By Vinod Gogoriya
Intelligent Gas Alarm India Pvt Ltd
www.gasalarm.co.in, www.automationindia.in(c) Intelligent Gas Alarm India Pvt Ltd 1
Carbon monoxide in news:Gladstone Wal-Mart evacuated for carbon monoxideLocal authorities stress CO detectors after carbon
monoxide kills one, poisons sevenCarbon monoxide sends man to hospital after he was
exposed to elevated levels of carbon monoxide in his garage
Mum's tribute to son killed by deadly gasCarbon monoxide clears schoolPeople found unconcious because of mysterious gas
(source: various sources from internet, google news etc)
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What is Carbon monoxide ??Carbon monoxide (CO) is a colorless, odorless gas produced
during combustion or incomplete combustion.
i.e HC (hydrocarbon or any fuel) or CH (carbohydrates or any biological substance eg. Skin, wood etc)
+ O2 (oxygen)= CO2 (full combustion of carbon) + CO (partial combustion) +
H2O
CO molecule is still unsatisfied and looking for oxygen atom (in air, blood oxygen) to form stable CO2 molecule.
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What is Carbon monoxide ?? (cont…)When CO molecule enter human body through breath, it
binds with hemoglobin (the oxygen-carrying molecule in human blood).
As COHb levels increase, less hemoglobin is available for the transport of oxygen. Thereby leading to drastic decrease in blood oxygen and hence, body cells and tissue start dying.
Brain cells are affected most due to inhalation of CO as these cells draws maximum of blood oxygen. This leads to unconsciousness, coma or death.
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Where is carbon monoxide found?Kitchen, restaurants, hookas, sheeshaVehicles (IC Engines) (even cars with catalytic converters
can produce substantial amounts of carbon monoxide if an idling car is left in an enclosed space such as a closed garage)
Fire (home, industrial)Furnaces, foundriesUnderground mines Indoor and underground parking garagesAny place where fire, heating, combustion, burning taking
place
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Where is carbon monoxide found?Concentration Source0.1 ppm Natural atmosphere level
0.5 to 5 ppm Average level in homes
5 to 15 ppm Near properly adjusted gas stoves in homes
100 to 200 ppm Exhaust from automobiles in the Mexico City central area
5,000 ppm Exhaust from a home wood fire
7,000 ppm Undiluted warm car exhaust without a catalytic converter
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Courtesy: www.wikipedia.org
What Standards says?? OSHA (USA) specifies
TWA (time weighted average) for CO: 25ppm(ie. A person can be exposed to TWA concentration for 8 hrs in a day and 40 hrs in
a week, after which he should be taken to fresh air and given rest to avoid any health problems.
STEL (Short term exposure limit) for CO: 35ppm(ie. A person can be exposed to STEL concentration for maximum 15 mins, before
any health problems arises) The NATIONAL BUILDING CODE OF INDIA – 2005 Specifies the following parameters for Ventilation:
CO level- within 29mg/cu.m (25 ppm) with Peak level not to exceed 137 mg/cu.m.(125 ppm)
As per ASHRAE Max Level for CO8 hrs exposure – 25ppm1 Hour exposure- 35 ppm
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Still Why to monitor CO level?? Having no colour, smell or taste means that it is very hard to detect
carbon monoxide by human Each year, over 50 people die in the UK as a direct result of
exposure to Carbon Monoxide Gas (CO). Many more people die through strokes and respiratory illness made worse by inhaling low levels of CO over prolonged periods. Still, more are left with permanent damage and invalidity.
As CO does not cause any biological, chemical change in body, many of deaths are reported as of other reasons(though caused by CO inhalation)
Carbon monoxide is an odourless, colourless, tasteless gas. You can't tell if it is there. It can build up quickly to deadly levels in confined spaces, sheds, tanks, and small or closed rooms.
Carbon monoxide can also build up in large spaces like parking garages and industrial sheds if the ventilation is poor.
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Levels CO poisoning:Concentration Symptoms
35 ppm (0.0035%) Headache and dizziness within six to eight hours of constant exposure
100 ppm (0.01%) Slight headache in two to three hours
200 ppm (0.02%) Slight headache within two to three hours; loss of judgment
400 ppm (0.04%) Frontal headache within one to two hours
800 ppm (0.08%) Dizziness, nausea, and convulsions within 45 min; insensible within 2 hours
1,600 ppm (0.16%) Headache, tachycardia, dizziness, and nausea within 20 min; death in less than 2 hours
3,200 ppm (0.32%) Headache, dizziness and nausea in five to ten minutes. Death within 30 minutes.
6,400 ppm (0.64%) Headache and dizziness in one to two minutes. Convulsions, respiratory arrest, and death in less than 20 minutes.
12,800 ppm (1.28%) Unconsciousness after 2-3 breaths. Death in less than three minutes.
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Courtesy: www.wikipedia.org
How to detect and monitor?? Electronic Carbon monoxide sensor detector should be installed at
probable leakage or required spot/location
Available sensor technology (for human comfort) Semi-conductor (solid state) based Electro-chemical (Galvanic cell) based
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How to choose between technology?Parameter Electro-chemical SemiconductorResponse Time Very low usually less
than 30 secVery high around 300 secs
Cross sensitivity (with other gases)
Very low High (thereby gives false alarms)
Repeatability High Low (because of high response time)
Accuracy High (± 3ppm) Low (± 15ppm)Life Around 5 years Around 5 yearsPower consumption Low HighTemperature effect Low High
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Installation and integration:As relative density of carbon monoxide ≈ 1, CO sensors are
recommended to be installed at nose level height ie. 5-7 feet from floor
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CO sensor continues signal to controller
Controller trips relays to turn on/off jet fans based on pre-set limits
Features of MSR CO Sensor:Electro-chemical (Gel based) sensor cell0-300 ppm measuring range4-20mA analog signal, 2 wire (loop current)Reverse polarity, short circuit protectedOver flooding protectedPlug-in based sensor cell (for easy replacement) IP44 protected enclosureAccuracy: ± 3ppmResponse time < 50 secLife > 5 years
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Contact Us:
Intelligent Gas Alarm India Pvt Ltd69, Ramgali 7, Raja ParkJaipur 302004Ph: +91-141-4033769, 99833 45452Web: www.gasalarm.co.in, www.automationindia.inEmail: [email protected]
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Stay Safe, stay healthy
Thank you!!!
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