When would I need to measure gas leaks at distance? 

The use of natural gas, of which methane is the principal component, is increasing worldwide. It also has many industrial uses, such as the manufacture of chemicals like ammonia, methanol, butane, ethane, propane and acetic acid; it is also an ingredient in products as diverse as fertiliser, antifreeze, plastics, pharmaceuticals and fabrics. With continuous industrial development, there is an increase in the risk of harmful gas being released. Although these emissions are controlled, there however, may be operations that involve the handling of hazardous gases in which lapses in preventive maintenance such as ensuring there are no faulty pipelines or equipment, can result in terrible outcomes. 

What are the dangers and ways of preventing gas leaks? 

Natural gas is transported in several ways: through pipelines in gaseous form; as liquefied natural gas (LNG) or compressed natural gas (CNG). LNG is the usual method for transporting the gas over a long distance, i.e., across oceans, whilst CNG is ordinarily transported using a tanker truck over short distances. Pipelines are the preferred transport choice for long distances over land (and sometimes offshore). Local distribution companies also deliver natural gas to commercial and domestic users across utility networks within countries, regions and municipalities. 

Regular maintenance of gas distribution systems is essential. Identifying and rectifying gas leaks is also an integral part of any maintenance programme, but it is notoriously difficult in many urban and industrial environments, as the gas pipes may be located underground, overhead, in ceilings, behind walls and bulkheads or in otherwise inaccessible locations such as locked buildings. Until recently, suspected leaks from these pipelines could lead to whole areas being cordoned off until the location of the leak was found. 

Remote Detection 

Modern technologies are becoming available that allow for remote detection and identification of leaks with pinpoint accuracy. Hand-held units, for example, can now detect methane at distances of up to 100 metres, while aircraft-mounted systems can identify leaks half a kilometre away. These new technologies are reshaping the way natural gas leaks are detected and dealt with. 

Remote sensing is achieved using infrared laser absorption spectroscopy. As methane absorbs a specific wavelength of infrared light, these instruments emit infrared lasers. The laser beam is directed to wherever the leak is suspected, such as a gas pipe or a ceiling. Due to some of the light being absorbed by the methane, the light received back provides a measurement of absorption by the gas. A useful feature of these systems is the fact that the laser beam can penetrate transparent surfaces, such as glass or Perspex, so there is a possibility to test an enclosed space prior to entering it. The detectors measure the average methane gas density between the detector and target. Readings on the handheld units are given in ppm-m (a product of the concentration of methane cloud (ppm) and path length (m). This method allows for methane leak to be found quickly and confirmed by pointing a laser beam towards the suspected leak or along a survey line. 

Overall Safety  

As there are several risks when using gas such as explosion from damaged, overheated or poorly maintained cylinders, pipes equipment or appliances. There is also the risk of carbon monoxide poisoning and burns caused by contact with flame or hot surfaces. By implementing real-time gas leak detection, industries can monitor their environmental performance, ensure better occupational health, and eliminate potential hazards for optimum safety. Also, early detection of gas leaks can trigger concerned engineers to curtail the spread and keep a safe environment for better health and safety. 

For more information on measure gas leaks at distance, contact our team or visit our product pages – LaserMethane Smart and L-Tek P100.

When to use Laser Gas Detection

Laser Gas Detection provide a solution to various gas detection challenges within emission monitoring and process control. Laser gas detectors use a near identical infrared technology to that seen on our other products, but where the transmitter and receiver are separated by a distance. When methane passes between the two, the ‘beam is broken’ and the receiver will let you know the concentration of gas.  

Leak detection of common gases usually detects flammable or explosive gas. This means that traditional (i.e., catalytic) leak detection methods are inadequate to successfully detect at a distance. This means that all gas resources or transmission lines must be observed in terms of a gas leakage.  

Using a Laser Gas Detector 

Laser technology enables gas leaks to be located, by pointing the laser beam towards the suspected leak, or along a survey line. Being very intuitive and easy to use, it is practically ‘point and shoot’ with a 2-button operation and touch display. The laser beam pointed towards areas such as gas piping, the ground, joins etc, is reflected from the target. The device receives the reflected beam and measures the absorptivity of the beam, which is then calculated into methane column density (ppm-m) and displayed clearly on the display. 

