Blogs listed by tag: portable

The importance of gas detection in the Petrochemical Industry

Closely linked to oil and gas, the petrochemicals industry takes raw materials from refining and gas processing and, through chemical process technologies, converts them into valuable products. In this sector, the organic chemicals produced in the largest volumes are methanol, ethylene, propylene, butadiene, benzene, toluene and xylenes (BTX). These chemicals are the building blocks of many consumer goods including plastics, clothing fabric, construction materials, synthetic detergents and agrichemical products.

Potential Hazards

Exposure to potential hazardous substances is more likely to occur during shutdown or maintenance work as these are a deviation from the refinery’s routine operations. As these deviations are out of normal routine, care should be exercised at all times to avoid the inhalation of solvent vapours, toxic gases, and other respiratory contaminants. The assistance of constant automated monitoring is helpful in determining the presence of solvents or gases, allowing their associated risks to be mitigated. This includes warning systems such as gas and flame detectors, supported by emergency procedures, and permit systems for any kind of potentially dangerous work.

The petroleum industry is split into upstream, midstream and downstream and these are defined by the nature of the work that takes place in each area. Upstream work is typically known as the exploration and production (E&P) sector. Midstream refers to the transportation of products through pipelines, transit and oil tankers as well as the wholesale marketing of petroleum-based products. The downstream sector refers to the refining of petroleum crude oil, the processing of raw natural gas and the marketing and distribution of finished products.

Upstream

Fixed and portable gas detectors are needed to protect plant and personnel from the risks of flammable gas releases (commonly methane) as well as from high levels of H2S, particularly from sour wells. Gas detectors for O2 depletion, SO2 and volatile organic compounds (VOCs) are required items of personal protection equipment (PPE), which is usually highly visible colour and worn near breathing space. Sometimes HF solution is used as a scouring agent. Key requirements for gas detectors are rugged and reliable design and long battery life. Models with design elements that support easy fleet management and compliance obviously have an advantage. You can read about VOC risk and Crowcon’s solution in our case study.

Midstream

Fixed monitoring of flammable gases situated close to pressure relief devices, filling and emptying areas is necessary to deliver early warning of localised leaks. Multi-gas portable monitors must be used to maintain personal safety, especially during work in confined spaces and supporting hot work permit area testing. Infrared technology in flammable gas detection supports purging with the ability to operate in inert atmospheres and delivers reliable detection in areas where pellistor type detectors would fail, due to poisoning or volume level exposure. You can read more on how infrared detection works in our blog and read our case study of infrared monitoring in refinery settings in Southeast Asia.

Portable laser methane detection (LMm) allows users to pin-point leaks at distance and in hard-to-reach areas, reducing the need for personnel to enter potentially dangerous environments or situations while performing routine or investigative leak monitoring. Using LMm is a quick and effective way to check areas for methane with a reflector, from up to 100m away. These areas include closed buildings, confined spaces and other difficult-to-reach areas such as above-ground pipelines that are near water or behind fences.

Downstream

In downstream refining, the gas risks may be almost any hydrocarbon, and may also include hydrogen sulphide, sulphur dioxide and other by-products. Catalytic flammable gas detectors are one of the oldest flammable gas detector types. They work well, but must have a bump testing station, to ensure each detector responds to the target gas and is still functional. The ongoing demand to reduce facility down-time whilst ensuring safety, especially during shutdown and turnaround operations, means that gas detection manufacturers must deliver solutions offering ease of use, straightforward training and reduced maintenance times, along with local service and support.

During plant shutdowns, processes are stopped, items of equipment are opened and checked and the number of people and moving vehicles at the site is many times higher than normal. Many of the processes undertaken will be hazardous and require specific gas monitoring. For example, welding and tank cleaning activities require area monitors as well as personal monitors to protect those on site.

Confined space

Hydrogen sulphide (H2S) is a potential problem in the transport and storage of crude oil. The cleaning of storage tanks presents a high hazard potential. Many confined-space entry problems can occur here, including oxygen deficiency resulting from previous inerting procedures, rusting, and oxidation of organic coatings. Inerting is the process of reducing the oxygen levels in a cargo tank to remove the oxygen element required for ignition. Carbon monoxide can be present in the inerting gas. In addition to H2S, depending on the characteristics of the product previously stored in the tanks, other chemicals that may be encountered include metal carbonyls, arsenic, and tetraethyl lead.

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 Clip SGD, Gasman, Tetra 3, Gas-Pro, T4, Gas-Pro TK 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, Fgard IR3 Flame Detector 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 petrochemical industry our panels include Addressable Controllers, Vortex and Gasmonitor.

