Paper Done! & more....

Just turned in the paper to Dawn.  We are officially done with the hard part!  Working on tweaking my lesson plan and Dave is working on the tech fest game.  Tech Fest will be a blast this year!

Poster is finally done! I HOPE

We have tweaked and tweaked till this is what is considered complete. 

Looking Good

Dressed up the assemblies so that they would look more professional today.  Had to mount the two boards required for the CO2 sensor/transmitter on a piece of wood.  Used #6 screws with 1/4" teflon standoffs.  Hopefully it looks good enough for being a prototype.  Fan wires are soldered to the board now.  Sharin & I tested it and everything is working as planned.  There is a little difference in voltage readings, but this will get addressed on Monday.

Sensor Board Updates

Spent yesterday afternoon soldering.  Sharin & I wanted to get the protoype off the bread board and into a permanent home.  The specific board we worked on was the receiver that communicates with the computer.  Looks much better with appropriate length wires. :-)

This morning was also very productive.  I started out at the hardware store looking for screws to mount the CO2 sensor/transmitter boards.  Miss judged sizes, so I had to make a second trip.  (This time I took a generic board for reference.)  Bought #6 screws & 1/4" teflon standoffs for mounting the boards to a 4" x 4" piece of wood.  The boards are mounted next to each other and we are now working on shortening the wiring to make it look better.  Functioning great!  Blow into or talk over the CO2 sensor & the fan kicks on right on que.

More to come.

The Plan

Actually, the plans. As the last trial with the cinder block takes place, I start to design the Tech Fest carnival apparatus. I trying to decide whether we should have 3 or 4 stations. We have the technical equipment for 4, but would it benefit us to have one more? I'l go ahead an design it, but go to EESAT and see the size of the room before buying materials. Off to plan...
(insert time here)
OK, done.
I just gotta buy the stuff and build it now.
Parsons

oh yeah, and we put a cinder block in an enclosure with 20000ppm CO2 and in 3 hours or so, it dropped below 200ppm. The room we were in was at 700ppm.

Monday, the first thousand light bulbs

Over the weekend, I took my large syringe to my room at school and calibrated it with water and a triple beam balance. I wanted to see whether or not the markings on the side of the syringe were in fact legitimate. If not, at least I will have measurements so that I know what each gradation actually is. According to http://www.csgnetwork.com/waterinformation.html tap water at the temperature I measured it at, has a density of .99624g/mL (interpolated).

 The slope (also the density) from my data was .9965g/mL accurate to 3 sig figs, so I have no worries about the precision of my instrument.

So today, one of the goals will be to oblige Dr. Rudi and place various building materials in a container with some CO2 and see if there are any changes in that level. Do the building materials exude or absorb the CO2. I expect nothing to happen, but that remains to be seen. I will try to test in the region where our fan will operate, 1000-5000ppm.

• First up: 2 pieces of dry wall about 5" x 26"(unpainted, unplastered)- no appreciable change

• Second: 1 cinder block (new)- CO2 ppm drops more than expected. Must do a more rigorous test. Sealed the entire container with the cinder block and CO2. The CO2 level dropped down from 1200ppm to a lowly 200ppm. The room we are in is at about 800ppm, so there is no excusing the drop in CO2. Upon doing some research, I see that to create lime in cement (and cinder blocks) CaCo3 is heated to 500-600 degrees celcius to create CaO and CO2. This reaction is reversible. Technically, the cinder block is a combination of coal ash, and portland cement, which is 3CaO•SiO2 and 2CaO•SiO2. Perhaps the CaO is being coaxed out of the block. This would eventually reach an equilibrium state, but it could take months for a new cinder block to reach that point. Very interesting, indeed!

• Third: 3 bricks (old)- no appreciable change

• Fourth: 2- 1sq. ft. ceiling tiles- no appreciable change

• Fifth: 1 linoleum adhesive floor tile- 

• Sixth:  3 carpet samples- no appreciable change

• Seventh: 2 small plants (a fern and a caladium)- There seems to be a trend of rising CO2....hmmm. Have I been lied to all my life? I have just been told that plants generate CO2 and O2 in different situations. Does everybody know this? I could swear that my biology teacher said plants make O2 with no mention of CO2 production. What is the net result? Sheesh. Too many variables in this little test.

Later, Dave

Tuesday, grinding away...

