eli5: Why do cheap lighters have a divide in their fuel reserve?

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I recently got a science teaching job and had to buy a cheap see-through lighter to ignite the Bunsens, I don’t understand why the tank has to have two different compartments on the inside. You can tilt it and fill up one or the other, could someone explain why this is necessary instead of one big tank?

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18 Answers

Anonymous 0 Comments

I’ve read through many answers and am surprised I don’t see one reason mentioned.

Lighters have a tube/wick that sucks up lighter fluid to bring it to the top where it fuels the flame.

A secondary purpose for the divided chamber (other than structural support for the pressure inside) is providing a way to keep the tube dipped in the fluid.

Without the two tall chambers separated by the divider, fluid would lay more flat on the bottom of the lighter, making it harder for the tube to dip into it.

You can see this by holding the lighter up to a light source and dipping it to move the fluid around.

Anonymous 0 Comments

No one concerned that OP is going to teach science and needs an ELI5 explanation for this?

Anonymous 0 Comments

I’m pretty sure the only reason is strength. Bic lighters also have a divided tank like the cheap crack lighters do.

Anonymous 0 Comments

They’re actually better than ones without the divider. As though the fumes and liquid are more concentrated in that section. The ones without always seem to pack in, due to lack of gas long before they’re empty.

Anonymous 0 Comments

Hold up… Science teaching job and your here asking what is basically a science question ?

Anonymous 0 Comments

You don’t have a flint striker? Those things are relatively cheap and last nigh on forever.

Anonymous 0 Comments

You’ll notice the straight walled lighters (like you described) have the divider which is actually more of a rib as it allows pass through to either side. Then there is your classic Bic, which is oval. Both speak to structural integrity.

Anonymous 0 Comments

Why did I just waste 30 min reading about this?

Anonymous 0 Comments

No one’s mentioned that it also helps you get that last bit of fuel? Actually great way to squeeze out a little more utility from the design that is there for structural and manufacturing purposes as people have said.

Think about it, it could have a hole in the middle, but that would lead to two separate tanks. A hole at the bottom would allow the fluid to gather at one of the corners away from the tube so it won’t get fuel.

A hole in the top allows the user to invert the lighter, move all remaining fuel to one well and have it pool up in one corner right by the tube.

Anonymous 0 Comments

The fuel tank is under enough pressure to force the butane gas into being a liquid. That’s quite a bit. The connecting rib in the middle is to keep it from exploding outwards, or being crushed inwards, while using less total plastic than making the walls thicker.