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

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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.  

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Our Partnership with Thorne and Derrick

Background 

Founded in 1985, Thorne & Derrick (T&D) and with offices in Chester-Le-Street and Bristol are leaders in product development and problem solving in hazardous areas. T&D distribute our full range of gas detection products, supplying industries such as utilities, power, renewable energy, construction, rail, offshore, oil, gas and petrochemical industries. Thorne & Derrick provide constancy to their global customer portfolio through high responsivity and are absolutely committed to providing world-class customer service. 

Views on gas detection

Portable gas detection is an essential piece of equipment when detecting toxic or explosive gases and measuring gas concentration. T&D put the customers needs at the forefront, by providing workers in all sectors with safety products that are correctly certified and efficient. This helps to alleviate the risk of working in hazardous areas alongside Thorne & Derrick’s provision of certified and safe portable & temporary lighting, power, heat and ventilation to ensure workers can carry out maintenance, repair and installation works safely. 

Through expertise and confidence given by their sales engineers as well as listening to the customer’s requirements, T&D confidently provide solutions that are fully compliant with regulations and that are tailored to what the customer needs. 

Working with Crowcon

A 10-year partnership and continued communication have allowed Thorne & Derrick to supply their customers with gas detection solutions and aim to continue to educate and meet legislation. “We’re thrilled to be working alongside T&D to provide gas detection to support a wide range of applications of applications in numerous industries”- Natalie Lundie, Marketing Lead. With over 35 years of experience, T&D delivers effective gas detection solutions providing confidence for those working in hazardous areas.  

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Are there dangers of gas in telecommunications? 

The telecommunication industry contains includes cable providers, internet service providers, satellite providers and telephone providers and confined spaces. Even simple above ground termination boxes may contain gas hazards generated from the cable runs underground. Gases such as methane, carbon dioxide and hydrogen sulphide can run through cable trunking accumulating in termination boxes and manifesting as hazards when the termination box is opened.

The risk of danger occurs when a worker is sent to carry out tasks involving opening up of enclosed volumes that may not have been accessed for a period of time. All telecommunications companies have these in abundance.

What are the Dangers?

Those working in the telecommunications industry are at risk from a variety of gaseous dangers, many of which could cause harm to their health and safety. Though less obvious, these risks should be taken as seriously as falls from heights or electrocution, and they require a similar level of training. A worker must not climb to an elevated position without a harness, similarly they shouldn’t be accessing confined spaces without appropriate confined space training. Awareness of the dangers present and minimising the risks that could lead to adverse effects is a well-known safety principle. Training and proper PPE can help protect workers from these hazards.

Gas Hazards and Risks

As there are many confined spaces in the telecommunication industry workers are at risk from the presence of hazardous and toxic gases there. Hazardous gases can also be linked to seemingly simple above-ground termination boxes. Gases such as methane, carbon dioxide and hydrogen sulphide sometimes travel through the cable trunking, and therefore, when the termination box is opened, a build-up of these gases can be released.

Enclosed or partially enclosed spaces with high levels of methane in the air reduce the amount of oxygen available to breathe and therefore can cause mood changes, speech and vision problems, memory loss, nausea, sickness, facial flushing and headaches. In more severe cases and prolonged exposure, there may be changes in breathing and heart rate, balance problems, numbness, and unconsciousness. There is also a risk of fire as methane is highly flammable.

Carbon monoxide (CO) consumption also poses serious health issues to workers, with those ingesting the toxic substance facing flu-like symptoms, chest pain, confusion, fainting arrhythmias, seizures, or even worse health effects for high or long lasting exposures. Hydrogen sulphide (H2S) poisoning causes similar issues, as well as delirium, tremors, convulsions, and skin and eye irritation. Carbon dioxide is an asphyxiant gas that can displace oxygen and hance dizziness.

Our solution

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 Tetra 3 and T4. Our fixed gas detectors are used where reliability, dependability and lack of false alarms are instrumental to efficient and effective gas detection, these include Xgard and Xgard Bright. Combined with a variety of our fixed detectors, our gas detection control panels offer a flexible range of solutions which are able to measure flammable, toxic and oxygen gases, report their presence and activate alarms or associated equipment, for the telecommunication industry our panels include Gasmaster.

To find out more on the dangers of gas hazards in telecommunication visit our industry page for more information.

