What is Compressed: Definition and 319 Discussions

Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches and others, as well as to atomize paint, to operate air cylinders for automation, and can also be used to propel vehicles. Brakes applied by compressed air made large railway trains safer and more efficient to operate. Compressed air brakes are also found on large highway vehicles.
Compressed air is used as a breathing gas by underwater divers. It may be carried by the diver in a high pressure diving cylinder, or supplied from the surface at lower pressure through an air line or diver's umbilical. Similar arrangements are used in breathing apparatus used by firefighters, mine rescue workers and industrial workers in hazardous atmospheres.
In Europe, 10 percent of all industrial electricity consumption is to produce compressed air—amounting to 80 terawatt hours consumption per year.

View More On Wikipedia.org
Recent contents Top users
  1. T

    Phases of hydrocarbons in a compressed gas cylinder

    I'm currently in the process of selecting gas mixtures to calibrate a gas chromatograph. One of the gas mixtures I'm interested in has the following composition by percent volume: methane (CH4): 95% carbon dioxide (CO2): 1% butane (C4H10): 1% acetylene (C2H2): 1% nitrogen (N2): 2% The gas...
  2. R

    Velocity of compressed air through pipe

    This started out as a thought experiment and then I realized I was stuck in how to figure it out. If I have an airsoft rifle that uses compressed air in the tank at 3000 psi. It leaves the bottle regulated down to 800 psi. It then goes into a second regulator that reduces the pressure further...
  3. J

    How much energy is stored in compressed air?

    Hi all, My name is Jesse and I love renewable energy and finding ways of beating coal. Right now Solar Photovoltaic energy competes with coal in sunny areas during the day, but at night, you need to store the energy from solar and it's not worth it due to the cost of storage mechanisms (might...
  4. B

    B Internal energy of compressed gas

    Hi, I've been reading about compressed air energy storage and keep coming across that in 300 bar containers the achievable energy is 0.1MJ/L. Is this 0.1MJ/L of the volume of the air it is compressed to or of the total L of air that was initially used? (E.g If 1500L is compressed to 300 bar...
  5. D

    Calculating the Impact of Compressed Air on Hydrostatic Pressure Testing

    Hello, I have a question regarding the effect of compressed air. I'm working on hydrostatic pressure testing a component. The component will be filled with water and compressed to 1000 psi. I'm concerned about the small amount of air that'll be present inside and worried about the effect in...
  6. A

    Adiabatic compressed air and energy calculations

    Homework Statement . Consider a pump that is required to compress air in a factory. The cylinder in the pump has an inner diameter of 2.00 cm and length 60.0 cm. Air is drawn into the pump at atmospheric pressure and 18 degrees celcius and the pump adiabatically compresses the air to a pressure...
  7. szopaw

    Final velocity of an air rifle pellet from compressed gas

    As in the title, I'm trying to establish the approximate velocity (sans friction and other losses) of a pellet propelled by compressed gas from a tank. Below is what I have came up with myself, I would appreciate if someone could review this as say whether the end values are reasonable. I have...
  8. W

    By how much is each post compressed?

    Homework Statement A large 30000 L aquarium is supported by four wood posts at the corners. Each post has a square 6.00 cm x 6.00 cm cross section and is 90.0 cm tall. Take Y=10^10 for wood Homework Equations ΔL = FL/AY F = ma ρ = m/V The Attempt at a Solution So the total area is 0.06 * 0.06...
  9. S

    What is the speed of air flow in a pipe driven by compressed air for 12 minutes?

    Homework Statement A tank with a 25.5 litre capacity contains air compressed into 355 atmospheres used to drive a torpedo by expansion into an engine via a pipe of diameter 0.08cm. A mechanism ensures that the gas flows to the engine at a constant rate and any cooling of the air during...
  10. LordChallen

    I Can time be compressed without affecting distance?

