Understanding Air Pollutants: A Guide to Carbon Monoxide (CO)

What is Carbon Monoxide (CO)

Carbon monoxide (CO) is an odourless, colourless, and tasteless but dangerous gas that primarily contributes to air pollution. The gas is made up of carbon and oxygen and is highly toxic, capable of causing acute illness and death in the most severe cases.

Sources

Carbon Monoxide (CO) is formed when materials don’t burn completely; this can occur with the burning of fossil fuels like natural gas, petrol, coal and oil, wood smoke, from car and truck exhausts, as well as through faulty gas heaters, BBQs, ovens, and cooktops.

Carbon monoxide is a significant element of exhaust fumes from road vehicles. These emissions are a source of CO and industrial processes such as petroleum refining, oil and gas extraction, and chemical production.

Common outdoor objects using hydrocarbons as a fuel can also be a source of CO emissions, including some power tools, lawnmowers, generators and open fires.

In the working environment, machinery such as propane-powered forklifts, pressure washers and gas-powered concrete cutters can contribute to the build-up of carbon monoxide in the atmosphere.

Environmental Impact

CO is itself a greenhouse gas. When CO is emitted into the atmosphere, it adds to the amount of greenhouse gases generated, which directly impacts global warming and climate change. As it is a relatively unreactive compound, it does not pose a significant threat to plant life. However, it can be quite harmful to oxygen transport systems in humans and other animals.

Health Impact

If inhaled, CO attaches to the haemoglobin in red blood cells, which generally carry oxygen throughout the body. When CO attaches, it “uses up” the oxygen-carrying capacity of the red blood cell and thus blocks the transport of oxygen the body needs, ultimately causing a wide range of health problems.

Inhaling low levels of carbon monoxide can lead to symptoms including nausea, confusion and disorientation, dizziness and headaches. Regularly breathing at low levels can lead to permanent mental or physical problems.

Very high levels of CO can lead to more severe consequences, including unconsciousness and death. There are around 60 deaths from accidental carbon monoxide poisoning in England and Wales each year. Whilst extreme levels of CO are uncommon outdoors; there is a particular concern for people with pre-existing conditions where the heart needs more oxygen than usual when outdoor levels of carbon monoxide are elevated. The greatest risks are indoors or within tents where CO from burning hydrocarbons can build up.

Sensit by Crowcon RAMP

The Sensit RAMP is a robust, remote and reliable low-cost air quality monitoring platform. The device is capable of monitoring up to five gaseous chemical pollutants including carbon monoxide. The device uses a laser scattering detection method to detect both PM2.5 and PM10 with a range of 1-1000 μg/m3.

The RAMP is suitable for use in a variety of industries including construction, transport, waste, oil and gas, chemical and petrochemical industries.

Our Partnership with Hatech Gasdetectietechniek B.V.

Service providers are vital in supplying products and solution services to customers. However, they also provide customers with a range of knowledge and expertise to ensure they supply their customers with the correct equipment.

Background

Founded in 1994 and located in Raamsdonksveer, North Brabant, Hatech Gasdetectietechniek B.V. are a gas detection specialist. With over 25 years of experience, Hatech is the biggest service provider in the Netherlands, operating as a seven-person organisation and supply gas detection for the office, workshop, factory, plants, offshore, biogas or any other industrial environment. Hatech supply a wide range of gas detection products, from portable devices to complete fixed setups and customised installations. In addition to the supply of gas detection, Hatech is also a ‘one-stop shop’ as they issue calibration, service and supply rental of gas detection equipment.

Views on Gas Detection

Gas detection is a crucial piece of safety equipment for those who work in hazardous environments; therefore, supplying the correct equipment for the job is vital. Hatech ensures they provide the knowledge and understanding to enable their customers to understand and know the equipment they are buying correctly. Hatech issues tailor-made advice that ensures they know what application and who will be entering these environments to ensure that they offer the most suitable solution for your gas detection application.