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Transportation and Key Gas Challenges 

The transportation sector is one of the largest industries in the world, spanning a variety of applications. The sector offers services concerned with the movement of people and cargo of all types, across air freight and logistics, airlines and airport services, road and rail, transportation infrastructure, trucking, highways, rail tracks, and marine ports and services.

Gas hazards during transportation  

The transport of dangerous goods is regulated in order to prevent, accidents involving people or property, damage to the environment. There a numerous gas hazards including the transportation of hazardous material, air conditioning emissions, cabin combustion and hangar leaks. 

The transportation of hazardous materials poses a risk to those involved. There are nine classification areas specified by the United Nations (UN) including explosives, gases, flammable liquids and solids, oxidising substances, toxic substances, radioactive materials, corrosive substances and miscellaneous goods. With the risk of an accident occurring being more likely when transporting these materials. Although the biggest cause for concern within the industry being the transportation of non-flammable non-toxic gas is asphyxiation. As a slow leak in a storage container can drain all of the oxygen in the air and cause the individuals in the environment to suffocate. 

Leaks within aircraft hangars and fuel storage areas of highly explosive aviation fuel is an area that must be monitored to prevent fires, equipment damage, and at the worst fatalities. It is essential to choose a suitable gas detection solution that focuses on the aircraft rather than the aircraft hangar, avoids false alarms, and can monitor large areas. 

Not only is it the external environment that faces gas risks in transportation, those working in the sector also face similar challenges. Air conditioning emissions poses a gas hazard threat due to the burning of fossil fuels leading to a subsequent emission of carbon monoxide (CO). high levels of CO in a confined area such as a vehicle cabin, of more than the normal level (30ppm) or an oxygen level below normal (19%) can result in dizziness, feeling and being sick, tiredness and confusion, stomach pain, shortness of breath and difficulty breathing. Therefore, proper ventilation in these spaces with the assistance of a gas detector is paramount to ensuring the safe of those working in the transportation industry. 

Similarly, in the air sector cabin combustion and fuselage fires, in the central portion of an airplane, poses a real threat. Although flame retardant materials are applied, if a fire does start the cabin’s trim and fittings can still generate toxic gases and vapours that could be more dangerous than the fire itself. Inhalation of harmful gases caused by a fire in these environments tend to be the main direct cause of fatalities.

Transportation Standards and Certifications 

Each mode of transport, (road, rail, air, sea and inland waterway) has its own regulations but they are generally harmonized with the United Nations Economic Commission for Europe (UNECE). The Hazardous Materials Transportation Act (HMTA), enacted in the USA in 1975, states that regardless of the type of transportation, any company whose goods fall into one of the nine categories specified as hazardous by the UN, must comply with the regulations or risk fines and penalties. 

Those working in the transport sector in the UK must comply with the requirements laid out in the UN Model Regulations which assigns each dangerous substance or article a specific class that correlates how dangerous it is. It does this via the packing group (PG) classification, according to PG I, PG II or PG III. 

From an European standpoint the International Carriage of Dangerous Goods by Road (ADR) governs the regulations on how to classify, pack, label and certify dangerous goods. It also comprises vehicle and tank requirements and other operational requirements. The Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations (2009) also is relevant in England, Wales and Scotland. 

Other relevant regulations include the International Carriage of Dangerous Goods by Inland Navigation (ADN), the International Maritime Dangerous Goods (IMDG) and The International Civil Aviation Organization’s (ICAO) Technical Instruction.

Our solution 

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, and T4. Our fixed gas detectors are used 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 which are able to measure flammable, toxic and oxygen gases, report their presence and activate alarms or associated equipment, for the transportation industry our panels include Gasmaster and Vortex.  

To find out more on the dangers of gas hazards in transportation visit our industry page for more information.  

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Our Partnership with CSL

Background

CSL is one of the largest providers of gas detection in the Irish market and the leading provider of plant and supporting services to the water, wastewater, environmental and industrial sectors. With headquarters in County Carlow, Republic of Ireland, CSL provide 24 hours, 7 days a week, 365 days a year maintenance and support to their customers nationwide through their network of engineers and support personnel located across the country. CSL is a customer-focused company providing a one-stop-shop to their clients. With over 30 years of experience, CSL delivers effective gas detection solutions for the long term. CSL supplies a wide range of gas detection products, from portable devices to complete fixed gas detection systems and customised installations in many sectors. 

