more stable.

kendall
08-01-2008, 12:51 PM
don't think it's the translucence, think it's simply that the container is plastic.
Plastic containers don't keep gas as viable as long as metal or glass does.

Think it has to with plastics not being truly sealed, I've used gasoline that's been stored for years in metal containers that has been perfectly fine, while gasoline stored over the winter in plastic was totaly useless come spring.

I understand that many plastics are permeable to the aromatics in gasoline, glass and metal aren't.

Recently picked up an old sailboat that came with an outboard and 6 gallon can of fuel (full) was going to dump it but noticed it smelled and looked good, so tried it in the mower where it ran fine, then tried it in the outboard and that also ran fine. Boat motor and gas have been sitting for 8 years, I'd looked at the boat off and on for 6 years before I finally decided to buy it. Plan to run it in the mower and put fresh fuel in it because I don't want to get out in the middle of the big lake then NEED the motor only to find it's finally turned.

Ken.

aboard_epsilon
08-01-2008, 02:06 PM
i dont know

but i know that red diesel can be turned into clear diesel ..after a couple of days in the sunlight

all the best.markj

ERBenoit
08-01-2008, 02:48 PM
I don't know either. In the northeast, the gas is a blend of gasoline and (??)10% ethanol. I undertand that ethanol blended fuel does not last long, about thirty days, in storage cans/jugs. Something about the ethanol drawing moisture from the air.

Raises havoc with small engines (chainsaws, weed wackers etc.). I do not know if the troubles that blend causes is related in any way to the engines being 2 cycle and having "wet gas" run through them, as I have had no problems with it in the regular lawnmower.

Evan
08-01-2008, 03:06 PM
From an Industry web-site:



Use Proper Containers

* Use only containers approved by a nationally recognized testing lab, such as Underwriters Laboratories (UL).
*Keep the container tightly sealed.
*Containers should be fitted with a spout to allow pouring without spilling and to minimize the generation of vapors.
* Keep gas containers out of direct sunlight.
*Always open and use gasoline containers in a well-ventilated area away from children and animals.
Store Carefully

*Store no more than ten gallons.
*Be certain to keep a closed cap on your gasoline container.
*Store the gasoline in a cool, dry place.
*Store at ground level, not on a shelf to minimize the danger of falling and spilling.
*Do not store gasoline in a car trunk. There is a threat of explosion from heat and impact.
*Do not store gasoline in your basement.
Gasoline moves quickly through soil and into groundwater, therefore, store and use gasoline and fuel equipment as far away from your drinking water well as possible.

http://www.gas-care.org/consumer_tips.htm

winchman
08-01-2008, 05:33 PM
Thanks for all the input.

I know it's best to keep containers out of direct sunlight, but I always thought it was a matter of heat/safety rather than aging/degradation.

I thought it might be nice to have a translucent gas tank so I could see how much was in it without having to take the cap off to look inside. It makes more sense to use an opaque or metal tank, though.

Roger

aboard_epsilon
08-01-2008, 05:49 PM
Many motor bikes of the 60's had a translucent pipe running from the top to the bottom of the tank that showed the level

you can just make one out on this Suzuki T10

running down the front of the tank ..

http://www.suzukicycles.org/photos/T/T10/1964_T10_black_450.jpg

i used to have a couple of those t10s

all the best.markj

JCHannum
08-01-2008, 06:30 PM
I have a Stihl weed whacker, a Simplicity riding mower and a Wheelhorse garden tractor, all with translucent tanks. They are not clear, but you can see the level of gas in them.

I see no problem with it, especially if it is in a somewhat active situation where the gas will be used in a relatively short time frame of say a season.

alanganes
08-01-2008, 06:59 PM
A slight thread hijack maybe, but is in keeping with the theme...

I have been told by a few folks that if you wish to store gasoline for an extended period of time, say a year or so, maybe for your generator or whatever, that the "smart" thing to do is to use aviation fuel from your local small airport. The stuff used in piston engine light planes and such. Supposedly it will not get varnish-y or go flat for a much longer time than automotive stuff.
It would be more costly, of course, but if this is true, might be worth it for the few small jerry cans that I tend to keep around for just such an occasion.Save all the hassle of constantly having to rotate stock.

