Crowcon wins export award at Oxford Business Awards

Gas Detection specialist Crowcon won an award for being one of three finalists in the Exports Category of the Oxford Business Awards recently.

Crowcon wins export award at Oxford Business Awards

Crowcon wins export award at Oxford Business Awards

(Left-right: Jon Silversides from Carter Jonas, the Award sponsor; Tim Wilkes, Marketing Manager at Crowcon; Kriss Akabusi).

The Exports Award recognizes organizations that have launched or significantly increased the export of products, services or intellectual property rights to non-UK markets within the last twelve months.

Tim Wilkes, Crowcon’s Marketing Manager who accepted the award on behalf of the company, said: “Reaching the final three in the awards from all the companies who entered was recognition of the investment in export capability and regional support that Crowcon has made. Though our headquarters and manufacturing base is in Abingdon, just south of Oxford, as these initiatives come to fruition over the next couple of years it will leverage the output from the site and really take the company forward.”

More than 500 people attended the awards ceremony which took place at the Four Pillars Hotel in Oxfordshire, with a total of 16 awards handed out to companies and individuals from across the county.

The awards were presented by former Olympic athlete Kriss Akabusi, who was guest speaker and compere for the evening.

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Gas Safety in Confined Spaces

Introduction
An offshore worker ensures a vessel is safe to enter; a plant manager enters a small plant room; a contractor inspects the lining of a sewage pipe.  All these personnel face common dangers, despite working in widely different industries.  Gas-related injury poses a serious threat in any confined space where the free movement of air is limited.

Gas Safety in Confined Spaces

Gas Safety in Confined Spaces

A confined space is usually defined as any space which is large enough for someone to enter and perform assigned work, which has limited means of entry or exit, and which is not designed for continuous worker occupancy. This definition covers just about any industrial activity, but is especially applicable to the utilities industries (water and wastewater, electricity, telecommunications and gas), construction, hydrocarbon exploration and processing, petrochemicals, marine applications, agriculture, food processing, wine making and brewing, as well as emergency services.

Employers are required to evaluate the risks these workplaces pose to their employees and then monitor to prevent them.  In most cases, both the assessment and the safe working system will require testing of the atmosphere with gas detection equipment.

The risks can be divided into three categories: combustible gas, toxic gas, and oxygen depletion or enrichment.  It is of course the duty of employers to find alternatives to manned work in these areas wherever possible.  However, in many cases such work cannot practicably be avoided, and so the priority must be to make it as safe as possible.

Combustible gas risks
For combustion to occur, the air must contain a minimum concentration of combustible gas or vapour.  This quantity is called the lower explosive limit (LEL).  At concentrations equal to or greater than this, combustion will occur in the presence of a suitable ignition source such as a spark or hot surface. For example the ATEX LEL of methane is 4.4% by volume, and a combustible atmosphere is usually described as “hazardous” at 10% LEL (equal to 0.44% volume). Differing hydrocarbons have different LELs, so it’s important to ensure that detectors are capable of detecting at the correct levels.

Typically, storage vessels which have contained hydrocarbon fuels and oils present a danger.  Other dangers come from fuel leaks: burst fuel containers; pipelines on and off site, gas cylinders and engine-driven plant.

For workers in pits, sewers and other sub-surface locations, methane is an almost universal danger.  Formed by decaying organic matter, this odourless gas collects in pockets underground.

Digestion of waste material in water treatment and oil production can see high levels of hydrogen sulphide. As well as being a very real toxic risk (dulling the olfactory nerves and causing loss of smell at dangerous limits which can make workers feel they are safe), hydrogen sulphide is highly corrosive and can damage standard pellistor sensors. Infrared is therefore commonly used in such applications, bringing with it the added benefit of extended lifetime and failsafe use.

Toxic gases and vapours
Confined-space workers may be exposed to any of a large number of toxic compounds, depending on the nature of the work and its environment.  A risk assessment should be made of which toxic substances a worker may be exposed to in any given work situation.

When generators, for example, are used in or near a confined space, carbon monoxide in the exhaust fumes from gas- or petrol-fuelled engines and nitrogen dioxide from diesel generators creates a serious poisoning risk.  Workers near to traffic on roads may be exposed to carbon monoxide and nitrogen dioxide from vehicle exhaust fumes.  The decomposing action of bacteria on organic matter releases toxic hydrogen sulphide and carbon dioxide, both of which are common sub-surface hazards. Work in chalky soils can also result in elevated levels of carbon dioxide as a result of the chalk reacting with air.

