SCHOOL OF SCIENCE AND TECHNOLOGY, SINGAPORE
INVESTIGATIVE SKILLS IN SCIENCE
Title: Development of an air quality sensor and air purifier
Names: Pang Cheng Feng, Zahid Afiq, Jericho Manguan
Group Reference: E
1. Indicate the type of research that you are adopting:
[ ] Test a hypothesis: Hypothesis-driven research
e.g. Investigation of the anti-bacteria effect of chrysanthemum
[ ] Measure a value: Experimental research (I)
e.g. Determination of the mass of Jupiter using planetary photography
[ ] Measure a function or relationship: Experimental research (II)
e.g. Investigation of the effect of temperature on the growth of crystals
[ ] Construct a model: Theoretical sciences and applied mathematics
e.g. Modeling of the cooling curve of naphthalene
[ ] Observational and exploratory research
e.g. Investigation of the soil quality in School of Science and Technology, Singapore
[ X ] Improve a product or process: Industrial and applied research
e.g. Development of a SMART and GREEN energy system for households
A. Problem being addressed
Haze. Being a dilemma in many countries, haze causes many problems to us. Haze is a phenomenon when dust, smoke and other particles fill up the air which makes the sky unclear and usually plagues certain parts of the world at certain times and seasons and can be very hazardous to the young and old. Despite being a taboo in many countries, many people cannot run away from the fact that the haze in their vicinity will always pose problems and they will have to fix it sooner or later. A more relatable example is the haze in Singapore. Haze from Indonesia blows off to Singapore and broke the record from 296 in 1996 to 401 in 2013. Many Singaporeans complain and try to protect themselves from the haze by buying the N95 masks but most could not acquire one. The haze got less serious by the end of June.
Being a huge problem, people suffering from asthma are much more vulnerable to the haze and its effects. Many will encounter difficulty breathing when walking out in the open. Taking a leisurely stroll might just be life threatening to them. However, with a very high psi, the haze will still pose a risk to the general public. Everyone might suffer conditions from the particles in the haze. Illnesses related to haze includes conjunctivitis, asthma, upper respiratory tract infection and bronchitis. These illnesses cause many problems to innocent, perfectly fit people. The smoke particles will damage the ecosystem because birds and other animals might not be able to take the smoke for a long period of time. They will often die and their corpses will lie all around. The food web will get disrupted and there will be many undesirable outcomes.
As earlier stated, haze causes health related issues when people face prolonged exposure to harmful particles and gases in the haze such as , PM 2.5, PM 10, ozone, sulphur dioxide, nitrogen dioxide, carbon monoxide and other harmful gases. Haze also causes a reduce in visibility, thus increasing the chances of traffic-related accidents to increase due to the fact that it would be harder to see while driving. Also, many tourist attractions have been affected during the haze in June 2013 due to the fact that it would be hazardous or would be unhealthy for the attractions and the staff to operate. This would affect our economy and our reputation of being a clean and green county and foreigners would be discouraged to return to Singapore in the future due to their bad experiences they had during the period when the haze struck.Despite the haze in June, many construction workers still had to continue working and this might have caused illness for the workers if they had not had taken the appropriate steps. Around 600 schools in Malaysia had been closed down since it was too hazardous for the students to attend school.
But why does it happen? Hazes are caused by many actions and events.Forest fires are the more widely-known cause of haze. Forest fires are caused by either humans or naturally. Farmers who use the ‘slash and burn’ method are the main cause of forest fires which produce the haze. Most of the time, farmers know that their actions are wrong but they do not have a choice because of the benefits the method towards their own crops. In terms of forest fires produced naturally, they are mostly common during summer, when temperatures get very high. It is still partly due to global warming, which is mostly associated with human activities, but will still be classified as naturally-caused. This is the main cause of haze that we would be focusing on. The other ways of producing haze, would be volcanic haze and industrial haze. Volcano haze are formed when volcanoes get active and smoke from the lava floods the nearby area around the volcano. This kind of haze is the most dangerous kind. They contain very toxic particles that can easily kill you. Industrial haze is usually caused when there are too many vehicles and/or too many factories polluting the air. It is more common in the city areas. Forest-fire related haze is still the main object of this project.
