If you\'ve ever lived through a natural disaster, you know exactly how precious of a commodity gasoline can be. When a storm necessitating evacuation is coming, gasoline becomes more valuable than gold it seems. Lines develop at service stations and people start to get very nasty if they are unable to fill their tanks. The battle between price gouging gas stations and those limiting purchases to the likes of $25.00-$50.00 only make bad situations worse. Then, when gas sells out, hysteria sets in quickly and is sometimes followed by violence as people do anything and everything to get the tank of gas they should have gotten hours or days earlier.
Suppose you did get that tank of gas a few days earlier. In due time even those with the best laid plans are going to have to think creatively to get what they need for continued survival. Perhaps your generator is out of gas and your only source of continued function is through gas obtained from your vehicle. Or if you are stranded on roads impassable by anything but a four wheel drive, the full tank of gas in your Honda Civic is not going to do you a whole lot of good. Moving that gas from your commuter car into your 4x4 would put you in a much better position and serve the needs you have in the now. Siphoning gas out of one vehicle to put into another is the way to again be mobile in situations such as this.
The way siphoning works is basically through a combination of gravity and air pressure. To make it possible, you will need a flexible tube (preferably clear) and a gas can for the siphoned gas. Place one end of the tube into the tank of the vehicle with gas. To do this, you may need a small stick to prop open access to the tank; this will depend on the rigidity of your tube as you do not want the hinged trap of modern cars to press on your tube, squishing it.
Once the tube is in and free of compression, place the other end in your mouth and suck until you see gas moving through the tube. This is why a clear tube is ideal, so you can see the gas as it moves. Taking care not to get gas in your mouth, remove the tube from your mouth and place it into the destination gas can. If you see bubbles in the line, stop and start the process over until you do not have bubbles. When you arrive near to the desired fullness, remove the tube from the tank of the vehicle to stop the flow.
When siphoning gas, you must establish a continuous chain between the starting and ending points of gas travel. The tank from which you are siphoning needs to be higher than the gas destination, which you should set on the ground to make things easier. When you being to suck the gas out of the vehicle, your tube needs to be below the surface of the gas in the tank; this will create pressure on the liquid gas by the air above it in the tank, essentially pushing the gas through the tube. As long as the gas is ultimately moving downward in accordance with gravity, even though it is initially travelling up out of the tank, the air will push the gas through the tube with no more effort from your lungs.
While we do not condone siphoning gas that belongs to other people, there may come a time when you need to move it between your own vehicles. Ideally we will exist in a world where morals apply even after TEOTWAWKI, but that will probably not be the case. When the day comes that all bets are off and we must do what is necessary to survive, having the know-how to siphon gas will come in handy, whether or not you ever need to apply it.