So the CO2 sensor that we ordered has some issues... at least the spec sheets do. Yes, that was plural...spec sheets. On one spec sheet the output voltage is 30-50mV, and the graph it provides reads that the output voltage is 265-325mV. On the spec sheet for the module the CO2 sensor plugs into, it refers to the CO2 sensor having a voltage output of 100-600mV. What?!?!?!?

It appears we must do our own calibration, using the grey wolf as gospel truth. Over 2 hours of careful measuring, we plotted the voltage function of the sensor in relation to the CO2 ppm and took 37 points of data, more closely spaced where we would be using the sensor. We measured from 800ppm to 80000ppm and found that the sensor becomes less responsive at very high concentrations. On a log graph, it looks fairly linear. The y-axis is ppm and the x-axis is voltage output by our sensor.

With that many data points, it should be fairly easy to interpolate ppm based on voltage. Our range of concern is between primarily 1000-5000ppm. The actual data looked like this, although the program cut off the first 25 minutes.

Testing stuff!!!!!!!!!

Whew! 2 solid days of testing. Monday was spent testing different places we could place the CO2 sensor.
First, I tested with the CO2 sensor on the bottom of the enclosure.

I had expected the CO2 to settle on the bottom and give a much larger reading than the true reading. I knew how much CO2 I was putting in because I was measuring it with a large syringe. I would put the mouth of the syringe in the bottom of a bucket that had dry ice in it for quite awhile. I would slowly draw the gaseous CO2 into the  syringe, and then set the syringe in a vertical orientation so that when it came to room temp, it would push the excess CO2 out of the top end of the syringe. I made some calculations to arrive at 5mL of room temp CO2 was adding 80.3ppm by mass (79.7 by volume) to the container we were using. Anyway, back to my hypothesis. I figured that if I added CO2 to the enclosure (to bring it up to 1000ppm), it would pool in the bottom where the sensor was and give a reading far above 1000ppm. I was half right. If I can put a copy of the graph in this I will. The reading from the grey wolf spiked high every time I put CO2 in (50mL per injection), but after about 6 minutes, it would achieve a steady state.

The steady state value almost agreed with the ppm I thought I was putting in (700ppm compared to the 800ppm I believed i was putting in), but I had not anticipated this. My interpretation of the spike goes along with my initial hypothesis. The CO2 is just really heavy compared to air. However, I thought it would stay at that high level. I was really surprised that the CO2 diffused throughout the enclosure.

Next came the middle test where the sensor was located vertically in the middle of he chamber.

I kept the 50mL addition the same every time, but the initial spike from the low test was smaller, and the time to reach equilibrium was much longer, about 15 minutes.

Even though I was adding 800ppm every time (from calculations based on the syringe), the steady state averaged out to about a 500ppm increase each time....hmmm.

High test

The grey wolf was put at the top of the container as well as our sensor, to do some initial voltage measurements.

I was concerned about this last graph, because I thought something had gone wrong. I couldn't find anything wrong with the set-up, so it must be accurate. As Julius Sumner Miller stated "Experiments do not fail, you must provide Nature the necessary provisions, or she won't do what you want her to do."

We added 160ppm at 3:51 and got a reading of about a 21ppm increase 3 minutes later.

We added 320ppm at 3:54 and got a reading of about a 400ppm increase 8 minutes later.

We added 320ppm at 4:03 and got a reading of about a 260ppm increase 7 minutes later.

We added 480ppm at 4:10 and got a reading of about a 410ppm increase 6 minutes later.

We added 800ppm at 4:16 and got a reading of about a 630ppm increase 11 minutes later.

The ideas of what was going on was starting to coalesce in my head. I had imagined the CO2 like it was water, sinking to the bottom of the container and staying there. That was the model in my head of the system. To paraphrase Kenn Amdahl, when pretending the universe is like a watermelon, with the seeds like stars, don't forget that the universe isn't actually a watermelon. What I had failed to account for was that CO2 is a compressible fluid and water is not. This new-found realization crystallized and it made sense of the data. What actually was occurring when CO2 was added, was an initial plunge as the CO2 dropped to the bottom of the container. As the gas diffused, it also set up a density gradient, with the highest density at the bottom, and decreasing as you go vertically upward. That at least partially explains the discrepancy between the ppm injected and the ppm measured. I need to do a little research a little into this phenomenon. The fluid mechanics class I took was a long time ago, and I'm not sure if we covered compressible fluids.

Dave out

Ready to test!

Ok, I think we're at a stage where we can begin testing.