There a few amendments which have already been taken by the countries affected by the haze. Firstly, Indonesia tried to stop the haze by stopping the main source of the haze, the forest fire. They did this by extinguishing the fire and by preventing their citizens from further burning the forest. Singapore on it’s part tried to provide masks for their citizens, such as N95 mask to protect them from breathing in harmful gases and particles. However, most department stores quickly ran out of masks and most people had to go without masks or stay indoors.
B. Goals / Expected Outcomes
• Engineering Goal: To develop a system to detect air quality levels as well as purify it
• Specify Requirements
o Must be cost saving
This is one of our requirements since we do not want to spend too much money on developing an air sensor and purifier, not like any others which cost way too much, making it unaffordable. An example is making a PM 2.5 sensor, which cost over a hundred thousand. The sensor itself will not cost as much as the PM 2.5 sensor, but maybe just a cheap light sensor, not radioactive or any sort.
We would also maybe like to make it available to the public use, where not only really wealthy people use. This way, everyone would not need to have a television wherever they are just to find out what the quality of the air
they are breathing is.
However, there are cons. Since we cannot make a PM 2.5 sensor like the NEA, the way we are using will not be as accurate as NEA’s reading.
Still, the pros overpower the cons, and we will want to make our project cost saving.
o Must be durable
This is one of our requirements since we want people to be able to use it for a rather reasonably long time, and such that it does not wear out very fast, like some cheap item where you buy from unprofessional stores. Since we might be promoting this to the public, we want it to last long, not like some items bought very cheaply which spoils really quickly.
Secondly, since this is not a cheap project to start with, we need to make use of our money as smartly as possible.
We will want to make it a value for the school’s money, and not throw it away as if it was for granted. The school gave us this chance to do this project and we will treasure it and not let this go to waste.
Lastly, if it is not durable, we might have to fix it or replace some parts every now and then. This will be a serious problem since we have certain time and money constraints. We rather make one nice and durable, so as to avoid problems in the future.
However, since it is durable, we might need to spend a little bit more of our budget so as to maybe strengthen the materials of the device, or other things.
Still again, the pros overpower the cons, thus we will want to make it durable.
o Must be efficient
Building an efficient device is crucial to the project. No one wants to wait an hour or two just to get a reading from a haze sensor. No one would want to wait another hour just for the air to be filtered. We would want it to be sensed and filtered on the spot, as accurate and fast as possible. Efficiency is so important in order for our project to be usable.
Also, if it is not efficient, people might not even want to use the device, and would rather turn on the television or the air-con to check the PSI of the air and to breathe in fresh air.
However, since it is durable, we might need to spend a little bit more of our budget so as to maybe strengthen the materials of the device, or other things.
Still again, the pros overpower the cons, thus we will want to make it efficient.
• Create Alternative Solutions (Air sensor)
o Light sensor
o Ionization Smoke detector
o Particulate detector
An optical detector uses a light source to measure the density smoke in the air. There are currently a few kinds of optical detectors. They all work in somewhat the same way in which they use a LED or other light-emitting objects, a lense to collimate the light into a sort-of beam,laser light and a photoelectric sensor as the light detector.
One type of optical detector uses the fact that light will scatter when blocked by smoke and the scattered light will reach a sensor and trigger it. Another typical type of detector uses a receiver/sensor to sense the visibility of the light projected to it. If there is smoke, the smoke will block some of the light and the sensor will sense that and will trigger. Studies have shown that photoelectric detectors are generally more responsive and more reliable and aren’t affected by high-air-flow areas which is essential. However, in some cases, photoelectric sensors react slower to weak smoke or haze.
Many smoke sensors use the both the above methods to increase effectiveness. However, It would require more parts to make it and would be alot more complicated and wouldn’t be very feasible in our filter because the sensor is suppose to be compact and simple to understand. It would also be repetitive and would only waste our time.
Ionization Smoke detector
The ionization smoke detector produces ionization in the air. When the detector detects a difference in the air due to smoke, it activates and generates an alarm. This method is another common way of detecting smoke.
The ionization smoke detector emits ionizing radiation in the form of particles into a chamber. The air molecules become ionized which allows a small passage for electric current. If any smoke were to enter the chamber, the ions will stick to the smoke particles which will stop them from carrying the current. An electric circuit detects the drop in electric current and will sound the alarm.