When looking at toxic gases related to specific applications, the water industry uses many toxic compounds for cleaning and processing both waste and clean water. Hazards such as chlorine, ozone, sulphur dioxide and chlorine dioxide then pose additional risks both in storage and treatment areas.

Oxygen – too high or too low?
The normal concentration of oxygen in fresh air is 20.9%.  An atmosphere is hazardous if the concentration of oxygen drops below 19.5% or goes above 23.5%.  If the concentration falls to 17%, mental and physical agility are noticeably impaired; death comes very quickly if it drops only a few percent more.  At these levels unconsciousness takes hold so rapidly that the victim will be unaware of what is happening.

Without adequate ventilation, the simple act of breathing will cause the oxygen level to fall surprisingly quickly.  Combustion also uses up oxygen, which means that engine-driven plant and naked flames such as welding torches are potential hazards.  A less obvious risk is the fermentation of rotting vegetable matter, which absorbs oxygen and may create a hazard in agricultural storage units.  Steel vessels and chambers which have been closed for some time are similarly dangerous because corrosion may have occurred, with rust using up vital oxygen in the process.

Oxygen can also be displaced.  Nitrogen, for example, when used to purge hydrocarbon storage vessels prior to re-use, drives oxygen out of the container and leaves it highly dangerous until thoroughly ventilated.

High oxygen levels are also dangerous.  As with too little, too much will impair the victim’s ability to think clearly and act sensibly.  Moreover, oxygen-enriched atmospheres represent a severe fire hazard.  From clothing to grease, materials which would not normally burn become subject to spontaneous combustion under these conditions.  Common causes of oxygen enrichment include leaks from welding cylinders and even from breathing apparatus. Oxygen is also used in the water industry to enhance the natural microbial decay of waste material.

Equipment types

Portable instruments and larger fixed systems can be used for confined space monitoring.  Fixed systems typically comprise one or more detector or “head” connected to a separate control panel. If a detector “sees” a dangerous gas level, the panel raises the alarm by triggering external sirens and beacons.  This sort of installation is suited to locations like plant rooms which have sufficient room for the hardware or remote stations that are usually unmanned.

However, much confined space work takes place in more restricted areas, making compact portable units more suitable. Ease of use, with one button operation, means minimal training is required while increased safety is ensured.  Combining one or more sensors with powerful audible and visual signals to warn when pre-set gas levels are reached, portable detectors can be carried or worn wherever they are needed.  In addition, a compact instrument is easily carried in a confined space, ensuring that pockets of high gas concentration are not missed.

Simple portable detectors contain a single sensor for a specific gas.  They are ideal for protecting workers where a risk assessment has identified only one foreseeable hazard.  The most basic product is a fixed life monitor.  Activated by the user when first required, they run continuously without maintenance for a set period, typically two or three years. User-settable alarms levels ensure that any changes in regulation or company procedure can quickly and easily be updated (such as changing hydrogen sulphide alarms from 5ppm to 2.5ppm).

More sophisticated but only slightly larger are one-channel detectors with an illuminated display showing measured gas levels.  Unlike disposable products, these units are designed for servicing rather than replacement, have rechargeable or replaceable batteries, and generally allow the user to set alarm levels.  They may also offer datalogging, a valuable feature which stores recorded gas levels for subsequent downloading and review, and so builds a long-term picture of users’ exposure to fluctuating gas levels.

Often, more than one hazard may be foreseeable in a single area.  In such cases, multi-channel instruments are used.  These generally monitor up to four to five gases together, with a typical sensor array for underground work covering combustible hydrocarbons, oxygen, hydrogen sulphide, carbon monoxide and in some situations carbon dioxide.  A wide range of other sensors can be specified, making this type of unit suitable for most confined space applications.  The slightly larger physical dimensions of a multi-gas detector allow for bigger displays showing a range of gas data from all channels simultaneously, as well as useful information relating to calibration and configuration.

Some multi-channel units incorporate a built-in sampling pump, allowing a flexible sample line to be fed into the space while the monitor remains outside with the user. Monitors that make pre-entry check functionality quick and simple ensure that the proper checks are carried out and data is logged to provide managers with peak reading information.  This easily enables the user to test the atmosphere before entry into the confined space.  Obviously, it is important that the sample line is free of kinks and blockages, and that sufficient time is allowed for the gas drawn from the chamber to arrive at the sensor.

Timed interval monitoring is particularly helpful in the oil and petrochemical industries.  When a vessel which has held combustible liquids is purged with inert gas, a monitor is set up outside to record falling hydrocarbon levels and indicate when it is safe to open the container to air.  The latest portable detectors incorporate an infrared sensor for just this purpose because, unlike conventional sensors for combustible gas monitoring, infrared devices can operate in the absence of oxygen and in the presence of very high hydrocarbon levels.

