Help locating a pump

NWCCTV

I am looking for an inexpensive, low dc voltage air pump that has enough psi to inflate a 2 liter balloon fairly quickly. I checked on EBay and about all I could find are 3 volt ones that do not have the psi needed. So, if anyone knows where I might find one please let me know.

Duane C. Johnson

Possibly 12V emergency tire inflation compressors.

Duane J

NWCCTV

I thought about that but they are kind of big. I could possibly strip one down to the guts but I would then need to worry about the heat dissipation. I need one that is small but powerful. I did find a small 12v RC boat air pump. I am waiting to hear back from the seller as far as the psi it delivers.

kwinn

Not sure if this would work for your application, but take a look at a car windshield washer pump.

ElectricAye

Does it need to be air? Could you use a charge of vinegar and baking soda and, activating a tilt mechanism, inflate with CO₂?

NWCCTV

@kwinn, A windshield washer pump just might work. Thanks for that. I will have to go to the local junk yard to see what I can find.

@ElectricAye, Yes, it has to be air.

pmrobert

Perhaps the air pump in a home sphygnomanometer (blood pressure measuring device) may have some potential.
Also, to clarify, do you need pressure or volume? Balloon inflation usually requires low pressure-high volume.

NWCCTV

Basically I want to simulate a lung. So the "balloon" that I end up using would be mostly filled until the electronics are turned on and then the pump will turn on and off to simulate breathing.

Edit: I will also be doing a heart but I do not need much air for that feature.

ElectricAye

NWCCTV wrote: »

Basically I want to simulate a lung. So the "balloon" that I end up using would be mostly filled until the electronics are turned on and then the pump will turn on and off to simulate breathing.

Edit: I will also be doing a heart but I do not need much air for that feature.

How about using an electric motor powering a crank that pulls on a diaphragm that then actually pulls on the "lungs" much the way the human body does it? It might be less noisy than a pump that actually buzzes air into and out of balloons. Just thinking out loud here.

NWCCTV

The pump will be pretty well insulated so I do not think noise will be much of an issue. Since it is going to be quite small and I am going to implement breathing sounds it should be fine. This will all be inside of a gutted out mannequin, ( if I can find one real cheap!!!!) The plan is to use plastic "skin" that will be painted over the torso and then the torso will be gutted. Once all the components are inside the "skin" will be placed over it and the lungs will inflate and deflate like the human body does. Does this make sense?

ElectricAye

NWCCTV wrote: »

... Does this make sense?

Yeah, it makes sense. But if what you're aiming for is realistic lung sounds, would it make more sense to implement some kind of sound recording? Doctors are trained to tell the difference between different kinds of lung sounds - pneumonia can create a squeaky sound, for example. Gun shot wounds, if they penetrate the lung, have another sound, etc. You would have lots more flexibility with your dummy if you could integrate recordings, I think, rather than just plain ole huffing and puffing. Besides, I doubt you could mimic human sounds with balloons and pumps very well, but that's just a guess.


Bend an ear to some of these:

http://faculty.etsu.edu/arnall/www/public_html/heartlung/breathsounds/contents.html

NWCCTV

I am a step ahead of you on that one. I need to install a different Creative Labs sound card so I can have the "What You Hear" feature back and I will be using the sounds from this web site: http://www.easyauscultation.com/lung-sounds-reference-guide.aspx as long as they give me permission which I have emailed and asked about.

Which brings me to another question. Can the Prop play MP3 sounds from an SD card or does it only do .wav?

ElectricAye

How about placing multiple speakers all around the dummy's chest and control the apparent position and intensity of each acoustic emission so it simulates, for example, problems in a particular lobe? The person could move their stethoscope around and pick up different intensities of the recorded sound, maybe be more realistic than a single point acoustic emission. Just a thought.

NWCCTV

Yea, I have a couple different ideas for this. One is to have the sounds changed by an instructor as all the functions will be controlled wirelessly. So, the instructor will be able to speed up or slow down the breathing and the heart rate. The wireless device will also be able to change the sounds for different simulations.

Edit: First and foremost is to get the mannequin!!!! I am going to hit up the major department stores in my area to see if someone will either donate or sell me one real cheap. I then need to get the skin made and I have a machine shop client that I am going to have cut out the torso once the skin is made. After that it will just be a matter of getting it all working together.

kwinn

I am pretty sure (99.44%) the prop cannot decode MP3 so WAV is the way to go. If the recordings are in MP3 there are free programs that can convert that to WAV.

For the pump you may want to consider making your own using a large diameter PVC pipe. With the piston moving back and forth at the breathing rate there would be minimal pump noise.

Duane C. Johnson

Kind of a nit pick here.

An expanding balloon is not a good analogy for the lung.

The lung, essentially, isn't elastic. Its more like a bag of constant surface area with a variable volume.

A balloon requires a fair amount of pressure to expand.
The lung needs very little pressure to inflate, what little pressure there is is mostly due to air flow resistance not static pressure.

Anyway, you might want to use a very large balloon that is suitably large at rest.
Or, a plastic bag cut into a lung shape.
We wouldn't want to mislead the little urchins in how the lungs actually work.

Since this technique requires very low pressure a small DC fan can inflate it.

Duane J

kwinn

The plastic bag is a good idea. It might even be possible to simulate the action of the diaphragm muscle with a rubber membrane and a small motor at the low pressures it would require.