Laser gas detectors allow for the detection of methane gas from a safe distance without the need for a worker to enter certain hazardous areas. Utilising infrared laser technology, methane leaks can be efficiently confirmed through the use of pointing a laser beam towards the suspected leak, or along the survey line. This revolutionary technology removes the need to access elevated places, under floor, hazardous areas or other hard to reach environments. It is also ideal for surveying large open spaces e.g., landfills or studying agricultural emissions. 

LaserMethane Smart 

Laser-based gas sensor technology is an effective tool for detecting and quantifying methane emissions. Laser sensors are sharp with a quick response that can detect the relevant gas.  

The LaserMethane Smart is a compact, portable methane gas detector, the latest laser methane device, replacing the obsolete LaserMethane mini. LaserMethane Smart can detect methane leaks at a distance up to 30m, enabling operators to quickly survey multiple leak risks, and safely, without having to enter a hazardous area. 

The device is made even easier to use with its integrated camera, so operators can pin-point exactly where the emissions are coming from. A screen recording of the image can be captured, recording the gas concentration, alarm set point and zoom information for further analysis or reporting later. 

Bluetooth devices can be paired to a mobile phone so the information can be transferred to an online portal for total data integrity and reporting, as well as capturing location so emissions can be traced to specific locations. This makes it even easier to ensure leaks are traced and any emission preventing actions can be recorded and used to prove their success against the previous emission readings at the same location. 

L-Tek P100

The L-Tek P100 uses advanced technology (TDLAS) to accurately measure methane gas in a specific areas. With precise and sensitive monitoring, a low risk of false alarms, and portability, it can be easily carried for safety checks, offering flexibility in detecting methane concentrations. Specifically designed for effective methane detection, the L-TEK P100 ensures reliable and efficient performance.

In summary

While both devices excel in methane detection, the Laser Methane Smart and L-TEK P100 cater to different needs. The Laser Methane Smart emphasises dimensions, weight, and rapid response time, making it suitable for various applications. In contrast, the L-TEK P100 focuses on extended battery life, flexibility in detection distance, and IP protection, enhancing its suitability for specific environmental conditions and operational requirements. The choice between the two devices depends on the unique demands of the intended application and the specific features prioritised by users.

Attribute Laser Methane Smart L-TEK P100
Dimensions (HxWxD mm) 200 x 53 x 55 138 x 49 x 35
Weight 500g 320g
Gases CH4 (Methane) CH4 (Methane)
Detection Distance Up to 30m Standard 20m; Increased range to 50m
Response Time (s) 0.1 ≤0.05 (Adjustable)
Sensitivity ±10% 5ppm m
Range 1 to 50,000ppm.m (5%vol.m) 0-99,999ppm∙m (9.99%vol.m)
Temperature/Humidity Range -17°C to +50°C -20°C to +55°C, 98% RH (Non-condensing)
IP Protection IP54
Battery Life 3.5 hours 6 hours
Camera and Storage Yes
Storage 16GB
Connectivity Optional Bluetooth, Online portal (Bluetooth) No Bluetooth or Online portal
ATEX Zone Zone 2 Zone 1
Certification Rating II 3 (1) G Ex ic [op-is Ga] II T4 Gc II 2 G Ex ib op is IIB T4 Gb (-20 °C ≤ Ta ≤ +50 °C)
SGS23ATEX0156X
IECEX SGS23.0078X

For more information about laser gas detection, visit our website or contact our team.

The Importance of Portable Detectors in Battery Energy Storage

Within battery energy storage, ensuring the safety of workers from the risks of battery fires and hazardous gases remains vital. The absence of early detection can expose personnel to unforeseen dangers, potentially resulting in catastrophic consequences. By investing in advanced gas detection technologies, you will be safeguarding your assets. 

Without the ability to detect gases early on, workers may unknowingly enter unsafe environments increasing the likelihood of severe injuries or fatalities. Overall, the absence of early gas detection significantly heightens the potential for catastrophic outcomes in battery energy storage incidents, underscoring the critical importance of investing in reliable gas detection technologies like the T4x to safeguard personnel and assets alike. 

