The importance of Gas Detection in the Water and Wastewater Industry 

Water is vital to our daily lives, both for personal and domestic use and industrial/commercial applications. Whether a facility focuses on the production of clean, potable water or treating effluent, Crowcon is proud to serve a wide variety of water industry clients, providing gas detection equipment that keeps workers safe around the world. 

Gas Hazards 

Apart from common gas hazards known in the industry; methane, hydrogen sulphide, and oxygen, there are bi-product gas hazards and cleaning material gas hazards that occur from purifying chemicals such as ammonia, chlorine, chlorine dioxide or ozone that are used in the decontamination of the waste and effluent water, or to remove microbes from clean water. There is great potential for many toxic or explosive gases to exist as a result of the chemicals used in the water industry. And added to these are chemicals that may be spilled or dumped into the waste system from industry, farming or building work. 

Safety Considerations  

Confined Space Entry 

The pipelines used to transport water require regular cleaning and safety checks; during these operations, portable multi-gas monitors are used to protect the workforce. Pre-entry checks must be completed prior to entering any confined space and commonly O2, CO, H2S and CH4 are monitored. Confined spaces are small, so portable monitors must be compact and unobtrusive for the user, yet able to withstand the wet and dirty environments in which they must perform. Clear and prompt indication of any increase in gas monitored (or any decrease for oxygen) is of paramount importance – loud and bright alarms are effective in raising the alarm to the user. 

Risk assessment 

Risk assessment is critical, as you need to be aware of the environment that you are entering and thus working in. Therefore, understanding the applications and identifying the risks regarding all safety aspects. Focusing on gas monitoring, as part of the risk assessment, you need to be clear on what gases may be present.  

Fit for purpose 

There is a variety of applications within the water treatment process, giving the need to monitor multiple gases, including carbon dioxide, hydrogen sulphide, chlorine, methane, oxygen, ozone and chlorine dioxide. Gas detectors are available for single or multiple gas monitoring, making them practical for different applications as well as making sure that, if conditions change (such as sludge is stirred up, causing a sudden increase in hydrogen sulphide and flammable gas levels), the worker is still protected.  

Legislation   

European Commission Directive 2017/164 issued in January 2017, established a new list of indicative occupational exposure limit values (IOELVs). IOELV are health-based, non-binding values, derived from the most recent scientific data available and considering the availability of reliable measurement techniques. The list includes carbon monoxide, nitrogen monoxide, nitrogen dioxide, sulphur dioxide, hydrogen cyanide, manganese, diacetyl and many other chemicals. The list is based on Council Directive 98/24/EC that considers the protection of the health and safety of workers from the risks related to chemical agents in the workplace. For any chemical agent for which an IOELV has been set at Union level, Member States are required to establish a national occupational exposure limit value. They also are required to take into account the Union limit value, determining the nature of the national limit value in accordance with national legislation and practice. Member States will be able to benefit from a transitional period ending at the latest on 21 August 2023.  

The Health and Safety Executive (HSE) state that each year several workers will suffer from at least one episode of work-related illness. Although, most illnesses are relatively mild cases of gastroenteritis, there is also a risk for potentially fatal diseases, such as leptospirosis (Weil’s disease) and hepatitis. Even though these are reported to the HSE, there could be significant under-reporting as there is often failure to recognise the link between illness and work.  

Under domestic law of the Health and Safety at Work etc Act 1974, employers are responsible for ensuring the safety of their employees and others. This responsibility is reinforced by regulations. 

The Confined Spaces Regulations 1997 applies where the assessment identifies risks of serious injury from work in confined spaces. These regulations contain the following key duties: 

  • Avoid entry to confined spaces, e.g., by doing the work from the outside. 
  • If entry to a confined space is unavoidable, follow a safe system of work.
  • Put in place adequate emergency arrangements before the work start. 

The Management of Health and Safety at Work Regulations 1999 requires employers and self-employed people to carry out a suitable and sufficient assessment of the risks for all work activities for the purpose of deciding what measures are necessary for safety. For work in confined spaces this means identifying the hazards present, assessing the risks and determining what precautions to take. 