    In tune with the idea that gravity can affect time, can gravity affect distance? Like, if I am traveling a specific velocity I can reach a place in a specific amount of time. But if time is compressed, relative a remote observer, I would reach my destination sooner. But, if you pull a...
  11. Kevin McHugh

    MIT Develops Compressed Graphene Sponge with Endless Uses

    http://www.nextbigfuture.com/2017/01/mit-makes-compressed-graphene-sponge.html My first thought was coal exhaust scrubber technology. But there seem to so many applications.
  12. A

    Using Isothermally Compressed Air to Cool a Refrigerator

    If I have a steady supply of isothermally compressed air at 7 psi (approximately 148 kPa) at a temperature of 4 degrees C, how would I calculate the amount needed of that air per unit time to maintain the temperature of a 14 cf refrigerator at 3 degrees C? A 18 cf freezer at -18 degrees C?
  13. A

    Force Analysis of a compressed spring

    Hi all, I am quite confused by the forces relating to a horizontlly placed spring when someone directly exerts a force to the compress it. If I exert a force F to the right to compress the spring, which, say, is placed against a wall, the spring exerts an elastic force on me but I don't see how...
  14. yudhi_chen

    A Force generate by compressed nitrogen at different volume

    Dear All, I have a question regarding compressed gas. I'm doing some experiment for testing some seal (see hatch area on sketch below) at 10,000PSI by using nitrogen gas. in this experiment, i accidentally got some different result based on two different situation. you can see my experiment...
  15. ChloeYip

    Find the maximum distance the spring will be compressed?

    Homework Statement A spring of negligible mass has force constant k = 1800 N/m . You place the spring vertically with one end on the floor. You then lay a 1.30-kg book on top of the spring and release the book from rest. Find the maximum distance the spring will be compressed. Homework...
  16. P

    Compressed Air Turbine: A Sustainable Solution for Power Generation

    I don't know whether this is appropriate for this part or not, but I am now looking for turbine/machinery that can be run by compressed air to produce power/electricity. Is there any manufacturer of such a machine is available?
  17. E

    Sound waves in a 'compressed' liquid

    Hi, I have a general question I was thinking about... So, in a liquid the particles are already very close together and as a result they are, in effect, not compressible. That being said, if we take water, for example, it is possible to compress is slightly. It requires, however, a great deal...
  18. P

    Low temperature production with compressed air

    Suppose, there are two cylinders of compressed gas, say air. Both are at same temperature and pressure and the amount too is same. Now, contents of both are released but in a different way. One has been released directly and the other has been released through compressed air turbine having a...
  19. G

    Effects of heat on compressed silicates

    Hi, I'm hoping to make small batches of synthetic minerals by compressing & heating small liquid or semi-liquid samples of sodium silicate w/ variable amounts of other salts dissolved within. As I understand it, many of these will require high pressure & temperature to form. So my strategy is to...
  20. kolleamm

    B Who Compresses More: Obj1 or Obj2 at C Speeds?

    You have obj1 and obj2. As something approaches c speeds it begins to compress. How do we determine which obj is compressed since the movement is relative to the other obj?
  21. S

    Conformability elastic material compressed on a wavy surface

    Hey there, I'm struggling in finding the useful equations to determine some conformability parameters for a finite elastic material (EPDM) compressed on a rigid slightly wavy surface. I would like to optimize the thickness of the elastic material in terms of indentation depth and thus contact...
  22. Monsterboy

    Work done by compressed air on the piston

    Homework Statement A closed cylinder of 0.25 m diameter is fitted with a light friction-less piston.The piston is retained in position by a catch in the cylinder wall and the volume on one side of the piston contains air at a pressure of 750 kN/m2. The volume on the other side of the piston is...
  23. Kara386

    Lead is compressed reversibly with T const, find dS

    Homework Statement Lead is compressed reversibly and with temperature kept constant at 300K, and from pressure of 1bar to 1000 bar. Assuming the change in volume is small, what is the change in entropy S? Use the Maxwell relation derived from Gibbs free energy function. V = ##10^{-3}m^3##...
  24. CK328

    Equation for spring force for a cylinder on compressed air

    Evening all, I've recently undertaken a project where my roll is to analyse the suspension of a mountain bike. The suspension unit in question is a Rock Shox Monarch RT3. To give a brief summary: The shock uses compressed air as the spring, the pressure is adjustable via an air valve. The shock...
  25. A