Gas hazards in tunnels

Internal combustion engines emit exhaust fumes that contain significant quantities of carbon monoxide and nitrogen dioxide, both highly toxic. If a tunnel is inadequately ventilated, these gases can accumulate to concentrations that can become hazardous to human health. Oxygen depletion is also a risk in tunnels and confined spaces where a fresh-air supply may be limited. In the absence of adequate ventilation the level of oxygen can be reduced surprisingly quickly by breathing or combustion processes. Oxygen levels may also be depleted due to dilution by other gases such as carbon dioxide (a naturally occurring toxic gas), nitrogen, argon or helium, and chemical absorption by corrosion processes and similar reactions.

Gas detection in tunnels

Gas detection in tunnels

Explosive gas hazards can also exist due to accumulations of methane (a naturally occurring gas produced by the under-ground decomposition of carbon-based organic materials), fuel spills or gas leaks from welding equipment. Effective fixed gas monitoring systems are therefore essential to ensure the safety of all tunnel users.

Gas Testing

Gas testing or bump testing, defined as ‘the application of a known concentration of gas to validate sensor and monitor functionality’, is becoming more prevalent. In fact, since EN60079-29 parts 1 and 2 have been harmonised with the ATEX directive, manufacturers are asked to state in their manuals the requirement to perform frequent gas tests. The provision of a bump test facility within the monitor and/or the provision of a gas test station to offer a managed gas test offers users a quick and simple way of performing the tests.

Universal features
Certain features should be expected in every portable gas detector.  Clearly, life-saving tools for demanding environments must be as tough as possible, with reliable electronics housed in impact-resistant casings.  While the need to leave gas sensors exposed to the atmosphere means that no instrument can be fully sealed, a high degree of protection against dust and water ingress is essential.  Toughness notwithstanding, a well-designed detector will also be light and compact enough to wear for an entire shift.

Finally, because of the difficulties of working in a cramped space, perhaps under poor lighting, instruments should be easy to use.  No matter how advanced a detector’s internal architecture or data management options, personnel in the field should be faced with nothing more daunting than a clear display, simple, one-button operation and loud/bright alarms.

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Crowcon showing the latest developments in gas detection technology at Health and Safety Expo 2012

Gas detection specialist Crowcon is showing its latest developments in gas detection technology at the Health and Safety Expo in Birmingham this May. Among the new products on show will be the Gas-Pro portable confined space entry (CSE) gas detector. Specifically designed for CSE work, the Gas-Pro has application-driven features that include a top-mount display, internal pump, detection of up to five gases simultaneously, and a tri-colour status indicator.

Crowcon showing the latest developments in gas detection technology at Health and Safety Expo 2012

Crowcon showing the latest developments in gas detection technology at Health and Safety Expo 2012

(Caption: Crowcon’s Gas-Pro confined space entry gas detector)

Crowcon will also be showing a number of other new gas detection products, including an un-powered gas test unit for the Tetra 3 portable gas detector, which utilises the functionality of the Tetra 3 to carry out a simple and fast gas test in a matter of minutes.

In addition, the IRmax infrared (IR) flammable gas detector will be on display. Unlike conventional IR gas detectors, IRmax does not use heaters to prevent condensation on windows and mirrors. Instead, its optical components are treated with a highly durable hydrophobic coating called STAY-CLIR that completely prevents signal faults due to condensation. The IRmax is also available with the HART (Highway Addressable Remote Transducer) Communication Protocol, a global standard for sending and receiving digital information across analog wires between smart devices and control or monitoring systems

All these new products, as well as Crowcon’s existing range of state-of-the-art gas detection products, can be found in Hall 1, stand number F80. Crowcon’s experts will also be on hand to answer any gas-safety related questions.

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Gas Detector Communication Technology for Offshore Oil and Gas Platforms

Introduction
In few applications is safety as important as on offshore oil and gas platforms. Explosive hazards from hydrocarbon gases and vapours are an ever-present risk, whilst toxic hydrogen sulphide gas and depleted oxygen environments can pose significant risks to personnel.

Gas detectors are therefore essential to provide dependable early warning of gas hazards. Gas detectors are permanently installed in strategic locations around fixed installations such as offshore platforms. As many as 700 gas detectors may be installed on a single offshore platform.

In this article we will first look at the main gas hazards found on offshore rigs and then discuss the various communication technologies available to integrate them into a network.

