Space Related Instructable - Atmosphere/Pressure Sensors

I am really into rocketry, aerospace engineering and space in general. I have met a few people at my college that are somewhat interested in the same but dont know alot about it. So i thought i could build a few different environment sensors like the astronauts use to simulate/demonstrate a few basics. For example i wanted to build a few different sensors. But i cant find any instructables to teach me how to make these....Can anyone help or can anyone direct me to a few instructables that could be used to tweak to work for this purpose? - To help show how the astronauts have to regulate their atmosphere in the ISS or even explain how we don't breathe just oxygen - we breathe a combination of O2 and Nitrogen since Earth's atmosphere is mostly nitrogen. O2 (oxygen) Sensor CO2 (Carbon Dioxide) Sensor N (nitrogen) sensor Display to show all sensor data - To help show how they manage pressure in the ISS and have it regulated by an airlock. Atmospheric Pressure Sensor and Display

Topic by acadena2 3 years ago  |  last reply 1 year ago


how much does air weigh? Answered

How much does 1 cubic foot of air at 1 atmosphere of pressure weigh? (and for the lmgtfy.com answerers, a google search returned conflicting answers)

Question by revelae 9 years ago  |  last reply 7 years ago


Pressure, vacuums, and the on earth equivalent?

One atm is equivalent to about 14.7 psi.  Does that mean that if one was in a perfect vacuum a vessel sporting 1 atm would need only hold the pressure of 14.7 psi?  It seems to me that in space (not a perfect vacuum) a craft would only need to hold maybe 12 psi (of course when messing with human life I would definitely allow for 150 to 200% tolerance, but in the end 24 psi still isn't very much is it.  Is there more to it than this, or are all those quotes about how hard it is to deal with a vacuum and how things must be super strong a little over blown.  Going just 11 meters under water exposes you to a little over double air pressure at sea level.  Someone in just a diving suit has been to over 60 times atmosphere and the deepest submarine dive I could find was 1083 atm at around 11000 m.  It just seems to make holding out a vacuum a little overrated.

Question by seedorfj 4 years ago  |  last reply 4 years ago


Can the change in atmospheric pressure inside the house automatically drive a mounted exhaust fan ?

I used to live in this house some 3 years ago, it had exhaust fans in every washroom , now if i opened up the doors of all the washrooms closed the windows and disconnected the exhausts from electricity and would just move any door in the house slightly it would cause the exhaust fans to go wild and spin like jets ! Now i need to know what principal is involved here ? or was it really happening because of what i hypothesized ? Does it happen in your house too ?  Thanks,

Question by cyber02000 5 years ago  |  last reply 5 years ago


What's the gas expansion ratio for ethanol?

At normal atmospheric pressure. Don't need too precise a figure, nearest 50 will do. Surprisingly difficult information to find...

Topic by SolarFlower_org 9 years ago  |  last reply 9 years ago


Looking To Pick Your Skilled Brains

Advice on best how to make a piezometer out of readily available hardware store parts without use of any power tools and access to only a very few hand tools. Basically a piezometer is a clear, straight plastic tube that you attach to the outside of (in my case) a plastic 250 Liter rain barrel (about 1.5 feet diameter, 4 feet high) from top to bottom. The top is exposed to the open air, while the bottom feeds into the bottom of the barrel (by going through the side very close to the bottom). It needs to have a diameter of about 1/2 inch, be very solid, straight and secure, and a 'water level mark' must be etchable in it somehow to indicate the normal level of water inside the barrel when the barrel is full (full means a few inches before the absolute rim of the barrel). The barrel is filled with gravel at the bottom, sand on top, and enough room for a 12" waterhead above the sand. I'm using it as a slow sand filter (SSF). The idea is that the pressure of water at the bottom of the barrel fills the tube up to the watermark against the action of the atmospheric pressure forcing the level in the tube down below the watermark. When the level of the water in the tube is about 15 inches below the water mark, it means the water pressure at the bottom of the barrel has decreased to the point where the sand in it needs to be cleaned (no water getting through). Any ideas will be greatly rewarded in the afterlife. Thanks!