Our solutions

Elimination of these gas hazards is virtually impossible, so permanent workers and contractors must depend on reliable gas detection equipment to protect them. Gas detection can be provided in both fixed and portable forms. Our portable gas detectors protect against a wide range of gas hazards, these include T4x, Clip SGD, Gasman, Tetra 3,Gas-Pro, T4 and Detective+. Our fixed gas detectors are used in many applications where reliability, dependability and lack of false alarms are instrumental to efficient and effective gas detection, these include Xgard, Xgard Bright and IRmax. Combined with a variety of our fixed detectors, our gas detection control panels offer a flexible range of solutions that measure flammable, toxic and oxygen gases, report their presence and activate alarms or associated equipment, for the wastewater industry our panels include Gasmaster.    

To find out more on the gas hazards in wastewater and water treatment visit our industry page for more information.  

Construction and Key Gas Challenges

Workers in the construction industry are at risk from a wide variety of hazardous gases including Carbon Monoxide (CO), Chlorine Dioxide (CLO2), Methane (CH4), Oxygen (O2), Hydrogen Sulphide (H2S) and Volatile Organic Compounds (VOC’s). 

Through the use of specific equipment, transport and the undertaking of sector specific activities, construction is a main contributor to the emission of toxic gases into the atmosphere, which also means construction personnel are more at risk of ingestion of these toxic contaminants. 

Gas challenges can be found in a variety of applications including building material storage, confined spaces, welding, trenching, land clearing and demolition. Ensuring the protection of workers within the construction industry from the multitude of hazards they may encounter is very important. With a specific focus on safeguarding teams from harm by, or the consumption of, toxic, flammable and poisonous gases. 

Gas Challenges 

Confined Space Entry 

Workers are more at risk from hazardous gases and fumes when they are operating within confined spaces.  Those entering these spaces need to be protected from the presence of flammable or/and toxic gases such as Volatile Organic Compounds (ppm VOC), Carbon Monoxide (ppm CO) and Nitrogen Dioxide (ppm NO2). Undertaking clearance measurements and pre-entry safety checks are paramount to ensure safety before a worker enters the space. Whilst in confined spaces gas detection equipment must be worn ongoingly in case of environmental shifts which make the space no longer safe to work in, due to a leak for example, and evacuation is needed. 

Trenching and Shoring 

During excavation works, such as trenching and shoring, construction workers are at risk of inhaling harmful gases generated by degradable materials present in certain ground types. If undetected, as well as posing risks to the construction workforce, they can also migrate through subsoil and cracks into the completed building and harm housing residents. Trenched areas can also have reduced oxygen levels, as well as contain toxic gases and chemicals. In these cases atmospheric testing should be performed in excavations that exceed four feet. There is also the risk of hitting utility lines when digging which can cause natural gas leaks and lead to worker fatalities. 

Building Material Storage  

Many of the materials used within construction can release toxic compounds (VOC’s). These can form in a variety of states (solid or liquid) and come from materials such as adhesives, natural and plywood’s, paint, and building partitions. Pollutants include phenol, acetaldehyde and formaldehyde. When ingested, workers can suffer from nausea, headaches, asthma, cancer and even death. VOCs are specifically dangerous when consumed within confined spaces, due to the risk of asphyxiation or explosion. 

Welding and Cutting 

Gases are produced during the welding and cutting process, including carbon dioxide from the decomposition of fluxes, carbon monoxide from the breakdown of carbon dioxide shielding gas in arc welding, as well as ozone, nitrogen oxides, hydrogen chloride and phosgene from other processes. Fumes are created when a metal is heated above its boiling point and then its vapours condense into fine particles, known as solid particulates. These fumes are obviously a hazard for those working in the sector and  illustrate the importance of reliable gas detection equipment to reduce exposure. 

Health and Safety Standards 

Organisations working in the construction sector can prove their credibility and safety operationally by gaining ISO certification. ISO (International Organisation for Standardisation) certification is split across multiple different certificates, all of which recognise varying elements of safety, efficiency and quality within an organisation. Standards cover best practice across safety, healthcare, transportation, environmental management and family. 

Although not a legal requirement, ISO standards are widely recognised as making the construction industry a safer sector by establishing global design and manufacturing definitions for almost all processes. They outline specifications for best practice and safety requirements within the construction industry from the ground up. 

In the UK, other recognised safety certifications include the NEBOSH, IOSH and CIOB courses which all offer varied health and safety training for those in the sector to further their understanding of working safely in their given field.  

