International Journal of Electrical & Computer Sciences IJECS-IJENS Vol:14 No:05
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A Device to Remove High Levels of Carbon
Monoxide
Jen-Yu Shieh, Bai-Hao Chang, Yu-Ting Liu, Guo-Jyun Liao
Department of Electro-Optics Engineering, National Formosa University, Yunlin County, 632, Taiwan
Abstract—
This paper adopted a Holtek HT66F50, featured
with Flash Memory A/D type 8-bit microcontroller (MCU), and
connected with a MQ7 gas sensor and ventilation fans on the
ceiling to input the level of carbon monoxide (CO) into the MCU
for calculating. As the level of CO in the air reaches 100 ppm, the
fans will be activated to exhaust CO out to the space; besides, if
the level of CO in the air is over 200 ppm, the buzzer will sound
indicating “Alarm”. Carbon monoxide detectors on the market
can only buzz during alarm and chirp if a trouble is found, and
the prices are high; thus, the study focused on designing a
low-cost and multi-functional carbon monoxide detector.
Index Term-microcontroller,
carbon dioxide detector, emergency lighting,
uninterruptable power supply (UPS)
I. INTRODUCTION
With GDP growth, people’s living conditions have been
improved. They also put emphasis on having a sound body;
therefore, developing new products for disease prevention and
disaster prevention has been the main goal, such as fire alarms,
fire sprinklers, and carbon monoxide detectors. However,
people normally neglect those invisible, untouchable, and
unheard things. Carbon monoxide poisoning frequently
happened in cold weather since the incomplete combustion of
gaseous fuel in a confined space which can produce carbon
monoxide (CO); if a person inhales CO unconsciously, s/he
may feel dizziness; if inhales too much, s/he may even die.
The detector is far different from those on the market due
to its uninterruptable power system (UPS) which can
continuously run the device during power failure and provide
an emergency lighting and be a USB charger. Nowadays,
people have relied on 3C products; therefore, the detector has
become practical, especially during power failure. The most
important feature is that it can monitor the level of carbon
dioxide indoor and prevent people from suffering carbon
dioxide poisoning.
A.
Purposes of the Study
The current carbon monoxide detectors found on the
market only emit a warning alarm to alert that level of CO is
too high but unable to make improvement under such
condition. As the majority of detectors are plug-in or battery
operated types, they would lose their effectiveness in the event
of power failure or dead batteries, and so likely to cause
unexpected tragedies. Therefore, the purpose of the study is to
propose a carbon monoxide detector built in with a UPS that is
capable of functioning properly even if power is shut off. It is
also very practical to use during power outrages for being able
to provide emergency lighting and has a USB charger to
charge mobile phones or other 3C products. Unlike standard
features found in conventional products, it will turn on the
ventilation fans automatically to draw CO away from the
space when the level of CO reaches 100 ppm, and sound a
warning alarm when the level of CO continues to rise and
reaches up to 200 ppm.
B.
Literature Review
The quality of most carbon monoxide detectors found on
the market today is mature and stable. Recalling the early
ancestor of measuring carbon monoxide, it can be retrieved to
the earliest 1913 when Franklin Institute conducted an
experiment to detect carbon monoxide content in the air [1,2].
The development has become more mature after 1990, and in
1996, the first carbon monoxide detector released was able to
sound a warning alarm to alert that the level of CO in the
environment was harmful to human beings [3]. It has become
a role model of carbon monoxide detector.
Nowadays,
many methods and applications have been used to detect CO,
such as the use of infrared fiber optic sensor to detect CO [4],
the use of rapid spectrophotometry to detect CO in the air [5],
the use of pyrotannic acid method to detect CO in the
bloodstream, the use in emergency rooms to take care of
patients [6]–[8], the use to detect CO and carbon dioxide (CO2)
simultaneously[9], and the use of multi-mode absorption
spectroscopy to measure the emissions of engines [10].
Being capable of measuring in the air [11], carbon
monoxide also comes in many other applications, such as
measuring the level of CO exhaled from the human mouths to
simulate CO2 in the environment [12], using an osmotic
device to measure the average level of CO in the atmosphere
[13], providing early warning of fire by detecting CO [14],
and detecting chemical fires [15].
As the current carbon monoxide detectors found on the
market only emit a warning alarm but unable to remove high
levels of CO; thus, the researcher compared the advantages
and disadvantages of the current carbon monoxide detectors
shown in Table 1.4, discussed the issues of power supply, and
provided solutions when the level of CO increases.
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International Journal of Electrical & Computer Sciences IJECS-IJENS Vol:14 No:05
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TABLE I
called the non-dispersion infrared method. If the light source
A COMPARISON OF CURRENT CARBON MONOXIDE DETECTORS
illuminating path is installed with a gas filter assembly, it is
ON THE MARKET
known as the gas filter correlation infrared method.