Gas Detector Communication Technology for Offshore Oil and Gas Platforms

Gas Detector Communication Technology for Offshore Oil and Gas Platforms

Gas Concentrations
The job of any gas detector is to sense the gas in concentrations low enough to provide an alarm before a hazardous concentration has accumulated. To this end, flammable gas detectors are scaled in the ‘%LEL’ range (100%LEL equating to the concentration at which as may become ignitable), toxic gas sensors are scaled in the ‘ppm’ range (parts per million), and oxygen sensors measure form 0-25% volume (with 20.9% representing the normal oxygen concentration in air).

Explosive Risk
In order for gas to ignite there must be an ignition source, typically a spark (or flame or hot surface) and oxygen. For ignition to take place the concentration of gas or vapour in air must be at a level such that the ‘fuel’ and oxygen can react chemically. The power of the explosion depends on the ‘fuel’ and its concentration in the atmosphere. The relationship between fuel/air/ignition is illustrated in the ‘fire triangle’.

Fire Triangle

Fire Triangle

The ‘fire tetrahedron’ concept has been introduced more recently to illustrate the risk of fires being sustained due to chemical reaction. With most types of fire the original fire triangle model works well – removing one element of the triangle (fuel, oxygen or ignition source) will prevent a fire occurring. However, when the fire involves burning metals like lithium or magnesium, using water to extinguish the fire could result in it getting hotter or even exploding. This is because such metals can react with water in an exothermic reaction to produce flammable hydrogen gas.

Fire tetrahedron

Fire tetrahedron

Not all concentrations of flammable gas or vapour in air will burn or explode. The Lower Explosive Limit (LEL) is the lowest concentration of ‘fuel’ in air which will burn and for most flammable gases it is less than 5% by volume. So there is a high risk of explosion even when relatively small concentrations of gas or vapour escape into the atmosphere.

LEL levels are defined in following standards: ISO10156, and IEC60079. The ‘original’ ISO standard lists LELs obtained when the gas is in a static state. LELs listed in the EN and IEC standards were obtained with a stirred gas mixture; this resulted in lower LEL’s in some cases (i.e. some gases proved to be more volatile when in motion).

Toxic Risk
Gases and vapours produced by offshore activities can, under many circumstances, have harmful effects on workers exposed to them by inhalation, being absorbed through the skin, or swallowed. Many toxic substances are dangerous to health in concentrations as little as 1ppm (parts per million). Given that 10,000 ppm is equivalent to 1% volume of any space, it can be seen that an extremely low concentration of some toxic gases can present a hazard to health.

Gaseous toxic substances are especially dangerous because they are often invisible and/or odourless. Their physical behaviour is not always predictable: ambient temperature, pressure and ventilation patterns significantly influence the behaviour of a gas leak. Hydrogen sulphide for example is particularly hazardous; although it has a very distinctive ‘bad egg’ odour at concentrations above 0.1ppm, exposure to concentrations of 50ppm or higher will lead to paralysis of the olfactory glands rendering the sense of smell inactive. This in turn may result in the assumption that the danger has cleared. Prolonged exposure to concentrations above 50ppm will result in paralysis and death.

Definitions for maximum exposure concentrations of toxic gases vary according to country. Limits are generally time-weighted as exposure effects are cumulative: the limits stipulate the maximum exposure during a normal working day.

Oxygen – too high or too low?
The normal concentration of oxygen in fresh air is 20.9%.  An atmosphere is hazardous if the concentration of oxygen drops below 19.5% or goes above 23.5%.  If the concentration falls to 17%, mental and physical agility are noticeably impaired; death comes very quickly if it drops only a few percent more.  At these levels unconsciousness takes hold so rapidly that the victim will be unaware of what is happening.

Without adequate ventilation, the simple act of breathing in a confined space will cause the oxygen level to fall surprisingly quickly.  Combustion also uses up oxygen, which means that engine-driven plant and naked flames such as welding torches are potential hazards.  Steel vessels and chambers which have been closed for some time are similarly dangerous because corrosion may have occurred, using up vital oxygen in the process.

Oxygen can also be displaced.  Nitrogen, for example, when used to purge hydrocarbon storage vessels prior to re-use, drives oxygen out of the container and leaves it highly dangerous until thoroughly ventilated.

High oxygen levels are also dangerous.  As with too little, too much will impair the victim’s ability to think clearly and act sensibly.  Moreover, oxygen-enriched atmospheres represent a severe fire hazard.  From clothing to grease, materials will burn much more vigorously under these conditions.  Common causes of oxygen enrichment include leaks from welding cylinders and even from breathing apparatus.

Communication Technology on Offshore Rigs

On a rig, gas detectors are connected to a centralised control system, which is responsible for indicating the current gas level and triggering alarms when pre-defined gas thresholds are exceeded. Gas detectors will typically be located within the hazardous area, with the control system mounted in the ‘safe area’ potentially hundreds of metres from the detectors.

