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WHY I have more faith in MoGas than AVgas: For over a decade I have worked with a company that makes instrumentation that meters and monitors watercuts in hydrocarbons. The main purpose of the instruments when used with finished fuels is to monitor and not pay for water delivered, sold, transported through pipelines, tanks, trucks, etc. Water is a funny thing when mixed with fuels. Diesel fuel can hold over 1 1/2% of water and remain homogeneously mixed. It will not separate with residence time. It is normally burnt with the fuel. Gasolines work differently, They can also scavenge humidity out of the air but in smaller proportions and it does separate. The only way to keep water homogeneously mixed with gasoline is by mechanical mixing / agitation. Gasolines, diesel, avgas and all other fuels are transported from the refineries by truck or a combination of pipeline and truck. The further you are from a refinery, the higher chance of a pipeline being involved. It does not matter who owns the refinery or the pipeline. If you believe that TEXACO gas stations only sell TEXACO gasoline with TECHRON and all that advertising, you are very wrong. One pipeline across Texas is shared by three refineries and the distribution centers trade, exchange and sell gasoline to each other as convenience and cost dictates. Pipelines range anywhere between 6 inch diamter to 28 inch lines with 12" to 18" being the most common sizes. The pipeline is always flowing. If a distribution center, lets say like the one in Hearne, TX owned by Texaco buys a shipment of unleaded gasoline, a refinery like the Citco refinery in Lake Charles takes the order because that day they had the best price. They wire SHELL refinery in Pasadena who owes them more money than anyone else. This refinery pumps 800,000 gallons of regular unleaded gasoline at a specified time into the pipeline with nothing to separate it from the products that are already in the line. The combination of the product ahead and behind of the slug with the fuel injected is called "interface". This means that after a certain amount of time the large slug of regular fuel reaches Hearne and they detect the shift in product. The interface ahead of their order. They send it into a tank until they detect the next interface. Here they shut off the line and pay for what they received after calculating volume and water content. They have also received a relatively small quantity of interface which is a mixture of other fuels at the beginning and end of the delivery. Inb a large shipment, this interface is not significant and they do try to make sure that the shipment ahead and after the delivery is as similar as possible. (They TRY, or so they say). When Hearne orders a small batch of Avgas, lets say 50,000 gallons, because they don't sell it as fast as regular unleaded, it is also received with interface. Sometimes they divert the interface into another tank and sell it as whatever octane range it is closest to, but with a significant difference in price, they would lose money if they sold their AVgas interface as regular unleaded. Secondly, the volume of the interface remains constant and in a small batch such as AVgas, it is a noticeable proportion of fuel that may or may not meet specifications. Compliance to specifications is done at the refinery and not at the point of final delivery. Sorry to disappoint all those of you who are faithful to one brand and quality, but I feel much more confident of a stable product buying regular unleaded fuel than AVgas, mostly because of the volumes handled. Both can have water in them, very low residence time will allow all of the water to separate and it is drained off the bottoms of tanks at every point in the road. Any pilot worth his salt should drain the sumps of his tanks regardless of the fuel used. It is best to keep tanks as full as possible. Air in the tanks can hold moisture which will condense and sink through the fuel. The less air in your tanks, the less moisture. Keeping a plane out in the rain with almost empty tanks is going to collect water. Coupes will burn anything octanewise between 80 and 110 octane safely. Aditives are another story and we will save that for a rainy day. I also buy fuel for our local airport and I make darned sure the fuel comes from the Phillips refinery in Pasadena, 30 miles by truck. No pipeline. I drain the tank 30 minutes after delivery and weekly in between. I have no control over where Phillips gets their Avgas though, They may have refined it or they may have traded with another refinery for all I know. I get my unleaded at the cheapest gas station, the one that handles the largest volumes. I keep the tanks as full as possible, drain my sumps before pulling the plane out of the hangar and have yet to find any water. AF ========================================================================== ==== To leave this forum go to: http://ercoupers.com/lists.htm
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