There are many measures to keep the mechanism accurate which includes placing a reference chamber to cancel effects that might change the mechanism’s readings such as temperature, air pressure and the age of the source. There are also self-system checks to see if anything isn’t functioning such as the battery, alarm device and the detector itself. The device itself can work for over a year which means less frequent checks and recharging of battery. It is so called a ‘self-sustaining mechanism’. Despite being and sounding complicated, it is the more cheaper kind of smoke detector. The best part about it is that it can detect particles of smoke that are too small to be visible.
Despite being efficient and functional, the one negative point to it is the reason why we will not use this type of detector. It is Radioactive. There is no way for it to function without radiation since radiation is the one way to ionize the air for its main function to even work. Therefore, this type is ruled out and will not be used for our final design.
The Sun photometer uses LEDs in the reversed way. Instead of making the LEDs produce light, they use the LEDs to absorb and detect light. Coincidentally, the LED works exceptionally well in detecting light. The LEDs detect a relatively low and narrow band of wavelengths. We could use the science behind the LEDs to detect the haze. Light from the sun causes the LED to produce an electrical current, somewhat like how a solar panel does. The current mentioned above passes through an amplifier which transforms the current into a voltage.
This device is used to measure the intensity of the sunlight in the atmosphere. It can be used to measure haze because the haze and/or smoke will block out some of the light and causes them to reflect away thus changing the detector’s readings. This method is a simple, practical and an inexpensive way of detecting haze.
Despite being a very reasonable kind of detector, the sun photometer has many cons, so many that the cons definitely overrules the pros. Firstly, there needs to be sunlight meaning that this sensor will only work in the day. It also means that the sensor would be impractical in many places and will make the whole device seem very troublesome and inefficient. It also means that the whole system would be inaccurate in so many ways. It will require ‘clear skies’ for it to be accurate and will be greatly affected by weather. If it is cloudy, the results won’t be accurate and the sensor will be counted as useless if it is raining.
Secondly, it requires exposed LED which will pose great risks for damage which will render is useless. The LED might get hit by an object and might break as a result. It also means, anything causing obstruction from the skies will make the sensor functionless. The surrounding temperature will greatly affect the accuracy of the sensor as the LED might not work as well when the surrounding temperature is at the two extremes, two cold or too warm. Lastly, this sensor requires a big space for it to function well. There are many wires and systems in it that requires alot of
space. This system is completely useless in our case.
• Create Alternative Solutions (Air purifier)
o Ionic air filter
o HEPA filter
o Carbon air filter
o UV light air filter
Ionic Air Filter
An Ionic Air Filter charge air molecules by using voltage. Basically, they work like static electric and how they attract particles. As the particles get attracted to the negatively charged ions, called anions, the particles are deionized and are removed from the air stream.
The Ionic Air filter does this by passing air over a charged electric coil which takes electrons from the air molecules thus creating negatively charged particles. These negatively charged particles collide with bigger positively charged electrons which are floating around in the air. Because of the difference of charges in the two, the two particles cling together to form an ionic bond. This continues until the particles get too large to stay in the air and fall to the floor. A continuous flow of negative ions would eventually cause a negatively charged environment.
Many air filters have ionizers which are independent help in trapping particles to more efficiently purify the air in your home. When the ionizer is activated, voltage is applied to a series of built in needles which generate electrons and are discharged into the air. Ions are formed when electrons attach to particles.
Negative ions would attach to dust, pollen and even cigarette smoke to form larger particles which can be easily trapped by filters. However, these larger particles may collect on the floor, positively charged surfaces in the vicinity or to the air purifier, and thus needing frequent dusting to ensure that the purifier remains clean.
HEPA air filter
HEPA stands for High-Efficiency particulate air. HEPA air filters are filters which are made up of randomly arranged fibres which form a mat. These fibres are made up of fiberglass and are ranged from 0.5 micrometers wide to 2.0 micrometers wide. The main things which affect how the HEPA air filters work is, filter thickness, fibre diameter and face of velocity. Unlike common assumptions by most people, HEPA filters do not just simply have filters where only certain particles can pass through the biggest opening like a funnel.
However, it is totally wrong. Even particles which are as big as the biggest opening cannot pass through at all. It is used to target much smaller particles, and these unwanted particles are trapped through processes.
