The Benefits of MPS Sensors 

Developed by NevadaNano, Molecular Property Spectrometer™ (MPS™) sensors represent the new generation of flammable gas detectors. MPS™ can quickly detect over 15 characterised flammable gases at once. Until recently, anyone who needed to monitor flammable gases had to select either a traditional flammable gas detector containing a pellistor sensor calibrated for a specific gas, or containing an infra-red (IR) sensor which also varies in output according to the flammable gas being measured, and hence needs to be calibrated for each gas. While these remain beneficial solutions, they are not always ideal. For example, both sensor types require regular calibration and the catalytic pellistor sensors also need frequent bump testing to ensure they have not been damaged by contaminants (known as ‘sensor poisoning’ agents) or by harsh conditions. In some environments, sensors must frequently be changed, which is costly in terms of both money and downtime, or product availability. IR technology cannot detect hydrogen – which has no IR signature, and both IR and pellistor detectors sometimes incidentally detect other (i.e., non-calibrated) gases, giving inaccurate readings that may trigger false alarms or concern operators. 

The MPS™ sensor delivers key features that provide real world tangible benefits to operator and hence workers. These include: 

No calibration  

When implementing a system containing a fixed head detector, it is common practice to service on a recommended schedule defined by manufacturer. This entails ongoing regular costs as well potentially disrupting production or process in order service or even gain access to detector or multiple detectors. There may also be a risk to personnel when detectors are mounted in particularly hazardous environments. Interaction with an MPS sensor is less stringent because there are no unrevealed failure modes, provided air is present. It would be wrong to say there is no calibration requirement. One factory calibration, followed by a gas test when commissioning is sufficient, because there is an internal automated calibration being performed every 2 seconds throughout the working life of the sensor. What is really meant is – no customer calibration. 

The Xgard Bright with MPS™ sensor technology does not require calibration. This in turn reduces the interaction with the detector resulting in a lower total cost of ownership over the sensor life cycle and reduced risk to personnel and production output to complete regular maintenance. It is still advisable to check the cleanliness of the gas detector from time to time, since gas can’t get through thick build ups of obstructive material and wouldn’t then reach the sensor. 

Multi species gas – ‘True LEL’™  

Many industries and applications use or have as a by-product multiple gases within the same environment. This can be challenging for traditional sensor technology which can detect only a single gas that they were calibrated for at the correct level and can result in inaccurate reading and even false alarms which can halt process or production if another flammable gas type is present. The lack of response or over response frequently faced in multi gas environments can be frustrating and counterproductive compromising safety of best user practices. The MPS™ sensor can accurately detect multiple gases at once and instantly identify gas type. Additionally, the MPS™ sensor has a on board environmental compensation and does not require an externally applied correctional factor. Inaccurate readings and false alarms are a thing of the past.  

No sensor poisoning  

In certain environments traditional sensor types can be under risk of poisoning. Extreme pressure, temperature, and humidity all have the potential to damage sensors whist environmental toxins and contaminants can ‘poison’ sensors, leading to severely compromised performance. Detectors in environments where poisons or inhibitors may be encountered, regular and frequent testing is the only way to ensure that performance is not being degraded. Sensor failure due to poisoning can be a costly experience. The technology in the MPS™ sensor is not affected by contaminates in the environment. Processes that have contaminates now have access to a solution that operates reliably with fail safe design to alert operator to offer a peace of mind for personnel and assets located in hazardous environment. Additionally, the MPS sensor is not harmed by elevated flammable gas concentrations, which may cause cracking in conventional catalytic sensor types for example. The MPS sensor carries on working. 

Hydrogen (H2)

The usage of Hydrogen in industrial processes is increasing as the focus to find a cleaner alternative to natural gas usage. Detection of Hydrogen is currently restricted to pellistor, metal oxide semiconductor, electrochemical and less accurate thermal conductivity sensor technology due to Infra-Red sensors inability to detect Hydrogen. When faced with challenges highlighted above in poisoning or false alarms, the current solution can leave operator with frequent bump testing and servicing in addition to false alarm challenges. The MPS™ sensor provides a far better solution for Hydrogen detection, removing the challenges faced with traditional sensor technology. A long-life, relatively fast responding hydrogen sensor that does not require calibration throughout the life cycle of the sensor, without the risk of poisoning or false alarms, can significantly save on total cost of ownership and reduces interaction with unit resulting in peace of mind and reduced risk for operators leveraging MPS™ technology. All of this is possible thanks to MPS™ technology, which is the biggest breakthrough in gas detection for several decades. The Gasman with MPS is hydrogen (H2) ready. A single MPS sensor accurately detects hydrogen and common hydrocarbons in a fail-safe, poison-resistant solution without recalibration.