Now it makes sense to me that avgas would of necessity be "better stuff" than what the local filling station sells, but does anyone have any objective truth on this, or is this another urban myth?

Evan
08-01-2008, 09:50 PM
Avgas is a totally different formulation. It has to work at 20,000 feet without vapor locking the fuel system so it has far lower vapor pressure ingredients. It also has better antiknock properties and higher octane ratings. The main thing that contributes to longer storage life is the low vapor pressure as that means that it contains less volatile components such as butane and propane.

Contrary to what Jim assumes car gas is formulated with varying amounts of dissolved light gasses including propane, butane and methane. They contribute to the starting ability in particular and are found in higher levels in cold weather formulations. These volatiles are rapidly lost in hot weather storage. A translucent tank left in the sun will permit direct heating of the gasoline as well as promoting chemical reactions between the numerous different chemicals that make up gasoline. Gasoline isn't a single chemical with a few additives, it's a complex blend of as many as 12 different hydrocarbons compounds as well as additives and volatiles.

JCHannum
08-01-2008, 10:01 PM
Contrary to what Jim assumes car gas is formulated with varying amounts of dissolved light gasses including propane, butane and methane.
Exactly what did Jim assume? I made no statement at all about auto or any other gasoline.

The manufacturers of the machines mentioned seem to be quite comfortable with the gas tanks provided with their equipment. Their manuals have the usual information concerning lay up for off season, but no disclaimers as to any other problems with normal use of these products.

Evan
08-01-2008, 10:41 PM
I see no problem with it,

Even in a short time frame there is a problem with leaving a translucent tank in the sun. The process is the same as that which produces "smog" from unburned hydrocarbons, mainly gasoline that has been released as fumes and incomplete combustion in engines. The process takes only hours to make very significant changes due to oxidation which is promoted by UV energy in sunlight.

Duffy
08-01-2008, 10:57 PM
I very much doubt that the UV energy from sunlight will penetrate the translucent tank wall with sufficient energy to initiate any chemical reactions to either degrade or enhance the mixture. What I do think is that the heating effect will cause a selective evaporation of the more volatile components, resulting in a mixture with properties that, in the long run, tend toward diesel fuel. That is, hard starting and rich running. As far as avgas is concerned Evan, I think you may have overlooked a very important property: it is DRY, since fuel line icing is not popular with pilots. Duffy

Evan
08-02-2008, 02:19 AM
Evan, I think you may have overlooked a very important property: it is DRY, since fuel line icing is not popular with pilots

I'm not sure what you mean. The water in gas isn't from the gasoline, it comes from the atmosphere, As the tank warms and cools the gasoline and fumes within expand and contract. When they contract the tank pulls in air through the vent and the moisture in the air condenses in the tank as it cools further. I have drained up to several liters of water out of an aircraft fuel tank that had been sitting for maybe a month. Aircraft fuel tanks aren't pressurized like an automotive tank. The rapid pressure change with altitude would destroy a sealed tank.


I very much doubt that the UV energy from sunlight will penetrate the translucent tank wall with sufficient energy to initiate any chemical reactions to either degrade or enhance the mixture

Polypropylene is used for gas tanks because of it's resistance to UV as well as gasoline. It is resistant to UV because it absorbs almost none, only a few percent. The rest passes right through. Solar UV is very effective at initiating chemical reactions.


