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Questions tagged [compressed-air]

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18 votes
4 answers
5k views

Why are train brakes so complicated?

The concept is simple enough: no pressure in the train line has the brakes locked, full pressure is loose, and partial pressure drags accordingly. So if pressure is lost for any reason, the train ...
AaronD's user avatar
  • 591
12 votes
1 answer
3k views

Why was Freon used in spray cans before it was declared a threat to ozone?

I've heard that in the past, spray cans (aerosol cans) contained Freon. I found that the Montreal Protocol made the usage of Freon illegal due to its effect on the ozone layer, but I can't find the ...
Physther's user avatar
  • 614
9 votes
2 answers
2k views

Air compressor that doubles as a pneumatic motor?

I am working on a compressed air energy storage system. The size and weight of the system are heavily constrained; nothing should (ideally) exceed a few pounds. For this reason, I would like to store ...
MikeJava's user avatar
8 votes
2 answers
3k views

Why does public transport uses compressed air to open doors instead of electromotors?

System with compressed air seems more expensive and harder to build and integrate neither using simple electromagnetic drives to open public transport doors.
PaulD's user avatar
  • 445
7 votes
5 answers
11k views

Is compressed air energy storage economically viable in the home?

If I install a small air compressor/engine, generator, and tank in my garage, and I charge it up at night when electricity costs $\frac{5.4p}{kWh}$ and use it during the day to power my house when ...
jhabbott's user avatar
  • 5,970
5 votes
1 answer
562 views

Are there any precedent designs for a mechanically-delayed pressure release valve?

I need to release pressure of around 50psi, after 3-4 seconds of initiating, from a vessel using a mechanical switch. I had considered a pneumatic solenoid, but I want to forgo the inconvenience of ...
SmugDoodleBug's user avatar
4 votes
2 answers
443 views

Turning an engine over with engine compression

When you compress a bicycle pump and seal the opening, the pump will automatically return to it's initial position when you release it. I suppose this is how air suspension works as well? if you have ...
Erik's user avatar
  • 163
4 votes
1 answer
124 views

How do you actually control the cooling level of AC?

I'm hoping this is a relatively simple question to answer, but I just couldn't find it on Google. With regard to air conditioning (or any cooling system that relies on compressing/evaporating), how ...
Izzo's user avatar
  • 189
4 votes
3 answers
455 views

Specific heat at constant volume used in non constant volume processes

I have commonly seen that the work for an isentropic compression is written as: $$ W_{in} = c_{v}(T_1 - T_2) $$ What confuses me is that since it is a compression (volume is changing) why do we use ...
RMS's user avatar
  • 275
4 votes
1 answer
2k views

Tankless air compressor for electronics desoldering station

I purchased a Weller WSD161V soldering station (similar to this one, at least with regards to the pneumatic system I'm about to describe -- sorry, I was unable to find a manual for my specific model ...
swineone's user avatar
  • 141
4 votes
0 answers
142 views

Simplifying head loss across a piping network

I am tasked with designing a compressed air piping network,with and would like to determine the pressure loss across the different layers of instruments -now here is the 3D layout of the network. ...
udidosa's user avatar
  • 161
4 votes
0 answers
2k views

Estimating Maximum Speed for a Pneumatic Cylinder

I am designing an machine that is going to use a pneumatic cylinder to accelerate a projectile. I have a tentative cylinder specified, and am working on the control and supply side. I have verified ...
Ethan48's user avatar
  • 4,541
3 votes
3 answers
691 views

What is the best method to generate heat from a compressed air canister?

I want to convert the pressured air exiting a valve to heat. I know that a vortex tube can be used to do this, but I am wondering if I need to make modifications to the vortex tube to make it more ...
layssi's user avatar
  • 51
3 votes
2 answers
469 views

Pneumatic Actuators - System Reversibility. Is it possible to use an actuator to store energy?

I'm very much new to pneumatics and I was wondering if there was such a thing as a reversible pneumatic actuator? I'm designing a system that has to be lightweight, pneumatic and use a mechanical ...
Alex's user avatar
  • 61
3 votes
2 answers
4k views

What's the difference between a vacuum regulator and pressure regulator?

When browsing through pneumatic parts, I notice that some vendors specify different components for pressure regulator and vacuum regulators. SMC for example does this. I'm curious why vendors would ...
Izzo's user avatar
  • 189
3 votes
2 answers
491 views

Check valve in compressed air pipe network?

I am working on a building that would like to used compressed air for some pneumatic actuators. They would like to bring the air in from an adjacent building that has more than enough capacity, but ...
Secundus's user avatar
  • 571
3 votes
2 answers
108 views

Compressed air energy storage?

I'm wondering, if you put an air compressor pipe into a micro turbine, lets say something like that attached to a motor, does air that get out of the turbine have the same energy as when it gets in ? ...
airturbineguy's user avatar
3 votes
2 answers
345 views

How to design a hemispheric flexible pressure vessel?