Working with Crowcon

A 15-year partnership and continued communication have allowed Hatech to supply their customers with a gas detection solution. Although Hatech Gasdetectietechniek is based in the Netherlands, our partnership provides them with a short lead time allowing for a quick turnaround in products. Hatech is an official service centre for portable devices and supplying service engineers for fixed products. “Crowcon detectors are a premier gas detection solution that is simple to operate, with a complete sales and service team. Our partnership has provided our customers with new technology and the knowledge and understanding allowing for the correct equipment for the right application.”

T4x a Compliance 4-gas monitor 

It is vital to ensure that the gas sensor you employ is fully optimised and reliable in the detection and accurate measurement of flammable gas and vapours, whatever environment or workplace it is within, is of the utmost importance. 

Fixed or portable? 

Gas detectors come in a range of different forms, most commonly they are known as fixed, portable or transportable, in which these devices are designed to meet the needs of the user and environment whilst protecting the safety of those within it.  

Fixed detectors are implemented as permanent fixtures within an environment to provide ongoing monitoring of plant and equipment. According to guidance from the Health and Safety Executive (HSE) these types of sensors are particularly helpful where there is the possibility of a leak into an enclosed or partially enclosed space which could lead to the accumulation of flammable gases. The International Gas Carrier Code (IGC Code) states that gas detection equipment should be installed to monitor the integrity of the environment that it is to monitor and should be tested in accordance with the recognised standards. This is to ensure that the fixed gas detection system operates effectively, timely and accurate calibration of the sensors is critical. 

Portable detectors normally come as a small, handheld device that can be used within smaller environments, confined spaces, to trace leaks or early warnings to the presence of flammable gas and vapour within hazardous areas. Transportable detectors are not handheld, but they are easily moved from place to place to act as a monitor ‘stand-in’ whilst a fixed sensor is undergoing maintenance. 

What is a compliance 4-gas monitor? 

Gas sensors are primarily optimised for detecting specific gases or vapours through design or calibration. It is desirable that a toxic gas sensor, for example one detecting carbon monoxide or hydrogen sulphide, provides an accurate indication of the target gas concentration rather than a response to another interfering compound. Personal safety monitors often combine several sensors for protecting the user against specific gas risks. However, a ‘Compliance 4-Gas monitor’ comprises sensors for measuring levels of carbon monoxide (CO) hydrogen sulphide (H2S), oxygen (O2) and flammable gases; normally methane (CH4) in one device.  

The T4x monitor with the ground-breaking MPS™ sensor is able to provide protection from CO, H2S, O2 risks with accurate measurement of multiple flammable gases and vapours utilising a basic methane calibration. 

Is there a need for a compliance 4-gas monitor? 

Many of the flammable gas sensors deployed in conventional monitors are optimized for detecting a specific gas or vapour through calibration but will respond to many other compounds. This is problematic and potentially dangerous as the gas concentration indicated by the sensor will not be accurate and may indicate a higher (or more dangerously) and lower concentration of gas/vapour than is present. With workers often potentially exposed to risks from multiple flammable gases and vapours within their workplace, it is incredibly important to ensure that they are protected through the implementation of an accurate and reliable sensor. 

How is the T4x portable 4-in-1 gas detector different? 

To ensure ongoing reliability and accuracy of the T4x detector. The detector utilises the  MPS™ (Molecular Property Spectrometry) Sensor functionality within its robust unit that provides a range of features to ensure safety. It offers protection against the four common gas hazards: carbon monoxide, hydrogen sulphide, flammable gases and oxygen depletion, whilst The T4x multi gas detector now comes with improved detection of pentane, hexane and other long chain hydrocarbons. It comprises a large single button and easy-to-follow menu system to enable ease of use for those wearing gloves, who’ve undergone minimal training. Tough, yet portable, the T4x detector features an integrated rubber boot and an optional clip-on filter that can be easily removed and replaced when needed. These features allow the sensors to remain protected even within the dirtiest environments, to ensure they can constant. 

