# Tag Info

### Could a vacuum tank ever be light enough to be boyant in air?

Start out by doing some basic calculations. Air is mostly N2, with a atomic mass of 28, and O2, with a atomic mass of 32. There is more nitrogen than oxygen, so let's say air has a average atomic ...
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### Easily compute a good approximation of heat conductivity of cooled semi-vacuum (water vapor + air)

In the molecular flow region of pressure, the thermal conductivity of an ideal, monatomic gas is obtained by this equation. $$k = \frac{1}{\pi^{3/2} d^2}\sqrt{k_B^3T/m}$$ where $d$ is the ...
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### Series O-ring in Vacuum Application

I'm assuming that the piece with the groove and the mating pieces are metal or a dense molded plastic. If this was a 3d printed piece, I'd be worried about porosity of the parts too. A second O-ring ...
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### How to design a vacuum climbing robot

You do not need full vacuum to accomplish your goal. A small amount of vacuum pressure adds up really quick over a large surface area. Try to make the entire footprint of your robot under vacuum; your ...
• 8,176
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### Replace mercury with silicone oil in diffusion pump

I did some internet searching and did not find anyone that had done a direct swap out. Granted, probably the majority of these replacements occurred before the existence of the internet ;-). As I am ...
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### Unsticking two glass elements fused by vacuum

Perhaps, depending on the materials, you could try gently heating one piece while cooling (or at least heat-sinking) the other piece, and hoping that the expansion mismatch will separate them. You ...
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### deep vacuum in the 19th century

Geissler invented the so-called "liquid piston" pump using mercury for the piston. The basic idea of the design is to entrap some of the air between two volumes of mercury in a pipe, and then force ...
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### What is the equivalent of a capacitor in pneumatics?

The equivalent of a capacitor in terms of pneumatics would be a chamber such as a metal sphere the size of a tennis ball. It would be necessary to have an external vacuum pump to evacuate the air ...
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### Inlet/outlet of a fridge compressor

The small tube I believe is for the freezer coil, or it could be a capillary tube (thank you Swift). Regardless, simply solder it shut and use the two larger lines for pumping. I would like to note, ...
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### How to design a vacuum climbing robot

An important point in the fluid dynamics design is about control points. A simple experiment - hold your hand over a hose on the vacuum cleaner, you'll notice a light vacuum pulling on it, but hold ...
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### How to backfill vacuum chamber with low pressure gas

The simplest way to do this would be to design your own. A commercially available spring, with an OD of 9mm, a length of 19mm, and a wire dia. of 1mm has a rate of 3.15 N/mm, with 11.5 mm compression ...
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### How to regulate a vacuum pump?

The device you're looking for is called a vacuum regulator and sits between the vacuum source and the process. This page from Equilibar shows some examples and provides links that explain how they ...
• 2,145
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### What is the equivalent of a capacitor in pneumatics?

The device is called a "receiver" in pneumatics - this is basically the tank you see on any garage compressor, or much larger and more elaborate setups in industrial settings. Its function can be ...
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### Are vacuum actuated artificial muscles as hard to control as the pneumatic ones?

With a vacuum you are limited to the pressure differential between zero and atmospheric (~100kPa or ~15PSI). With pneumatic you are limited to the pressure differential between atmospheric and ...
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### Vacuum Pump hg" vs Pa units?

I think your confusion is in absolute vs gauge pressure. Atmospheric pressure is about 101 kPa, or 101,000 Pa, or about 30 inches of Hg. Vacuum is commonly measured relative to atmospheric pressure, ...
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### Series O-ring in Vacuum Application

Simply adding another o-ring in series will not give much improvement in the leak rate. This is because the leak rate of the inner o-ring will prevent the internal space (between the two o-rings) ...
• 6,426

### How to protect a pressure gauge from condensation in a vacuum steam boiler?

Have you tried a gauge guard? It's a simple diaphragm that allows pressure to transmit, without the liquid crossing the barrier.
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### What type of positive displacement pump is used for vacuum liquid extraction?

Condensors in steam plant are a common application - about 90% vacuum and you have to extract the condensate at the rate the engine is using steam - something like 9 lbs per hp/hour if you'll excuse ...
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### Vacuum vessel at 10mbar with a diaphragm pump: do I need a venting valve?

I am not a vacuum expert, but if you look at the technical data for your pump, you'll find this "Leak rate 6x10-3 Pa m³/s". I take this to mean that your 10 liter = 0.01 m$^3$ vessel will leak at a ...
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### What's the difference between a vacuum regulator and pressure regulator?

The difference is the side on which pressure is regulated, and the reaction curve. Typical pressure regulator takes arbitrary input pressure (from compressor) and provides specified (lower) pressure ...
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### How fast could a Mini Cooper go in a vacuum?

In an atmosphere, the top speed is probably limited by air resistance more than anything, but in a vacuum it would be limited by other factors. Rolling resistance is a major effect that would ...

### Does a pump like this exist?

I've owned a hand-held pistol-type vacuum pump, useful for testing distributor advance (yeah, long time ago). A quick search shows the inexpensive versions are capable of 0.6-0.7 atm, not quite what ...
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### Can I use a NPT fastened device to vacuum or 10^-2 Torr?

Are you going to continue pumping or have intermittent pumping ? As a engineering professor of sealing once told me "everything leaks, it is a matter of how much". Without continued pumping you will ...
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### Need help identifying this vacuum chamber flange

I have some experience with high vacuum so thought I put in my two cents along with what I was able to find on this particular flange. My first inclination was this is a custom unit and I have since ...
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### Diffusion Pump Copper Cooling Coil Repair

Do this: set up the water flow plumbing with the pump OFF, turn on the water flow, and measure the flow rate by running the discharge into a bucket of known volume for a known period of time, and ...
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### Is it possible/practical to mold a single hollow piece of carbon fiber with a sealed vacuum in the middle?

If I understand correctly, it sounds like you want to make a short carbon fiber tube. This can be done by wrapping the carbon fiber cloth around a mandrel that has the diameter that you want the ...

### Is it possible/practical to mold a single hollow piece of carbon fiber with a sealed vacuum in the middle?

As far as I know, you can't mold a sphere or cylinder unless the material is on the outside of the mold and you keep the mold in place. Think paper machee over balloons. There is no way to get the ...
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### Vacuum Pump Specs

Evacuating 10 psi of pressure from a 500 cu ft chamber in under a second is pretty insane. This is a good calculator, as you will probably need to change your parameters (most likely time) in order to ...
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