Detectors are typically connected to the control system via cables, using ‘point-to-point’ topologies where each detector connects to a discreet input on the control system via an independent cable (or separate cores within a multi-core cable from a ‘marshalling cabinet’).
This conventional ‘point-to-point’ method of operation has been the preferred technique for decades for signal reliability and system security reasons. With a dedicated cable and controller input for each detector, a single failure will affect that specific detector only: the rest of the system can remain operational.

Point-to-point systems typically utilise analogue signals from the detector to indicate the gas level. Analogue signals however can only communicate a limited amount of information from the detector, typically: gas value (4-20mA), fault (<3mA), gas reading over-scale (>21.5mA).

The emergence of digital and communications technologies has enabled a far greater range of information to be communicated to a control system, as well as providing opportunities to reduce the amount of cables needed to connect detectors.

The HART Communications Protocol (www.hartcomm.org) complements conventional 4-20mA systems by super-imposing additional diagnostic information onto the 4-20mA signal. This data can be read using a HART enabled hand-held device or Asset Management System (AMS) to diagnose faults and manage system calibration and maintenance.

Whilst the safety function of the detector is still performed by the analogue 4-20mA signal and conventional controller, the HART data enables access to additional information such as device temperature, serial number, calibration, last calibrated date, fault status, supply voltage and signal current.

Developed by Modicon Inc, the Modbus protocol has been in existence since the early-1990s and is an address-based protocol whereby each ‘node’ or gas detector in this case is communicated with using a unique address. Information such as gas level, alarm and fault status is stored in registers within the detector, and the ‘Modbus Master’ control system routinely addresses individual detector ‘nodes’ to retrieve data. A full guide to Modbus can be downloaded from www.modbus.org/docs/PI_MBUS_300.pdf.

Like the HART Communications Protocol, Modbus can be used in conjunction with the analogue signal to provide additional detector information, or can be used as the primary means of communication with a control system such as a PLC (Programmable Logic Controller) or SCADA (Supervisory Control and Data Acquisition) system.

IRmax HART

IRmax HART

Foundation Fieldbus (FF) is a well-established solution widely used for process instruments, but as ever the safety industry is slower to change from established and trusted systems and practices. FF provides the opportunity to use alternative cabling interfaces: data can be transferred via conventional copper cables or fibre-optic cables. Data can also be transferred via Intrinsically Safe (I.S.) interfaces. For more information visit www.fieldbus.org.

All of the communications technologies listed above enable detectors to be installed in an addressable cable configuration rather than the conventional point-to-point topology. Thus cable installation costs can be significantly reduced by connecting multiple detectors onto a single cable where the cable loops from one detector to the next. The cost of control equipment can also be significantly reduced as a single controller can communicate with a fleet of detectors (addressing each detector ‘node’ individually on a sequential basis).

Wireless communications are a very attractive proposition where running additional cables to new or additional detectors is impractical. Detectors may be powered locally (via cables, batteries or solar panels), and transmit the gas levels and status information to a control system via a radio signal. Although wireless products are available on the market, a global ‘standard’ for the protocol and frequency deployed has yet to be established and therefore suitability will depend on local regulations in the region in which the device is to be used.

Installing wireless devices also requires very careful consideration to the characteristics of each detector location to ensure guaranteed signal integrity and security. In practice, at present wireless devices are viable mainly where they are needed for temporary area monitoring or where gas detection is needed in a location where installing a conventional cabled detector is impractical.

The majority of gas detection systems on offshore installations continue to use conventional 4-20mA point-to-point systems. For established platforms where safety systems are already installed there are no installation savings to be made by using addressable systems as the assets are already in-place. There is however an option to replace older gas detectors with HART enabled devices to realise the benefits of access to additional diagnostic data for asset management purposes.

For new installations, communications technologies such as Foundation Fieldbus may provide a better overall solution to conventional analogue systems, but as always the individual safety case assessment is the critical determining factor.

Crowcon Gas Detection Systems
Crowcon offers a very wide range of both fixed and portable gas detectors for use on offshore platforms. The company also offers control systems for monitoring multiple arrays of fixed detectors, and gas sampling systems which use pumps or compressed air-driven vacuum generators to extract air/gas samples from the area to be monitored and present the samples to one or more gas sensors.

Most gas detectors, including Crowcon’s, should be calibrated every six months to ensure optimum operation. However, a new range of IR (infrared) detectors allow users to extend maintenance checks to once every 12 months – and this only requires a ‘gas test’, not full re-calibration, which is more time consuming. ‘Bump-test’ stations and intelligent instrument management hubs, also enable simple day-to-day testing of portable gas detectors and easy management of maintenance cycles.