Model
Power
Digital
Extra
Supply
Display
Functions
Kidde
KN-LCB-A
Plug-in
(a backup
battery)
N
N
Kidde
COPP-B
Battery-p
owered
Y
N
MK350
Plug-in
N
N
The study
Plug-in
(UPS)
N
-Emergency
lighting
-Lowering
levels of CO
- USB charger
II. RELEVANT PRINCIPLES
Carbon Monoxide
CO is a colorless, odorless and an inorganic compound gas
that is highly toxic. It is also known as a silent killer [16],
being slightly lighter than air and constituted only a small
amount in the atmosphere. Even the metabolism of animals
will also generate a small amount of carbon monoxide [17].
Carbon monoxide poisoning is governed under the U.S.
National Fire Protection Association (NFPA) specifications
[18]. In this study, the warning value settings were made in
accordance with Table II.1[19].
A.
TABLE II
THE U.S. NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)
SPECIFICATIONS
CO Level
(ppm)
100
Condition and Health Effects
200
Slight headache after 2-3 hours of
exposure
Headache and nausea after 1-2 hours of
exposure / Life threatening in 3 hours
Headache, nausea, and cramp after 45
minutes of exposure
Headache and dizziness after 20 minutes
of exposure / Death within 2 hours
Headache and nausea after 5-10 minutes
of exposure / Death within 30 minutes
Dizziness after 1-2 minutes of exposure /
Death within 10-15 minutes
Death within 1-3 minutes
400
800
1600
3200
6400
12800
B.
Slight headache in 6-8 hours
The Infrared Measuring Method
The level of CO can be detected through the use of
absorption characteristic of carbon monoxide. If the light
source comes in the non-dispersion infrared version, it is
Fig. 1.
The infrared absorption spectrum
CO and CO2 feature a high absorption spectrum in the
infrared wavelength range as shown in Fig. 1. The levels of
CO and CO2 can be detected within the infrared wavelength
range through the use of infrared absorption characteristic.
C. The Gas Detector Measuring Method
It is a method that converts the level of CO in the air into
electrical signal (voltage, current, resistance) to ease
monitoring purpose. Among the common types are:
(1) Semiconductor gas detectors
It is mainly composed of N-type semiconductor of SnO2
and a heater, featuring rapid heat conduction and gas
explosion prevention effects. If it is generally heated up to 200
~ 300 ℃, it will cause the resistance of semiconductor to
increase after absorbing CO in the air. The value of the level
of CO can then be extracted from the output voltage.
(2) Electrochemical gas detectors
The electrochemical activity existed in some flammable
and toxic gases can be electrochemically reduced or oxidized;
thus, identifying the gas components and detecting the gas
concentrations can be distinguished by the reactions.
(3) Catalytic combustion type gas detectors
It involves burning electric wire in gas to generate heat,
allowing its resistance value to change and then obtaining the
gas concentration. However, this type of the detector is not
sensitive in non-combustion gases.
D.
Uninterruptible Power Supply
Also known as a UPS, it works as a backup power source
to provide a constant circuit under the abnormal electrical
power supply to maintain the normal operation of electrical
appliances [20].
Early in the era before batteries were being used,
flywheels and internal combustion engines were once being
employed by a UPS to provide electrical power. The UPS was
called a flywheel UPS or a rotary UPS. As the use of internal
combustion engine to provide power [21,22] has a large body
size and would generate loud noise, so it is currently being
used in emergency cases and some harsh natural occasions.
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International Journal of Electrical & Computer Sciences IJECS-IJENS Vol:14 No:05
Now, the battery backup consists of batteries, a control circuit
and an AC/DC converter. On the normal power supplying, a
UPS will charge itself and supply electricity from the stored
batteries in the event of power anomalies. According to
working principles, it can be classified into on-line, off-line,
and line-interactive types [23].
E. Performance Comparison of Different Types of UPSs
Off-line UPS system was adopted in the study due to its
low cost and high efficiency. Although there is a transition
time during power conversion, but it will not cause serious
problems.
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TABLE III
COMPARISON OF UPS FUNCTIONS
On-line
Off-line
Line-interactive
Battery
Protection
Transition
Time
Efficiency
Excellent
Excellent
Excellent
Excellent
Poor
Excellent
Low
High
High
Cost
High
Low
Medium
III.
THE STRUCTURE OF THE DEVICE
Fig. 2.
IV. EXPERIMENTAL MEASUREMENTS
A. Restart Efficiency
The MQ-7 detector was turned off 30 minutes, 1 hour, 6 hours,
1 day and 3 days, respectively and then re-started. From Fig. 5,
it is evident that the MQ-7 detector needs to take a certain of
preheat time to warm up before it can get correct values
steadily. The longer the power outage is, the longer the preheat
time needs. Thus, the detector does not work well as a
portable product as it needs to be supplied with power
constantly before it can measure the level of CO steadily.
The structure of the device
The device is a system consisting of a carbon dioxide
detector, ventilation fans, a buzzer, a LED light strip, and a
UPS installed on the ceiling. Fig. 3 and Fig. 4 are the
experimental simulation designs comprising of three 3×3 cm
ventilation fans, a 2×10 cm LED light strip, a USB charging
port and a 32,000 mAh UPS battery. For simple installation,
the device can be directly embedded on the ceiling which is
different from other products that need to do DIY work.