To find out more on the gas challenges in construction visit our industry page for more information. 

The Dangers of Gas in Farming and Agriculture 

Farming and agriculture is a colossal industry the world over, providing more than 44 million jobs in the EU and making up over 10% of total US employment. 

With a wide range of processes involved in this sector, there are bound to be hazards that must be considered. These include gas hazards from the likes of methane, hydrogen sulphide, ammonia, carbon dioxide and nitrous oxide. 

Methane is a colourless, odourless gas which can have harmful effects on humans resulting in slurred speech, vision problems, memory loss, nausea and in extreme cases can impact breathing and heartrate, potentially leading to unconsciousness and even death. In agricultural environments, it is created through anaerobic digestion of organic material, such as manure. The amount of methane generated is exacerbated in areas which are poorly ventilated or high in temperature, and in areas with particular lack of airflow, the gas can build up, become trapped and cause explosions. 

Carbon dioxide (CO2) is a gas which is naturally produced in the atmosphere, levels of which can be heightened by agricultural processes. CO2 can be emitted by a range of farming process including crop and livestock production and is also emitted by some equipment which is used in agricultural applications. Storage spaces used for waste and grain and sealed silos are of particular concern due to the capacity for CO2 to build up and displace oxygen, increasing suffocation risk for both animals and humans alike. 

Similarly, to methane, hydrogen sulphide comes from the anaerobic decomposition of organic material and can also be found in a range of agricultural processes relating to the production and consumption of biogas. H2S prevents oxygen from being carried to our vital organs and areas where it builds up often have reduced oxygen concentrations, furthering the risk of asphyxiation where H2S levels are high. Whilst it could be considered easier to detect due its distinct ‘rotten egg’ smell, the intensity of the smell actually decreases at higher concentrations and prolonged exposure. At high levels, H2S can cause severe irritation of, and fluid build-up in the lungs and impact the nervous system. 

Ammonia (NH3) is a gas found in animal waste which is often then spread and emitted further through slurry spreading on agricultural land. As with many of the gases covered, the impact of ammonia is heightened when there is a lack of ventilation. It is harmful to the wellbeing of both livestock and humans, causing respiratory diseases in animals whilst high levels can lead to burns and swelling of the airways and lung damage in humans and can be fatal. 

Nitrogen oxide (NO2) is another gas to be aware of in the agriculture and farming industry. It is present in synthetic fertilisers which are often used in more intensive farming practices to ensure greater crop yields. The potential negative health impacts of NO2 in humans include reduced lung function, internal bleeding, and ongoing respiratory problems.  

Workers in this industry are frequently on the move, and for this specific purpose Crowcon offers a wide range of fixed and portable gas detectors to keep workers safe. Crowcon’s portable range comprises T4, Gas-Pro, Clip SGD and Gasman all of which offer reliable, transportable detection capacities for a variety of gases. Our fixed gas detectors are used where reliability, dependability and lack of false alarms are instrumental to efficient and effective protection of assets and areas, and include the Xgard and Xgard Bright. Combined with a variety of our fixed detectors, our gas detection control panels offer a flexible range of solutions that measure flammable, toxic and oxygen gases, report their presence and activate alarms or associated equipment, for the farming and agriculture industry we often recommend our Gasmaster, Vortex and Addressable Controllers panels.

To find out more on the gas hazards in farming and agriculture visit our industry page for more information.

The Dangers of Gas Exposure in Wineries

Wineries face a unique set of challenges when it comes to safeguarding workers from the potential harm caused by hazardous gases. Gas exposure has the potential to occur at every stage of the wine production process, from the moment that the grapes arrive at the winery facility, through to the fermentation and bottling activities. Care must be taken at each stage to ensure that workers are not exposed to unnecessary risk. There are several specific environments within the winery facility that pose a risk of gas leakage and exposure, including fermentation rooms, pits, barrel cellars, sumps, storage tanks and bottling rooms. The main gas hazards that are found during the winemaking process are carbon dioxide, and oxygen displacement, but also hydrogen sulphide, sulphur dioxide, ethyl alcohol and carbon monoxide.

What are the Gas Hazards?

