## Introduction: Beer Tin Barometer

Make a super simple barometer form a beer can and beans tin.

I am a 1st year student at Huddersfield University (studying software development) and being a student I am both skint and up to my elbows in trash (lazy flatmates never clear up after themselves!). So I though I`d combine weather and trash utilisation in one simple project.

There are simpler designs for barometers (though not much simpler it must be said). But this I think is effective, although quite vulnerable to temperature fluctuations, but if you keep it indoors it should be okay.

Here is the result (see image), apologies for the poor quality photo`s, rubbish camera and poor lighting I`m afraid. I will do my best to supplement poor pictures with hand drawn graphics where required.

Although everything featured in this instructable is found around the common household it doesn`t make it safe. Beware of sharp edges from opened tins, never allow minors to work with sharp objects. Keep Away from electrical items! It may spill, water is used in this project after all, and yes, keyboards are electrical items. I accept no responsibility for injuries or damage caused by this instructable, although the probability of any injury/damage is slight, to say the least.

This is my first instructable so please, lots of feed back (if you have any, that it) and don`t hold back on the comments, whatever you do, don`t `go easy` on me, nobody ever learns anything from that, thanks.

Enjoy

## Step 2: Theory

Basically this is how it works as far as I understand it. If anyone has anything to add correct or point out as blatantly wrong, please don`t hesitate to comment here and or message me, thanks.

Atmospheric pressure exerts a force on all bodies within it that are at a different pressure. Therefore, if we seal off part of the atmosphere, by, for example taking an open ended container and turning it upside down into water, then we effectively preserve that (atmospheric) pressure level in the container.

The pressure is equalised by the can floating at a relevant depth to keep the pressure inside the can the same as out (remember that it is not truly sealed, so water enters/exist the can to make up the pressure difference, thus altering buoyancy).

The level at which the can floats is then altered by the atmospheric pressure because it exerts more or less force on the water that the can is floating in causing more or less water to be present within the can an causing the water to be slightly more or less dense thus effecting buoyancy.

These changes can then be measured as changes in buoyancy, namely as rises and falls in the height that the can floats.

## Step 3: Materials

1 Standard tin of beer (see picture)

1 Standard food tin, beans, soup or peas, you know the kind (see picture)

1 measuring jug

About 100ml of water (about 3 and a half US fluid ounces)

(Optional) Some coins (I used 2pence coins, I don't know the US equivalent) but these are probably not needed anyway

## Step 4: Prepair the Materials

(I will assume you are using a beer tin beans can, just because it is easier to refer to)

Consume the beer and beans in the normal way. Fully remove the lid from the beans tin. Then discard the lid, it is not needed in this project.

So now you have an empty beans tin with no lid (but is SHOULD have a base, i.e. if you pour some water in it the water will not run away) see pictures for details.

Push the ring flat against the can or pull it off, just so it is out of the way.

## Step 5: Make the First Mark

Put the beer tin upside down (so that the opening that you drink out of is pointing down) into the can, let it fall to the bottom and gently scratch off a little line of the paint on the tin as close as is visible to the beans tin, see picture, a compass can be used for this. This will be the starting point for your gauge.

## Step 6: Make the Gauge

Using a ruler mark off every millimetre for 2 centimetres, I suggest you make the 5 and 10 millimetre markings distinctive in some way so that it is easier to read later.

Put roughly 100ml in the beans tin. You may need to add a little/take a little away depending on dimensions of can etc.

## Step 8: Set the Level

Do this over a sink, please, or at least be very careful.

This step `sets` a specific level; you probably want a fine sunny day, that way major change in pressure will hopefully be marked by a notable change in height on your beans tin. This said it should work whenever it is set.

Put the beer tin upside down (so that the opening that you drink out of is pointing down) into the can. Tip the can to the side, thus allowing water to enter the can. You should hear it go GLUG GLUG. Be wary or accidentally tipping it too far and watering that nice keyboard.

You may need to keep track of which side the beer can ring pull hole is so that you don`t have to tip it quite so far.

The idea of this is to get the can to float exactly on the half way marking. If you made 2cm worth of markings it should float freely at 1cm.

If it goes to far simply take the beer tin out, tip the water back into the can and try again.

Unfortunately this is purely trial and error; it took me a few attempts. If you cannot manage go ahead to the next step and try that instead.

## Step 9: Setting With Coins Instead

If the previous step is too fiddly try instead adding some coins to the top (hold them in place with tape, movement makes for wild inaccurate readings so they need to be kept still. See picture.

## Step 10: Take a Reading

Make sure you are not in direct sunlight. This can significantly alter the value displayed (temperature and pressure are closely entwined).

Make sure the tin is leaning towards the markings (it has an ability to lean slightly in any direction, make sure that it`s always the same when you take a reading, give the beans tin a few gentle flicks to free up the beer can from the beans tins inner surface.

Level your eyes with the rim of the beans tin. So that the top looks exactly straight (not like an oval or a curve but absolutely dead level). Now count the markings from the top.

The higher it floats the lower the pressure, the lower it floats, the higher the pressure.

Why not try making regular recordings? Notice any correlations in readings and weather? If so, please leave comments on this page, it would be cool to hear if it works well enough to be useful! If it doesn't work, please do say so!