T4x: The Optimal Solution for Personal Safety 

Within these challenges, the importance of portable detectors in ensuring personal safety cannot be overstated. T4x is the best solution for detecting hazardous and monitoring residual gases to workers in battery energy storage. Equipped with advanced sensor technology and intuitive user interface, the T4x offers real-time monitoring of gas concentrations, allowing workers to promptly respond to changing conditions and mitigate risks effectively. 

Moreover, the T4x is designed with the specific needs of battery energy storage in mind, featuring rugged construction, long battery life, and intrinsically safe design to withstand the rigours of hazardous environments. Its compact size and lightweight design make it easy to carry and deploy in the field, ensuring that workers have access to reliable gas detection wherever they go.  

Personal protection is crucial for providing safety in battery energy storage. Portable detectors, such as the T4x, play a crucial role in safeguarding the health and safety of workers by detecting hazardous gases and providing early warning of potential dangers. By investing in advanced detection technology and prioritising worker safety, organisations can mitigate risks and ensure a safe battery energy storage environment. 

Want to know more about how Crowcon can help provide personal protection in battery energy storage? Visit our website or click here to get in touch for an obligation-free chat with a member of our team.  

Xgard Type 3: The mV Advantage

Xgard Type 3 is the ideal solution for detecting lighter-than-air flammable gases such as methane and hydrogen. Detectors in such applications usually have to be mounted high-up in roof spaces or above equipment where access for calibration and maintenance is  likely to present problems.

Gas detectors require calibration (usually every six months) and sensors may need to be replaced every 3-5 years. These activities usually require direct access to the detector to make adjustments and replace parts. National regulations such as the ‘UK Work at Height Regulations 2005’ stipulate safe working practices when working on equipment at height, and compliance usually requires the use of scaffolding or mobile ‘cherry pickers’ which entails significant cost and disruption on-site.

The advantage of mV pellistor type detectors

The terms ‘mV’ and ‘4-20mA’ describe the type of signal which is transmitted through the cable between the gas detector and the control system (for example a Crowcon Gasmaster). Calibration of  4-20mA detector (e.g. Xgard Type 5) entails removing the lid, and zeroing/calibrating the amplifier using a meter, test-points and potentiometers. Even more sophisticated detectors with a display and non-intrusive calibration still require direct access to operate the menu system using a magnet in order to perform calibration.

Xgard Type 3 is a mV pellistor-based detector which has no internal electronics (i.e. no amplifier); just terminals to connect via three wires to the control system (e.g. Gasmaster). Commissioning simply entails measuring the ‘head voltage’ at the detector terminals, and performing zero and calibration adjustments at the Gasmaster input module. Ongoing 6-monthly calibrations are then performed by remotely applying gas (via a ‘spray deflector’ or ‘collector cone’ accessory), and any necessary adjustments are made at ground level via the control system input module.

Hence once commissioned, mV pellistor type detectors do not need to be accessed until the sensor needs replacing; usually 3-5 years after installation. The routine need for expensive access equipment; scaffolding or cherry-pickers in thus avoided.

Xgard Type 3 can be directly connected to Gasmaster and Gasmonitor systems, and to Vortex via an ‘Accessory Enclosure’ accessory which converts the mV signals to 4-20mA.

Remote calibration of a mV pellistor type detector
Remote calibration of a mV pellistor type detector.

What is IR beam technology?

Infrared detection technology (IR) is used within a range of applications including agriculture, oil and gas extraction, waste management, utilities and food and beverage production, to detect specific gases that absorb IR light at characteristic wavelengths. An infrared light beam passes through a gas cloud and onto collection optics where it is split and sent through filters onto infrared sensors.  

Infrared emitters within the sensor generate beams of IR light that are measured by photo-receivers. Hydrocarbon gas molecules absorb light at 3.3 microns, Carbon dioxide molecules at 4.25 microns and other molecules at different wavelengths, so the beam intensity is reduced if there is an appropriate concentration of absorbing gas present. A “reference” beam (around 3.0μm) is not absorbed by gas, so arrives at the receiver at full strength. The %LEL of gas present is determined by the ratio of the absorbed and reference beams measured by photo-receivers.  

How do IR Beam Sensors Works? 

The Infrared beam sensor uses near identical infrared technology, but where the transmitter and receiver are separated by a distance. When a gas passes between the two and is absorbed by the IR light, the ‘beam is broken’ and the receiver will let you know. Typically, infrared open path detectors have a single gas detection beam 10m to 200m in length. 