Hydrogen sulphide (H2S)

Hydrogen sulphide is a gas that can be present during the fermentation process. It is more commonly present in damp conditions where bacterial action has acted on natural oils. It hides dissolved in standing water until disturbed. The most dangerous occurrence is when cleaning a confined space e.g., a tank where released gases cannot easily escape. A pre-entry check comes up clean, and the standing water is then disturbed upon entry. The risks associated with H2S are that it is potentially hazardous to health, upsetting breathing patterns. Hydrogen sulphide poses severe respiratory risks, even at a relatively low concentration in the air. The gas is very easily and rapidly absorbed into the bloodstream through the lung tissue, which means it is distributed throughout the whole body very quickly.

Sulphur Dioxide (SO2)

Sulphur Dioxide is a natural by-product of fermentation, but it is also commonly used as an additive in the process of organic wine making. Extra SO2 is added during the wine making process in order to prevent the growth of any undesirable yeast and microbes within the wine. Sulphur dioxide can be highly hazardous to health and is a highly toxic gas, causing numerous irritations in the body upon contact. Sulphur dioxide is a gas that can cause irritation to the airways, nose, and throat. Workers who are exposed to high levels of sulphur dioxide may experience vomiting, nausea, stomach cramps, and irritation or corrosive damage to the lungs and airways.

Ethanol (ethyl alcohol)

Ethanol is the main alcoholic product of organic wine fermentation. It helps to maintain the flavour of the wine and stabilizes the aging process. Ethanol is created during fermentation as the yeast converts sugar from the grapes. Wine typically contains somewhere between 7% and 15% ethanol, which gives the drink its alcohol by volume (ABV) percentage. The amount of ethanol actually produced depends on the sugar content of the grapes, the fermentation temperature, and the type of yeast that is used. Ethanol is a colourless and odourless liquid that gives off flammable and potentially hazardous fumes. The fumes given off by ethanol or ethyl alcohol can irritate the airways and lungs if inhaled, with the possibility of intense coughing and choking.

Where are the dangers?

Open Fermentation Tanks

Any worker whose job involves carrying out operations over an open fermentation vessel or tank may be at a high risk of gas exposure, especially to CO2, or oxygen depletion. It has been shown that a worker who leans over the top of an open fermenter during full production, even though they may be as much as 10 feet off the ground, can potentially be exposed to 100% CO2. Therefore, particular care and attention to gas detection should be taken in these areas.

Exposure Due To Inadequate Ventilation

The fermentation process needs to take place in environments that are well ventilated to avoid the build-up of toxic and asphyxiant gases. Fermentation rooms, tank rooms, and cellars are all places that may pose a risk. During cold weather or night-time, increased levels of gas may build up as door and window vents may be shut.

Confined Spaces

Confined spaces such as pits and sumps are often problematic and well known for the potential build-up of hazardous gases. The definition of a confined space in a winery is one that contains, or may contain, a hazardous atmosphere, has the potential for engulfment by material, or an entrant to the environment may become trapped or asphyxiated.

Multiple Units

As a winery grows and expands their operations, they may want to add new production units to meet the demand. However, it is important to remember that potential gas exposure risks differ between environments, e.g., the gas risk in a fermentation cellar is not the same as a barrel room. Therefore, different types of gas detectors may be needed in different areas.

For more information about gas detection solutions for wineries, or to ask further questions get in touch today.

Gold Mining: What gas detection do I need? 

How is gold mined?

Gold is a rare substance equating to 3 parts per billion of the earth’s outer layer, with most of the world’s available gold coming from Australia. Gold, like iron, copper and lead, is a metal. There are two primary forms of gold mining, including open-cut and underground mining. Open mining involves earth-moving equipment to remove waste rock from the ore body above, and then mining is conducted from the remaining substance. This process requires waste and ore to be struck at high volumes to break the waste and ore into sizes suitable for handling and transportation to both waste dumps and ore crushers. The other form of gold mining is the more traditional underground mining method. This is where vertical shafts and spiral tunnels transport workers and equipment into and out of the mine, providing ventilation and hauling the waste rock and ore to the surface.

Gas detection in mining

When relating to gas detection, the process of health and safety within mines has developed considerably over the past century, from morphing from the crude usage of methane wick wall testing, singing canaries and flame safety to modern-day gas detection technologies and processes as we know them. Ensuring the correct type of detection equipment is utilised, whether fixed or portable, before entering these spaces. Proper equipment utilisation will ensure gas levels are accurately monitored, and workers are alerted to dangerous concentrations within the atmosphere at the earliest opportunity.