For more on Crowcon, visit https://www.crowcon.com or for more on MPSTM visit https://www.crowcon.com/mpsinfixed/  

What is IR Technology? 

Infrared emitters within the sensor each generate beams of IR light. Each beam is measured by a photo-receiver. The “measuring” beam, with a frequency of around 3.3μm, is absorbed by hydrocarbon gas molecules, so the beam intensity is reduced if there is an appropriate concentration of a gas with C-H bonds present. The “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 beams measured by the photo-receiver. 

Benefits of IR technology 

IR sensors are reliable in some environments that can cause pellistor-based sensors to function incorrectly or in some cases fail. In some industrial environments, pellistors are at risk of being poisoned or inhibited. This would leave a worker on their shift unprotected. IR sensors are not susceptible to the catalyst poisons so significantly enhance safety in these conditions. 

Pellistor technology is considerably less expensive than IR technology, reflecting the comparative simplicity of the detection technology. However, there are several advantages of IR over pellistors. These include IR technology provides fail-safe testing. The mode of operation means that if the infrared beam failed, this would register as a fault.  In normal pellistor operation, conversely, a lack of output is ordinarily an indication that no flammable gas is present, but this could also be the result of a fault. Pellistors are susceptible to poisoning or inhibition; a particular concern in environments where compounds containing silicon, lead, sulphur and phosphates, even at low levels. IR instruments don’t, themselves, interact with the gas.  Only the IR beam interacts with the gas molecules, so, IR technology is immune to poisoning or inhibition by chemical toxins. In high concentrations of flammable gas, pellistor sensors can burn out. As with poisoning or inhibition, this would probably only be picked up by testing.  Again, IR sensors are not affected by these conditions. Low levels of oxygen mean that pellistor sensors won’t work. This can be the case in recently purged tanks, but also in confined spaces generally, where pellistors may be ineffective.  IR technology is effective in areas where oxygen may be reduced or absent. 

Factors that affect IR technology  

Exposure to high levels of flammable gas can cause “sooting” of pellistors, reducing their sensitivity and potentially leading to failure. Pellistors require oxygen to function, however, IR sensors can be relied on in applications such as fuel storage tanks where there is little or no oxygen, due to flushing with inert gas prior to maintenance, or which still contain high levels of fuel vapours. The fail-safe nature of IR sensors, which automatically alert you to any fault, provides an additional layer of safety. Gas-Pro IR measures in %LEL and has been certified for use in hazardous areas as defined by both ATEX/IECEx and UL. 

Knowing when the technology has failed  

IR sensors are reliable in environments that can cause pellistor-based sensors to function incorrectly or in some cases fail. In some industrial environments, pellistors are at risk of being poisoned or inhibited. This leaves workers on their shifts unprotected. IR sensors are not susceptible to these conditions, so significantly enhance safety. 

Problems with IR sensors 

IR sensors do not measure hydrogen, and they usually don’t measure acetylene, ammonia of some complex solvents either except for some specialist sensor types. 

If nothing is done to prevent it, moisture can build up inside IR sensors on the optics scattering the IR light and causing a fault.  

The fail-safe nature of IR sensors, which automatically alert you to any fault, provides an additional layer of safety, and this results in a fault if there isn’t enough light getting through the system e.g., if the light is being scattered form the beam. 

IR sensors have very high resistance to interference or inhibition by other gases and are suitable for both high gas concentrations and use in inert (oxygen free) backgrounds where catalytic pellistor sensors would perform poorly. 

Products  

Our portable products such as Our Gas-Pro IR and Triple Plus+ help customers to detect potentially explosive gases where traditional, “pellistor,” catalytic sensors will struggle – especially in low oxygen or ‘poisoning’ environments. And allow for the measurement of hydrocarbons at both % LEL and % Volume ranges making this instrument ideal for tank and line purging applications. 

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

World Hydrogen Summit 2022

Crowcon exhibited at the World Hydrogen Summit & Exhibition 2022 on the 9th – 11th May 2022 as part of the event designed to advance development in the hydrogen sector. Based in Rotterdam and produced by the Sustainable Energy Council (SEC), this year’s exhibition was the first Crowcon has attended. We were excited to be part of an occasion which fosters connections and collaboration between those at the forefront of the heavy industry and drives the hydrogen sector forward.

Our team representatives met various industry peers and showcased our Hydrogen solutions for gas detection. Our MPS sensor offers a higher standard of flammable gas detection thanks to its pioneering advanced molecular property spectrometer (MPS™) technology that can detect and accurately identify over 15 different flammable gases. This showcased an ideal solution for hydrogen detection due to hydrogen having proprieties that allow for easy ignition and higher burn intensity compared to that of petrol or diesel, therefore poses a real explosion risk. To find out more read our blog.