Author:
Andy Avenell.
Andy is Crowcon’s Fixed Systems product manager and has over 15 years’ experience in gas detection.

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HART® Communication Protocol Ensures Reliable Communication with Crowcon’s IRmax Gas Detector

Easy and reliable connection and communication is vital when using a gas detector, which is why Crowcon has introduced the HART Communication Protocol for its IRmax infrared (IR) hydrocarbon detector.

The HART (Highway Addressable Remote Transducer) Communication Protocol is the global standard for sending and receiving digital information across analog wires between smart devices and control or monitoring systems. More specifically, it is a bi-directional communication protocol that provides data access between intelligent field instruments like gas detectors and host systems. A host can be any software application, from a technician’s hand-held device or laptop to a plant’s process control, asset management or safety system using any control platform.

Crowcon IRmax HART

Crowcon IRmax HART

The HART Communication protocol is available with the IRmax in two formats:

1.    Local hand-held communicator connection. In this format, HART communicators are used on industrial sites for maintaining and calibrating a host of instruments. The key benefit is that site maintenance staff can use a common communicator to maintain all of their safety and process instruments. The user simply needs to upload and install the DD (Device Description) file to their communicator to access a wide range of IRmax functions and displays, alarm thresholds and diagnostic information.

2.    HART over a 4-20mA signal line. In this format, the safety function is performed by the 4-20mA signal (connected to a conventional controller or PLC/DCS). A HART device can then also be connected in parallel with the signal connections to read the detector’s status information.

Featuring dual-wavelength IR sensor technology in a rugged 316 stainless steel package, the ultra-compact IRmax is designed to detect methane gas and other potentially explosive hydrocarbons in the harshest conditions.

As the IRmax contains no components for artificially heating optical surfaces, power consumption is dramatically reduced. It requires less than 1 Watt of power, typically 75-90% lower than conventional IR gas detectors. A gas detection system using IRmax detectors therefore requires smaller (and lower cost) power supplies and battery back-up systems. Longer cables can also be used and more detectors can be powered on addressable networks.

Unlike conventional IR gas detectors, the IRmax does not utilise heaters to prevent condensation on windows and mirrors. Instead, its optical components are treated with a highly durable hydrophobic coating called STAY-CLIR that completely prevents signal faults due to condensation.

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Crowcon’s Gas Detectors Ensure Safe Operation at Indian Oil and Gas Terminal

100 Nimbus flameproof (Exd) detectors supplied to Cairn Energy’s Mangala facility in Rajasthan

100 of Crowcon’s Nimbus flameproof (Exd) hydrocarbon gas detectors have been installed at Cairn Energy’s Mangala oil and gas processing terminal in Rajasthan, India. Supplied via Larson & Toubro, the Nimbus units are located at strategic locations throughout the facility and ensure the safety of workers and equipment by detecting elevated levels of flammable hydrocarbon gases.

Crowcon Nimbus gas detector

Crowcon Nimbus gas detector

“Hydrocarbon gas detectors are required by local legislation,” commented Crowcon’s Indian distributor, Mr Kishore Degwekar of Detection Instruments Pvt. Ltd. “Larsen and Toubro, our customer, purchased the Nimbus detectors as they are certified by the Indian Directorate General of Mines Safety”.

Crowcon’s Nimbus gas detectors have an excellent 10-year proven track record and, as well as having local certification, are also ATEX and UL certified. The detector is also assessed to the globally recognised functional safety standard IEC61508 and is suitable for use as part of SIL 2 systems.

Many thousands of Nimbus detectors are installed in locations across the globe, in all climatic conditions, such as the north of Sweden with its sub-zero winters, the deserts of Qatar, where summer temperatures can exceed 50oC and where sandstorms are common, and hot and very humid regions such as Malaysia.

It is used in all manner of locations, including underground tunnels, oil and gas rigs, oil and gas refineries, over-ground pipelines, compressor stations, turbine halls, pumping stations, sewage works, chemical works, aerosol filling plants, floating production ships (FPSO’s) and power stations.

Designed to be integrated with existing gas detection systems, Nimbus can be used in conjunction with digital communication networks (via RS-485 Modbus) or conventional 4-20mA control systems such as Crowcon’s Gasmonitor.

Rated to IP67, Nimbus functions in even the dirtiest conditions. The optics operate at up to 90% obscuration, with a dirty optics warning light activating at 75% obscuration.  An external status light indicates whether the unit is in normal function or fault, alerts users to rising gas levels, and also identifies 22 further conditions for simple diagnosis.