These processes are:
Interception - Particles which are following the air in a line comes within the radius of the fibre sticks on it.
Impaction - This is when the particles cannot avoid the fibres due to the air flow curving, thus having forced to embed on one of the fibres directly. The way this can be sped up is to increase the speed of air that is being filtered.
Diffusion - Gas molecules below 0.1 nanometer will collide with each other. This will slow down the
speed of the air flowing through the filter. This will allow the first two processes to occur more frequently.
Diffusion targets particles of 0.1 nanometers, while Interception and Impaction targets particles 0.4
nanometers or above. Keep in mind that this does not filter odor or gas molecules.
Carbon Air Filter
Carbon Air Filters work by treating carbon with oxygen and this makes the carbon highly absorbent. The carbon is now considered to be "activated" and is said to be able to trap chemicals and gases, and can even filter cigarette smoke. It also removes odor from most substances, whether or not they are liquid or gas.
The activated carbon works by absorbing molecules of chemicals, toxins, impurities from the air, then trapping it in the pores of the carbon substrate. This method is not only used for purifying air, but water too. Another interesting fact is it is even used to recover metal such as gold, and used for purifying sugar came. Also, it is used in masks for respiring.
The range of particle size that this method of filtering is removing is more than enough for filtering air, especially smoke in air. It can potentially turn thick, acrid smoke to clean, transparent air. It will also remove the smell if there is any, making it almost perfect for human respiration. It will remove most of the dust particles from the smoke, and remove its odor.
Activated carbon is also known as activated coal or charcoal. They are made in a certain way such as to increase surface area of that the particular thing that is going to be filtered will meet the activated carbon more frequently, in this case air.
Due to this efficiency in filtering, it is often used in finishing of metal, not really often for air. However, we feel that if we use this carbon air filter in the right way, it will work as effectively. Companies use it to remove certain organic impurities from metals such as air, while we will be using it to remove impurities in air, mostly used for smoke. It makes certain metals reach their desired level, and we are going to make the air clean enough for human consumption.
Activated carbon can remove hydrocarbons from the air, such as its odor. It also can be used to retain certain radioactive things, which gets trapped there for a while, then they start to decay, and become not radioactive any more. They become solid, thus allowing filtered air to pass through.
In a nutshell, carbon filters are being used for a variety of ways, and many applications of life. From medicine, to air filtration. Surprisingly, it is not a Jack of all trades, however it works well for most of the applications. The immense amount of particles carbon can trap is a lot.
UV Light Air Filter
Lastly, UV light air filters work by using the process when titanium dioxide is exposed to UV light. As air flows through the process, particles such as mould and bacteria are neutralized. The effectiveness of the UV light air filters depend on the intensity of the light and length of exposure of the particles to the UV light.
About 240 - 280 nanometers of light is enough to break down most carbon organic compounds. People usually make use of UV light filters together with HEPA filters for medicinal purposes. However, UV light will not filter things like smoke and others, but only things like mold and bacteria, technically
microorganisms. Since this removes this kind of impurities, it will also work as water or even food purification.
What causes the microorganisms to die? The UVGI in the UV light does. UVGI stands for Ultraviolet
germicidal irradiation. This is really harmful to microorganisms such as pathogens, and viruses. This is mostly used for medical sanitation in sterilisation factories.
UV light filters are relatively simple to operate, at least easier than most other filters. It also does not cost a lot. An example of it being easier to operate is if you spend your time and energy to boil water over a stove, or rather just filter it through the UV light?
However, since we are making an air filter, UV light may not be the brightest idea. This is because there is very little time for the UV light to kill the microorganisms as the air is travelling is
travelling at a rather high speed. Although not applicable for smoke or haze, it is still usable for taking away small impurities and should not be ignored.
• Choose the Best Solution: Light + Photoelectric Air Sensor (Air sensor)
The most suitable air quality sensor for our project would be the light-based sensor. There are two kinds of light sensors, one being the normal light sensor which detects the different light densities from the light source. We will be using this mainly for the sensor which will display the measurement of the quality of the air. However, the problem with this concept is that it requires a lot of smoke to block off sufficient light to count it as smoke, thus we need a very sensitive light receiver. Considering this, haze, in general, will need to be at least 250 psi for the sensor to detect it. Thus without a sensitive light receiver, the sensor will not be accurate.