A unique benefit to the T4x detector is that it ensures toxic gas exposure is calculated accurately throughout an entire shift, even if it is switched off momentarily, during a break or when travelling to another site. The TWA feature allows for uninterrupted and disrupted monitoring, So, when powering up, the detector begins again from zero, as if starting a new shift and ignores all previous measurements. The T4x allows the user the option to include previous measurements from within the correct time frame. The detector is not just reliable in terms of accurate detection and measurement of four gases, it is also dependable due to its battery life. It lasts for 18 hours and is useful for usage across multiple or longer shifts without requiring charging as regularly.  

During usage the T4 employs a handy ‘traffic light’ display offering constant visual assurance that it is operating soundly and conforming to the site bump test and calibration policy. The bright green and red Positive Safety LEDs are visible to all and, as a result, offer a quick, simple and comprehensive indication of the monitor’s status to both the user and others around them. 

T4x helps operations teams focus on more value adding tasks by reducing the number of sensor replacements by 75% and increasing sensor reliability. Through ensuring compliance across site T4x helps health and safety managers by eliminating the need to ensure each device is calibrated for the relevant flammable gas as it accurately detects 19 at once. Being poison resistant and with battery life doubled, operators are more likely to never be without a device. T4x reduces the 5-year total cost of ownership by over 25% and saves 12g of lead per detector which makes it much easier to recycle at the end of its life. 

Overall, through the combination of three sensors (including two new sensor technologies MPS and Long-life O2) within an already popular portable multi-gas detector. Crowcon allowed for the enhancement of safety, cost-effectiveness and efficiency of individual units and entire fleets. The new T4x offers longer life with a higher accuracy for gas hazard detection whilst providing a more sustainable build than ever before. 

National Mental Health Awareness Week 2022

In the UK we are marking Mental Health Awareness Week as well as the month-long observance in the US, we’re reminded that with society changing at a fast pace new norms arise, such as working from home. Many of us try to adapt to both home and hybrid working while building and maintaining both work and personal connections. However, 1 in 5 people are experiencing loneliness. We all get affected by loneliness at one time or another. It can be a driver for and/or a product of poor mental health. Although Mental health problems can affect anyone, any day of the year, this week aims to promote reaching out to a friend, family member or colleague and reflecting on your own wellbeing too.

At Crowcon, we are focused on looking after our people, and have put in place programmes and resources to help them feel safe, healthy, and fulfilled. This includes our company employee assistance programme, which provides a range of methods of support and advice.

Crowcon is playing a part in providing an environment that supports and nurtures our people. From mental health first aiders to walking challenges, we try to ensure that our people are supported and feel connected where they work.

There are lots of advice and support to help you on your way:

10 practical ways of looking after your mental health

https://www.samaritans.org/

https://unitedgmh.org/

https://www.nhsinform.scot/healthy-living/womens-health/later-years-around-50-years-and-over/menopause-and-post-menopause-health/menopause-and-your-mental-wellbeing/

Our Partnership with Tyco (Johnson Controls)

Background 

Johnson Controls has over 120 years’ experience in providing complete life safety to the oil and gas industries world-wide helping to provide 90% of the world’s top fifty oil and gas companies. Merging with Tyco in 2018 they now provide a full turn-key solution for the global marine and navy industries. The merge has allowed for the protection of over 80% of the vessels at sea for all types of assets and facilities including fixed and portable devices. Johnson Controls also supply gas detection to the renewable industry.

Views on Gas Detection 

Johnson Controls is uniquely positioned to offer comprehensive and integrated solutions for a wide range of proven products and systems across several industries and applications. Johnson Controls have a culture that focuses on innovation and continuous improvement which in turn helps to us to solve current challenges whilst constantly looking to ‘What’s next’. As gas detection is an essential instrument for many workers within the oil and gas and marine industries, providing honestly and transparency is key as well as upholding the highest standards of integrity and honour in the commitments they make, ensure that their customers are given a solution that not only solves their pain but also protects their workers.  

Working with Crowcon 

Through continuous communication, our partnership with Johnson Controls has allowed them to provide honesty and transparency to their customers. This partnership has allowed Johnson Controls to reach a variety of industries and applications. Although previously our partnership has predominately been focused on our portable product range, future hopes will be focussed on our fixed product range, of which will allow Johnson Controls to expand their customer base as well as providing a solution to a wider audience. “Our partnership with Crowcon has allowed us to offer a solution to all customers, ensuring that those who we supply equipment to are protected.”  