MCMT is presently being used as a component of gasoline fuels to improve the octane number thereof. However, in the proportions in which it is present in the gasoline fuels, usually between about 0.05 and 0.20 gm/gal (as manganese), MCMT is unstable. In the presence of sunlight, or other source of ultra-violet radiation, MCMT rapidly oxidizes to components that precipitate, with the rate of oxidation being dependent upon the concentration of dissolved oxygen in the gasoline. Thus, when gasoline containing 0.1 gm/gal MCMT (as manganese) is exposed to sunlight, within about 2-3 hours nearly complete oxidation of MCMT occurs, and a precipitate of oxidation products is formed. Similar oxidation takes place in the absence of sunlight, but at a somewhat slower rate. Cnsequently, gasoline compositions containing MCMT which are placed in storage for even few weeks suffer a significant decrease in octane rating and form a solid precipitate capable of clogging valves, transfer lines, etc.

http://www.freepatentsonline.com/4067699.html

dp
08-02-2008, 03:13 AM
Water comes from the pumps, too. All the problems of condensation in the aircraft fuel tanks is a problem in underground tanks and transport vehicle tanks. When I zero timed my airplane over a 3 year period I drained the tanks completely and vented them for hours to ensure they were dry and fume free. The airframe was stored in my garage during the overhaul and I didn't want there to be a mess on the first flight. Within 6 months of first flight I found over a gallon of water in the main fuselage tank. It was far more than could be accounted for from condensation, and also far more than the normal water trap could deal with.

JCHannum
08-02-2008, 07:12 AM
Even in a short time frame there is a problem with leaving a translucent tank in the sun.

I suggest that you take that up with the various manufacturers who seem to be quite comfortable in using these tanks on their equipment. It does not appear to be an uncommon application, which would indicate that it is acceptable in normal use.

Note that it is a sales feature on these Stihl trimmers, Item C.

http://www.stihlusa.com/trimmers/features.html

As well as these Stihl blowers, Item L.

http://www.stihlusa.com/blowers/features_handheld.html

Evan
08-02-2008, 09:30 AM
I suggest that you take that up with the various manufacturers who seem to be quite comfortable in using these tanks on their equipment. It does not appear to be an uncommon application, which would indicate that it is acceptable in normal use.

It's cheap, easy to form to complex shapes and durable. It's acceptable for those reasons. If you want something better suited you will have to be willing to pay more than the lowest price you can find. Unfortunately that does not describe the majority of the buying public.

JCHannum
08-02-2008, 09:53 AM
I used the Stihl literature as they are a premium manufacturer of portable power equipment. They do not produce to the mass market box stores and are generally considered a high end product. They do not achieve and maintain this reputation by cost cutting.

HDPE is the usual material for gas tanks, and it is quite commonly used in auto tanks as well as portable power equipment.

I suspect Roger is looking for a suitable tank for his B&S powered winch. Translucent HDPE or PP would not be a poor choice for that application. If concerned about direct sunlight, a simple sheet metal sunshade over the top will provide more than ample protection from the sun plus a degree of mechanical protection as well.

Evan
08-02-2008, 10:34 AM
HDPE is the usual material for gas tanks, and it is quite commonly used in auto tanks as well as portable power equipment.

Automotive fuel tanks do not need to be UV resistant so other plastics will do. Even so, HDPE is also reasonably transparent to UV unless it is filled with an opaque filler. In fact, most clear and translucent plastics are UV transparent to a significant degree.

Stihl cuts cost the same as anybody, the only difference is how much compromise they are willing to deliver. The major reasons for plastic tanks are the ones I enumerated above. Resistance to UV isn't as important to the manufacturers because it isn't important to the customers. It isn't important to the customers because they don't know it matters.

JCHannum
08-02-2008, 11:12 AM
Plastic tanks are common to many machines using gasoline, automobiles as well as portable power equipment. It is more economical than steel in many instances and can be easily molded to complex shapes to fit in areas not easily available to the common steel shaped tanks.

In most cases, the colors of choice seem to be either natural or black. Black pigment is quite commonly added to recycled or regrind mix to cover color differences and degradation from regrind. It is quite possible that the natural or virgin polymers used for the translucent tanks are actually more expensive than the black material, and that the black or pigmented tanks are of inferior and cheaper materials.