Our MPS technology had interest due to this not requiring calibration throughout the life cycle of the sensor, and detects flammable gases without the risk of poisoning or false alarms, thereby having a significant saving on total cost of ownership and reduce interaction with units, ultimately providing peace of mind and less risk for operators.

The Summit allowed us to understand the current state of the hydrogen market, including key players and current projects, allowing for potential developed a greater understanding of our product needs in order to play a major role in the future of hydrogen gas detection.

We look forward to attending next year!

T4x a Compliance 4-gas monitor 

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

Fixed or portable? 

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

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

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

What is a compliance 4-gas monitor? 

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

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

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

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

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

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

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

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

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

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

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. 

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.

The Benefits of ‘Hot Swappable’ Sensors

What are ‘Hot Swappable’ Sensors?

Hot swappable sensors allow for the replacement or addition of components to a device without the need for stopping, shutting down or rebooting the production process, thus allowing for high productivity and efficiency.

Other benefits of ‘Hot swappable’ sensors

Another benefit is that it eliminates the need for hot work permits. Hot work is regularly undertaken during construction and maintenance projects and is a high-risk activity that requires careful and active risk management. These environments pose a significant risk of fire as well as safety. Hot swappable sensors are designed to avoid these potential problems entirely.

Why are they important?

Some gas detection products are designed to go into zoned areas where there can be flammable (explosive) gas present. Therefore, in environments such as a refinery, if you were to disconnect normal electronics, it usually would cause a small spark, and this is a risk as it could potentially lead to a fire or explosion. However, if the electronics have been designed so there is not a spark and have been approved as “not capable of causing an spark” by the certifying authority, these products can be disconnected and reconnected even in an explosive atmosphere without fear of sparking, ensuring that those working in these environments are kept safe.

It is possible to calibrate hot swappable sensors outside a zoned area and thus allow a rapid swapping exercise instead of a far longer calibration process. Thus, the operator need spend only a fraction of the time in the zoned area substantially avoiding personal risk.

Products with ‘Hot Swappable’ Sensors

XgardIQ is a fixed detector and transmitter compatible with Crowcon’s full range of sensor technologies. Available fitted with a variety of sensors for fixed flammable, toxic, oxygen or H2S gas detection. Providing analogue 4-20mA and RS-485 Modbus signals as standard, XgardIQ is optionally available with Alarm and Fault relays and HART communications. The 316 stainless steel is available with three M20 or 1/2“NPT cable entries. (SIL-2) Safety integrity level 2 certified fixed detector.

Find out more

What is Photo-ionisation Detection (PID) Technology? 

Photo-ionisation detection (PID) technology is generally considered the technology of choice for monitoring exposure to toxic levels of VOCs. The sensors include a lamp as a source of high-energy ultraviolet (UV) light. The lamp encases a noble gas, most commonly krypton, and electrodes. The UV light’s energy excites the neutrally charged VOC (Volatile Organic Compounds) molecules, by removing an electron. 

The amount of energy needed to remove an electron from a VOC molecule is called the ionization potential (IP). The larger the molecule, or the more double or triple bonds the molecule contains, the lower the IP. Thus, in general, the larger or more fragile the molecule, the easier it is to detect.  

This technology does not require use of a sinter, which might prevent the gas reaching the sensor. It is also not susceptible to poisoning by chemicals in cleaning products, or silicone, although some cleaning agents containing large fragile molecules can cause positive readings. 

Benefits of PID Technology  

A high number of solvent species are sensed by this technology. Books have been written detailing the PID cross calibration responses to more than 750 solvent and gas types at ppm concentrations. It does not need air to function, it does not suffer from poisons and gives minor variation for moderate changes in temperature. 

PID is extremely sensitive and will respond to many different VOCs. The magnitude of the response is directly proportional to the concentration of the gas. However, 50ppm of one gas will give a different reading to 50ppm of a different gas. To cope with this, detectors are usually calibrated to isobutylene and then a correction factor is employed to get accurate readings for a target gas. Each gas has a different correction factor. Therefore, the gas must be known for the right correction factor to be applied. 

Consequently, pellistor sensors and photo-ionization detectors can be considered complementary technologies for many applications. Pellistors are excellent at monitoring for methane, propane, and other common combustible gases at %LEL (Lower Explosive Limit) levels. On the other hand, PID detects large VOC and hydrocarbon molecules that may be virtually undetectable by pellistor sensors, certainly in the parts-per-million range required to alert to toxic levels. Thus, the best approach in many environments is a multi-sensor instrument equipped with both technologies. 