The LED light sensor will be rather usable since its one of the only affordable costs. It is also rather effective since the haze in Singapore is quite thick, and we are also using a very sensitive light receiver.
Since the LED sensor is very straightforward, and more accurate than most of the other solutions, there is nothing much to say about it, since we are under a budget and a set of safety rules that will not enable us to spend too much or use radioactive things to make the sensor. More will be elaborated about the photoelectric sensor.
The photoelectric sensor will be the most efficient and accurate sensor to be used in our design. The photoelectric sensor uses about the same materials to make except it uses a different concept. The photoelectric sensor still measures the light density but does so in the opposite manner.
Instead of directing light straight to the light sensor, the photoelectric sensor directs light 90 degrees off the sensor. The light will hit the wall instead of the sensor itself and uses the smoke to direct light to sensor. Basically, the smoke causes the light from the LED or other light-emitting objects to bounce off and a certain amount of light from the light source will reflect and hit the sensor, activating it.
There are many easy-to-get materials to make the photoelectric sensor. There will have to be a light source which will most probably be an LED but may be changed if need be. There should also be a lens to collimate the light into a beam so that the light would be more concentrated and will be more affected by the smoke thus making the sensor more accurate. There needs to be a photodiode or light sensor in the mechanism for the actual overall sensor to work. There should also be an opaque material for the sensor such as aluminium alloy. Such material is durable, light and cost-effective. However, considering the fact that we will be handling light in an enclosed area, we may need to find a more suitable ‘wall’ for the light so that it does not bounce off so much to keep the sensor as accurate as possible but aluminium alloy will still be an option.
In terms of the actual design of the mechanism, we will need to look at every single factor that will affect the overall product which is the filtering system itself. We will need to make sure the sensor is compact and air tight except from the opening. There should be no external light present in the system so the actual opening leading to the sensor should not be allowing any light in and keeping the mechanism dark, obviously disregarding the light source itself. The sensor should be in front of the fan so that when the sensor detects bad quality air or smoke, the fan will begin to spin and suck in the air from the sensor into the filtering and then out. The sensor will then check for any subtle changes to the air quality and when the air quality is at a normal or healthy state, it will stop the fan and the filtering process will cease.
The sensor should be made of a durable material, one of the options being aluminium alloy, or maybe plastic, due to its affordability. The system will need to be compact and small, so light will not escape. The light source will need to face 90 degrees from the sensor but may need to be a little more than 90 degrees if the situation in building it needs be. The openings need to be small so that the sensor will be more accurate yet big enough to let considerable amounts of air to be sucked in by the fan and filtered. The sensor should not interfere with the filtering process and the suction process and should be 100 percent working and accurate.
No matter what kind of system it is, there will always be certain pros to them and certain cons to them. In the perspective of the photoelectric sensor, there are many cons to it, which are mostly unavoidable but some are variables as well. One con of the design is that when we are going to build it, there will be many complications that come up. The light will need to be 90 degrees from the sensor and it cannot be exposed to light for it to work so in order for us to test the mechanism, we will need to close it up properly and we will need to prepare the arduino and attach it to the sensor. We will have to open it up again if we need to change the system and we also cannot check if the insides are actually light tight and air tight which might affect the accuracy of our sensor. There are so many problems and troubles we will face when we are building this part of the overall mechanism.
Another con to this design is that because it requires light and a sensor, it will need alot of electricity and we may face complications with a battery powered mechanism. There will also be a mechanism to make the sensor check every 5 minutes. Making and programming this will be very hard considering we will be dealing with light, a very-hard-to control medium. The material for the sensor walls will need to be non-reflective and also needs to be durable. There is a good chance that we will have to make the material absorb some of the light to keep the sensor accurate and if we are unable to find any, the sensor might not be accurate and might just be a nuisance instead. The fact that the sensor needs to be light-proof might just make it really difficult to design it. There will need to be small openings to keep light away but that might influence the amount of air that will be allowed to be sucked in by the mechanism and might just leave the device useless.
• Choose the Best Solution: Carbon Filter + HEPA Filter (Air purifier)
To recap, a Carbon Filter works by treating carbon with oxygen to activate it and make it highly absorbent. This carbon which is now highly absorbent would help to remove harmful gases in the air. This is highly relevant in helping us to combat the haze considering that the haze has many harmful gases. Since the haze also contains many particles, the Carbon Filter would help to reduce the amount of particles in the air. Despite the fact that Carbon Filter is mainly used by companies in the finishing of metal, it would still help in minimizing harmful particles and gases and also help in purifying the air.