Topic by SozzledBoot 12 years ago  |  last reply 12 years ago


New Vacuum Pump Idea

I have a new idea about a new type of positive displacement vacuum pump.  Its of the piston variety, but instead of a one way valve which doesn't work when the pressure gets low enough, another piston is used to act as a valve switching between the vessel to be evacuated (when the main piston is pulling a vaccum) and the atmosphere (when the piston pushes the air evacuated out). This solves the one way valve problem.  Could this pull a much lower vacuum?  I need a fairly strong vacuum, but I don't want to have to build/buy a turbomolecular pump. Also, i have a metal lathe, that's why i'm going with the piston variety.

Topic by guyfrom7up 9 years ago  |  last reply 9 years ago


Solar Power Towers Efficiently Using Brayton Cycle

I want to point out a solar to electric generation concept that has yet to be seen anywhere, even though it originated back during the Carter Administration's ERDA programs of the late 70's. I’m talking about solar power towers that convert solar energy into electricity at the hundreds of mega-watt level. While power towers do exist today, and the world currently does have a handful of them as shown in Fig-1, none use the Brayton Cycle nor can they boast an energy conversion efficiency at the mid to upper thirty percent level.  A group of engineers got together at a think tank organization called Sanders Associates in Nashua, N.H., several decades ago, and designed a unique Brayton Cycle, 100 MW solar Power Tower concept for generating electricity. This was accomplished under ERDA (Energy Research Development Administration) who gave us a phase-2 follow-up contract that took our phase-1 design and built a working scale model at the 10 KW level. This model was tested at the Georgia Tech Solar Research Facility and "registered" ~37% electric solar conversion efficiency. The system used ambient air as its working fluid, and was to be located in open-spaced desert regions. Phase-2 was lost to competition using a closed-loop liquid sodium system that boiled water into superheated steam at 900F to run a turbine that generated ~21% overall electric conversion efficiency.  Apparently, at that time ERDA would rather haul water out to the desert than use ambient air to generate electricity? The politics of their decision is beyond reason and clashes with improving the world’s development of green technology energy.  ERDA shut out our better technological performer and safely locked it away for another day! ERDA's official reason for turning us down: "this technology uses excessively high temperatures (2500F versus 900F) that are dangerous to workman maintaining the equipment". But that was back in the 70’s, maybe we’ve learned to deal with high-temp heat by now?   Solar Energy Concept Using Low Pressure Storage Our solar power tower would collect the sun’s energy by locating its ceramic heat exchanger on top of a tall tower as shown in Fig-1. The tower was located in the center of a field of active sun-searching mirrors (heliostats, Figure-2). These mirrors reflected sunlight onto our ceramic honeycomb heat exchanger, producing a concentrated flux intensity level that heated it to around 2500F. At the same time, low pressure fans generating only a few psi pressure would suck the ambient air through the honeycomb, heating it to just under the 2500F and then passing it through energy storage silos which stored the heat down to ~150F. We purposely designed the energy storage charging phase of our hot air system to work at only a few psi above ambient as a safety feature. The sun effectively acts as the combustor of our jet engine or Brayton cycle engine. Once the sun heats the air, it passes through heat exchangers consisting of a labyrinth of underground silos that are temperature segregated. These silos receive our 2300F airflow and cool it down to about 150F, transferring this heat into solid salt containers which turn to liquid once they have absorbed sufficient heat. Figure-3 is a schematic of this underground energy storage facility and shows the airflow being heated by a fully charged set of silos containing liquid salt-bricks. This airflow direction is reversed when we charge the silo’s salt-bricks. The bricks are kept in specially insulated, high pressure silos (located underground for added insulation) that store the heat energy at one atmosphere for later use. These underground silos act as our energy storage batteries, and when needed would discharge their heat energy accordingly into the moving airflow. This energy storage concept permitted the generation of electricity at night and during overcast days. Two sets of storage systems are required for continuous operation. One would be charging at low pressure while the other is discharging at high pressure through the Brayton engine to generate electricity.   Electric Energy Generation at High Pressure Electricity would be created by turning an electric generator at high speed. The generator was turned by running a jet engine connected to it.  The engine’s combustor for heating the air is effectively the sun, hence the name Brayton cycle for generating our solar electricity (Figure-4). The heat from the molten salt containers would increase the energy of the high pressure air coming from the compressor, and would then force it through a typical turbine that turns this energy into high rotational speed to run the generator and make electricity. Our solar jet engine sucks in ambient air using its compressor, as all jet engines do, and blows it through a series of silos at high pressure whose stacked bricks are held at different temperature levels. We start our airflow through a silo held as low as 150F and work our way up to ~2300F as we pass through our last, hottest silo which acts to complete the effective solar combustion process. This air preheating technique dramatically improves our energy turnover capability and allowed us to convert solar energy into electricity at near 37% efficiency. During our electric energy generation phase, the silos of our Brayton system requires operating at many atmospheres of pressure just as in any jet engine combustor using petroleum-based JP-fuel.      