Understanding Air Pollutants: A Guide to Ozone (O3)

What is Ozone (O3)

Ozone (O3 ) is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in both the Earth’s upper (stratosphere), and lower (troposphere) atmosphere. Depending on where it is in the atmosphere, ozone can affect life on Earth in both beneficial and non-beneficial ways. Many people will be familiar with the ozone layer which is naturally occurring in the upper atmosphere and forms a protective layer from the suns rays. The less widely known form of ozone (sometimes referred to as tropospheric ozone) occurs in the lower atmosphere and is one of the most common pollutants impacting the quality of our air.

Sources

In contrast to many air pollutants, almost no ozone is directly caused by human activity. Instead, the ozone is formed in the air where high concentrations of energy interact with oxygen molecules. This can be high energy photons from the sun interacting high up in Earths stratosphere, or lightning in Earth’s lower atmosphere, or from reactions between other pollutants in sunlight. Tropospheric ozone is formed where concentrations of those pollutants are greatest, as sunlight causes reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs) – often near cities and industrial areas. Volatile Organic Compounds (VOCs) are generated in a variety of ways, and are often associated with the oil refining and petrochemical industries, whilst nitrogen oxides (NOx) originate from the combustion of fossil fuels in stationary sources, such as heating and power generation, as well as in motor vehicles.

Environmental Impact

Ozone itself is a greenhouse gas. As such, increasing concentrations of ground-level ozone contributes directly to global warming, and is significant as one of the pollutants causing the increase in the overall average temperature of earth’s atmosphere. Ozone is also generally an ingredient in the ‘smog’ which forms over large cities.

Tropospheric ozone has a significant impact on ecosystems, wildlife and plants. It can cause plants, trees and crops to suffer from slowed growth rate and has the potential to cause mass die-off in crops. Tropospheric ozone pollution is often seen to be an urban issue as it is in these areas where it is primarily formed. However, ozone also finds its way to more rural areas, potentially being carried hundreds of miles by wind or forming as a result of other sources of air pollution in these areas.

Health Impact

High levels of ozone gas can cause irritation and inflammation of the lungs, as well as irritate the eyes, nose and throat which can lead to persistent coughing and chest discomfort. This is of particular concern for asthmatic individuals, as ozone pollution episodes can increase breathing difficulties. Studies across Europe, Asia and North America have repeatedly found that risk of premature death increases with higher levels of ozone pollution.

Depending on level of exposure, ozone can cause coughing and sore throats, inflame and damage airways, aggravate existing conditions such as asthma and make the lungs more susceptible to infection.

Sensit by Crowcon RAMP

The Sensit RAMP is a robust, remote and reliable low-cost air quality monitoring platform. The device is capable of monitoring up to five gaseous chemical pollutants. The device uses a laser scattering detection method to detect both PM2.5 and PM10 with a range of 1-1000 μg/m3.

The RAMP is suitable for use in a variety of industries including construction, transport, waste, oil and gas, chemical and petrochemical industries.

What causes Hydrocarbon Fires?  

Hydrocarbon fires are caused by fuels containing carbon being burned in oxygen or air. Most fuels contain significant levels of carbon, including paper, petrol, and methane – as examples of solid, liquid or gaseous fuels – hence hydrocarbon fires. 

For there to be an explosion risk there needs to be at least 4.4% methane in air or 1.7% propane, but for solvents as little as 0.8 to 1.0% of the air being displaced can be enough to create a fuel air mix that will explode violently on contact with any spark.

Dangers associated with hydrocarbon fires

Hydrocarbon fires are considered highly dangerous when compared to fires that have ignited as a result of simple combustibles, as these fires have the capacity to burn at a larger scale as well as also having the potential to trigger an explosion if the fluids released cannot be controlled or contained. Therefore, these fires pose a dangerous threat to anyone who works in a high-risk area, the dangers include energy related dangers such as burning, incineration of surrounding objects. This is a danger due to the ability that the fires can grow quickly, and that heat can be conducted, converted and radiated to new sources of fuel causing secondary fires. 