About Cairn Energy’s Mangala oil processing terminal
The Mangala processing terminal covers an area equivalent to 200 football pitches and includes oil, gas, power and water infrastructure. At an eventual length of 670 km, the pipeline will provide access to more than 75% of India’s refining capacity. At the peak of construction, approximately 16,000 workers were involved: 5,000 on the pipeline and 11,000 on the processing terminal.

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Dependable gas detection without heated mirrors

Crowcon’s IRmax detector uses STAY-CLIR optical coating

IRmax is an ultra-compact infrared (IR) flammable gas detector which delivers rapid, fail-safe detection of hydrocarbon gases and vapours. Featuring dual-wavelength IR sensor technology in a rugged 316 stainless steel package, IRmax is designed to detect methane gas and other potentially explosive hydrocarbons in the harshest conditions.

Crowcon’s IRmax detector uses STAY-CLIR optical coating

Crowcon’s IRmax detector uses STAY-CLIR optical coating

Unlike conventional IR gas detectors, IRmax does not utilise heaters to prevent condensation on windows and mirrors. Instead, its optical components are treated with a highly durable hydrophobic coating called STAY-CLIR that completely prevents signal faults due to condensation.

IR type gas detectors detect tiny reductions in transmitted infrared energy due to absorption by molecular resonation in hydrocarbon gases and vapours. It is essential that the light path of the detector is not obscured by condensation or dirt to ensure dependable hazard detection. Conventionally, the windows and mirrors in IR detectors are heated to prevent condensation forming. Although an effective solution, heating components require significant amounts of power to operate and can result in the build-up of dissolved deposits (such as salt).

As IRmax contains no components for artificially heating optical surfaces, power consumption is dramatically reduced. It requires less than 1 Watt of power, typically 75-90% lower than conventional IR gas detectors. A gas detection system using IRmax detectors therefore requires smaller (and lower cost) power supplies and battery back-up systems. Longer cables can also be used and more detectors can be powered on addressable networks.

A further benefit of the STAY-CLIR coating is resistance to contamination from dirt and dust, rendering routine cleaning of the optical components unnecessary.

IRmax is Crowcon’s third-generation IR gas detector, and the 15 years of experience with previous IR products guided the products’ design and development. A key design goal was to find an effective alternative to heated optics whilst retaining long-term dependable operation with minimum maintenance.

Specialised coatings are well established for use on a myriad of products, from footwear to mobile phones, but Crowcon is the first company to apply the technique to gas detection with the intention of completely removing heaters.

Detailed research and development was undertaken by Crowcon’s scientists, resulting in a highly durable coating that was proven by being subjected to aggressive corrosion and resilience tests in extreme locations such as the Australian desert and the north coast of Scotland. The tests included:

  • Long-term immersion in salt-water
  • Long-term immersion in vessels filled with sulphur, hydrogen sulphide and sulphur dioxide
  • Direct exposure to continuous sand-spray
  • Continuous rubbing to simulate excessive cleaning
  • Long-term site trials on offshore platforms, petrochemical plants and sulphur recovery plants

IRmax has been continually in use on petrochemical sites from the North Sea to Singapore since September 2009, providing ‘real world’ evidence of the effectiveness and durability of the STAY-CLIR coating.

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New Gas-Pro Confined Space Gas Detector from Crowcon

Crowcon’s new Gas-Pro portable gas detector is designed with just one purpose – ensuring safety in confined spaces. It is robust, reliable and simple to use with a bright, easy to read display and long battery life.

New Gas-Pro Confined Space Gas Detector from Crowcon

New Gas-Pro Confined Space Gas Detector from Crowcon

(Photo caption: Worker wearing Crowcon’s new Gas-Pro confined space entry detector)

The Gas-Pro has a number of special features specific to confined space entry (CSE) work:

  • Compact and comparable in size to leading front-mount diffusion detectors, which means it will not get in the way of other personal protection equipment (PPE) and not interfere with the worker’s primary activity.
  • Bright, clear top-mount display that can be read at a glance without having to even touch the detector. A dual colour backlight adds an extra level of alert should the Gas-Pro enter alarm status.
  • Automated pre-entry check function. This is recorded in the event log making it traceable and proving the check was carried out prior to CSE.
  • An internal pump allowing pre-entry testing to be done quickly and easily. This also keeps the size of the detector small and removes the problems of poor sealing or the need for extra equipment and chargers.
  • +ve Safety™ (positive safety). Tri-colour status indication giving quick and effective monitoring of gas test (bump), calibration, over range and recent alarm notification. Because the indication light is visible to all it offers the fleet manager a quick, simple and comprehensive visible indication of monitor status.
  • Multiple gas sensors for up to five potentially hazardous gases from a wide range, including: hydrogen sulphide, carbon monoxide, carbon dioxide, oxygen and flammable gases, as well as industry-specific gases such as ozone, ammonia, chlorine, chlorine dioxide and sulphur dioxide.
  • Extremely rugged with IP65 and IP67 ingress protection with an extremely loud >95 dB alarm as well as a vibrating and dual colour visual warnings as standard.

