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.

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  1. D

    Future - Innovation in Compressed Air Technology

    Let's talk about the future of compressors and compressed air technology. Of course, the first compressor appeared a long time ago and the technology is developing to provide more efficient and modern models. Do you see any breakthrough innovation for this technology in the future, like a move...
  2. G

    What Is the Density of Compressed Air?

    does anyone happen to know the density of compressed air?
  3. M

    Compressed air storage for energy production

    Hi everyone! This is the first time I post a topic here so forgive me if there are some shortcomings. I have just taken a project about design and implementation of a compressed air storage and then release compressed air to produce electricity. This is not new project and has been installed...
  4. K

    Compressed spring momentum problem

    Homework Statement Two lab carts, one heavy and one light, are placed ed to end with a large, compressed spring placed between the two carts. The spring is suddenly released. Describe the motions of the two carts after the spring is released. Homework Equations An equation isn't needed...
  5. V

    How to calculate compressed air temperature and pressure

    How to calculate compressed air temperature and pressure at combustion chamber inlet? Small Example I want to calculate compressed air temperature and pressure at combustion chamber inlet in single stage centrifugal compressor, RPM = 10 000 Temperature and Pressure of the Air before...
  6. C

    Using Compressed Air to Lift a 400lb Load

    can compressed air be used to lift a load of 400lbs about 30 feet into the air i came up with using an air compressor to route compressed air into 4 small rocket nozzles to lift it off the ground how powerful of an air compressor would i need if i wanted a constant thrust of 500lbs coming...
  7. D

    Heating compressed air to provide lift

    Just a question about heating compressed air.. I know generally how hot air works.. You heat it and particles expand and creates lift. So my question is, Does heating compressed air provide any lift? if so how much in relation to normal air? eg if I had 100m^3 of air heated to 120C...
  8. P

    Compressed gas and heat transfer

    compressed gas...and heat transfer... If you were to take a cylinder of air, at room temp, and let's say it is 100ml in volume. If you were to take this cylinder of air, compress its volume to half its size, how much heat would that create (btu's) and if the heat were to dissipate, would the...
  9. W

    Compressed air at high pressure can cause frostbite?

    Is it possible to get frostbite from compressed air? How does this happen?
  10. G

    Finding distance that a pad is compressed after being dropped

    Homework Statement An egg is dropped from a third-floor win- dow and lands on a foam-rubber pad without breaking. The acceleration of gravity is 9.81 m/s2 . If a 56.3 g egg falls 11.9 m from rest and the 7.29 cm thick foam pad stops it in 6.32 ms, by how much is the pad compressed...
  11. S

    Compressed Air Pressure Drop Across a Restriction

    I would like the formula that describes the reduction in pressure that results when a constant flow (cfm) of compressed air travels from a 3" diameter pipe through a bell reducer that provides a smooth transition to a 1.5" diameter pipe. Also, in the same piping configuration as described...
  12. A

    Maximum distance spring compressed.

    A block of mass m = 1.9 kg is dropped from height h = 77 cm onto a spring of spring constant k = 1510 N/m (Fig. 8-38). Find the maximum distance the spring is compressed. My attempt: mgh = 1/2kx^2 (1.9)(9.8)(.77) = (.5)(1510)x^2 x = 0.138m But it's not the correct answer. What am I...
  13. R

    Car's vibration after being compressed, and released on springs

    [b]1. When seven people whose average mass is 83 kg sit down in a car they find that the car drops down 0.87cm lower on its springs. Then they get out of the car and bounce it up and down. The acceleration of gravity os 9.8m/s^2. What is the frequency of the car's vibration if its mass (empty)...
  14. J

    Soft drink bottle using compressed air for thrust to act like a rocket.

    Hey! This is the first time I have used this forum so I hope it all goes well and I am sorry if I break any rules on my first attempt. I have been given a question which I believe will involve quite a lot of work, so I thought I would get some suggestions as to where I need to start...
  15. A

    Compressed Air Bottle Rocket (Variable Mass)

    Homework Statement I need to find the maximum distance a rocket (which is actually a bottle filled with compressed air to 654kPa) can travel when the exhuast nozzle is 22cm (and can be changed to any smaller size if needed). Neglect air resistance. The bottles original mass is 50g...
  16. S

    Thermodynamics - compressed gas P-V graph, how much work is done?

    Homework Statement A gas is compressed, allowed to expand linearly, and then cooled at constant volume as shown in the P-V graph. How much work is done by the gas in this cycle? in the graph: compression is a straight line at P(atm)=3 that goes from V(liters)=1 to V=5; cooling occurs at...
  17. B

    Calculate Distance & Velocity of Mass with Spring Compressed

    Homework Statement A 1864 g mass is on a horizontal surface with mk = 0.380, and is in contact with a massless spring with a force constant of 631 N/m which is compressed. When the spring is released, it does 3.15 J of work on the mass while returning to its equilibrium position. Calculate the...
  18. D

    How Much Should a Spring Be Compressed to Launch a Brick 3.6m High?

