: Never fill up on gas when...



dom418
04-29-05, 09:28 AM
I have heard that you should never get gas when the tanker truck is filling the station's tanks because it stirs up all the grud at the bottom of the tank which will get into your car and clog your injectors. Is that true? Isn't that what a fuel filter is for?

dkozloski
04-29-05, 10:08 AM
It takes an overnight wait for all the water and dirt to settle after a gas station receives a load of fuel. In extreme cold weather the ice crystals in the fuel will plug the stations filters and fuel cannot be dispensed. That being said, there are filters in the system to catch the crud but some gets through. Unless you are there to see it, you wouldn't know about the delivery anyhow.

Katshot
04-29-05, 10:40 AM
Ice crystals? What ice crystals?
We only had one gas tank and one diesel tank so we never had the capability to allow the fuel to "settle" overnight. Still, we never had any problem with anything getting into our car's fuel systems. The filters on the gas pumps are plenty good enough to keep anything from getting into your tank.

dkozloski
04-29-05, 10:57 AM
Katshot, when the truck is loaded at the refinery there is water in the fuel. It is a fact of life. The percentage of water is low but it is there after the refining process. Look at the ASTM specs for allowable water in the fuel. If the truck drives around in extreme cold weather the fuel cools and the water freezes into ice crystals. If you pop the lid on the truck and shine a flashlight into the product you can see the sparkles of the ice crystals. If you pay extra, alcohol will be added to the fuel while it is being loaded on the truck. Now the fuel is dropped into the customers tank. It takes an overnight wait for the crystals to settle and it takes another two to three days for the fuel to absorb enough heat from the ground to get back above 32deg and the crystals to melt. If you attempt to dispense fuel while the crystals are still circulating around in the tank the pump filters will plug and all you will get is a dribble. Even if you do not have extreme cold weather and ice crystals in your area the fuel will still have the same percentage of water in it when it is delivered. Of course the further you are from the refinery the better the chance that the water has settled into somebody elses tank enroute. Aviation fuel is filtered every time it is transferred but auto gas can be anything. Why take a chance?

dkozloski
04-29-05, 11:07 AM
Katshot, one time I filled up at a gas station operated by a major chain, right after a rain storm. I bet I didn't get a block before my car quit. I looked around and I'll bet there were another dozen irate motorists within shouting distance. A walk back to the station and a look around showed where a plugged storm drain had funneled gallons of water into the underground tank. I was told it just couldn't have happened there because all their fuel was filtered. After we all grouped around the manager and told him how the cow ate the cabbage he was ready to pay to get about 20 cars drained and filters changed.

Ranger
04-29-05, 12:27 PM
I have always believed that and always tell my wife and daughters, if you see a tanker unloading, go to another station. If it is a newly built station the tanks should be pretty clean and filters at the pump as well as the car should catch anything but why take a chance. On the other side of the coin, you never know if a tanker left five minutes before you pulled in.

dkozloski
04-29-05, 12:42 PM
Modern underground tank installations have leak detection and level monitoring equipment that tells you everything about the product in the tank. You can see the water level in the bottom go to zero when the tank is stirred up with a delivery and you can see it come back as the water settles. When the tank service guy pumps the water it comes out filthy with dirt, bacteria slime and the Lord knows what. This is the stuff you are putting in your car. When you are handling jet fuel it goes without saying that the fuel is allowed to settle before using it even though it is filtered as it goes from the delivery truck to the storage tank, as it comes out of the storage tank to the refueling truck and as it comes out of the refueling truck to the aircraft.

eldorado1
04-29-05, 12:56 PM
Modern underground tank installations have leak detection and level monitoring equipment that tells you everything about the product in the tank.

They still use marked sticks in my neck of the woods..... :thumbsup:

Kev
04-29-05, 01:07 PM
You guys sound like a bunch of worried little girls! There may always be a few exceptions but for the most part, if the fuel system of the gas station is in working order with no leaks at their tanks and your inline fuel filter is not clogged the chances of you having a problem are rare.