Toxic hazards may be present in combustion products, for example, carbon monoxide (CO), hydrogen cyanide (HCN), hydrochloric acid (HCL), nitrogen dioxide (NO2) and various polycyclic aromatic hydrocarbons (PAH) compounds are dangerous for those working in these environments. CO uses the oxygen that is used to transport the red blood cells around the body, at least temporarily, impairing the body’s ability to transport oxygen from our lungs to the cells that need it. HCN adds to this problem by inhibiting the enzyme that tells the red blood cells to let go of the oxygen they have where it is needed – further inhibiting the body’s ability to get the oxygen to the cells that need it. HCL is a generally an acidic compound that is created through overheated cables. This is harmful to the body if ingested as it affects the lining of the mouth, nose, throat, airways, eyes, and lungs. NO2 is created in high temperature combustion and that can cause damage to the human respiratory tract and increase a person’s vulnerability to and in some cases lead to asthma attacks. PAH’s affects the body over a longer period of time, with serve cases leading to cancers and other illnesses. 

We can look up the relevant health levels accepted as workplace safety limits for healthy workers within Europe and the permissible exposure limits for the United States. This gives us a 15-minute time weighted average concentration and an 8-hour time weighted average concentration. 

For the gases these are: 

Gas  STEL (15-minute TWA)  LTEL (8-hour TWA)  LTEL (8hr TWA) 
CO  100ppm  20ppm  50ppm 
NO2  1ppm  0.5ppm  5 Ceiling Limit 
HCL  1ppm  5ppm  5 Ceiling Limit 
HCN  0.9ppm  4.5ppm  10ppm 

The different concentrations represent the different gas risks, with lower numbers needed for more dangerous situations. Fortunately, the EU has worked it all out for us and turned it into their EH40 standard. 

Ways of protecting ourselves

We can take steps to ensure we do not suffer from exposure to fires or their unwanted combustion products. Firstly of course, we can adhere to all fire safety measures, as is the law. Secondly, we can take a pro-active approach and not let potential fuel sources accumulate. Lastly, we can detect and warn of the presence of combustion products using appropriate gas detection equipment. 

Crowcon product solutions

Crowcon provides a range of equipment capable of detecting fuels and the combustion products described above. Our PID products detect solids and liquid-based fuels once they are airborne, as either hydrocarbons on dust particles or solvent vapours. This equipment includes our GasPro portable. The gases can be detected by our Gasman single gas, T3 multi gas and Gas-Pro multi gas pumped portable products, and our Xgard, Xgard Bright and Xgard IQ fixed products – each of which has the capability of detecting all the gases mentioned. 

The Impact of Air Pollution Around Schools

The dangers posed by air pollution are a key concern for people and communities around the world. One area in particular that has seen increased attention in recent years is the impact of poor air quality around schools.

Research commissioned by leading respiratory charities in the UK has found that more than ¼ of British schools and colleges are in areas where there are dangerously high levels of air pollution. This means that there are over three million children learning in an environment which can be damaging to their health. Research from Queen Mary’s University finds that children are disproportionately exposed to higher levels of air pollution whilst they are at school.

Air pollution around schools is a worry due to children’s increased susceptibility to the negative effects of air pollutants. Children are at increased risk due to their higher breathing rate compared to adults and the fact that their airways are still developing.

It has long been accepted that air pollution can have severe impacts on the respiratory system and lead to increased levels of asthma, lung cancer and heart disease, with a recent study finding that one in 12 cases of asthma in children could be caused by nitrogen dioxide exposure. More recent research is now pointing to the impact of air pollution on the brain and cognitive development.