Advantages of Infrared Beam Sensors 

  • Infrared beam detectors do not need any contact with the gas to be detected. They don’t need the gas to come to them
  • The IR sensors have a quick response. Any target gas crossing the beam is detected
  • One beam detector can cover an area, potentially replacing many fixed-point detectors
  • They are considered secure due to the point-to-point detection principle
  • All the normal pros and cons of IR sensors apply, including fail to safe, no poisoning, long lasting

Disadvantages of Infrared Beam Sensors 

  • If it is very foggy, that counts as a beam interruption and gas cannot be detected until the fog clears
  • Beam detectors can sometimes be quite costly since extra measures need to be designed in to avoid sunlight interaction or excessive vibration affecting the receiver and causing reading inaccuracies
  • Cannot detect hydrogen

Why have beam detection? 

When detecting gases, it is usual to build a gas detector, install it in a relevant place and wait for the gas to come to it to be detected. Sometimes, that is impractical due to a need to keep some working areas uncluttered for safety reasons, or where the gas needs to be detected close to a leak because the delay in it reaching a detection point would be unacceptable for a critical safety purpose. Under these circumstances having a gas detection system that can be pointed through the region of risk is often a good option.  

Sometimes it is thought better to cover a whole enclosed volume with beam IR detectors instead of using many fixed-point detectors. The same applies with hand-held portable laser methane detectors.  

A typical installation may be installing 2 beams across the top of several turbines in a power station instead of many fixed-point detector heads. 

Here 2 beam detectors are being used instead of 23 fixed point gas detector heads to allow similar coverage. Typically beam detectors are about 6 times the cost of fixed-point detectors to manufacture, making system cost differences marginal. It has been known for some installations e.g., large FPSO floating refineries, to have their operational areas designed around their beam detector gas detection systems. 

When detecting and monitoring methane leaks and emissions using portable handheld equipment, it is preferable to use laser IR detection methods. This helps save time as multiple areas can be analysed from one spot and often without having to access a hazardous area, improving worker safety, associated risk assessments and work permit paperwork. 

LaserMethane Smart: The latest in laser methane detection

With increasing global regulation around methane emissions and reporting, the innovative technology of the LaserMethane Smart, the latest in laser methane detection. The innovative technology to measure methane leaks at a distance, uses a laser and camera system to provide a highly capable solution to various gas detection challenges within emission monitoring. It uses an infrared laser beam, where the transmitter and receiver are separated. When methane passes between the two, methane absorbs the infrared light, and the beam is disrupted. The device therefore accurately reports the concentration of the methane gas cloud. The device’s reading and camera’s image are overlaid and records the levels at time of inspection, all from a safe distance from the source. The readings can later be used to report on emissions and check that leak mitigation methods are successful.  

Other handheld leak detectors usually detect flammable or explosive gas but in much closer proximity to the hazard and take much longer as it involves more travel to each specific measurement point. This means that traditional hand-held detection methods are inadequate to successfully detect leaks quickly or as safely. 

Remote Detection 

Modern technologies are becoming available that allow for remote detection and identification of leaks with pinpoint accuracy. Hand-held units, for example, can now detect methane at distances of up to 100 metres, while aircraft-mounted systems can identify leaks half a kilometre away. These new technologies are reshaping the way natural gas leaks are detected and dealt with. 

Remote sensing is achieved using infrared laser absorption spectroscopy. As methane absorbs a specific wavelength of infrared light, these instruments emit infrared lasers. The laser beam is directed to wherever the leak is suspected, such as a gas pipe or a ceiling. Due to some of the light being absorbed by the methane, the light received back provides a measurement of absorption by the gas. A useful feature of these systems is the fact that the laser beam can penetrate transparent surfaces, such as glass or Perspex, so there is a possibility to test an enclosed space prior to entering it. The detectors measure the average methane gas density between the detector and target. Readings on the handheld units are given in ppm-m (a product of the concentration of methane cloud (ppm) and path length (m)). This method allows for methane leak to be found quickly and confirmed by pointing a laser beam towards the suspected leak or along a survey line. 