If the UV rays cause degradation of the gas, it would be reflected in the performance of the equipment. While consumers might not be aware of the cause, anything that affects the performance of the equipment will be perceived as a fault of the equipment manufacturer. That is, hard starting, missing, low power, smoking & choking, all effects of poor gas, will be seen as a bad engine. A poor reputation and concomitant loss of sales will effect Stihl's bottom line much more than the penny or so that might be saved per tank.

Evan
08-02-2008, 03:15 PM
The fact remains that UV penetrates translucent tanks and UV degrades gasoline rapidly.


Plastic tanks are common to many machines using gasoline, automobiles as well as portable power equipment. It is more economical than steel in many instances and can be easily molded to complex shapes to fit in areas not easily available to the common steel shaped tanks.

Precisely, and that is a very big advantage over metal tanks as I said. It's pretty hard for a manufacturer to ignore. It happens that although I have several machines with such translucent tanks none of them are exposed so that sunlight can reach the tank. If I did have one where the tank is exposed I would paint it with the new plastic compatible paints, perhaps leaving a small stripe to observe the fuel level.

JCHannum
08-02-2008, 05:30 PM
The fact remains that UV penetrates translucent tanks and UV degrades gasoline rapidly.

Strangely, I can find no information that supports the "fact" of rapid UV degradation. There is mention of UV stabilizers in several places, and the post you included on MCMT includes a link to an antioxidant to prevent oxidation of MCMT. Most gasoline blends have enough stabilizers and other additives in to provide an adequate service life in most normal applications.

Paint if you wish, or provide a sunshade as I suggested if it concerns you.

Evan
08-02-2008, 06:05 PM
All hydrocarbons are subject to oxidation, preservatives notwithstanding. UV promotes the oxidation process in all cases by providing the energy necessary to split apart the molecules so they may recombine with oxygen. It may not be mentioned much because the process is so common and well known to those that need to know. It's basic organic chemistry. UV serves as an initiator for the oxidation process. It doesn't just apply to gasoline but any hydrocarbon compound ranging from crude oil to refined motor oil and diesel fuels. Different hydrocarbon compound will oxidize at differing rates depending on the exact molecular structure. The light volatiles are much more susceptible to oxidation than the heavier fractions. That is why they burn more easily.

Evan
08-02-2008, 06:21 PM
Looks like there is another good reason to keep this type of tank out of the sun. This would aslo include such quality products as plastic tanks from Stihl.



The U.S. Consumer Product Safety Commission (CPSC) staff appreciates the opportunity to
provide comments

to the Outdoor Power Equipment Institute (OPEI) on the draft standard,
ANSI B71.10 Small Off-road Ground Supported Outdoor Power Equipment Gasoline Fuel
Systems Performance Specifications and Test Procedures. CPSC staff understands that these
comments are part of the canvass review process for approval of the draft standard.

A review of CPSC recall data identified as many as 42 recalls involving gasoline-powered
outdoor equipment due to fuel leaks since January 2000. Recalled equipment included backpack
blowers, hedge trimmers, walk-behind lawn mowers, chain saws, generators, and garden tractors.
The number of units of gasoline-powered outdoor equipment recalled from January 2000 to
present is approximately two million.

CPSC staff understands that the fuel tanks for handheld and non-handheld outdoor power
equipment are manufactured through similar molding processes, and using the same or similar
materials. The fuel lines and fuel tanks for both types of equipment have demonstrated identical
performance-related failures. For this reason, CPSC staff believes that the scope of the B71.10


CPSC recall information shows that plastic fuel tanks can develop stress cracks after one or
several years of use by consumers. CPSC staff believes these stress cracks can be caused by
several factors including cyclic temperature flux, impact with hard surfaces, UV (ultraviolet
light) exposure, vibration, elevated pressure, and elevated temperature.


UV Exposure: UV can decrease the toughness of plastic fuel tanks and therefore
influence failures in the tanks. ASTM G 154, Standard Practice for Operating
Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials, provides
guidelines for appropriate UV test and exposure conditions based on material properties.
CPSC staff recommends adding a UV exposure test based on the material guidelines
included in ASTM G 154.

http://www.cpsc.gov/volstd/fueltank/ansi11806.pdf

JCHannum
08-02-2008, 06:50 PM
Of course gasoline constituents are subject to UV degradation and oxidation, that is why UV stabilizers and antioxidants are added.