Living in California's Central Coast I wouldn't know about ice crystal problems, I suppose if the filters at the gas station don't screen them out or if you have water in you tank already and have a sudden drop in temperature you might clog your fuel lines for a little while.

BeelzeBob
04-29-05, 01:16 PM
We stopped into a rather isolated gas station in the wilds of Ontario, Canada on our snowmobiles one time. The station actually had huge, above ground tanks off to the side in a tank farm. We filled up 12 sleds and left. One stalled on the lake 1 mile away. 2 more stalled and started running poorly several miles futher. One sled melted a piston from leaning out. Water in the fuel. AFTER this all happened we recalled seeing the gasoline tanker heading out the access road from where were went into the camp. The tanker had just filled the tank we filled from and everyone got a load of water/ice crystals. The 8 people that had been running a lot of isopropyl gas line antifreeze in their fuel had no problems....the other 4 had big problems. I have seen this same sort of thing happen several other times.

I was in Northern Michigan one trip and had some 5 gallon, plastic gas cans that I filled my self with fresh, premium fuel. These were my cans and I know that they were clean and uncontaminated. On a -40 morning I was filling my sled with the gas in those cans and the fine strainer on the filler neck clogged up with ice particles filtered from the fuel. Apparently there was enough moisture in the fuel to case ice particles to form sufficient to plug up the strainer. Those cans were clean, dry and completely filled and capped so there is no way that water got in them later. In the other can you could look in with a strong flashlight and see the ice crystals floating in the fuel. So moisture does get into it.

I think the filters in a commercial gas station are probably adequate to catch whatever dirt and crud might be stirred up from the tanks being filled but a sufficient amount of water can overwhelm water separators.

Most water separators in fuel tanks like in a station and the water separator that is in the fuel tank of the car (the sock over the end of the pickup) are very very effective at eliminating any water from entering the system. They work on the principle of the surface tension of the liguid and rely on the fact that gasoline has lower surface tension than water. Stick the water separator in a layer of water (water always lies at the bottom of the tank) and it will still allow nothing but gasoline thru....as long as there is gasoline present and as long as the water is no so deep as to completely cover the pickup. At that point it will suck water as there is no option....but as long as there is gas touching the sock somewhere along the way it will pull the gasoline. That is why running some gas line antifreeze, preferably the isopropyl alcohol type, is a good idea especially in the winter to remove any water from the tank.

Katshot
04-29-05, 01:23 PM
I understand what you're saying but at least in our area, the fuel doesn't come straight to the station from the refinery. It usually goes to a depot first. Beyond that, ALL motor fuels MUST be dispensed at a standard temp (usually 60-65 degrees I think) to provide a point of referance for weights and measures. The fuel expands and contracts so much that if this is not done, you have no idea how much fuel you have at any given time. If you're seeing ice crystals in motor fuel, it must've been sitting quite a while since it was loaded.
As for what's in the tank, any station these days has to have a system for controlling water in the fuel (we used a Veeder-Root system) but sure, there's always a chance that water can get to your tank since it will pass right through a filter. Remember, the pump pick-up is near the bottom of the tank so "if" there IS water in the underground tank, you stand a better chance of getting it once it settles to the bottom. Yeah, of course in your case, there was an extreme amount of water do to a unique circumstance.
Bottom line, like I said before, we had in-ground tanks for all the 20 years I was in my position and we never once had clogged filters due to ice crystals, and never once had a problem with fuel contamination in our cars from using the fuel immediately after the load was delivered. So I'm more likely to call this issue more of a myth than anything.
Oh, and BTW, finding some water in jet fuel is nothing new. I found it from time to time while doing pre-flights and/or taking fuel samples on the flight-line during my time in the Navy.

dkozloski
04-29-05, 02:08 PM
Fuel is dispensed at what ever temperature it happens to be and you take your chances with expansion and contraction. I compared the billing from hundreds of fuel drops from the delivery trucks with what showed up in the storage tanks. Our fuel monitoring system had a computer that corrected everything for temperature but the bulk plant did none of this. They just went with what the meter showed. It still worked out that if you were delivered -40deg fuel you made out like a bandit and if you got fuel on a hot day right from the refinery you were a loser. The temperature in our underground tanks would stabilize out to around 30deg in the winter and about 45deg in the summer.