Views on gas detection

As a critical safety issue, CSL put the design, equipment selection, long-term maintenance, and clarity of the alarm system to the forefront of our gas detection solutions. “We understand that there is always a balance between investment and striving for the highest level of gas safety. Still, from our point of view, safety wins every time as cutting costs in an area as vital as gas safety is a false economy. This is one of the main reasons we work very hard to develop the relationship and partnership and promote the Crowcon Gas Safety product range. When we meet with our clients and discuss their gas safety challenges, the conversation inevitably discusses costs. Because of the sizeable Crowcon product range, we always have a solution that will meet their budget and safety requirements.”- Peter Nicholson, Head of Marketing. 

Working with Crowcon

A 30-year partnership and continued communication have allowed CSL to supply their customers with gas detection solutions. “Providing fixed and portable solutions ensures a gas safety package that will work for any company or organisation that depends on high-quality gas detection and related equipment.” – Peter Nicholson, Head of Marketing. We’re thrilled to be working alongside CSL to provide gas detection to the Irish market and support with services to the water, wastewater, environmental and industrial sectors. With over 30 years of experience, CSL delivers effective gas detection solutions for the long term through the supply of our portable devices and fixed gas detection systems. 

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Our Partnership with Shawcity 

Background

Established in 1976, Shawcity was one of the first companies to introduce specialist gas detection devices to the UK and Irish markets from leading manufacturers around the world. For over 45 years, they have focused on providing the latest monitoring technology in partnership with leading manufacturers to customers across the UK and Ireland.  

Shawcity supports those working in health and safety, occupational hygiene and environmental applications who rely on achieving the highest levels of performance. With instruments available to hire or buy, Shawcity has the capacity to ensure each order is tailored to meet individual project demands. Their portfolio offers an extensive range of monitoring detection including fixed gas detection, potable gas detection and air quality.  

Views on Gas Detection

As the focus on workplace health continues to develop, a better understanding of the ways workers can be impacted is leading to changes in legislation and an increasing responsibility for employers to protect their employees at work. Gas detection, in particular, is critical in terms of potential safety and can, in some cases, involve an immediate threat to life. Ensuring the correct equipment is provided and maintained is one of the key responsibilities that health and safety officers have.  

The latest technology also means that effective monitoring on a personal, area or environmental level has never been easier to achieve. Shawcity works with every customer to ensure the right equipment is supplied for the job every time and also offer free product training. 

Working with Crowcon

The partnership between Crowcon and Shawcity provides an unbeatable combination of industry knowledge and expertise. The two companies work closely together on fixed gas detection projects across many sectors to provide the complete package, from site surveys, planning and design through to installation, commissioning and ongoing service and maintenance.  

Now supplying our portable range, Shawcity now can support an even wider range of new markets and sectors. “Shawcity is an official Trusted Partner. Crowcon and Shawcity collaborate at every stage of the gas detection process – from product development through to technical support – to deliver the best possible service to customers” – Nathan Marks, Fixed Gas Detection Manager at Shawcity. 

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Carbon Dioxide: What are the dangers in the Food and Beverage Industry? 

Almost all industries must monitor gas hazards, with the food and beverage industry no exception. Although, there is a lack of awareness regarding the dangers of carbon dioxide (CO2) and the dangers those working in the industry face. CO2 is the most common gas in the food and beverage industry because it is used in the carbonation of drinks, to propel beverages to the tap in pubs and restaurants and to keep food items cold during transportation in the form of dry ice. It is also naturally produced in beverage manufacturing processes by leavening agents like yeast and sugar. Although CO2 may seem harmless at first glance as we exhale it with every breath, and plants need it for survival, the presence of carbon dioxide becomes a problem when its concentration rises to dangerous levels.

The Dangers of CO2

Carbon dioxide occurs naturally in the atmosphere (typically 0.04% in air). CO2 is colourless and odourless, heavier than air, and tends to sink to the floor. CO2 collects in cellars and at the bottom of containers and confined spaces such as tanks or silos.

Since CO2 is heavier than air, it quickly displaces oxygen at high concentrations can result in asphyxiation due to a lack of oxygen or breathable air. Exposure to CO2 is easy, especially in a confined space like a tank or a cellar. Early symptoms of exposure to high levels of carbon dioxide include dizziness, headaches, and confusion, followed by loss of consciousness. Accidents and fatalities occur in the food and beverage industry due to a carbon dioxide leak. Without proper detection methods and processes in place, everyone at a facility could be at risk.

Gas Monitors – what are the benefits?

Any application that uses carbon dioxide puts workers at risk, and the only way to identify high levels before it’s too late is to use gas monitors.