What are the gas hazards and what are the dangers?

The dangers those working within the mining industry face several potential occupational hazards and diseases, and the possibility of fatal injury. Therefore, understanding the environments and hazards, they may be exposed to is important.

Oxygen (O2)

Oxygen (O2), usually present in the air at 20.9%, is essential to human life. There are three main reasons why oxygen poses a threat to workers within the mining industry. These include oxygen deficiencies or enrichment, as too little oxygen can prevent the human body from functioning leading to the worker losing consciousness. Unless the oxygen level can be restored to an average level, the worker is at risk of potential death. An atmosphere is deficient when the concentration of O2 is less than 19.5%. Consequently, an environment with too much oxygen is equally dangerous as this constitutes a greatly increased risk of fire and explosion. This is considered when the concentration level of O2 is over 23.5%

Carbon Monoxide (CO)

In some cases, high concentrations of Carbon Monoxide (CO) may be present. Environments that this may occur include a house fire, therefore the fire service are at risk of CO poisoning. In this environment there can be as much as 12.5% CO in the air which when the carbon monoxide rises to the ceiling with other combustion products and when the concentration hits 12.5% by volume this will only lead to one thing, called a flashover. This is when the whole lot ignites as a fuel. Apart from items falling on the fire service, this is one of the most extreme dangers they face when working inside a burning building. Due to the characteristics of CO being so hard to identify, I.e., colourless, odourless, tasteless, poisonous gas, it may take time for you to realise that you have CO poisoning. The effects of CO can be dangerous, this is because CO prevents the blood system from effectively carrying oxygen around the body, specifically to vital organs such as the heart and brain. High doses of CO, therefore, can cause death from asphyxiation or lack of oxygen to the brain. According to statistics from the Department of Health, the most common indication of CO poisoning is that of a headache with 90% of patients reporting this as a symptom, with 50% reporting nausea and vomiting, as well as vertigo. With confusion/changes in consciousness, and weakness accounting for 30% and 20% of reports.

Hydrogen sulphide (H2S)

Hydrogen sulphide (H2S) is a colourless, flammable gas with a characteristic odour of rotten eggs. Skin and eye contact may occur. However, the nervous system and cardiovascular system are most affected by hydrogen sulphide, which can lead to a range of symptoms. Single exposures to high concentrations may rapidly cause breathing difficulties and death.

Sulphur dioxide (SO2)

Sulphur dioxide (SO2) can cause several harmful effects on the respiratory systems, in particular the lung. It can also cause skin irritation. Skin contact with (SO2) causes stinging pain, redness of the skin and blisters. Skin contact with compressed gas or liquid can cause frostbite. Eye contact causes watering eyes and, in severe cases, blindness can occur.

Methane (CH4)

Methane (CH4) is a colourless, highly flammable gas with a primary component being that of natural gas. High levels of (CH4) can reduce the amount of oxygen breathed from the air, which can result in mood changes, slurred speech, vision problems, memory loss, nausea, vomiting, facial flushing and headache. In severe cases, there may be changes in breathing and heart rate, balance problems, numbness, and unconsciousness. Although, if exposure is for a longer period, it can result in fatality.

Hydrogen (H2)

Hydrogen Gas is a colourless, odourless, and tasteless gas which is lighter than air. As it is lighter than air this means it float higher than our atmosphere, meaning it is not naturally found, but instead must be created. Hydrogen poses a fire or explosion risk as well as an inhalation risk. High concentrations of this gas can cause an oxygen-deficient environment. Individuals breathing such an atmosphere may experience symptoms which include headaches, ringing in ears, dizziness, drowsiness, unconsciousness, nausea, vomiting and depression of all the senses

Ammonia (NH3)

Ammonia (NH3) is one of the most widely used chemicals globally that is produced both in the human body and in nature. Although it is naturally created (NH3) is corrosive which poses a serve concern for health. High exposure within the air can result in immediate burning to the eyes, nose, throat and respiratory tract. Serve cases can result in blindness.

