# Tag Info

18

Spray cans work by containing a propellant which has a boiling point a small amount below room temperature. When the can is sealed the liquid and vapour reach equilibrium at a relatively modest pressure. When the spray valve is opened this pressure forces out the contents as an aerosol and more of the propellant evaporates as the internal pressure drops. ...

13

Do you mean, for example, a bus entry door? It may be as simple as the "service factor" for motors ("electromagnetic devices") as compared to pneumatics. Inexpensive motors with sintered bronze bushings wear out, and better ones with actual bearings must be routinely lubricated. Air-operated cylinders are cheap and last a very long time, with the air ...

7

They are smoother and if something gets caught in between them then the maximum force it can exert is capped depending on the pressure and the piston area. This means that a trapped limb is less likely to get crushed. In an emergency (a typical concern for public transport) you only need to open a valve (pulling the emergency open will do that) and push to ...

6

There is another reason for this in multi-cylinder engines. While one cylinder is compressing the air, another is decompressing it. The net result is that the torque as a function of position gets smoother as the number of cylinders is increased.

6

Simply because it's so wasteful regarding energy. If you employ the flow and height difference of water for a hydroelectric generator to power a standard compressor (be it piston, centrifugal, or just a big fan), you can achieve vastly better pressures and air flow than with a trompe. Additionally you won't need to have the water drop and air intake in the ...

5

It isn't completely infeasible. Just to get a ROM (rough order of magnitude), let's assume that a typical household that isn't using electricity for heating uses about 1 kW on average, and that you'd like to be able to store a half day's energy, or 12 kWh, which is roughly 45 MJ. Commercial air compressors can easily achieve 15 bar or so (over 200 PSI). The ...