Gas detection can be provided in both fixed and portable forms. Installation of a fixed gas detector can benefit a larger space such as plant rooms to provide continuous area and staff protection 24 hours a day. However, a portable detector can be more suited for worker safety in and around the cylinder storage area and in spaces designated as a confined space. This is especially true for pubs and beverage dispensing outlets for the safety of workers and those unfamiliar with the environment, such as delivery drivers, sales teams or equipment technicians. The portable unit can easily be clipped to clothing and will detect pockets of CO2 using alarms and visual signals, indicating that the user should immediately vacate the area.

Personal gas detectors continuously monitor the air in workers’ breathing zone when worn correctly,  to give them better awareness and the information they need to make smart decisions in the face of danger. Not only can gas monitors detect carbon dioxide in the air, but they can also alert others if an employee is in danger. Carbon dioxide can be monitored using a single gas monitor or by using a multi-gas monitor with a dedicated carbon dioxide sensor. It is important to note the carbon dioxide can escalate to dangerous levels before an oxygen sensor would alarm.

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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. 

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What is a Pellistor (Catalytic Beads)? 

Pellistor sensors consist of two matched wire coils, each embedded in a ceramic bead. Current is passed through the coils, heating the beads to approximately 230˚C. The bead becomes hot from the combustion, resulting in a temperature difference between this active and the other ‘reference’ bead.  This causes a difference in resistance, which is measured; the amount of gas present is directly proportional to the resistance change, so gas concentration as a percentage of its lower explosive limit (% LEL*) can be accurately determined. Flammable gas burns on the bead and the additional heat generated produces an increase in coil resistance which is measured by the instrument to indicate gas concentration. Pellistor sensors are widely used throughout industry including on oil rigs, at refineries, and for underground construction purposes such as mines, and tunnels. 

Benefits of Pellistor Sensors?

Pellistor sensors are relatively low in cost due to differences in the level of technology in comparison to the more complex technologies like IR sensors, however, they may be required to be replaced more frequently. With a linear output corresponding to the gas concentration, correction factors can be used to calculate the approximate response of pellistors to other flammable gases, which can make pellistors a good choice when there are multiple flammable gases and vapours present. 

Factors affecting Pellistor Sensor Life

The two main factors that shorten the sensor life include exposure to high gas concentration and poisoning or inhibition of the sensor. Extreme mechanical shock or vibration can also affect the sensor life.  

The capacity of the catalyst surface to oxidise the gas reduces when it has been poisoned or inhibited. Sensor lifetimes of up to ten years is known in some applications where inhibiting or poisoning compounds are not present. Higher power pellistors have larger beads, hence more catalyst, and that greater catalytic activity ensures less vulnerability to poisoning. More porous beads allow easier access of the gas to more catalyst allowing greater catalytic activity from a surface volume instead of just a surface area. Skilled initial design and sophisticated manufacturing processes ensure maximum bead porosity. 

Strength of the bead is also of great importance since exposure to high gas concentrations (>100% LEL) may compromise sensor integrity causing cracking. Performance is affected and often offsets in the zero/base-line signal result. Incomplete combustion results in carbon deposits on the bead: the carbon ‘grows’ in the pores and causes mechanical damage or just gets in the way of gas reaching the pellistor. The carbon may however be burned off over time to re-reveal catalytic sites.  

Extreme mechanical shock or vibration can in rare cases cause a break in the pellistor coils. This issue is more prevalent on portable rather than fixed-point gas detectors as they are more likely to be dropped, and the pellistors used are lower power (to maximise battery life) and thus use more delicate thinner wire coils. 

What happens when a Pellistor is poisoned? 

A poisoned pellistor remains electrically operational but may fail to respond to gas as it will not produce an output when exposed to flammable gas. This means a detector would not go into alarm, giving the impression that the environment is safe.  

Compounds containing silicon, lead, sulphur, and phosphates at just a few parts per million (ppm) can impair pellistor performance.  Therefore, whether it’s something in your general working environment, or something as harmless as cleaning equipment or hand cream, bringing it near to a pellistor could mean you are compromising your sensor’s effectiveness without even realising it. 

Why are silicones bad? 

Silicones have their virtues, but they may be more common than you first thought. Some examples include sealants, adhesives, lubricants, and thermal and electrical insulation. Silicones, have the ability to poison a sensor on a pellistor at extremely low levels, because they act cumulatively a bit at a time.  

Products  

Our portable products all use low power portables pellistor beads. This prolongs battery life but can make them prone to poisoning. Which is why we offer alternatives that do not poison, such as the IR and MPS sensors. Our fixed products use a porous high energy fixed pellistor. 

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

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