Siphoning gas out of a tank or water out of an elevated jacuzzi is an excercise in physics. Unlike what many of us assume though, a siphon does not rely on atmospheric pressure (it works just fine a vacuum, should you ever need to siphon gas from your spaceship), but rather gravity (a potential problem for the spaceship senario) and the cohesive forces at work in columns of liquid.

So now that you understand how it works, here's our guide to siphoning.

== Siphoning ==

At the most basic level you need three things for a siphon to work -- a source of liquid, a place for the liquid to go and a hose. Ideally the hose would be clear you can see what's going on, but that's not absolutely necessary.

In order for a siphon to work the source liquid must be above wherever you're trying to make it go (remember, gravity is doing the work here).

In the case of siphoning gas out of a tank, feed the hose into the tank and then put your gasoline approved contain on the ground.

Now you need to suck the gas out of the tank and get rid of any air in the tube. If you're slighly crazy you can do this with your mouth. We've seen it done by the side of the road in countless backwater places, but unless you're in dire straits it's far safer to buy a siphon pump.

A siphon pump does the same thing your mouth does, but eliminates any chance of you swallowing gasoline and ending up in the hospital.

Once the air is out of the tube and the liquid has reached the end of the hose, maintain suction on the hose and carefully crimp the hose or use your thumb as a stopper. In either case to goal is to  prevent any air from entering the hose.

Now just drop the the hose into your gas can and release the crimp. Viola, siphon complete. 

== Tips ==


#   The trick to avoiding air bubbles in your siphon line is hold the hose straight up and down so you're sucking the liquid up, rather than sideways or down.
#   be sure to keep an eye on your source liquid and make sure the hose stays fully submerged otherwise you'll end up with bubbles.
#   It's illegal to siphon gas out of someone's car, you will go to jail.
#   Yes you can siphon with your mouth. That's fine if you're draining the jacuzzi, but it's a really bad idea with more toxic liquids like gasoline.