Katshot
04-29-05, 04:46 PM
We stopped into a rather isolated gas station in the wilds of Ontario, Canada on our snowmobiles one time. The station actually had huge, above ground tanks off to the side in a tank farm. We filled up 12 sleds and left. One stalled on the lake 1 mile away. 2 more stalled and started running poorly several miles futher. One sled melted a piston from leaning out. Water in the fuel. AFTER this all happened we recalled seeing the gasoline tanker heading out the access road from where were went into the camp. The tanker had just filled the tank we filled from and everyone got a load of water/ice crystals. The 8 people that had been running a lot of isopropyl gas line antifreeze in their fuel had no problems....the other 4 had big problems. I have seen this same sort of thing happen several other times.

I was in Northern Michigan one trip and had some 5 gallon, plastic gas cans that I filled my self with fresh, premium fuel. These were my cans and I know that they were clean and uncontaminated. On a -40 morning I was filling my sled with the gas in those cans and the fine strainer on the filler neck clogged up with ice particles filtered from the fuel. Apparently there was enough moisture in the fuel to case ice particles to form sufficient to plug up the strainer. Those cans were clean, dry and completely filled and capped so there is no way that water got in them later. In the other can you could look in with a strong flashlight and see the ice crystals floating in the fuel. So moisture does get into it.

I think the filters in a commercial gas station are probably adequate to catch whatever dirt and crud might be stirred up from the tanks being filled but a sufficient amount of water can overwhelm water separators.

Most water separators in fuel tanks like in a station and the water separator that is in the fuel tank of the car (the sock over the end of the pickup) are very very effective at eliminating any water from entering the system. They work on the principle of the surface tension of the liguid and rely on the fact that gasoline has lower surface tension than water. Stick the water separator in a layer of water (water always lies at the bottom of the tank) and it will still allow nothing but gasoline thru....as long as there is gasoline present and as long as the water is no so deep as to completely cover the pickup. At that point it will suck water as there is no option....but as long as there is gas touching the sock somewhere along the way it will pull the gasoline. That is why running some gas line antifreeze, preferably the isopropyl alcohol type, is a good idea especially in the winter to remove any water from the tank.

-40 degrees huh? Pretty cold. Never got that cold in NJ so I guess I can't comment about that but I would say that tiny ice crystals (floating?) in the fuel are probably more likely to be caused by condensation than anything. That's why most people in real cold areas should be using dri-gas religiously. Also, wouldn't you think that above-ground fuel tanks located in a remote, severely cold area would be much more likely to have a problem with condensation?

dkozloski
04-30-05, 12:40 AM
Fuel as it leaves the refinery has water in it that is fully dissolved. The amount depends on the temperature. A typical number would be 150PPM at 70degrees F. At a high activity refinery the fuel is pretty darn warm as it is pumped into the trucks. Diesel or jet fuel would have more dissolved water than gasoline. As the fuel cools the water separates. If the fuel cools as the truck is on the road the water separates as crystals. These crystals accumulate in the bottom of the storage tank at delivery. The next delivery stirs up what's already there and leaves more. There is not much to be done about it until spring when the whole tank is above freezing and can be pumped. The international standard for dry air is a dew point of -40F. The air in the described incident would have had a zero humidity so the possibility of condensation is nil. Some bulk suppliers add enough alcohol to prevent the water from freezing and others do not. Those of us who handle fuel in the arctic are fully aware of the dangers and take precautions especially if it is aviation fuel. If the temperatures are moderate the water is still a problem because of the bacteria that live in it, comsume the petroleum, and leave slime and more water behind. The white crap that you find contaminating your fuel system is not corrosion products but bacteria poop. This stuff is a real problem in turbine fuel and requires the addition of fuel treatments such as "Prist"(diethylene glycol mono methyl ether). Turbine aircraft are also equipped with fuel heaters to deal with the ice crystals.

