Instructables

An extremely simple and effective vacuum pump

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Picture of An extremely simple and effective vacuum pump
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I will show you how to make a very simple but effective venturi vacuum pump out of cheep laboratory material. You will need several minutes to make it. The principle of this pump is that when the water flows through the vertical tube, the vacuum is generated at the horizontal tube.This type of pump is widely used in chemistry labs for many purposes as filtrating under reduced pressure for example.
 
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Step 1: Material

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In this case I have used an 1.5 mL eppendorf tube and 3 pipette tips of 1 mL. You can use any sort of pipes as long as you follow the rule from the drawing (intro). To glue the parts I used a glue gun and to attach the pump to the faucet, I used the plastic hose that can fit to the pipette tips and a piece of a bicycle tube.

Step 2:

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Cut one pipette tip at the place where it becomes to get narrower, about 3 cm from the top (the tip on the left), and cut the other one about 2 cm from the top. You should now have 2 pipette tips with different radii.

Step 3:

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Cut the eppendorf tube about 1 cm from the bottom and drill a hole close to the other end as in the picture. You can cut of the cap. The dimensions don't have to be exact. Just make the parts so they can fit to each other. (See the further steps).

Step 4:

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Cut the third pipette tip several millimeters from the top so it can come in the hole you made in the eppendorf tube but it shouldn't go deep into it.

Step 5:

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Take the shorter pipette tip from the step 2 and push it into the eppendorfe tube from the bottom. It should end several millimeters under the hole you made. Put the pipette tip from the previous step into the hole and glue all the gaps with a glue gun.
alpump11 days ago

I am asking a question. Not comment at this time. It is clear vacuum is created when the water faucet is turned on. Is it possible to attach the middle hose where vacuum creates to a vacuum chamber? Vacuum should create in the chamber. If I am correct, then I might make it. Your labels R1, R2 and R3 has to be radius sizes.

luani (author)  alpump11 days ago
I tried to do that with the plastic bottle and it collapses so I suppose that the vacuum is created.
alpump luani11 days ago

wow. I will look for a T- type PCV pipe at Home Depot. Maybe 1/4 inch diameter with rubber hose. And I will post as soon as I have it and results.

Actually my original intention is to make a hand vacuum pump with two check valves. One in and One out. I have thought one check valve is necessary. When push the cylinder down, the air will push the check valve out. Then pull the cylinder up, the check valve is closed. Then repeat the process to drain the remaining air out. then vacuum should be created. I am wondering why it requires two check valves. Maybe the other valve is to connect to vacuum gauge for measurement. I am not sure if its okay to ask questions because it says "Make Comments".

luani (author)  alpump10 days ago

I suppose its ok to ask questions. I have already tried to use such T plastic pipes but I didnt get good results. I believe that they are to wide and the water goes to slow so the vacuum is very weak. When I used these thin pipes as in this instructable, I got much better results. The water flows really fast through the pump and generates much stronger vacuum. I suppose the pump you want to make is similar to a bicycle pump, just opposite direction. You can find some instructables about that, but this pump, I created constantly produces vacuum as long as the water flows, it is used in chemical laboratories.

alpump luani9 days ago

I am aware of the Venturi effect (air flow) in carburetors. This is an anology to water flow used in your experiment. Inside the venturi, the pipe has to be constrained to create stronger vacuum on the change of pressure. It drops dramatically. Therefore your reply is helpful about the width in hoses being too wide. So I will give thoughts about using pipets. They are laboratory supplies.

I want to say something interesting about your collapsed bottle. It can be replaced with a tank of gasoline. It creates suction in the tank on air flow. Gasoline droplets in the tank will be vacuumed into venturi area and creates air/water mixture.

i don't intend to do this experiment. Your experiment is very good. I can then use it as an anology to carburetor. It becomes clear that carburetors work on vacuum.

luani (author) 13 days ago

Yes, it should be close to the drawing. I got the better vacuum with the second variation where the pipes are narrower (step 12), but the water produces higher pressure inside the pipe so I suggest using some stronger glue. I couldn't measure the vacuum (I don't have proper equipment) but I compared to the commercial pumps by placing a hand at the end of the hose and there were some difference but it was not very big. You can definitely use this pump in the lab for some purposes instead of a commercial one.

looks interesting... I don't think it can pump a good pressure... Anyway, is it just a couple pipes of different diameter? I mean it looks neat and I'm gonna try making it when I get home, but I don't think I have exact same materials, so how should this look in general? Something like a pipe going in top of a container, other pipe of bigger diameter coming out at the bottom and a small diameter pipe going in through a hole at the side, right?