Topic by RT-101 6 years ago  |  last reply 6 years ago


Hydrogen for renewable energy storage- total system efficiency?

This is a question that has been bugging me for some time, especially since the questions about methanol synthesis revived my interest in energy storage. Say I have a wind turbine or solar panel or whatever, that produces 1000 Wh per day.  If I use that electricity to electrolyse water, store the generated hydrogen at roughly atmospheric pressure in an upside-down water butt or a big gas-tight bag in my shed (don't worry, I'm not going to actually do this) and then feed it into a generator converted to run on H2, what percentage of that initial energy input would I get back out?  20%?  5%? 1%? The follow-up questions to this are a) How does that compare against a battery bank? What about a similar DIY-style pumped water storage system? b) What one component of the system should be improved to raise the overall system efficiency? Electrolyser, storage, generator? c) Are there any other DIY-friendly methods for storing intermittently generated electricity that I'm not thinking of? And, I suppose, d) Does doing this and providing 5-10x your overall power requirements in wind turbines work out cheaper than spending thousands on batteries?

Topic by PKM 7 years ago  |  last reply 7 years ago


A glimpse into nuclear disaster.

A team of engineers has used an endoscope to carry out the first visual inspection of Windscale 1 nuclear reactor for more than 50 years. In October 1957, it was the scene of what was the world's worst nuclear accident when it caught fire and released radioactive material into the atmosphere.Just over 50 years ago, British nuclear scientists, under political pressure from a succession of Prime Ministers, had been pushing the reactor to and beyond operating limits in an attempt to develop the UK's own independent H-bomb and achieve an "alliance of equals" with the US.When the fire occurred, the scientists were faced with a choice: let it burn, and contaminate Europe, or dump water on it, and potentially die in a nuclear explosion. They chose the latter, risking their own lives to save people who didn't even know there was a problem.That sounds heroic, but the official report into the incident blamed the scientists for the accident, rather than let the US find out about the H-bomb programme just in the days before signing a treaty to share their existing knowledge with the UK.Windscale (now known as Sellafield - the name was changed after the accident) is now in the long process of closing down. Along with jobs, buildings that marked the dawn of the nuclear age are being slowly demolished and moved ... somewhere else. They don't know where, yet, but it will probably end up remaining on site in deep holes (down in the porous sandstone that carries the local water-table).The original piles were shut down immediately after the accident, and the site's AGR reactor was closed down 27 years ago, but it is only recently that they figured out what to do with them, and they are now being decommissioned as a "UK's demonstration project (meaning; "we've never done this before, we'll work out the bugs in remote Cumbria before we try it on a reactor near a city").As part of the decommissioning work, they now need to see what is left in the ashes of the world's second reactor disaster before working out what to do next.I don't know about you, but I'm not convinced that a paper boilersuit would be enough protection. Maybe that's why the chap on the right looks like he's crossing himself...