BeelzeBob
04-30-05, 01:24 AM
I think the idea of condensation causing the ice in fuel is greatly over-rated. If you fill the tank then it pushes all the vapor out and any air vapor that might have contained moisture will be expelled...what little air is left couldn't contain enough moisture to account for droplets in the fuel.

The vapor volume in fuel tanks such as in ground tanks, above ground tanks used exclusively for fuel, gas tanks in cars, etc....contain very little to no "air" per se. Fuel is very volitile and the vapor volume is made up primarily of fuel vapors...not air and not air with moisture in it. Air does not get into fuel tanks...as the tank is emptied the fuel vapor fills up the void. That is why there are charcoal canisters on the fuel tank vents to catch the vapor generated. There is more vapor generated than blank space created so "air" is not pulled in.

Even if the tank was filled with air everytime it was emptied there is precious little moisture in the air , especially in the winter when the humidity is very very low.

I think that most of the water gets "delivered" and or leaks into the tanks from faulty caps or fittings on the tank. The water lays on the bottom of the tank in a thin layer harming nothing until something stirs it up...like filling the tank from the tanker.

Above ground fuel tanks...???....They are extremely common in Northern areas from my observation. Especially in outback areas, where the ground is swampy or wet the yearly frost cycle will simply push underground tanks to the surface because the frost goes so deep. There are many camps in rocky areas that prevent burying tanks anyway. I see above ground tanks for fuel in many many places.

dkozloski
04-30-05, 01:34 AM
In the Alaska bush it is common to see prefabricated fuel "skids" that are more or less a plug and play gas station. The tanks, hose reels, pumps, meters, monitoring equipment, lights and whatever else you might need is assembled at a population center and delivered as a unit. Our operation has these all over the state in sizes from one to twelve thousand gallons.

WoodShoe
05-01-05, 06:45 PM
Fuel is definatelly temp corrected at the pumps to 15C..thats a fact.

dkozloski
05-01-05, 07:30 PM
Woodshoe, Please describe to me in detail the mechanism in the meter that makes this correction. I know that electronic fuel monitoring systems in fuel storage tanks have this capability but mechanical meters on trucks have no such technology. When I look at the meter slip from the truck it matches up with the uncorrected field in the monitoring system and this is what you pay the bulk supplier. In fact you have to be careful and monitor how much the truck dumps because the delivery driver will check the empty room in the tank from the monitoring system that is corrected and make a corresponding fill with very cold fuel and as it warms you can get either an overflow alarm or an actual overflow. The difference in the reading can amount to tens of gallons. The delivery meters on our pumps give a rotational output that is converted to a gallonage reading on a Veeder-Root counter with no computer involved. In order to get a temperature correction from a mechanical meter it would have to have something in it that would vary the displacement of the metering chambers or continuously change the ratio of the gear train that drives the counter. Temperature correction from an electronic meter is easy but there are tens of thousands of mechanical meters still out there. Temperature correction at the pump is only required in Canada and Hawaii, and for deliveries over 5000 gallons elsewhere. All generalizations are false, including the one you made.

WoodShoe
05-01-05, 08:17 PM
How canadien of me. Sorry. All MY has is temperature corrected to 15C.

dkozloski
05-01-05, 09:09 PM
Woodshoe, it looks to me like your way is the fair way to do it but as long as they are metering and filling the truck with warm fuel and delivering it to me after it cools I won't look the gift horse in the mouth.