Fig. 5.
The restart efficiency of the MQ-7 detector
B. Levels of CO Measurements
(1) Confined space measurements:
The MQ-7 detector and a conventional carbon monoxide
detector were placed in a 20x20x20 cm confined container to
carry out measurements, as shown in Fig. 6. Incenses were
initially burnt for 20 seconds to fill the container with CO, and
the average values of the levels of CO were noted to be
compared, shown in Fig. 7.
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(3) Measurements at three-meter range
The MQ-7 detector was measured three meters away from
the combustion point as shown in Fig. 10. With the incenses
burning, the levels of CO were noted at every 10-minute till
they were extinguished after one hour, followed by noted the
levels of CO continuously after extinguishing the incenses,
shown in Fig. 11.
Fig. 6.
Fig. 7.
The photo in the confined space
The curve chart for the levels of CO in a confined space
Fig. 10.
(2) Measurements at one-meter range
The MQ-7 detector was measured one meter away from
the combustion point as shown in Fig. 8. With the incenses
burning, the levels of CO were noted at every 10-minute till
they were extinguished after one hour, followed by noted the
levels of CO continuously after extinguishing the incenses,
shown in Fig. 9.
Fig. 11.
Measurements at three-meter away from fire source
The curve chart for the levels of CO at three-meter range away
from fire source
C.
The Experimental Measuring System of CO
The MQ-7 detector was placed in a 20x20x20 cm
confined container to perform measurements as shown in Fig.
12. Incenses were initially burnt for 20 seconds to fill the
container with CO, and the levels of CO were noted. When the
level reached to 100 ppm, the ventilation fans would switch on
to draw CO out. Fig. 13 is a data comparison chart showing
the general carbon monoxide detector and the simulated effect
done by the study.
Fig. 8.
Fig. 9.
Measurements at one-meter range away from fire source
The curve chart for the levels of CO at one-meter away from fire
source
Fig. 12. The experimental device
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International Journal of Electrical & Computer Sciences IJECS-IJENS Vol:14 No:05
Fig. 13. A comparison chart of the levels of CO with ventilation fans and
without ventilation fans
D.
Analysis of the Experiment
The result of the experiment shows that the level of CO is
very high at the very beginning, and it needs a certain time to
preheat and to be stable. It usually takes about two to three
hours to obtain the right data. If it is not used for a long time,
it is suggested to power up for over one day. Thus, the system
proposed by the study will not be suitable to produce as a
portable product.
Those CO detectors on the markets can measure the levels
of CO immediately; however, the sensor MQ-7 adopted by the
study needs a certain time to preheat in order to run the
function perfectly. This is the only weakness, but if it starts to
run with UPS, there is no need to worry about power off and
the preheat time.
V. CONCLUSION
The CO detector proposed by the study can measure levels
of CO between 20 to 2000 ppm. Generally, levels of CO
between 100 to 400 pm may be harmful to human beings.
Thus, the levels of CO between 100 to 200 ppm set up by the
researcher would be reasonable. Besides, promptly turning on
ventilation fans and a buzzer would play a crucial rule,
especially in a confined space. If the system could be installed
onto the ceiling, it would save space, reduce levels of CO
automatically, and provide emergency lighting and USB
charger, which is far difference from those CO detectors on
the market.
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Authors’information
Jen-Yu Shieh received the B.S. degree in
electrical engineering from Feng-Chia University,
Taichung, Taiwan, in 1984 and the M.E. degree in
computer engineering and Ph.D. degree in electrical
engineering from Florida Atlantic University, Boca
Raton, in 1989 and 1992, respectively. While
completing graduate degrees at FAU, he was an
associate professor of Department of Electro-Optics
Engineering at National Formosa University, Huwei,
Taiwan. Since February 2010, he has been an
professor. His current research interests include
innovation and consumer products. He also has 47 patents and 4 consumer
products.
144705-6363-IJECS-IJENS © October 2014 IJENS
Bai-Hao Chang was born in Changhua, Taiwan,
on June 4, 1990. He received the degree in
Optical-Electro from the National Formosa University,
in 2012. He is a student of graduate institute of
Electro-Optical and Materials Science, National
Formosa University of Huwei, Yun Lin, Taiwan.
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International Journal of Electrical & Computer Sciences IJECS-IJENS Vol:14 No:05
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Yu-Ting Liu was born in Taipei, Taiwan, on May
8, 1991. He graduated from Department of
Electro-Optical Engineering of National Formosa
University , in 2013. He studies in graduate institute of
Electro-Optical and Materials Science, National
Formosa University of Huwei, Yun Lin, Taiwan.
Guo-Jyun Liao was born in Yunlin, Taiwan, on
July 16, 1991. He received the degree in Department of
Electronic Engineering from the I-Shou University of
Taiwan, in 2013. He is a student of graduate institute
of Electro-Optical and Materials Science, National
Formosa University of Huwei, Yun Lin, Taiwan.
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