Research from the University of Manchester has shown that exposure to air pollution can negatively impact brain health, potentially leading to ADHD, learning disabilities and other cognitive impairments. The study has shown that air pollutants can have a negative impact on cognitive functioning in children. In particular, it was found that exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) adversely affects attention control and working memory. Attention control is the ability to focus for extended periods without distraction whilst working memory is the ability to keep information in mind temporarily. These are skills which are vital to successful learning in schools, with working memory being found to have a direct link to academic achievement. As well as these cognitive impacts, it has been found that growing up in an area with poor air quality can have  other harmful effects on children including stunted growth and worsened chronic illnesses.

A number of changes can be made to make an improvement to air quality around schools and decrease the exposure of children to harmful air pollutants. Things such as moving school entrances and play areas away from busy roads, promoting cycling and walking, ensuring there is enough parking for scooters and bikes,  reducing traffic congestion directly outside the school, and creating incentives for cleaner travel can all help improve the air quality in the area directly around schools. Air quality monitoring can help schools understand when and where pollution is worst and use this data to put the most effective measures in place.

To read more about Crowcon’s air quality monitoring solution please visit crowcon.com/air-quality.

The importance of Gas Detection in the Waste to Energy industry 

Waste is composed of materials that are no longer needed, and thus are discarded. Waste can be classified as solid or liquid according to its form, and further categorised as hazardous and non-hazardous waste. Liquid waste includes municipal wastewater, storm water run-off and industrial wastewater discharge. 

Solid waste includes household rubbish, which is also called municipal solid waste (MSW), industrial waste – for example, from agriculture – medical and electronics waste. 

The treatment of solid waste is challenging because it may contain one of more contaminants (which may include heavy metals, explosive and flammable materials) and these must be dealt with before the waste can be treated. 

What are the gas hazards? 

There are many processes to turn waste into energy, these include, biogas plants, refuse collection, leachate pool, combustion and heat recovery, exhaust air scrubber and ash pit. All these processes pose gas hazards to those working in these environments.  

Within a Biogas Plant, biogas is produced. This is formed when organic materials such as agricultural and food waste are broken down by bacteria in an oxygen-deficient environment. This is a process called anaerobic digestion. When the biogas has been captured, it can be used to produce heat and electricity for engines, microturbines and fuel cells. Clearly, biogas has high methane content as well as substantial H2S (Hydrogen Sulphide), and this generates multiple serious gas hazards. (Read our blog for more information on biogas). However, there is an elevated risk of, fire and explosion, confined space hazards, asphyxiation, Oxygen depletion and gas poisoning (H2S, NH3). Workers in a biogas plant must have personal gas detectors that detect and monitor flammable gas, oxygen and toxic gases like H2S and CO. 

Within a refuse collection it is common to find flammable gas CH4 and toxic gases H2S, CO and NH3. This is because refuse bunkers are built several metres underground and gas detectors are usually mounted high above them, this makes those detectors hard to service and calibrate. In many cases, a sampling system is a practical solution as air samples can be brought to a convenient location and measured. 

Leachate is a liquid that drains (leaches) from an area in which waste is collected, with leachate pools presenting a range of gas hazards. These include the risk of flammable gas (explosion risk), H2S (poison, corrosion), ammonia (poison, corrosion), CO (poison) and adverse oxygen levels (suffocation). Leachate pool and passageways leading to the leachate pool requiring monitoring of CH4 (Methane), H2S, CO, NH3 (Ammonia), O2 and CO2. Various gas detectors should be placed along routes to the leachate pool, with output connected to external control panels. 

Combustion and heat recovery requires the detection of O2 and toxic gases SO2 (Sulphur dioxide) and CO. These gases all pose a threat to those who work in boiler house areas. 

Another process that is classed as a gas hazard is an exhaust air scrubber. The process is hazardous as the flue gas from incineration is highly toxic. This is because it contains pollutants such as NO2, SO2, HCl and dioxin. NO2 (Nitrogen dioxide) and SO2 are major greenhouse gases, while HCL and dioxides are harmful to human health 

Additionally, ash pits contain toxic gases as well as oxygen monitoring, through both O2 and CO.  

To read more on the waste to energy industry, visit our industry page.  

How do Electrochemical sensors work? 