    Homework Statement An ingenious bricklayer builds a device for shooting bricks up to the top of the wall where he is working. He places a brick on a verticle compressed spring with force constant k=350N/m and negligible mass. When the spring is released, the brick is propelled upward. If...
  19. A

    Velocity of air in compressed air tube

    This is more like personal homework and I have searched everywhere to find the answer to this with no luck. I was watching mythbusters re-runs the other night and the hurricane episode was on. They were trying to prove that straw could go through a tree in hurricane force winds. What...
  20. B

    Equivalent energy stored in compressed gas

    Hi All I'm trying to work out a method to determine the efficiency of a compressed air motor. Obviously I can measure the input pressure and flow rate of the compressed air, and I can measure the output power of the motor with a dynomometer. What I want to know is how much energy is...
  21. K

    Lifting power of Compressed Air

    Hi, Question: Is the Lifting Power of Air in Water solely based on its Volume or does the pressure of the Air factor in? As an example, in Salt water if you have a Bell with 2 Cubic ft of Air in it, at the Oceans Surface it can lift 128 Lbs, because air can lift the amount of Water it...
  22. D

    Air fuel Mix Ambient psi vs. compressed energy ouput

    Internal combustion engines, Ram Jet, Turban engines etc. require that the air fuel mix be compressed. Is the compression of the air fuel mixture required to give a higher or more efficient energy output? Otherwise if the air fuel mix were at a static or ambient pressure vs. compressed would the...
  23. A

    Find the maximum distance the spring is compressed.

    Homework Statement A block of mass 2.0kg is dropped from height h=70cm onto a spring of spring constant k=1960 N/m. Find the maximum distance the spring is compressed. Homework Equations KE initial + PE initial = KE final + PE final KE = 1/2(mass)(velocity)^2 PE = mgh or, when dealing...
  24. K

    Energy stored in compressed air?

    Hi, I am trying to figure out how much energy is stored in compressed air. I have figured out that a device I am looking at compresses about 174 cubic feet per minute into 35 cubic feet and that the temperature would rise from 70 F to 550 F. I now want to know how much energy, in the form...
  25. magi

    Wood fire in compressed air chamber?

    Hi. What happends when i put fire to wood that I have in a chamber with a pressure of about 15 kg/cm2 = 14.710 Bar = 213,3 Psi. Will it burn as usuall or much faster? Will I get a very high pressure? How High pressure can I get? Magi
  26. Q

    Calculating Force of Expanding Compressed Gas

    Hello, is it possible to figure out how much force in Newtons is created when a compressed gas expands?
  27. K

    Filling small compressed air bottle with a big one

    How can I figure the pressure in a 80 cubic inch tank at 0 psi being refilled with a 8000 cubic inch tank with a pressure of 3600 psi?
  28. M

    Force Spring Compression of 13kg Block on 35° Incline

    Homework Statement A block of mass 13.0 kg slides from rest down a frictionless 35.0° incline and is stopped by a strong spring with k = 2.60 x 10^4 N/m. The block slides 3.00 m from the point of release to the point where it comes to rest against the spring. When the block comes to rest, how...
  29. K

    Conceptual problem about two blocks released from a compressed string

    Homework Statement Two blocks, A and B, are connected by a compressed string. The mass of bock A is twice that of block B. Immediately after release, compare the net force on block A to the net force on block B. The table is frictionless and the mass of the spring is zero. 1)There is no...
  30. C

    Two blocks and compressed spring

    Two blocks with masses m1 = 1.2 kg and m2 = 3.5 kg are at rest on a frictionless surface with a compressed spring between them. The spring is initially compressed by 65.0 cm and has negligible mass. When both blocks are released simultaneously and the spring has dropped to the surface, m1 is...
  31. S

    Potential Energy of a compressed gas cylinder

    Hello, This is not a homework problem, but an engineering office problem. I’m looking to replace a steel compression spring with a gas cylinder. The spring is presently designed to absorb a known amount of kinetic energy which it ideally converts to potential energy (neglecting friction...
  32. R

    How Much Energy Can Compressed Gas Release During Discharge?

    Guys , Pl. help me out with this one. I got a vessel of vol. V and its filled with air to a pressure P. I want to know the energy contained in the compressed gas. The gas is going to be suddenly discharged via an orifice and I want to know how much work it can do. I had imagined that the...
  33. S

    Heating Time of Compressed Air

    HI, If you compressed 300 litres (about 12 moles) into a 3 litre cylinder which was already at 3,000 degrees C. Would the air reach this temperature in an instant? Im trying to get my head around this stuff about heat capacities and amounts of energy needed to heat materials. Please...
  34. W

    Calculating Heat Required for Compressed Gas to Become a Gas Again

    I don't know what to research or where to start but I would like to know much energy a compressed gas a requires to turn back into a gas if it is a liquid. Is there a term I should research and a formula like with specific heat? The problem I am trying to solve is how much heat does X...
  35. D

    Can Electric Cars Be the Solution to Efficient and Non-Polluting Transportation?