    Design a Venturi Pump with Compressed Air and Water: Feasibility & Parameters

    I am trying to develop a Ventury https://www.physicsforums.com/javascript: Pump using Compressed Air a d Motive Fluid and Suction Fluid is Water from Shallow Well. Compressed Air parameter is 6CFM Air at 7 bar using 2hp Motor & Compressor set, and required Suction Lift is about 5m. Discharge...
  26. O

    Analyzing a Compressed Spring System

    It's not a homework/coursework question but I did get the system from my textbook. http://puu.sh/o03h7/32cdf7cffb.jpg I solved the question by analyzing the system at different stages. Initially both objects are moving with a velocity and having some mass so their kinetic energies are the...
  27. C

    Compressed air under immersion

    Hello everyone, I am designing a machine that will utilize jets of compressed air underwater. Does anyone have information about the physics of gas underwater? I would like to know how far the jet will travel before floating upwards, based on the pressure of the air and diameter of the nozzle. I...
  28. henrco

    Ideal Gas compressed at constant pressure

    Hi, Could I please get some guidance on my approach and solution, for this particular problem. Any assistance welcome. 1. Homework Statement An ideal gas is compressed at a constant pressure of 1.3 atm from a volume of 20 L to 12 L. During this process it gives off 3.69 kJ of heat. What is...
  29. R

    Can a gas expand and be compressed simultaneously?

    This is a thermodynamics question.I am a beginner and know only algebra.Here's a description.A cylinder full of CO2 gas at 670 psi is compressed by a piston.At the far end of the cylinder is a pipe,through which the CO2 gas flows to push a piston into another cylinder.At one third of the stroke...
  30. AEGIS

    Adiabatic or Isothermal? Compressed air energy storage

    Hi, I'm doing a high school physics project and am trying to figure out if a certain setup that I'm using is adiabatic or isothermal, in order to determine what equation I can use to calculate the work that my setup does-- the threads I've come across so far only explain the difference, but not...
  31. HBurch614

    Spring constant of each spring when compressed

    Homework Statement A car with a mass of 1,500 kg sits on a suspension system that has four springs. When the mass of the car was originally placed on the springs, they compressed by 10 cm. What is the spring constant for each spring? Homework Equations k = F/x or k = mg/x The Attempt at a...
  32. D

    Question about cooling due to expansion of compressed air

    Hi! I'm a teacher in Mechanical Engineering, and I organize a (yearly) student's project where they design and create a cooling machine. The machine works by compressing air, cooling the compressed air, and then rapidly expanding it. This can lead to temperatures of minus 7 degrees Celsius. I...
  33. Z

    Stress and deformation compressed cube

    Hi, sorry for my bad english. PART A I have a cube of 10mm x 10mm x 10mm which is compressed with a stress of 0.5 Mpa on his superior face (σz=-0.6) young modulus=20Mpa, poisson coef=0.5 I have the stress tensor: [ 0 0 0] [ 0 0 0] [ 0 0 -0.6] And then, the deformation tensor is : [0.015 0 0] [...
  34. K

    Need a valve for retention of compressed air in cylinder

    Hello all! I am designing a machine which consists of a horizontally mounted vessel which has a movable lid. The lid is moved up-down with the help of a pneumatic cylinder & is guided on linear bearings. My question is during maintenance, when the lid is UP, and for any reason there is a...
  35. J

    Thermodynamics -- piston-cylinder device with helium is compressed....

    Homework Statement A piston-cylinder device initially contains 0.5 m^3 of helium gas at 150 kPa and 20°C.Helium is now compressed in a poytropic process(Pv^n = constant) to 400 kPa and 140°C. Determine the entropy change of helium and whether this process is reversible, irreversible, or...
  36. T

    Compressed Air Reverse Thruster

    Hello everyone, I'm attempting to determine the impulse that can be generated by expelling compressed air from a pressure vessel stored aboard a moving craft through nozzles in the nose of the craft. The vessel has a forward momentum of roughly 2,000,000 Ns. EDIT: For semantics sake, consider...
  37. David Gin

    Mixing compressed air with different dew points

    Two compressed air(A, B) at 100 PSIG: Air A - Compressed with -70C dew point. Air B - Compressed without entering an air dryer. If this two compressed air is distributed into a tank together, would the the air mix to form Air C (same pressure with dew point between air A and B)? I have read a...
  38. N

    Does a compressed spring create work?