The recall information does little to identify the materials, color or design parameters, just that there were failures, as such it is meaningless in this context. In any case, the integrity of the tank was not a consideration, just the longevity of the gasoline. It would appear however that UV is but one of many possible causes of failure. Temperature, vibration, pressure and impact with hard surfaces will also cause steel tanks to fail. Steel tanks are also subject to rust and pinholes. A small amount of water in the fuel can cause pinholes to develop in very short order, BTDT. Nothing is perfect.

Evan
08-02-2008, 07:38 PM
Of course gasoline constituents are subject to UV degradation and oxidation, that is why UV stabilizers and antioxidants are added.

They serve to slow the process somewhat, at least long enough to make the product useful. They aren't intended to prevent the effects of prolonged UV exposure since that isn't a consideration for automotive fuel.

Of course nothing is perfect. Some things are less perfect than others. The integrity of the tank should be a consideration apparently. Have you checked to see if your tools with such tanks are on the recall list?

JCHannum
08-02-2008, 09:23 PM
They serve to slow the process somewhat, at least long enough to make the product useful. They aren't intended to prevent the effects of prolonged UV exposure since that isn't a consideration for automotive fuel.

Which is why I said the use of such a tank should present no problem with normal usage in a relatively short time frame, say a season. This is consistant with the manufacturers instructions.

I do not see a recall list, and am quite able to determine if a tank is leaking. The Stihl weed wacker is 12 or 14 years old, the Craftsman leaf blower, which I had forgotten about is over 10 years old. I wouldn't feel cheated if either were to develop a problem.

J Tiers
08-02-2008, 10:58 PM
Eh, gasoline for less fussy uses is not a big problem.

I routinely store several gallons in the garage, in a metal can, one of the FM approved vapor-releasing cans that will not explode. Isn't tightly sealed, so water vapor etc can infiltrate, and gas vapor can escape.

Whatever is left in the tank of mower, tiller, compost shredder, and miscellaneous other motors is in there over winter. Ditto for the gas can.

The ones that typically start first pull at any other time still start first pull, the ones that are a pain to start are just as much of a pain after being stored dry as with fuel in them. No difference noticeable from old tank gas, old can gas, or brand-new just-filled can gas.

Analyze to your heart's content, but my experience over many years (I have had some of the equipment for 25 years) is that gas works fine in any of these engines, regardless. If they DON'T work, the problem has always shown up as something like actual dirt in the carb.

Now, I DID once get a load of gas for the CAR that was really bad.

I got horrible mileage (something like 10 or 12 mpg instead of 25), really poor power, generally worked like crap. Couldn't get from St Paul to Madison Wisc on a tank, when I should have gotten well into Illinois. No knocking at all, I could (actually had to) floor it without any knocks, and it was late summer, I think.

Filled up in St Paul, at Grand and Cleveland Ave, and by the time I got on I94 at Vandalia ave, car was feeling weird. Stayed weird, but kinda working, that whole tank, so I decided to burn it out and fill up, as opposed to filling up early to dilute.

Filled up in the Dells (tank was nearly empty!), and within a mile everything was fine again.

I put it down to water in 10% ethanol gas, but since then I am not so sure. I don't know now if that blend was even SOLD in MN at that time (1997 or so). Was sold here.

Possibly it was lacking in volatiles, or maybe it got mixed with diesel or other "non-burnable" material. Dunno.

Clearly it was bad gas.

Evan
08-03-2008, 01:48 AM
I always run the tank and carb dry on my various engines when putting them away for winter. If you don't it will catch up to you eventually as the varnish will build up in the carb passages where it is really difficult to remove. If I can't run it dry for some reason I use fuel stabilizer.