Topic by Kiteman 10 years ago  |  last reply 10 years ago


Technology Makes Cheap Drinking Water from Air

INTRODUCTION:   How can we best apply basic technology to help the underprivileged and/or disaster-hit countries like Haiti? Daily hygiene and nourishment are among the top needs for disaster ridden regions!  Simply put, no water means no hygiene. The Romans understood that over two millennia ago and created their complexly beautiful aqueduct networks for handling both fresh and wastewater! Other ingenious water systems like “air wells” have been found in the city of Theodosia (cf: discovered in 1900 by Zibold, see Zibold’s Collectors/Dehumidifiers) dating back to Greco-Roman times during the Byzantine Empire. These were strictly passive systems that naturally dehumidified air, collecting its potable water in underground basins. All air, even in relatively dry desert regions, will precipitate or release its natural water content (initially in the form of vapor) through condensation when it hits its dew-point temperature and below. That means you “chill” it to an appropriate level that is anywhere from 5F to 50F below its current air temperature, depending upon how much water content (relative humidity) it has locally absorbed. The condensation of the water vapor releases its internal latent heat (reheating the cooled air) which must be constantly dissipated (absorbed by something) in order for water formation to steadily continue. So how do we dissipate this resultant vapor-heat and chill our air without any infrastructure or electricity, in an underprivileged or disaster-ridden region? We simply bury a long cast-iron or any metallic drain-pipe sufficiently underground where the temperature of the earth is naturally held to a constant at around 45F to 55F. That’s our “free” chiller gift from nature. One end of the pipe, Figure-1,  sticks out of the ground to suck-in local outside hot air, and the other end dumps cooled dry air and water into an underground cistern where it gets collected and is piped to the surface to both exhaust the cooled dry air and connect to a water pump. We need a hand operated water pump to lift up the water above ground, and we need an electric fan to constantly pump air through the ground-chilled piping system. We can even force the cooled piped air to exhaust into a tent-like structure where it provides air conditioning as an added bonus, but this adds the penalty of both power and the increased fan size necessary to drive our required airflow further into an enclosure! While this concept is not “passive” (requiring electricity to work) like those clever Byzantine air-wells, it will produce much more potable water and within a smaller volume than those elegantly passive historic devices. The electricity for our fan power requirements can be produced by any one of four ways using either “active” or “passive” techniques: 1) An active playground or bike-pedaling-person or oxen-driven mechanism-generator, 2) A passive windmill generator, 3) A passive solar energy collection system that directly generates electricity, or 4) A passive thermo-electric system that directly generates electricity using the Peltier effect, operating solely on temperature differences between the cell’s top and bottom surface (we jury-rig the cool pipe and hot ambient air to contact separate sides of the cell). Depending upon how much water is needed, the required air volume plus pipe length and diameter, together with the fan will be sized accordingly. We can also configure groups of parallel fan-driven air pipes that are radially fed into the cistern. The sizing of this underground network depends upon the ambient air’s local average temperature and relative humidity (how much water gets absorbed into the air) plus buried pipe depth and effective underground temperatures achieved. The basic concept is one where we “wring” water from air at some given humidity content. The higher its relative humidity the more water is recovered from the air. The air-wringing process simply chills the air as it scrubs along the cooled internal pipe surface until it starts to rain inside the pipe from condensation onto its surface. The condensation is like the dew that forms on car windows, grass or any cooled surface in the early morning, before the sun comes out and evaporates the dew back into the heating air. A further bonus is that our dew-formed water is naturally distilled and very clean. It is potable water ready to drink without the need for additional sterilizing agents. Of course, we must make sure that the interior piping and cistern network is biologically cleansed before burying it underground. The hand pump with its 10 to 15 foot extended piping to reach the underground cistern must also be cleansed. The beauty of this constantly replenishable water supply is its convenient underground installation anywhere! After the in-ground installation, we have a virtual, partially passive, no moving parts, non-breakdown system containing above ground total access to all moving parts that could breakdown, namely the water pump and electric fan. Also, it is easily maintained, with few moving parts (water hand-pump and electric fan) and basically lacking any technical complexity which makes it ideal for technologically backward regions. The example below uses a relatively small industrial fan moving air at 1500 CFM (Cubic Feet per Minute) with a DC motor rated at 1kW. This fan together with our underground piping system will conservatively generate 12 GPH (Gallons Per Hour) of potable drinking water without need for any purification chemistry. Based on an average electrical cost of 14-cents per kWh (kilo-Watt hour), the typical commercial distillation of