Electrochemical sensors are the most used in diffusion mode in which gas in the ambient environment enters through a hole in the face of the cell. Some instruments use a pump to supply air or gas samples to the sensor. A PTFE membrane is fitted over the hole to prevent water or oils from entering the cell. Sensor ranges and sensitivities can be varied in design by using different size holes. Larger holes provide higher sensitivity and resolution, whereas smaller holes reduce sensitivity and resolution but increase the range.  

Benefits  

Electrochemical sensors have several benefits.  

  • Can be specific to a particular gas or vapor in the parts-per-million range. However, the degree of selectivity depends on the type of sensor, the target gas and the concentration of gas the sensor is designed to detect.  
  • High repeatability and accuracy rate. Once calibrated to a known concentration, the sensor will provide an accurate reading to a target gas that is repeatable. 
  • Not susceptible to poisoning by other gases, with the presence of other ambient vapours will not shorten or curtail the life of the sensor. 
  • Less expensive than most other gas detection technologies, such as IR or PID technologies. Electrochemical sensors are also more economical. 

Issues with cross-sensitivity  

Cross-sensitivity occurs when a gas other than the gas being monitored/detected can affect the reading given by an electrochemical sensor. This causes the electrode within the sensor to react even if the target gas is not actually present, or it causes an otherwise inaccurate reading and/or alarm for that gas. Cross-sensitivity may cause several types of inaccurate reading in electrochemical gas detectors. These can be positive (indicating the presence of a gas even though it is not actually there or indicating a level of that gas above its true value), negative (a reduced response to the target gas, suggesting that it is absent when it is present, or a reading that suggests there is a lower concentration of the target gas than there is), or the interfering gas can cause inhibition. 

Factors affecting electrochemical sensor life  

There are three main factors that affect the sensor life including temperature, exposure to extremely high gas concentrations and humidity. Other factors include sensor electrodes and extreme vibration and mechanical shocks. 

Temperature extremes can affect sensor life. The manufacturer will state an operating temperature range for the instrument: typically -30˚C to +50˚C. High quality sensors will, however, be able to withstand temporary excursions beyond these limits. Short (1-2 hours) exposure to 60-65˚C for H2S or CO sensors (for example) is acceptable, but repeated incidents will result in evaporation of the electrolyte and shifts in the baseline (zero) reading and slower response.  

Exposure to extremely high gas concentrations can also compromise sensor performance. Electrochemical sensors are typically tested by exposure to as much as ten-times their design limit. Sensors constructed using high quality catalyst material should be able to withstand such exposures without changes to chemistry or long-term performance loss. Sensors with lower catalyst loading may suffer damage. 

The most considerable influence on sensor life is humidity. The ideal environmental condition for electrochemical sensors is 20˚Celsius and 60% RH (relative humidity). When the ambient humidity increases beyond 60%RH water will be absorbed into the electrolyte causing dilution. In extreme cases the liquid content can increase by 2-3 times, potentially resulting in leakage from the sensor body, and then through the pins. Below 60%RH water in the electrolyte will begin to de-hydrate. The response time may be significantly extended as the electrolyte or dehydrated. Sensor electrodes can in unusual conditions be poisoned by interfering gases that adsorb onto the catalyst or react with it creating by-products which inhibit the catalyst. 

Extreme vibration and mechanical shocks can also harm sensors by fracturing the welds that bond the platinum electrodes, connecting strips (or wires in some sensors) and pins together. 

‘Normal’ life expectancy of electrochemical Sensor  

Electrochemical sensors for common gases such as carbon monoxide or hydrogen sulphide have an operational life typically stated at 2-3 years. More exotic gas sensor such as hydrogen fluoride may have a life of only 12-18 months. In ideal conditions (stable temperature and humidity in the region of 20˚C and 60%RH) with no incidence of contaminants, electrochemical sensors have been known to operate more than 4000 days (11 years). Periodic exposure to the target gas does not limit the life of these tiny fuel cells: high quality sensors have a large amount of catalyst material and robust conductors which do not become depleted by the reaction. 

Products  

As electrochemical sensors are more economical, We have a range of portable products and fixed products that use this type of sensor to detect gases.  

To explore more, visit our technical page for more information.