• First, measuring CO2 at different heights of the big tub. Hoping it will answer a question I have about how fast the CO2 will sink since it is much denser than air. Measure the concentration low, middle, high with the grey wolf given a known ppm.  
• I have calculated the ppm CO2 (by weight and by volume (for those of you playing at home, its only .16% different)) we will be adding to each of our containers per mL of CO2 we add from a large syringe.
• I measured and calculated the actual volume of our enclosures +/- 2% for the bucket, and +/- 5% on the enclosure.  These measurements were about 10% off from the listed size of the bucket, and less than 1% off for the enclosure.
• I should be able to show my team and whoever else the bubbles floating on the CO2 that we were going to employ at Tech Fest. I'll insert a video later today 

Parsons

Vaisala CO2 info

I have looked & looked for a company that deals with CO2 sensing combined with ventilation.  I found lots of good information on several types of sensing units from a company called Vaisala.  I have sent an email requesting more information about the company & where the sensor are manufactured.  I could only locate sales offices from the web page, but was able to get spec sheets for the sensors.  This company advertizes that they have applications appropriate for home, school, and business.  I will see what else I can determine about the company that is not on the web page.

Shopping Trip!!!!!

Dave, Dawn, & myself went to Lowes for testing supplies.  We wanted to add materials to our "plastic test room" that would simulate the types used in walls, floors, and ceilings actually present in schools.  We purchased carpet & tile flooring samples, 2 plants, a concrete cinder block, and a bucket with a lid that can be sealed.  We will add CO2 to the bucket & use our battery powered sensor to check for different results. (OH....we also bought two 9V batteries.)  Dave and Sharin are currently brain storming on the battery power issue.  Hopefully by mid day on Monday we will be able to go get dry ice (CO2 source) & begin testing. 

Happy Friday!

Presentation & more

I think that the Prezi that Dave put together was AWESOME!  It was informational & everyone in the room seemed to enjoy it.  It might not be appropriate for a Scientific Panel to review, but it would definately keep our students interested in the material being presented.  Seems like Prezi might be better for keeping students engaged than Power Point is!  Will have to test this theory when school starts.

Suprise Surprise.....The amplifier/filter part we needed to make the CO2 sensor function properly arrived this morning!  We can now concentrate on CO2 levels triggering a fan instead of only using VOC.  We will continue to use VOC measurements in our documentation, but our primary focus will now be on CO2 levels.

Today's activities

Dave, Dawn, Sahrin, and myself met with Dr. Rudi Thompson this morning regarding project progress & proposed tech fest activities.  I am very proud to say that Dr. Rudi liked our proposed activity for tech fest enough that she wants to add it as a permanent activity for children who visit EESAT.  Kuddos Dave for thinking of such a fun CO2 activity.

We also have more direction on proposed testing for our VOC monitoring.  We will gather supplies for our mini-building and test our ideas regarding the effects of different materials on VOCs.  Current suggestions include concrete cinder blocks (un painted & painted), sheet rock (un painted & painted), carpet, ceiling tiles, brick, tile flooring, laminate flooring, and wood (either flooring or paneling for walls).  We will also test using plants to check for variations.  It will be interesting to see the results.

We are also going to use a smaller container (maybe a Homer Bucket) with a lid that seals better than the container we currently use for a test room.  We will have to work out the issue of having the wires to the sensor (don't have battery operation worked out yet) not getting pinched or keeping the container from being as air tight as possible.

Dave is also working on a Prezi that is "out of sight" for our Friday Presentation meeting. 
Very Interesting and Entertaining for all!

We tested the programming for the sensor today to make sure it would turn on and back off the ventillation fan as wanted.  The pictures below were taken during setup and testing.  It appears the ventillation fan doesn't move air very quickly, or we need to use a smaller container to represent the room.  Dave had to take the lid off of the container & fan fresh air into it to get the sensor to shut off the fan.  Something else to think about!

Sharin & Dave setting up test.

Sensor in container to simulate room.

Ventillation fan.

Complete sensor set up with fan running during test.