Consider a balloon, it is a flexible, expanding pressure vessel made of synthetic rubber. I am trying to design a system that will use hemispheric pockets of neoprene to grip an object, much like the ...
Sam Weston's user avatar
2 votes
1 answer
494 views

Why air compressing mechanism "Trompe" is not popular in usage?

I was amazed when I got to know that there is such a simple mechanism know as Trompe to compress air. It has no moving parts which make it cheap to construct and do not require any servicing. Even the ...
Tank's user avatar
  • 87
2 votes
1 answer
59 views

Slow Driving an Air Compressor

Do off-the-shelf air compressors have minimum driving speeds, below which they cannot build the necessary pressure? Reciprocating compressors and scroll compressors are available—is there a difference ...
PProteus's user avatar
  • 170
2 votes
1 answer
565 views

volume comparison of compressed air and gas duster

I'm currently using 400ml Dust Off 67 gas dusters and want to replace them with compressed air and a blow-out gun. In order to select the right equipment and get a better understanding I would like ...
muffel's user avatar
  • 123
2 votes
3 answers
124 views

Is there a good way to passively dry air in the input of a vacuum pump?

I'm using an a/c compressor as a vacuum pump for small projects that don't need a good vacuum pump, and I'm looking for a way to dry the air in the input, to prevent water from mixing with the oil ...
user2934303's user avatar
2 votes
1 answer
107 views

Recommended compressed air source and location for separate air compression system

I am investigating what would be the most appropriate compressed air source (fan/blower/compressor) for designing a separate air compressor system. The information is as follows: the compressed air ...
udidosa's user avatar
  • 161
2 votes
1 answer
270 views

Air tool to compressor backflow

As I was reorganizing my air tool arsenal, a theoretical question popped in my mind I'd like to know the answer to. In designing air flow between an air compressor and a tool (such as a nailer or an ...
amphibient's user avatar
2 votes
1 answer
68 views

Can air velocity be supersonic in a straight pipe?

Consider a sufficiently large reservoir of compressed air at a pressure of $7 \text{ bar}$ (abs.). A tapping of $25 \text{mm}$ diameter of pipe length $1 \text { m}$. The pipe is open to the ...
Utility ZC's user avatar
2 votes
0 answers
70 views

How to balance flow and pressure in nitrogen purged chambers?

I have an instrument that is technically a humidity controlled chamber. It measures how much moisture is picked up by the sample through a microbalance(Zone 1). Nitrogen gas flows from zone 3 and ...
Zaid assaf's user avatar
2 votes
1 answer
1k views

Out of the three types of Stirling Engines, which one is the most efficient and delivers the most amount of power?

I was thinking that the beta Stirling engine would be the most efficient as it has a displacer to block heat transfer from the hot to cold regions in between thermodynamic cycles. However, I heard ...
ARJ's user avatar
  • 105
1 vote
4 answers
718 views

Tubing for explosive gas or hydrogen transfer

Recently, I heard that there is a law/ OSHA/ ASME piece of regulation dictating that hydrogen should be transferred (suppose from a tank of hydrogen to another location) by using specially approved ...
Hypnos Stratagem's user avatar
1 vote
1 answer
774 views

Is using your mouth and lungs to blow away dust inside your computer somehow bad for the computer?

Bottles of compressed air are very expensive where I live. While it would be nice and ideal to have and do a "proper" cleaning, I've always used my mouth and lungs to blow air onto the dust ...
D. Madrueno's user avatar
1 vote
2 answers
259 views

Compressing gas with liquid

This question, in short, is: Can a gas be compressed with high pressure liquid? As a scenario, imagine a tank full of atmospheric gas at STP. Could something like a pressure washer pump (in this case ...
Gabe's user avatar
  • 13
1 vote
3 answers
1k views

How do you read a blower/compressor curve with multi-curves for inlet guide vanes?

I am trying to apply an existing blower curve in a hydraulic model for a single stage blower with variable inlet diffuser vanes. The variety of curves shown on the plot does not seem to make sense to ...
Secundus's user avatar
  • 571
1 vote
2 answers
1k views

How to calculate added lift from ground effect

I'm trying to build a hovercraft of sorts, and I thought I'd take advantage of the ground effect. I've done some searches, but I can't seem to find any guides on the actual physics. How do I go about ...
Megalonychidae's user avatar
1 vote
3 answers
336 views

What type of air blower/compressor to use?

I need a way to move air which is somewhere in between a compressor and a fan: something along the lines of 20-40 cfm at 2-3 psi (500-1000 liters/minute at 10-20 kPa). Typical small compressors (of ...
Alex I's user avatar
  • 175
1 vote
1 answer
5k views

Basic difference between "compress" and "pressurise"

We call air which is pressurised as "compressed air". But we don't call pressurised liquid as compressed. I know that liquids are incompressible. So, why particular word "compressed" is the created, ...
Fennekin's user avatar
  • 585
1 vote
1 answer
99 views

Why are double-acting reciproating compressors more efficient than single-acting ones?

