ebook diy building a homemade vacuum pump instructions & plans

8/3/2019 eBook Diy Building a Homemade Vacuum Pump Instructions & Plans

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Chapter 6: Aerodynamics

Building the Bernoulli levitation ball.

Building a Homemade Vacuum Pump.A Classic Propellor Toy.

Building a homemade vacuum pump

Some wonderful things can be done once we get rid of the pesky atmosphere we live in.Feathers drop like rocks. Bells go silent. Water boils at room temperature. Balloonsinflate themselves. Frozen foods dry out but keep their shape.

Sometimes all you need is a little bit of vacuum to help dry something out, or move aliquid through a tube, or remove gasses from a liquid.

In this project, we will make a vacuum pump from common inexpensive plumbing parts.We will then use it to inflate marshmallows to twice their size, remove the air fromthem, and then shrink them down to a wrinkled, rubbery candy with the density of agumdrop.

If all of the materials are at hand, the pump goes together in about a half hour.

What you need

q Four feet of 1 inch diameter Schedule 40 PVC pipe.q Four feet of inch diameter Schedule 40 PVC pipe.q One foot of inch diameter Schedule 80 (thin wall) PVC pipe.q One 1 inch diameter PVC check valveq One inch diameter PVC "T" fittingq One foot (or so) of clear vinyl hoseq One barb fitting to match hoseq One foot of PVC to fit barb fittingq One elbow to mate 1 inch PVC pipe to inchq One rubber "O" ring. This must fit snugly inside the 1 inch pipe, but loosly over the

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inch pipe. Some experimenting with different sizes may be called for.q One can of clear PVC cementq One canning jar to act as our "bell jar"q One brass barb fitting to match hose. This can be plastic but you will have to use

epoxy instead of solder to attach it to the jar lid

Click on image for a larger picture

To see how the pump works, look at the drawing below.

The pump consists of a small diameter pipe (called the piston) inserted into a largerdiameter pipe (called the cylinder).

The drawing shows the pump at two points during its operation. The top drawing showsair being drawn into the pipe by pulling out the piston. The bottom drawing shows airexiting the pipe when the piston is pushed back in. At the right end of the pipe is acommercially bought one-way valve. This valve lets air into the pipe, but will not let airout of the pipe.

At the end of the piston is a home-made one-way valve.

The home-made one-way valve is made using a rubber "O" ring that slides up or downon the piston. A hole is drilled into the piston, and two "stops" are attached, so the "O"ring cannot slide past them.

When the piston is being pushed into the cylinder, the "O" ring slides back, letting theair in the cylinder exit through the drilled hole, and out through the hollow piston.

When the piston is pulled out of the cylinder, the "O" ring slides towards the stop at theend of the piston, and blocks the air from getting to the drilled hole. The right end of thepiston is closed off (the pipe is sealed). The left end is open, to let the air escape.

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This will all become easier to understand as you see the parts go together in the photosbelow.

The first step is to make the piston. We start by adding the stops that keep the "O" ringfrom sliding. These stops are made from short pieces of the thin-walled inch tubing.We cut slots along the length of the thin-wall tuning to allow it to be compressed ontothe inch piston tube.


Using liberal amounts of PVC cement, we glue the stops onto the piston, compressingthem into place with rubber bands. The stops should be about inches apart.

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In the center of the space between the stops, we drill holes in the inch pipe. Here yousee we have drilled three holes, spaced at roughly equal distances around the pipe.


The photo below shows several simple steps all completed.

The commercial one-way valve has been cemented onto the 1 inch cylinder pipe. Makesure that the arrow on the valve is pointing towards the cylinder.

A short length of 1 inch pipe is cemented into the other end of the commercial one-wayvalve, and some reducing fittings are cemented to that so that we end up with a hosebarb at the end. I found it convenient to use a right angle reducing fitting, followed by agray threaded pipe, and a gray hose barb that threads onto the gray pipe. Be sure tocement any threaded parts, to ensure a vacuum tight seal.

We also cemented on a inch "T" fitting onto the far left end of the piston pipe, to actas a convenient handle.

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The next step is to make a thin plastic disk to close off the right end of the piston pipe.

We make the thin disk by flattening a small piece of the thin-walled inch pipe, andthen cutting a circle out of it.

To flatten the pipe, cut a slot in it lengthwise, and then heat it over a stove to soften theplastic.


When the plastic is soft, it can be flattened by pressing it against a heat resistantsurface such as a tile countertop, or concrete floor. We used pliers, but fingers inside

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leather gloves (to prevent being burned) will also do the trick. Placing the bottom of adrinking glass onto the plastic will flatten it and cool it at the same time.


Draw a circle on the flat plastic by tracing around a piece of inch pipe.

Cut the circle out of the plastic using tin snips or some other strong cutting tool.

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petroleum jelly to lubricate the "O" ring and ensure a vacuum tight seal.

The piston can now be placed into the cylinder. It should be somewhat of a tight fitgetting the "O" ring into the cylinder, but the petroleum jelly should help lubricate it as itslides down in.


The hose can now be attached to the hose barb. To make this easier, place the end ofthe hose into a cup of very hot water for a few minutes to soften it. It will now fit easilyonto the barb, and shrink to fit very tightly.

The completed pump is shown below, attached to a vacuum gauge from an automotiveparts store. The gauge is showing 23 inches of mercury, although with more pumpingwe can get up to 26 inches of mercury with this pump.

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Next, we will make a "bell jar". This is a jar that we will connect to the pump using thehose. We can put things into the jar, and then pump the air out of the jar. Canning jarsare best, since they are made to withstand a vacuum.


Ch 6 A d i
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To make the bell jar, we drill a hole in the center of the jar lid, and attach a hose barb.In the photo we used a brass hose barb, and soldered it into the hole. You can use aplastic hose barb if you like, and use epoxy to attach it to the jar lid.



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Chapter6:Aerodynamics


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The parts are shown in the photo above. We need:

q One four foot length of inch PVC pipe.q Two three inch lengths of inch PVC pipe.q One inch PVC "T" fitting.q Two inch PVC one-way valves (also called "check valves").q One four foot length of wooden dowel that fits inside the pipe.q One rubber stopper whose large end fits snugly into the pipe.q One three-inch long wood screw.


We start by drilling a hole in the end of the wooden dowel just a bit smaller than thewood screw. We also drill a hole in the rubber stopper. We then screw the rubberstopper onto the end of the dowel, as shown below.

We can control the thickness of the rubber stopper by tightening the screw to make itfatter if necessary. The stopper must completely block the pipe, yet still be able to slidein and out when lubricated with petroleum jelly.


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The next step is to glue the PVC pieces together. Make sure that the arrows on both one-way valves are going in the same direction!




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Here is a closeup of the one-way valve before gluing. On this valve, the arrow is moldedinto the plastic to the left of the label.


When the glue has dried, liberally grease the stopper with petroleum jelly, and slide itinto the pipe. As you slide the stopper in, you will hear air coming out of the valvewhose arrow points away from the pump. As you then pull the stopper back out, you willhear air entering through the other valve.


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p y


This pump is very effective for pumping water. The inside diameter of the pipe is 0.8inches. With each 36 inch stroke of the piston, the amount of water pumped is

36 (0.4)2= 18 cubic inches.

That's about 10 fluid ounces, or 0.3 liters.

Next: A Classic Propellor Toy

Send mail toSimon Quel len F ield viasf ield@sci toys.com

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