Overall Safety  

As there are several risks when using gas such as explosion from damaged, overheated or poorly maintained cylinders, pipes equipment or appliances. There is also the risk of carbon monoxide poisoning and burns caused by contact with flame or hot surfaces. By implementing real-time gas leak detection, industries can monitor their environmental performance, ensure better occupational health, and eliminate potential hazards for optimum safety. Also, early detection of gas leaks can trigger concerned engineers to curtail the spread and keep a safe environment for better health and safety. 

Laser-based gas sensor technology is an effective tool for detecting and quantifying polluting gases such as carbon dioxide or methane. Laser sensors are sharp with a quick response that can automatically detect the relevant gas. The LaserMethane Smart is a compact, portable methane gas detector, the latest laser methane device, replacing the now obsolete LaserMethane mini. LaserMethane Smart can detect methane leaks at a distance up to 30m, it enables companies to quickly survey multiple leak risks, and safely, without having to enter a hazardous area. 

For more information about las gas detection, visit our website or contact our team 

Did you know about the Sprint Pro Gas Leak Detector?

Are you still using a stand-alone gas leak detector, or thinking of buying one? If you have a Sprint Pro 2 or higher, then there’s no need, because these Sprint Pros all have gas leak detection capabilities built in. In this post we’ll be looking at that capability in detail.

How to detect leaks with a Sprint Pro 

Before you begin, you’ll need to have a gas escape probe (GEP) handy – if you have a Sprint Pro 3 or higher, this will have been supplied with the machine, but if you have a Sprint Pro 2 you’ll need to buy it separately.  

Having plugged in your GEP, go into the test menu and scroll down to select gas escape detection. Your sensor must reach the correct temperature before you can go any further; the machine will do this automatically and progress is shown on the menu (the machine will let you know when the probe is ready). The Sprint Pro will then ask you to verify that you’re in clean air, at which point you zero the machine.  

Then, place the probe in the area you wish to inspect, and keep it in place for at least a few seconds before moving it on to the next area to be checked. The Sprint Pro will make a sound like a Geiger counter (a series of clicks) and show a full colour bar graph display of gas levels as you approach a gas leak the sound will increase in pitch and the bar graph will indicate higher levels. Once you have located the leak, you can stop the test by pressing ESC. 

Once you have finished looking for leaks, it’s best practice to use leak detection fluid to check all disturbed, suspected and inspected pipework, joints, fittings, test points and flanges in line with your local regulations. 

Incidentally, the GEP is a precision instrument and can be damaged by impact. If your GEP is dropped, struck or otherwise damaged, it’s a good idea to check that it still works by plugging it into the Sprint Pro to make sure it’s recognised. If the Sprint Pro finds a fault in the GEP, it will let you know by means of a visual warning on the display. If this happens, or the GEP is visibly damaged, it must be repaired or replaced. 

You can find more information about using the Sprint Pro to detect gas leaks on page 22 of the Sprint Pro manual (click here for a PDF version).  

An Introduction to the Oil and Gas Industry 

The oil and gas industry is one of the biggest industries in the world, making a significant contribution to the global economy. This vast sector is often separated into three main sectors: upstream, midstream and downstream. Each sector comes with their own unique gas hazards. 

Upstream

The upstream sector of the oil and gas industry, sometimes referred to as exploration and production (or E&P), is concerned with locating sites for oil and gas extraction the subsequent drilling, recovery and production of crude oil and natural gas. Oil and gas production is an incredibly capital-intensive industry, requiring the use of expensive machinery equipment as well as highly skilled workers. The upstream sector is wide-ranging, encompassing both onshore and offshore drilling operations. 

The major gas hazard encountered in upstream oil and gas is hydrogen sulphide (H2S), a colourless gas known by its distinct rotten egg like smell. H2S is a highly toxic, flammable gas which can have harmful effects on our health, leading to loss of consciousness and even death at high levels. 

Crowcon’s solution for hydrogen sulphide detection comes in the form of the XgardIQ, an intelligent gas detector which increases safety by minimising the time operators must spend in hazardous areas. XgardIQ is available with high-temperature H2S sensor, specifically designed for the harsh environments of the Middle East. 

Midstream

The midstream sector of the oil and gas industry encompasses the storage, transportation and processing of crude oil and natural gas. The transportation of crude oil and natural gas is done by both land and sea with large volumes transported in tankers and marine vessels. On land, transportation methods used are tankers and pipelines. Challenges within the midstream sector include but are not limited to maintaining the integrity of storage and transportation vessels and protecting workers involved in cleaning, purging and filling activities. 