On many websites, I read that double-acting reciprocating compressors are more efficient than single-acting compressors. These sources say it's because they complete two compression cycles on each ...
Daniel's user avatar
  • 48
1 vote
3 answers
220 views

Can air compressors be used to boil water?

I was just reading an article about how air compressors can be used as an energy source. As the air is compressed, its temperature increase significantly, and this energy stored as heat can be used to ...
Belal Bahaa's user avatar
1 vote
2 answers
132 views

How can I build a regulated pressurised air supply?

I need a source of air pressure for an air bearing (3D printed cylinder that expands air upwards like an air hockey table). I would like to be able to control the flow of air. I don't have a lab air ...
555's user avatar
  • 13
1 vote
1 answer
43 views

What is this "johnson controls" device on the wall in airport?

I was passing column in waiting area of Pearson airport when my sweater cought some kind of device on the wall. Device was without cover and looks like old thermostat. When my sweater caught it, it ...
user61244's user avatar
  • 111
1 vote
1 answer
31 views

How to handle saturated hot air at the inlet of a blower

I have hot (around 60°C) saturated air entering a side channel blower. Due to process constraints, I can't use a condenser or air dryer (such as desiccant) at the blower inlet. However, water vapor ...
jasw's user avatar
  • 11
1 vote
1 answer
39 views

Cumulative effect of two axial fans

If I already have a small DC axial 2m3/h fan blowing air at something, what will happen if I add a larger more powerful 6m3/h DC axial fan blowing from behind that one (i.e. its the larger fan first, ...
Oliver Walters's user avatar
1 vote
2 answers
33k views

Define Free Air Delivery for an air compressor

Free Air Delivery (FAD) is a common measure of the capacity of an air compressor. I have a question that comes at the end here. My question is a little different from what you might be expecting. So ...
IanS's user avatar
  • 111
1 vote
1 answer
205 views

can we run rotary compressor of Air conditioner with different frequency level?

I am working on split type AC compressor. I actually want to know, if i changed the frequency of the compressor to run on different power level, will it affect the life of the compressor. My actual ...
fame's user avatar
  • 23
1 vote
1 answer
43 views

Are "Imperial Eastman" compression connections sized the same as regular imperial connections?

I have some high pressure and vacuum lines off of a tool from the 1980s and they are labeled as, for example, "3/8 imperial - eastman," which seems to be different from how normal compression ...
Transistor's user avatar
1 vote
1 answer
68 views

How long it takes to fill an inflatable to a certain pressure?

I am trying to figure out the inflation/how to calculate the time it takes to fill something to a certain pressure. I have an inflatable dock I am filling with a portable pump. The dock is 7ft x 7ft x ...
nk13's user avatar
  • 13
1 vote
0 answers
35 views

A 40L compressed air cylinder at 100 bar is emptied in pulses at the rate of 41kg/s. How many such cycles would it take to empty the cylinder? [closed]

I am constructing a blowback gas system where clogged debris needs to be removed with compressed air using compressed air cylinder. 40L compressed air cylinder at 100bar pressure is available as ...
Yadunandan's user avatar
1 vote
0 answers
56 views

What's the most efficient air compressor to reliably deliver up to 15 litres per second at 10 bar? [closed]

Suppose I wanted to continuously supply up to 15 litres of air per second, compressed to 10 bar - what would be the most efficient type of compressor, i.e. the type requiring the least energy input in ...
it's a hire car baby's user avatar
1 vote
1 answer
192 views

How to calculate rock permeability in m^2 from gas flux in m/s?

I am studying rock caverns lined with concrete for compressed air storage. I would like to know if it's possible to convert the permeability coefficient from m/s to m^2 or Darcy. Thank you.
Davide's user avatar
  • 13
1 vote
0 answers
31 views

Why does use with air or water reduce the maximum temperature of certain high temperature / pressure hoses?

This example is a Parker Hannifin model 426/436 "SAE 100 R1 AT / SAE 100 R16 High Temperature Hose". Here are the temperature specifications: (Full data sheet) Although there is an asterisk ...
StayOnTarget's user avatar
1 vote
1 answer
23 views

How do cavity resonators differ from tubes of uniform width?

I read that wine bottle produces sound when u blow sideways onto its rim because some frequencies of the white noise produced in your mouth gets amplified when they match the natural frequency of the ...
never took courses but why's user avatar
1 vote
0 answers
132 views

What happens when throttling in an isothermal process

Consider an isothermal expansion of an ideal gas (always at ambient temperature $T_0$), from some initial pressure $p_i$ to the ambient pressure $p_0$, such that the maximum work available is: $W = ...
Barbe's user avatar
  • 11