Other gas risks

Whilst Hydrogen Cyanide (HCN) doesn’t persist within the environment, improper storage, handling and waste management can pose severe risk to human health as well as effects on the environment. Cyanide interferes with human respiration at cellular levels that can cause serve and acute effects, including rapid breathing, tremors, asphyxiation.

Diesel particulate exposure can occur in underground mines as a result of diesel-powered mobile equipment used for drilling and haulage. Although control measures include the use of low sulphur diesel fuel, engine maintenance and ventilation, health implication includes excess risk of lung cancer.

Products that can help to protect yourself

Crowcon provide a range of gas detection including both portable and fixed products all of which are suitable for gas detection within the mining industry.

To find out more visit our industry page here.

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. 

You won’t find Crowcon sensors sleeping on the job

MOS (metal oxide semiconductor) sensors have been seen as one of the most recent solutions for tackling detection of hydrogen sulphide (H2S) in fluctuating temperatures from up to 50°C down to the mid-twenties, as well as humid climates such as the Middle East.

However, users and gas detection professionals have realised MOS sensors are not the most reliable detection technology. This blog covers why this technology can prove difficult to maintain and what issues users can face.

One of the major drawbacks of the technology is the liability of the sensor “going to sleep” when it doesn’t encounter gas for a period of time. Of course, this is a huge safety risk for workers in the area… no-one wants to face a gas detector that ultimately doesn’t detect gas.

MOS sensors require a heater to equalise, enabling them to produce a consistent reading. However, when initially switched on, the heater takes time to warm up, causing a significant delay between turning on the sensors and it responding to hazardous gas. MOS manufacturers therefore recommend users to allow the sensor to equilibrate for 24-48 hours before calibration. Some users may find this a hinderance for production, as well as extended time for servicing and maintenance.

The heater delay isn’t the only problem. It uses a lot of power which poses an additional issue of dramatic changes of temperature in the DC power cable, causing changes in voltage as the detector head and inaccuracies in gas level reading. 

As its metal oxide semiconductor name suggests, the sensors are based around semiconductors which are recognised to drift with changes in humidity- something that is not ideal for the humid Middle Eastern climate. In other industries, semiconductors are often encased in epoxy resin to avoid this, however in a gas sensor this coating would the gas detection mechanism as the gas couldn’t reach the semiconductor. The device is also open to the acidic environment created by the local sand in the Middle East, effecting conductivity and accuracy of gas read-out.

Another significant safety implication of a MOS sensor is that with output at near-zero levels of H2S can be false alarms. Often the sensor is used with a level of “zero suppression” at the control panel. This means that the control panel may show a zero read-out for some time after levels of H2S have begun to rise. This late registering of low-level gas presence can then delay the warning of a serious gas leak, opportunity for evacuation and the extreme risk of lives.

MOS sensors excel in reacting quickly to H2S, therefore the need for a sinter counteracts this benefit. Due to H2S being a “sticky” gas, it is able to be adsorbed onto surfaces including those of sinters, in result slowing down the rate at which gas reaches the detection surface.

To tackle the drawbacks of MOS sensors, we’ve revisited and improved on the electrochemical technology with our new High Temperature (HT) H2S sensor for XgardIQ. The new developments of our sensor allow operation of up to 70°C at 0-95%rh- a significant difference against other manufacturers claiming detection of up to 60°C, especially under the harsh Middle Eastern environments.

Our new HT H2S sensor has been proven to be a reliable and resilient solution for the detection of H2S at high temperatures- a solution that doesn’t fall asleep on the job!

Click here for more information on our new High Temperature (HT) H2S sensor for XgardIQ.

An ingenious solution to the problem of high temperature H2S

Due to extreme heat in the Middle East climbing up to 50°C in the height of summer, the necessity for reliable gas detection is critical. In this blog, we’re focusing on the requirement for detection of hydrogen sulphide (H2S)- a long running challenge for the Middle East’s gas detection industry.

By combining a new trick with old technology, we’ve got the answer to reliable gas detection for environments in the harsh Middle Eastern climate. Our new High Temperature (HT) H2S sensor for XgardIQ has been revisited and improved by our team of Crowcon experts by using a combination of two ingenious adaptations to its original design.

In traditional H2S sensors, detection is based on electrochemical technology, where electrodes are used to detect changes induced in an electrolyte by the presence of the target gas. However, high temperatures combined with low humidity causes the electrolyte to dry out, impairing sensor performance so that the sensor has to be replaced regularly; meaning high replacement costs, time and efforts.