Monitoring of storage tanks is essential to ensure the safety of workers and machinery. 

Downstream

The downstream sector refers to the refining and processing of natural gas and crude oil and the distribution of finished products. This is the stage of the process where these raw materials are transformed into products which are used for a variety of purposes such as fuelling vehicles and heating homes.  

The refining process for crude oil is generally split into three basic steps: separation, conversion and treatment. Natural gas processing involves separating the various hydrocarbons and fluids to produce ‘pipeline quality’ gas. 

The gas hazards which are typical within the downstream sector are hydrogen sulphide, sulphur dioxide, hydrogen and a wide range of toxic gases. Crowcon’s Xgard and Xgard Bright fixed detectors both offer a wide range of sensor options to cover all the gas hazards present in this industry. Xgard Bright is also available with the next generation MPS™ sensor, for the detection of over 15 flammable gases in one detector. Also available are both single and multi-gas personal monitors to ensure workers safety in these potentially hazardous environments. These include the Gas-Pro and T4x, with Gas-Pro providing 5 gas support in a compact and rugged solution.

Why is gas emitted in cement production?

How is cement produced?

Concrete is one of the most important and commonly used materials in global construction. Concrete is widely used in the construction of both residential and commercial buildings, bridges, roads and more. 

The key component of concrete is cement, a binding substance which binds all the other components of concrete (generally gravel and sand) together. More than 4 billion tonnes of cement is used worldwide every year, illustrating the massive scale of the global construction industry. 

Making cement is a complex process, starting with raw materials including limestone and clay which are placed in large kilns of up to 120m in length, which are heated to up to 1,500°C. When heated at such high temperatures, chemical reactions cause these raw materials to come together, forming cement. 

As with many industrial processes, cement production is not without its dangers. The production of cement has the potential to release gases which are harmful to workers, local communities and the environment. 

What gas hazards are present in cement production?

The gases generally emitted in cement plants are carbon dioxide (CO2), nitrous oxides (NOx) and sulfur dioxide (SO2), with CO2 accounting for the majority of emissions. 

The sulphur dioxide present in cement plants generally comes from the raw materials which are used in the cement production process. The main gas hazard to be aware of is carbon dioxide, with the cement making industry responsible for a massive 8% of global CO2 emissions. 

The majority of carbon dioxide emissions are created from a chemical process called calcination. This occurs when limestone is heated in the kilns, causing it to break down into CO2 and calcium oxide.  The other main source of CO2 is the combustion of fossil fuels. The kilns used in cement production are generally heated using natural gas or coal, adding another source of carbon dioxide into addition to that which is generated through calcination. 

Detecting gas in cement production

In an industry which is a large producer of hazardous gases, detection is key. Crowcon offer a wide range of both fixed and portable detection solutions. 

Xgard is a fixed multi gas detectors that meet the diverse requirements for gas detection in industries. Xgard has options for the detection of carbon dioxide and sulphur dioxide, the gases of most concern in cement mixing. 

For portable gas detection, the Gasman’s  rugged yet portable and lightweight design make it the perfect single-gas solution for cement production, available in a safe area CO2 version offering 0-5% carbon dioxide measurement. 

For enhanced protection, the Gas-Pro multi-gas detector can be equipped with up to 5 sensors, including all of those most common in cement production, CO2, SO2 and NO2.

Gas-Pro TK: Dual readings of %LEL and %Vol

Gas-Pro TK (re-branded from Tank-Pro) dual range portable monitor measures the concentration of flammable gas in inerted tanks. Available for methane, butane and propane, Gas-Pro TK uses a dual IR flammable gas sensor – the best technology for this specialist environment. Gas-Pro TK dual IR features auto-range switching between %vol. and %LEL measurement, to ensure operation at the correct measurement range. This technology isn’t damaged by high hydrocarbon concentrations and does not need oxygen concentrations to work, as are the limiting factors of catalytic bead/ pellistors in such environments. 

What problem is Gas-Pro TK specifically designed to overcome? 