Hello , sports fans!
Well, there are so many things floating up in my head, i need to get them out. Not necessarily in an organized form, but we'll see:
1. ( I guess by putting numbers, it automatically became organized. Yea me.) We are running into focus issues.  Originally slated to create an exhaust fan whose speed depended on the CO2 concentration, turned into VOCs. We tested several VOCs that we were comfortable with breathing in the room (Isopropyl alcohol, Pine-sol, Acetone and ammonia) and compared them to the Grey Wolf to correlate the voltage given off by our sensor to the ppm observed by the Grey Wolf. Pine Sol was a hot mess with seemingly no correlation; just vomited points on a graph. The windex (ammonia), isopropyl and acetone had better curves, with acetone being the least precise.
2. Looking at the health risks of windex and isopropyl, the dangerous levels are far above what the sensors can read. So, do we provide proof of concept, or try out some other VOCs at a toxic level in the room we are in? If you guessed proof of concept, you are correct!  What we are currently doing is programming the arduino hooked up to the sensor to trigger an exhaust fan to come on when the isopropyl concentration reaches 2500ppb.  As the concentration increases, the fan speed will increase to its full value when 21000ppb is reached. This is only proof of concept the lower level of health safety is 400000ppb.  The lower limit of explosivity (I made that word up)  is even higher, at 20000000ppb.
3. So how is our presentation going to work? Here's what can be done if we had the part? No one needs a ventilation system if the air quality is fine...
4. Assuming the concept works with CO2, how feasable is it to evacuate the air from, say, a classroom?  You cant just turn the HVAC system on...that would just recycle the air already in the building. It would have to vent to the outside like a Chemistry vent hood. No one is going to do that with a building that is already built. It would be incredibly expensive. Where would the new air be coming in from? If the temp outside is considerably different from the inside, that new air will have to be heated/cooled which cost additional money.
5. How powerful a fan is needed for a room? How loud would it be? Where would it be mounted? CO2 is heavy so the fan might need to be low...

out, Dave

91% Isopropyl Alcohol

Follow the link below for an example of a Material Safety Data Sheet for Isopropyl Alcohol.  We are using this chemical for our VOC monitoring system.  The 91% Isopropyl Alcohol is picked up quickly by the VOC sensor and makes a better looking graph of data points.

Example MSDS sheet for Isopropyl Alcohol

MSDS sheets provide exposure warnings, precautionary suggestions, and other information required to be available by OSHA when this chemical is in use.

We also have a graph of the testing we did with the sensor while using Alcohol as our VOC example.

Tech Fest Work

Dave came up with a wonderful CO2 based game to engage students for Tech Fest.  We want to set up a game where the students blow into a straw which is connected to individual containers that each has a CO2 sensor set up in it.  The 1st student that gets the highest concentration of CO2 (3 to 4 competing at a time) gets to blow bubbles at a container containing CO2.  Since CO2 is more dense than air and is invisible the students will see that CO2 is present in the container due to the bubbles coming to rest on the top of the CO2 layer.  Rough sketches are below for the room layout.

Dave is going to write a formal proposal for approval by Dr. Thompson.

Smelly Afternoon Activities 6/20/2013

We have spent the afternoon testing the VOC sensor on how it reads different house hold chemicals. 

We used Windex for the Amonia in it, Pine-Sol, 91% Isopropyl Alcohol, and 100% Acetone nail polish remover.  The gases were introduced with care from a syringe.

Data points were taken for each chemical used.  Graphs of data will follow.

Thursday 6/20/2013

BRICK WALLS is what we have run into for this project.  Filter/Amplifier part coming from China did not get ordered early enough, so it is not here.  Therefore the CO2 sensor will not be used until it comes in.  Seems that the CO2 sensor will not put out enough voltage to run a ventillation fan (needs 12V DC) without amplification.  Original CO2 voltage output starts at .2 VDC and decreases when CO2 levels increase.  This prompted the need for the additional component for the sensor unit.

Due to the above difficulties, the team has opted to try measuring VOCs instead of CO2.  Sharin thinks adapting the VOC sensor to have the needed voltage output to power the ventillation fan is possible considering the addition of the Arduino and Mosfet circuitry. 

Currently we are testing the VOC sensor in a closed plastic container with the Grey Wolf sensor to compare readings.  Grey Wolf measures in parts per billion (ppb) and the TGS 2602 VOC sensor measures in voltage and results will have to be converted into a parts per million (ppm) or parts per billion (ppb) format. We will see tomorrow if there is a lag between sensors, or something is hinky...

Tuesday June 18th

I brought a fan from home that actually has a spec sheet and decided to test it out.