one gallon of drinking water costs roughly 35-cents as compared to our cost of only 1.2-cents. Furthermore, if we decide to go green and use solar energy for generating our water, it would effectively cost us nothing beyond the initial installation! USING A PSYCHROMETRIC CHART TO SIZE OUR WATER SUPPLY: The following gets a little technical and is only provided for those die-hards who are truly interested in how the science works. Those non-technically schooled may skip this part and not miss the basic concept. Figure-2 shows a Psychrometric Chart for air. This chart summarizes some of the basic thermodynamic properties of air throughout its typical range of operating temperature. The chart uses six basic air properties that defines the physical chemistry of water evaporation into air:  (1) the enthalpy or total energy contained within a unit of air which is a combination of its internal and external energy, expressed as the amount of BTU-energy per unit mass of reference dry-air, (2) the specific volume or the ratio of a unit volume of local air to its mass of reference dry-air, (3) the humidity ratio or the amount (mass) of moisture in a local unit of air divided by its reference mass of dry-air, (4) the percent relative humidity per unit of local air, or the mass ratio (expressed in percentage form) of the partial pressure of water vapor in the air-water mixture to the saturated vapor pressure of water at those conditions (the relative humidity depends not only on air temperature but also on the pressure of the system of interest),  (5) the dry-bulb temperature or the locally measured air temperature, and (6) the wet-bulb temperature or saturation temperature which is the local air temperature experienced during constant water evaporation (a wet-bulb thermometer is typically used:   a thermometer that measures resultant temperature while wrapped in a water wet-gauze and spun to generate local air movement and max-evaporation)  1.0   The Process and A Sample Calculation Our Psychrometric Chart uses six thermodynamic properties that help to determine the amount of water available for extraction from the local ambient air as a function of its temperature, pressure and relative humidity.  Let’s assume the following local ambient conditions for the region we plan to construct our water system at:  (1) Typical daily air temperature Td = 106F and one atmosphere pressure assumed at sea-level, (2) Relative Humidity, RH = 55%, and (3) Typical underground temperature down at six feet is measured at Tu=55F (at 12ft. it drops to ~45F). This yields the following calculated results for obtaining a steady-state supply (changes at night) of water to fill the cistern:      1)      In our example, the “local” air (dry-bulb) temperature is Td=106F, at a relative humidity of RH= 55%.  Fig-2 indicates that the resultant Humidity Ratio is HR= 0.0253 Lbs-water/Lb-Dry-Air (intersection of Td=106F line and RH=55% line, then horizontal to HR value).  We then determine the “gulp” of air volume containing the HR Lbs-water which corresponds to the point of intersection of Td and RH. Interpolating on specific volume “mv” yields mv=14.7 ft3/Lb-Dry-Air (this value sets the optimum unit airflow for our given ambient conditions, and creates a ballpark pipe length to diameter ratio needed later). It represents the basic unit of air volume that will enter our underground pipe per given time, and ultimately defines the size of our fan and piping network. For increased water creation, multiples of this unit volume will scale up the additional amounts of water that can be collected. 2)      As the inlet air cools down to a temperature of Tu=55F, from contact with the relatively cold underground pipe, we follow the constant enthalpy line (red upward left-diagonal) from the intersection of Td and RH to its saturated air temperature condition of Ts= ~88F, which is its dew-point temperature where the corresponding local RH=100%.  At this temperature or under, the air precipitates and releases its moisture content, resulting in water condensation onto the pipe walls.  Since our air will chill to a final pipe temperature of Tu=~55F, we follow the RH=100% saturated curve (green) down to yield an HR=~0.009 Lbs-water/Lb-Dry-Air. This is how much water is left in the air when it gets to 55F.  Therefore for every pound of local outside air that enters the pipe, mw=0.0253 – 0.009 = 0.0163 pounds of absolute pure, distilled potable water precipitates onto the inside pipe wall (per pound of dry air that is cooled and dehydrated) to gravity-flow out the pipe exit and into the cistern. 3)      We now convert pounds of air per unit time into a unitized volumetric airflow that yields gallons of hygienically pure potable water production per unit time. For every Va=100 ft3 of local volumetric air movement per minute (CFM) through the pipe, which translates into ma=Va/mv= 100/14.7 = 6.8 lbs. of dry air per minute or 6.8 * 60 = 408 lbs. per hour (PPH), to yield a water-flow of mwf=ma * mw = 408 * 0.0163 = 6.65 PPH or 6.65/8.345 = 0.8 GPH of water.  An industrial fan rated at 1kW DC will typically move 1500 CFM at a pressure of 8-iwc, to continuously produce 15 * 0.8 = 12 GPH of pristine potable water. 4)      Not shown here are the design details of sizing our pipe, fan and solar collection system for electric power requirements using heat transfer principles coupled with a thermodynamic heat balance, and aerodynamic fan performance assessment. These details help to size the electric power generation requirements plus margin used to properly size a solar collector containing further margins for overcast days. The engineering involved here is straight forward but beyond the scope of the current project.