The Gas-Pro is therefore ideally suited for CSE work. Personnel entering these spaces can now focus on their core activities, safe in the knowledge that their gas detector is focused on its core activity.

According to the UK’s Health and Safety Executive (HSE) a confined space means ‘any place, including any chamber, tank, vat, silo, pit, trench, pipe, sewer, flue, well or other similar space in which, by virtue of its enclosed nature, there arises a reasonably foreseeable risk’.

This definition covers just about any industrial activity but is especially applicable to the utilities industries (water and wastewater, electricity, telecommunications and gas), construction, hydrocarbon exploration and processing, petrochemicals, marine applications, agriculture, food processing, wine making and brewing, as well as emergency services. The Gas-Pro is ideal for these and many other applications.

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Crowcon’s Gasman Diving portable gas detector protecting divers from H2S gas in diving bells

Crowcon’s Gasman Diving H2S personal gas detector is protecting divers in the North Sea by monitoring hydrogen sulphide (H2S) gas in diving bells.

The diving industry has long been aware of the danger of H2S on subsea worksites and the danger of it getting into the diving bell. The severity of the problem varies worldwide and is particularly bad in waters which have effectively been used as ‘chemical dumps’.

Crowcon’s Gasman Diving portable gas detector protecting divers from H2S gas in diving bells

Crowcon’s Gasman Diving portable gas detector protecting divers from H2S gas in diving bells

When approached  by a major North Sea oil producer, concerned about  divers working on sites with elevated H2¬S levels, Unimed Scientific Limited (USL) considered Crowcon’s Gasman portable gas detector as a possible solution. USL is a leading provider of scientific back-up and guidance to the North Sea diving industry. The company is also a leading auditor of dive systems.

Dr. Valerie Flook, together with Crowcon, put the Gasman Diving through a range of tests to prove its suitability for use in diving bells. Initial tests subjected the device to high pressures of up to 20 bar, while exposing it to known concentrations of H2S to test its accuracy. USL also evaluated the hysteresis (the response to a rising signal differs from that to a falling signal) of the response at these gas levels and pressures. In addition, tests were carried out to ensure there was no risk of the detector being damaged by rapid pressure changes.

Following this testing, a few minor changes were made to ensure the Gasman Diving was fully fit for purpose. These included a small hole being placed in the back of the instrument to allow for rapid equilibration of pressure changes, with the addition of a small Gore-Tex membrane to protect the internal components of the detector from water ingress.

The Gasman Diving is now in use with several of the leading diving companies in the North Sea and is available worldwide.

It is a reliable and robust detector that provides accurate gas readings, even under high pressures, which can be easily downloaded and stored. Its small size and easy to read display makes it especially suitable for the confined spaces of the diving bells. Initial feedback from divers has also been positive.

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Crowcon’s Gas-Pro Confined Space Gas Detector at Offshore Europe in Aberdeen

Crowcon will be showing its new Gas-Pro confined space entry gas detector at the Offshore Europe show in Aberdeen between 6-8 September. The Gas-Pro has a number of special features that make it ideal for confined space use, including a top-mount display, an internal pump, five gas capability and Positive Safety™ (tri-colour status indicator).

Crowcon will also be showing other new products, including its IRmax infrared (IR) hydrocarbon fixed gas detector and its ATEX approved LaserMethane® mini Gen2 (LMm) portable methane detector.

The IRmax is an ultra-compact IR gas detector which delivers rapid, fail-safe detection of hydrocarbon gases with very low power consumption. Far smaller and lighter than comparable IR detectors, the IRmax is easy to install in even the most inaccessible locations and its remote display feature makes it extremely versatile.

The second generation LMm is designed to detect methane at a distance of up to 100 metres in seconds and has turned what used to be a time consuming and potentially hazardous procedure into a quick and easy one.

All these products, as well as Crowcon’s existing range of state-of-the-art gas detection products, can be found at stand number 4B140. Crowcon’s experts will also be on hand to answer any gas-safety related questions.

More information about the show and registration/ticketing details can be found on the organiser’s website.

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