5

Don't do it!! Just buy a pressure regulator to put between the two tanks that will decrease the pressure to below 125. You can get these for \$17 at home depot (https://www.homedepot.com/p/Husky-1-4-in-NPT-Regulator-with-Gauge-41155HOM/205331831) and maybe even cheaper elsewhere. I'm terrified of the tank exploding and covering me with shrapnel. This is a ... 4 In theory, it should perform as you say. This is how prop starting an aircraft engine works. An internal combustion engine, unlike your bike pump, is designed for high speed, high power, and high temperatures. These design considerations give it higher internal friction and leakage (valves and cylinder seals) when doing a slow and cold propping operation. ... 4 The temperature of evaporated refrigerant gas is constant as a property of refrigerant material. And usually it is considerably below the thermostat setting in the controlled space. The design of the system relies on the circulation of cooled air and its gradual warming up to deliver the cool air at desired temperature so that it is still cool enough to be ... 3 According to to the SDS found here the product contains tetrafluoroethane as an ingredient. I looked around and found other similar products with the same ingredient. For sake of simplicity lets say that all the$400 ml$are tetrafluoroethane and the compressed density is$1.01 g/cm^3$according to your table. With this information we know that one can ... 3 I would say that it is true and for that case there will be many relevant codes / regulations that need to be respected. Make sure you read them all before designing / altering the system. 3 In the case of aircraft carriers the compressed air is generally a working fluid for a mechanical catapult rather than providing direct thrust like a rocket (steam is also used for the same job on carriers using steam plant). Having said that compressed gas can be useful in providing small amounts of thrust, although air may not be the best choice because ... 3 As your question implies 'pressurise' can apply to increasing the pressure of any fluid whereas 'compression' indicates a change in volume. To illustrate; a typical industrial gas cylinder will be filled to around 200 bar and might have a volume of 100l at 1 bar that gas would occupy 20000l. Often this is as much about storing and transporting produced ... 3 There are three possibilities here that come up offhand, between my own mind and ratchet freak's comment: The choke that ratchet freak mentioned -- this is the simplest approach if you are OK with a slow decay of pressure The dampened piston that ratchet freak also mentioned, where the mechanical switch pulls out a lock from the piston to allow pressure to ... 3 This is fully doable. This is the in the higher range as bicycle tires (although with the outer tire as well and not the inner tube alone). Alright, here goes: What equations do I need to calculate a solution? The pressure in a tube can can be modelled by the following equations: Hoop Force: $$\sigma_H = \frac{pr}{t}$$ Axial Force$$\sigma_A = \... 3 For 1. and 2., you can solve the problem by having an adjustable valve from the output line to free air. This way you let some of the compressors output flow escape, leaving enough of flow and pressure for the soldering station. To operate: Fully open the "release valve" before starting the compressor. Monitor air pressure with a gauge, ideally next to the ... 3 One possibility would be to use the air to drive a turbine (probably a radial turbine as they are used in turbochargers). The turbine could be connected to a generator and the generator to a resistor. You will most likely need to cool the bearing of the turbine and the generator as well, so you will generate a lot of heat. Assuming that your pressurised air ... 3 Yes indeed, air can be compressed by pressurized liquids directly as you suggest. However, there are problems that accompany this sort of scheme. First, if the gas is significantly soluble in the liquid, then the liquid will pick up gas while being pressurized which will then come forcibly foaming out of solution when the pressure is released. Second, you ... 3 That is on the high pressure end of normal pneumatic conveying blowers, but they are out there. See the notice at the bottom of the attached chart. http://www.hsiblowers.com/products/high-speed-turbo-blowers.html You don't want a high pressure compressor, you just need to find the right compressor that will deliver at 18 psi. You need to specify if the ... 3 There is a simple reason and a useful added benefit. As you compress air of a fixed mass it occupies less volume. If you give it more space again, it will immediatly decompress and the multiple stages become useless. If you give it just enough space to occupy at its current pressure, the air will compress further. You could reduce space by reducing the ... 3 Google dugout aeration windmill system. There are various makers. Here's one: https://koenderswatersolutions.ca/ The compressor on them does one cycle per revolution of the windmill. While not as slow as 1 rpm the one I have is only rarely over 50 rpm. Internally they are a diaphragm pump. This means you only have the leaking of the valves to contend with.... 3 Another option would be to use a vacuum cleaner, that way any dirt is not pushed inside the computer but its pulled outside. 2 The existing answers do a pretty good job of explaining the sizing and the economics, but surprisingly for an engineering site, skip over the equipment. And that's where this becomes totally infeasible. LightSail is arguably the closest to making compressed air energy storage (CAES) economically feasible at any scale. According to LightSail's CEO, the ... 2 I'm going to do some naïve math. So while charging your setup at night, you take in$x$kilowatt-hours per hour. Multiply this by 7 hours, and you've taken in$7x$kilowatt-hours. At a cost of$\frac{5.4\text{p}}{\text{kWh}}$, you've paid$37.8x \text{ p}$. Let's say that when the electricity is on, you use$y\$ kilowatt-hours per hour. Multiply this by 17, ...

2

A,B,C, and D are normally closed solenoid valves. The valves with the arrows above them are pneumatic check valves, such as reed valves, with the arrow indicating flow direction. So basically, with no power, pushing the piston in and out of the air cylinder causes an inlet check valve to open and a check valve to the flask to open and you act to ...

2

The SAFER, used by NASA for EVAs ("Space Walks"), uses compressed nitrogen for thrust. Air is mostly nitrogen, and the properties are fairly similar. So, essentially it not only could be done, but even has been done.

2

No, because the pump is designed to limits and if you exceed its working or maximum pressure then, for example, its seals fail and it just does not pump any more.

2

It might have been a old thermostat. In ancient times, thermostats sometimes worked pneumatically. When the temperature got too low, the thermostat would open a valve that released the pressure on some pressurized air. This would then directly actuate the valve on the radiator. There was a small bleed system so that when the system was closed, it would ...

2

Any engine that can run on compressed air will do this. There are quite a few, but as an example imagine a cylinder that has a bit of compressed air in it. The pressure will push on the piston doing work until it has equalized with the atmospheric pressure. Then a valve opens and perhaps a flywheel or another piston on a crankshaft pushes the piston back and ...

2

Old topic but... to be sure you have the correct info : The IGV positions are given by the seperate lines as indicated at the top (continious, dashed, dotted and dash-dot) At these IGV positoins, tests are done at several outlet diffuser positions (the numbers at the bottom of these lines in the curves) Example; There are several dashed lines (IGV pos 04) ...

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