Topic by RT-101 6 years ago  |  last reply 1 year ago


Tin Can Turbine Engine

Hello!               Let me give you some insight into this project (Tin Can Turbine). I'm going to school to get an Airframe and Power Plant Cert. (Aircraft Mechanic). I stumbled across this idea on YouTube one day in class and it really got my gears turning. It's purely for fun, and I'm not even sure if I have the technical skills to get it to work.             First of all the way a turbine engine works in layman's terms is Suck, Squeeze, Bang, Blow. The fan section sucks air in from the atmosphere, Where it is moved to a compressor section which squeezes the air into a tighter pocket of air; which makes the air hotter and more explosive. When the compressed air is pushed into the combustion chamber, it is more volatile than normal air due to the compression. When you add a fuel (jet fuel, gasoline, propane, kerosene etc...) it will ignite with the compressed air (given that there is a spark to get the fuel vapors to ignite). When the fuel/air mixture is lit the fire will continue to burn without an ignition source due to the explosive nature of the compressed air. And the gas (burnt fuel/air) is pushed out the exhaust. There are blades in the rear of the engine called turbine blades, which are connected to the front of the fan/compressor section, in some cases there are two or three turbine blades, which drive the fan, compressor sections independently. Due to the turbine blades being pushed by the exiting gasses, the engine becomes self sustaining. And through black magic, you have a jet engine!!!              I'm going to attempt to construct a jet engine (not a motor!) out of a "tin can". I'm really not going to use a tin can, I'm actually going to use .032" thick 3" wide, and about 6" long exhaust piping made out galvanized steel. It's a lot thicker than a typical soup can, thus willing to stand up to more heat. My proposed fuel source will be propane, because it's cheap, and the I'm sure that I'm capable of controling the amount of fuel going into the engine. I'm not sure yet how many fan blades vs. turbine blades that I'm going to use. Right now I'm in the experiment phase. My blades are going to be made out steel can tops, because there is very little cutting involved, beside the actual cutting and angling the blades. and they fit perfectly into the pipe. As for the fuel delivery i'm going to use a copper pipe that is approx .042 thick and hallow. I'm going to cap the end, and wrap it around the inside of can. There will be eight holes drilled into the copper, which should give it plenty of fuel at equal pressure all the way around the can, equals same heat all around.         As for the drive shaft, I'm not exactly sure of what to use for that. I may want to go with something hardened already, so the heat surrounding it won't melt it. (that's the hope anyways) . I'm also not sure of what sort of bearings I will use. I was thinking skate board bearing with the plastic crap around the middle taken out (so it doesn't melt and seize the bearings) and extreme high temp. white lithium grease for lube.          This is an experiment and I guarantee myself absolutely no success. But I think it will be fun to try. Questions or comments are more than welcome. Please, if you see any problems with the design, let me KNOW!!!

Topic by shawnpc 6 years ago  |  last reply 9 months ago