Something to be aware of is that gasoline with alcohol has a much higher vapor pressure than without alcohol. If you live in an area with a real winter season the alcohol/gas (E85 for instance) sold in winter will cause vapor lock in summer in many engines, large and small. Any winter gas should be used up before real warm weather comes around.

JCHannum
08-03-2008, 08:09 AM
Like Jerry, I prefer wet storage to running it dry. It will not be dry, but will leave residual gas which then will evaporate, leaving gum & varnish. It is really a matter of personal preferences as either method has it's positives and negatives.

In either case, dismantling and spritzing with carb cleaner through the various passages will quickly remove most accumulations of varnish and crud. This is usually all that is needed to "restore" most of the engines I pick up at curbside. It usually takes about 15 minutes to produce a running engine.

A properly designed and fitted gas cap will prevent excess evaporation, and topping the tank with fresh gas will replenish all the goodies. I do use only one gas can, and it is used for the lawn tools in the summer & the snowplow in the winter, so it stays relatively fresh.

Jerry, I have had similar performance when the catalytic convertor became plugged. Your mention of diesel contamination got me to thinking that could have been the cause. The diesel could have been enough to plug the cat. It would burn clear with fresh gas.

I will now leave this discussion so Evan can have his obligatory final word and it can be put to rest.

Evan
08-03-2008, 10:06 AM
"I will now leave this discussion so Evan can have his obligatory final word and it can be put to rest."

J Tiers
08-03-2008, 10:46 AM
Not looking for final word, but.........

As a matter of actual fact, having disassembled carbs for other reasons after "wet" winter storage for a few years (unrelated mechanical problems), I have yet to see the build-ups that are commonly mentioned as the inevitable result of such storage.

We use a gas here with at least 10% ethanol year around, so it is possible that it has a cleaning effect. Whatever the reason, only ONE carb has a recurring issue, and it has that issue whether run dry or not.

Would diesel plug the cat? Didn't know that, I figured that anything that had excess unburned fuel might overheat it, and damage it permanently. Wasn't thinking about plugging.

If so, it's certainly possible, although it started so fast after filling up that it seemed only the required time for the lines to purge and the new gas to get through. Ditto for the "recovery".

How long would it take to plug or clear the cat?

JCHannum
08-03-2008, 11:36 AM
I had an '81 Buick that, tiring of it's usual pastime of self destruction of the transmission, on two occasions managed to plug it's cat.

The onset was rather rapid, and symptoms were much as you described. The cat was replaced in one instance and had roadside surgery performed with a jack handle in the second instance, so I cannot speak to time required to clear. It is conceivable that metering in just enough excess HC could keep it fouled enough to effect performance, and for it to clear in short order once the source has been removed. Just a guess, but it would be a source of excess backpressure.

JRouche
08-03-2008, 10:21 PM
Hey, nice thread. I looked into gasoline storage information some time back. Mainly cause I have a gasoline emergency generator, you know, for the "Big One" I was in the semi big one for the Northridge EQ and edison had us off the grid for five days. We were at the center of the EQ so we got some damage.

Anyway, I store a lil gasoline to be able to run my gen for on and off times mainly to keep the perishable foods (like ice cream LOL) stable.

I have six five gallon steel "Jerry Cans" full of fuel with some "Stabil".

From what I read it was the air getting to the gas that caused the most problems. The plastic containers can be permeable for the fuel and air where the steel can protects it better. I made sure to fill it up the the threads and while screwing on the cap the fuel would be pushed out some. Mainly to reduce the headroom of air.

Dunno, may or not work. Im hoping to never find out cause I wont dip into that fuel unless I need to and by that time it may be one of my lesser concerns... I may swap the fuel out after eight or ten years. Curious to see it it will still run a generator. Diesel would be the best choice for long term storage but Im not going that route. JR

Evan
08-04-2008, 02:54 AM
After eight or ten years you will be lucky to start a bonfire with it. The fuel contains dissolved oxygen just like a soda pop contains dissolved CO2. I also would never fill a container right to the top with gasoline. It has a very large volumetric expansion coefficient with temperature.