The spec sheet says the RPM should be 2600. Since I didn't have a strobe light, and since the photogate wouldn't work at the speed we were operating on, I hit upon the idea of matching the pitch to obtain the speed. The fan blades whooshing through the air create a pitch that can be matched with a frequency generator. Any musician (like me) can match the note.  Matching the pitch gave me either 302Hz or 604 Hz (one octave apart, which can be tough to tell. With 7 blades on the fan, 302Hz divided by seven is 43rotations per second, or 2589RPM. As the spec sheet says 2600RPM, this is probably correct. Probably is not good enough for me...
I knew I could strobe the fan to get the speed but my strobe is at school, so I wrote an easy arduino code to blink an LED at a high frequency to act as a strobe. Since the arduino is limited to whole numbers of milliseconds, this made it tough. The code I wrote would blink a light about 43 times per second (really 45). The arduino would flash the light every 22milliseconds.

To get the measurement, we had to bring the voltage of the fan up to 13V, but we got confirmation that the 2600RPM on the spec sheet was probably correct. Based on the bust yesterday from the pressure sensor, we needed to find a way to measure the CFM (cubic feet per minute) that the fan could pull when attached to the box.        

We took a trash bag (very thin) and taped it to the exhaust port on the box. We then ran the fan and timed how long it would take to fill the bag. It took about 33 seconds. OK, now to measure the volume of the bag......hmmmmmm. Can't submerge it and do water displacement. "I do have a giant 60mL syringe! I'll just take the air out 60mL at a time," I said stupidly. After 2100mL of air had gone out and the bag hadn't changed shape, I decided to go with another approach. Since the method of determining how long it took until the bag was "full" was sketchy at best, we didnt need measurements to 4 sig figs. I refilled the bag and squashed into a pumpkin shape.

The measurements on the bag were roughly 22.2 cm tall and 34.5 cm in diameter. This puts the volume at 21000mL or cm^3, which is .73 ft^3. This gives us a CFM of 1.3, far from the 30 on the spec sheet. But at least we have numbers!

The rest of the day was spent practicing arduino, and coming up with ideas for tech fest. More later.

monday, june 17th

Georgette found 9 articles relating to CO2 and IAQ.
Sherin and I tried to measure the speed of a fan based on its voltage from 5 to 12 volts. The first method  we used was with a photo gate which should have measured the time for the fan to turn 40degrees. After about 50 measurements, I discovered a problem. I dont think the photogate was fast enough to measure the speed of the fan...UGH! I then hit upon the idea of using the pitch of the fan as a speed indicator. Using an online frequency generator and my techniques aquired in many years of band, I was able to match the generator to the pitch of the fan and get a measurement to +/- 1Hz.  I was also introduced to Dr. Garcia and he showed me some sound analyzing equipment. He was very kind, but I was almost already done.  Disappointment #2 of today was trying to measure the speed of the gas in the tube as the fan pulls it through.  I was going to measure the pressure drop in side the tube and use Bernoulli''s Law to find the speed. The pressure sensor, however, was not sensitive enough to measure the drop in pressure.  Based on the data sheet ( which is junk), the air should have been flowing at 17m/s. My guess would put it at under 2m/s. Sheesh!  Disappointment #3 was finding out that we may need to change from CO2 to VOC which would negate the work we have done looking in journals, experimental setup, etc......frustrated,
Dave

Purpose

Indoor air quality is an important factor affecting public health.  The US Environmental Protection Agency (EPA) and its Science Advisory Board consistently rank indoor air pollution among the top five environmental public health risks.  Average person spends an estimated 90% of their time indoors so that poor indoor air quality is a substantial risk to public health.  For example, poor indoor air quality may cause increased short-term health problems such as fatigue and nausea as well as long-term health problems such as chronic respiratory diseases, heart disease, and lung cancer.  It is even more alarming when we consider air quality conditions in schools and classrooms and its implications to the health as well as learning achievements of the young generation.  Students are particularly at risk for health problems such as asthma and allergies linked to indoor air pollutants commonly found in schools.  According to the US General Accounting Office, 20% of all US schools currently report indoor air quality problems [EPA11a].  

In this project, teachers will learn to build a small IAQ control system using Arduino microcontroller board and micro gas sensors (CO2, O3, etc.).  The microcontroller system will continuously monitor IAQ. Based on a set of pre-configured trigger conditions, the system will send control signals to HAVC system.  In this implementation of a small demo system, HAVC system will be simulated using a desk fan.  Air quality (or the amount of air contaminants) in the conditioned space will be controlled by properly adjusting ventilation rate.

From this project, teachers will gain hands-on engineering experience in building small electronic system and programming microcontrollers.  Teachers will also be able to acquire a good understanding of IAQ-related issues, government regulations and policies, and best practices.