    A venture airvalve is a mechanical device which for a given valve position results in a constant flow independent of inlet pressure (within a given range). If pressure increases, flow increases resulting in a low pressure in the throat of the venture which sucks the plunger in thereby reducing...
  39. C

    How to apply Eulers Eq and continuity eq to compressed air

    Can we apply Euler's Equation and continuity equation to compressed air flow from tank or orifice.
  40. M

    Calculating temp change releasing a compressed gas

    Hello, I understand when you release a compressed gas generally it comes out cooler than atmosphere. But here are my questions: When you fill the container, the gas warms up as the pressure builds. Generally it takes a long time to compress and I believe the temperature of the gas when it's...
  41. C

    Valve lift & variable air flowrate in compressed air

    How we can incorporate valve lift and variable flow rate in compressed air engine Mechanical power = air power torque * angular velocity = pressure * flow rate
  42. S

    Compressed Spring Between Two Boxes

    Homework Statement Two blocks of masses M and 2M are on a frictionless horizontal surface and are held in place with a compressed spring of negligible mass between them. If the blocks are then released and the block of mass 2M leaves the spring with a velocity v, the velocity of the center of...
  43. M

    Compressed Sensing: Solving an Optimization Problem with Minimum l1 Norm

    I finally got a problem in my reading, so my problem is I am given a matrix ##A##, column vector ##f##, and a relation ## f = Ag## where ##g## is a column vector. The dimensions of those vectors and matrices are such that the above matrix multiplication makes sense, that is ## A## is not...
  44. AlephNumbers

    Compressed spring between two particles

    Homework Statement Particle A and Particle B are held together with a compressed spring between them. When they are released, the spring pushes them apart, and they then fly off in opposite directions, free of the spring. The mass of A is 2.00 times the mass of B, and the energy stored in the...
  45. M

    Beginner's Guide to Compressed Sensing in Signal Processing

    I hope this is the right place for this post. I'm originally a physics student but my thesis supervisor assigned me a work in which the concept of compressed sensing (CS) becomes the underlying aspect. I have searched some sources online but, no good. I guess this is because this CS thing is...
  46. A

    Spring problem: compressed and pushed down with a velocity

    Homework Statement I'm trying to come up with a problem and solve it. As of right now, I have a vertical spring with an equilibrium length of .38 m hanging. A .61 kg mass is attached to the bottom, and the new equilibrium length is 1.05 m. If the spring is compressed .1 m upwards then pushed...
  47. Evanish

    Some help on Compressed Air Energy Storage

    I was reading this article about different types of energy storage, and it gave this formula for compressed air. Joules = P0V0ln(P/P0) Where P0 = Atmospheric pressure 105 Pa V0 = Volume of air to be compressed in m3. P = Pressure in tank when compressed in Pa. Note: This formula is for...
  48. A

    Designing a compressed air vehicle

    I am doing a school project, building a compressed air powered vehicle to reach desired destination. What I am thinking is: I will use a paintball compressed air tank. Four nozzles. And an controller board to control valve opening. Valve will only open for certain time like (50ms). After each...
  49. N

    How would you explain what compressed sensing is

    Hello, I would like to know your definition of what compressed sensing is. As well as its applications/uses. It's a subject I hear thrown around a bit but I have not received a complete answer on what the area/focus is? As well as the concept of sparsing (parsing?) and it's use with compressed...
  50. Y

    Compressed nitrogen v flow rate question

    Currently i have a system using bulk argon and i am changing to nitrogen. To trial this i am going to use cylinders of OFN(oxygen free nitrogen). how do i caculate how many cylinders i need based on a flow rate of 16 liters/min. Thanks
Back
Top