A HEPA Filter is a filter which uses fiberglass which form a mat to filter harmful particles in the air. HEPA air filters cannot filter harmful gases such as smoke and thus, it needs to be paired up with a Carbon Air Filter. However, we cannot just have a Carbon Air Filter alone to ensure that as many particles are filtered as possible.
Compared to the rest of the air filters, this is the best way we could pair any filter. Firstly, it would be way more easier compared to the Ionic Air Filter and the UV light filter as it would be rather unfeasible for us to construct either an Ionic Air Filter and a UV Light Filter. Moreover, it would be less effective if we were to use Ionic Air Filters or a UV Light Filter since these two filters are not so related to our project. Our project is to build an air purifier which is targeted at combating the haze. Firstly, an Ionic Air filter would only just make the particles clump together and these particles, overtime get too heavy to stay afloat and will just fall to the floor, thus requiring extra effort in trying to remove the particles on the floor. Also,some of these particles might even collect onto the air purifier and will thus need frequent maintaining. Secondly, the UV Light Filter is often paired up with a HEPA air filter for medicinal purposes. A UV light filter removes mold, bacteria and other microorganism. Despite being cost effective and easy to build, it does not help us much in helping us build an air purifier which is targeted at purifying smoke and haze.
However, there are still cons in having a Carbon + HEPA air filter. A Carbon Air Filter alone is unable to remove particles from the air despite being able to capture harmful gases such as smoke. However for the HEPA Air Filter, it is unable to capture harmful gases and is not as effective in capturing the smallest viruses. However, if we combine these these two air filters, we would be able to have an air purifier which is able to filter particles and also gases.
1) Arduino (x2)
2) Wires (x20, 0.2m)
3) Plastic (an airtight box, and 5 tubes)
4) Fan (x1)
5) Hot glue gun
6) Duct Tape
1. LED (x3)
2. PX Series: heavy duty Photoelectric sensor (x2) -http://www.keyence.com/products/sensor/photoelectric/px/features/index.jsp
1) Fan (x1)
2) Activated Carbon Panel (x1)
3) HEPA fibreglass sheet (x2)
4) High-speed motor (x2)
1. Get and organize the items and equipment for the project
2. Start by cutting a small circular hole in one side of a container
3. Place the torchlight at the outside of the container, with some light passing through the small hole into the container
4. Attach a Light sensor onto the other side of the container such that the light from the torchlight hit directly onto the sensor
5. Test the light sensor and check the reading on it. The reading will be very important as it will greatly affect how we are going to code the arduino later on.
6. Begin coding the arduino suiting the reading made by the sensor previously such that the reading should be substantially lower before the fans get activated.
7. Connect the two fans to the arduino
8. Test functionality of fan with the arduino
9. Hook up the sensor to a display and connect the sensor to the arduino
10. Run a test by smoking the sealed container and make sure the container is airtight. If the coding and the equipment works, the fans should activate quickly
11. Clear the container of smoke and test the mechanism again but this time without smoke for 10 minutes. It should not activate and if it does, the mechanism is faulty
12. After making sure the mechanism works, cut a hole through the top of the container that fits the fan exactly and glue the fan to the opening with the glue gun making sure the circuitry did not get damaged from the glue
13. Place an airtight pipe on the other side of the fan and glue them together, again making sure its airtight and does not damage the circuitry of the fan.
14. Get another big container and begin laying out the place for the HEPA filter and the carbon filter in the container
15. Cut the HEPA Filter to fit the measurements of the container and place the filter to the marked out location in the container
16. Fold the edges of the sheet of filter and tape it to the container walls with duct tape. Make sure it is airtight
17. Glue the remaining holes in the tape and sheet edges to make sure the air passes through the sheet instead of the edges or openings
18. Cut the Carbon Filter to fit the measurements of the container and place the filter to the marked out location in the container
19. Fold the edges of the sheet of filter and tape it to the container walls with duct tape, Making sure it is airtight
20. Glue the remaining holes in the tape and sheet edges to make sure the air passes through the sheet instead of the edges or openings
21. Place the earlier mentioned(step 13) pipe to the opening of the filter container and glue them together making sure it is airtight
22. Get the second fan and attach it to the other end of the filter container with glue
23. Get a larger container and partially fill it with water
24. Cut a hole with the diameter of the default pipe that we are using.
25. Get another pipe and attach one end to the second fan and another end to the earlier mentioned hole on the container with glue.