    The compressed air car is a much desired development in the search for an alternative cleaner, non-polluting form of motivating power that can be used in transportation. For the past 150 years the IC Piston engine, working on the Otto cycle and first invented in 1866 by Nicholaus Otto, has been...
  36. H

    Compressed Air Cars: Benefits & Concept

    hey guys can any1 tell me wats the concept behind cars using compreesed air as fuel...
  37. G

    Calculating Compressed Air Propulsion: Methods and Formulas for Model Torpedoes

    Hi, I'm currently designing a model torpedo and plan to use compressed air for it's propulsion and am working out if it's feasible. At the moment I'm trying to calculate how long it takes for X volume of compressed air at Y pressure to leave (IE return to atmospheric pressure) through a...
  38. M

    Where to find formulas for acceleration of compressed steel tubes

    Hi all Looking for simple formulas to describe maximum acceleration of steel tubes when tubes are compressed and suddenly released when submerged in water (dont know if the water does anything else than supply buoyancy). Please, also feel free to comment freely on the topic and formulas...
  39. W

    How do I calculate CO2 output from a compressed air tank with 5% CO2?

    If I have a tank of compressed air with 5% CO2 and 95% air, and I know the flow rate coming out of the tank is 0.01 LPM, how do I determine the number of [moles/L] of CO2 coming out of the tank?
  40. U

    How Many Air Molecules Were Released from the Compressed Tank?

    A tank of compressed air of volume 1.0 m^3 is pressurized to 50 atm at T = 273 K. A valve is opened and air is released until the pressure in the tank is 17 atm. How many air molecules were released? I tried this problem using PV = NkT and PV = nRT. I realize the difference in these...
  41. I

    Compressed spring (trampolin)

    Homework Statement A 60kg person is at rest with a vertical distance 1 m above the groud, compressed against the a spring. The spring is compressed a distance of .2m from its equilibrium position, with a spring constant of 1000 N/m. The person lands into a springy trampoline with a spring...
  42. V

    Calculating Workdone of a Compressed Diatomic Gas

    Homework Statement A certain mass of a diatomic gas (gamma=1.4) occupies a volume of 100 cm^3 at a pressure of 75 cm of Hg. It is compreseed adiabatically until the pressure increases to 80 cm of Hg. Calculate the workdone in the process. Homework Equations W=1/(gamma -1)* (p1v1-p2v2)...
  43. W

    Determine the distance that the spring is compressed

    A 2 kilogram block is dropped from a height of .45 meter above an uncompressed spring. The spring has an elastic constant of 200 Newtons per meter and negligible mass. The block strikes the end of the spring and sticks to it. A) Determine the distance that the spring is compressed B)...
  44. B

    Compressed Chamber: Perfect Vacuum, Pull Apart?

    Just thinking here. What would happen if you had two pieces of something that connect perfectly and form a chamber of air inside. Then you took all the air out to make a perfect vacuum. Now if you were to pull the sides would it break apart. I don't understand how there would be a perfect...
  45. E

    Compressed spring with work

    The force required to compress an imperfect horizontal spring an amount x is given by F = 150x + 12x3, where x is in meters and F in Newtons. If the spring is compressed 2.0m, what speed will it give to a 3.0 kg ball held against it and then released? I know how to integrate F(x) to get the...
  46. M

    Removing oil aerosols(mist) from compressed air

    Hello! My process looks like this: i've oil container with constant vacuum of 3-10 mbar for removing oil aerosols from container.that vacuum is produced by ejector(vacuum pump) down the line in which goes air at 6 bar.oil aerosols then together with air goes to atmosphere. what I'm trying to...
  47. S

    Calculating Electric Power Output of Compressed Air System

    Hello, I am interested in finding out the electric power output from a compressed air system. i see that there is a formula for calc. it with the amount of compressed air required to generate about 1 W with a pressure of 1 bar is given by Compressed air(cu.mm/s) = (1000 N-mm/s) / (0.1...
  48. B

    Speed of Glider After Compressing Spring 0.14m

    A glider of mass 0.13 kg moves on a horizontal frictionless air track. It is permanently attached to one end of a massless horiztonal spring, which has a force constant of 9.1 N/m for both extension and compression. The other end of the spring is fixed. The glider is moved to compress the spring...
  49. I

    A simple question in regards to Gravitys effect over compressed gas

    This is a question which I am sure i already know the answer to. Its purpose is simpley to clear up a dispute between my self and someone i know. In a canister where gas is compressed into a state of liquid. Is the liquid suspended toword the top side of the can held up by some non-liquid...
  50. M

    What Happens When Atoms are Compressed?

    I couldn't really simulate this in my brain, What will happen when atoms are compressed up to an infinite level ( extreamly great presure ) Will the atoms split up? if so what will the product be?
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