When you wish to enter a fuel storage tank for inspection or maintenance, you may start with it full of flammable gas. You can’t just start pumping air in to displace the flammable gas because at some point in the transition from only fuel present to only air present, there would be an explosive mixture of fuel and air. Instead, you must pump in an inert gas, usually nitrogen to displace the fuel without introducing oxygen. The transition from 100% flammable gas and 0% volume nitrogen, to 0% volume flammable gas and 100% nitrogen enables a safe transition from 100% nitrogen to air. Using this two-step process enables a safe transition from fuel to air without risking an explosion. 

During this process there is no air or oxygen present, so catalytic bead / pellistor sensors will not work properly and will also be poisoned by the high levels of flammable gas. The dual range IR sensor used by Gas-Pro TK does not require any air or oxygen to function, so it is ideal to monitor the whole of the process, from %volume to %LEL concentrations, while also monitoring oxygen levels in the same environment. 

What is LEL? 

The Lower Explosive Limit (LEL) is the lowest concentration of a gas or vapour that will burn in air. Readings are a percentage of that, with 100%LEL the minimum amount of gas needed to combust. LEL varies from gas to gas, but for most flammable gases it is less than 5% by volume. This means that it takes a relatively low concentration of gas or vapour to produce a high risk of explosion.
Three things must be present for an explosion to occur: combustible gas (the fuel), air and a source of ignition (as shown in the diagram). In addition, the fuel must be present at the right concentration, between the Lower Explosive Limit (LEL), below which the gas/air mixture is too lean to burn, and the Upper Explosive Limit (UEL), above which the mixture is too rich and there is not enough of a supply of oxygen to sustain a flame. 

Safety procedures are generally concerned with detecting flammable gas well before it reaches an explosive concentration, so gas detection systems and portable monitors are designed to initiate alarms before gases or vapours reach the Lower Explosive Limit. Specific thresholds vary according to the application, but the first alarm is typically set at 20% LEL and a further alarm is commonly set to 40% LEL. LEL levels are defined in the following standards: ISO10156 (also referenced in EN50054, which has since been superseded) and IEC60079. 

What is %Volume? 

The percent by volume scale is used to give the concentration of one gas type in a mixture of gases as a percentage of the volume of gas present. It is just a different scale with, for example the methane lower explosive limit concentration is displayed at 4.4% volume instead of 100% LEL or 44000ppm, which are all equivalent. If there was 5% or more methane present in air, we would have a highly dangerous situation where any spark or hot surface could cause an explosion where air (specifically oxygen) is present. If there is 100%volume reading, it means that there is no other gas present in the gas mix. 

Gas-Pro TK 

Our Gas-Pro TK has been designed for use in specialist inerted tank environments to monitor levels of flammable gases and oxygen, as standard gas detectors will not work. In ‘Tank Check Mode’ Our Gas-Pro TK device is suitable for specialist application of monitoring inerted tank spaces during purging or gas freeing, as well as doubles as a regular personal gas safety monitor in normal operation. It enables users to monitor the gas mix in tanks carrying flammable gas during transport at sea (as it is marine approved) or on shore, such as oil tankers and oil storage terminals. At 340g, Gas-Pro TK is up to six times lighter than other monitors for this application; a boon if you have to carry it with you all day. 

In Tank Check mode, the Crowcon Gas-Pro TK, monitors concentrations of flammable gas and oxygen, checking that an unsafe mixture is not developing. The device auto-ranges, switching between %vol and %LEL as gas concentration demands, without manual intervention, and notifies the user as it happens. Gas-Pro TK has real-time oxygen concentrations from within the tank on its display, so users can track the oxygen levels, either for when the oxygen levels are low enough to safely load and store fuel, or high enough for safe tank entry during maintenance. 

The Gas-Pro TK is available calibrated to methane, propane or butane.  With IP65 and IP67 ingress protection, Gas-Pro TK meets the demands of most industrial environments. With optional MED certifications, it is a valuable tool for tank monitoring on-board vessels. The optional High H₂S Sensor addition allows users to analyse possible risk if gases vent during purging. With this option, users can monitor over the 0-100 or 0-1000ppm range. 

Please note: if the fuel in the tank is hydrogen or ammonia, a different gas detection technique is required – and you should contact Crowcon. 

For more information on our Gas-Pro TK visit our product page or get in contact with our team.