26. Make sure the pipe falls into the water and then curved upwards in the water to make air pass through the water without much disturbance from the water itself
27. Make another hole and attach it to another pipe at the top of the container.
28. Create a hole in the first container with the sensor and attach the pipe to it with glue.
29. Test the entire system with the smoke generator and check if the filtered air will turn off the sensor. If it does, the filtered air is clean. If it doesn’t, the filtered air needs to be filtered again.
• Risk and Safety: Identify any potential risks and safety precautions to be taken.
1. Handling electrical parts (Arduino, sensor)
We should make sure we handle with care and make sure the equipment is not spoilt and does not pose any risks.
2. Handling the Fan
We should make sure the fan is far away from hands reach because the fan will be very strong and dangerous with a modified motor.
3. Power Outlet
We should make sure we do not use the power outlet dangerously when we are plugging in the device into it
4. Shaping the building material
If we are going to shape the material, we are going to need to make sure we do not bruise, burn or cut ourselves when we try to shape the material. We should also keep ourselves from the glue gun and the glue itself so as to not endanger ourselves in any way.
5. Making the Filters
There are many risks in building the filter. Cuts, bruises, etc. We should make sure the material is not sharp when we are going to handle it.
6. Storing of materials
Though this might not be highly relevant pertaining to safety issues, we need to be careful in keeping and storing our materials and parts as they might get damaged or might even hurt people if placed in inappropriate ways
7. Unhealthy levels of smoke
During our building process, we might have to test our product by flooding it with smoke to make sure that our product is working well. Thus, this might pose as a threat to us if we face the smoke without taking any precautionary measures such as wearing a mask or clearing the room.
8. Faulty Materials
Before starting the actual building process, we need to check all our materials and parts to make sure none of them are faulty to curb the risk of anything going wrong or malfunctioning. However, if we do not check the materials, things such as harmful gases might escape while we test our product.
9.Buying of materials
Despite the fact that this takes place outside of the lab, we still need to make sure that we are safe and that we do not go to unsafe places. We must not take this lightly and if possible, we should have a teacher accompany us while we get the parts and materials.
10.Following of lab procedures
More often than not, lab procedures are often ignored. These rules include not running around, wearing of gloves and safety goggles and so on. These rules are important and must not be broken to ensure everyone’s safety in the lab.
11.Well planned procedures
We need to carefully plan our procedures before we execute them. A poorly planned procedure would lead to careless mistakes or even getting someone injured. So, we need to make sure that everything we plan is in order. Like the famous saying by Benjamin Franklin, “If you fail to plan, you are planning to fail!”.
After the completion of the construction of the system, we will test it and check if the air is suitable for respiration. The factors of the test are included below. This is to ensure that our system is able to produce clean air similar or better than commercial filtration, and with a much smaller amount of money spent.
The PSI can easily be checked with a PSI checker. All we have to do is:
1. Place a PSI checker in the container with the sensor.
2. Use the smoke generator to generate smoke into the container with the PSI checker and the sensor.
3. Test the system
4. Monitor the changes in PSI after the first round off the filtering
- Particle Count
The particles can be counted by a few methods. One of the simpler ways is to:
1. Use the smoke generator to generate smoke into the container with the sensor.
2. After the first round of filtering, check the particles in the HEPA filter and let the already filtered air to be filtered again
3. Check the number of particles again and make a conclusion as to whether the amount of particles of decreased.
Smell is one of the easiest ways of figuring out if the air is already filtered. If the air smells like smoke, it has not been properly filtered. If the air smells fresh or odourless, it has been filtered properly. If the air smells like carbon, there is too much carbon in the carbon filter or the air has been filtered too much.
- Visibility of Air
Visibility of the air is another easy way of figuring out if the air is filtered. If the air is dark, it is still smoke. If the air is like a fog or smog, it has not been properly filtered. If you can see clearly through it, the air has been filtered properly.
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