Making the new sensor so advanced from its predecessor is its ability to retain the moisture levels within the sensor, preventing evaporation even in high temperature climates. The updated sensor is based on electrolytic gel, adapted to make it more hygroscopic and avoiding dehydration for longer.

As well as this, the pore in the sensor housing has been reduced, limiting the moisture from escaping. This chart indicated weight loss which is indicative of moisture loss. When stored at 55°C or 65°C for a year just 3% of weight is lost. Another typical sensor would lose 50% of its weight in 100 days in the same conditions.

For optimal leak detection, our remarkable new sensor also features an optional remote sensor housing, while the transmitter’s displays screen and push-button controls are positioned for safe and easy access for operators up to 15metres away.

 

The results of our new HT H2S sensor for XgardIQ speak for themselves, with an operating environment of up to 70°C at 0-95%rh, as well featuring a 0-200ppm and T90 response time of less than 30 seconds. Unlike other sensors for detecting H2S, it offers a life expectancy of over 24 months, even in tough climates like the Middle East.

The answer to the Middle East’s gas detection challenges fall in the hands of our new sensor, providing its users with cost-effective and reliable performance.

Click here for more information about the Crowcon HT H2S sensor.

Explosion hazards in inerted tanks and how to avoid them

Hydrogen sulphide (H2S) is known for being extremely toxic, as well as highly corrosive. In an inerted tank environment, it poses an additional and serious hazard combustion which, it is suspected, has been the cause of serious explosions in the past.

Hydrogen sulphide can be present in %vol levels in “sour” oil or gas. Fuel can also be turned ‘sour’ by the action of sulphate-reducing bacteria found in sea water, often present in cargo holds of tankers. It is therefore important to continue to monitor the level of H2S, as it can change, particularly at sea. This H2S can increase the likelihood of a fire if the situation is not properly managed.

Tanks are generally lined with iron (sometimes zinc-coated). Iron rusts, creating iron oxide (FeO). In an inerted headspace of a tank, iron oxide can react with H2S to form iron sulphide (FeS). Iron sulphide is a pyrophore; which means that it can spontaneously ignite in the presence of oxygen

Excluding the elements of fire

A tank full of oil or gas is an obvious fire hazard under the right circumstances. The three elements of fire are fuel, oxygen and an ignition source. Without these three things, a fire can’t start. Air is around 21% oxygen. Therefore, a common means to control the risk of a fire in a tank is to remove as much air as possible by flushing the air out of the tank with an inert gas, such as nitrogen or carbon dioxide. During tank unloading, care is taken that fuel is replaced with inert gas rather than air. This removes the oxygen and prevents fire starting.

By definition, there is not enough oxygen in an inerted environment for a fire to start. But at some point, air will have to be let into the tank – for maintenance staff to safety enter, for example. There is now the chance for the three elements of fire coming together. How is it to be controlled?

  • Oxygen has to be allowed in
  • There may be present FeS, which the oxygen will cause to spark
  • The element that can be controlled is fuel.

If all the fuel has been removed and the combination of air and FeS causes a spark, it can’t do any harm.

Monitoring the elements

From the above, it is obvious how important it is to keep track of all the elements that could cause a fire in these fuel tanks. Oxygen and fuel can be directly monitored using an appropriate gas detector, like Gas-Pro TK. Designed for these specialist environments, Gas-Pro TK automatically copes with measuring a tank full of gas (measured in %vol) and a tank nearly empty of gas (measured in %LEL). Gas-Pro TK can tell you when oxygen levels are low enough to be safe to load fuel or high enough for staff to safely enter the tank. Another important use for Gas-Pro TK is to monitor for H2S, to allow you judge the likely presence of the pryophore, iron sulphide.

Hydrogen Sulphide Hazards

Next in our series of short videos is our hydrogen sulphide detection factoid.

Where is H2S found?

Hydrogen sulphide is a significant danger to workers in many industries. It is a by-product of industrial processes, such as petroleum refining, mining, paper mills, and iron smelting. It is also a common product of the biodegradation of organic matter; pockets of H2S can collect in rotting vegetation, or sewage itself, and be released when disturbed.

Continue reading “Hydrogen Sulphide Hazards”