PID sensor technology is very versatile and can be used, for example, for clearance measurements during shutdowns in the chemical and petrochemical industries, monitoring operations in shafts and enclosed spaces, detecting leaks and many other applications. 

Factors that affect PID Technology and their problems

Lack of voltage to the sensor affects the function of a PID sensor, also extremely high humidity, or particle densities. Also, the lamps last 2 years, but they will not last for 3 so the output must be monitored to check it has not gone into a fault condition. 

The problems with this sensor are limited to age related issues.  

  • Lamps age, voltage stacks work less well when they get dusty 
  • Some common gas types have zero response, e.g., methane and propane. The risk assessment needs to show the gas types expected have a response. If this information is not known for a gas type, then our website or customer support personnel can help. 
  • PID sensors are the highest cost sensors we use in our products. They are good, but with the quality comes the cost. 

How do I know when the technology is failing? 

The results drop from the pedestal value sensed by out PID bearing products, causing our instrumentation to go into fault. 

Products 

Our portable and fixed products are fitted with PID sensors that will detect large VOC and hydrocarbon molecules that may be virtually undetectable by pellistor sensors, certainly in the parts-per-million range required to alert to toxic levels.  

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

Make your business safer without compromising budgets

Unless your business has very few employees, all of whom work on site, you have probably experienced challenges when it comes to tracking, logging, aggregating and using the data from portable gas detectors. Until recently, this was a widespread problem.

The advent of connected safety, however, has transformed the situation – and for organisations that detect gas hazards, connected gas safety applications (like our own Crowcon Connect) can give you automated compliance records and risk management information, a 24/7 overview of both historic and current training needs and device use, as well as lots of gas safety insights that can be used (for example, with predictive analytics) to make your internal processes and business operations more efficient and effective.

Connected safety solutions can also help you to reduce costs and get better value for the money you do spend.

We’ve already published a couple of posts about aspects of connected safety: you can read them here and here. In this post we’ll look at the ways a connected safety solution and gas safety insights can make your business safer (in terms of both secure business data and better gas safety protocols) without the need for large investments.

What is a connected gas safety solution?

We have defined this term in an earlier post but in a nutshell, a connected safety application links all of your portable devices to a cloud-based software application, which downloads all of the data from each device and presents it to you in a flexible and user-friendly way.

A key advantage is that the connected safety app can aggregate your data both for single instances and over time, which means you get the top quality data you need to make optimal, cost effective, decisions – all in a user-friendly, intuitive format.

For example, Crowcon Connect uploads all data from portable gas detectors when they are docked at the end of a work session (this can be done via a fixed docking point and/or via Bluetooth when the device is charged). It then presents the information (whichever element(s) and from whichever perspective you choose) on a dashboard.

You can see this in action in our interactive online demo.

How does connected safety make my organisation safer?

A connected safety solution safeguards your organisation in two primary ways. Firstly, it gives you proof that your gas protection protocols are being used correctly and that you are complying with all relevant regulations. Secondly, it stores your gas detection data securely and maintains the integrity of that data.

That final point is important because the quality of the data you collect and analyse is imperative. Only top quality (current, accurate and correctly aggregated) data can be used to prove compliance, and with the analysis required to improve operational efficiency and productivity.

You are probably familiar with the need to store data securely – data protection has been a topic of debate and legislation for years now – but you may be less familiar with the extent to which data can be corrupted when it is read, stored, transmitted or processed, unless the correct safeguards are in place.

That’s why we have integrated multiple layers of security, corruption prevention, data backup and testing protocols into our Crowcon Connect product; for more detail, please read our IT security FAQs, which are here.

What is more, by sending your data to the cloud (and it can be hosted on your own private cloud, or link to your existing reporting tools using a bespoke API solution, if you prefer,), you may be able to make substantial savings on storage costs while finding it much easier (and less expensive in terms of time and human resource) to get the most value from your data (which may yield further cost savings). Being on the cloud also ensures that updates to the portal happen immediately and automatically when richer insights and more features are released s you always get the best experience possible.

Crowcon Connect improves organisational and practical safety

By using a cloud data system such as Crowcon Connect, you can use your gas safety insights and employee information to monitor compliance (both regulatory and with internal protocols) and to spot gaps in knowledge and training. You can then fix these – for example, by refreshing safety training, developing bespoke programs or discussing issues with staff – which may prevent catastrophe and save lives.

With the bird’s eye view that Crowcon Connect provides, you can clearly see if your detectors are ready to go and being used properly. You can also spot patterns of alarm events or gas exposure, and act to remedy these before they cause major issues.

Cloud data storage and processing lets you review data logs in a timely manner, assess measurements and response times and implement data-backed training and protocols. This can transform your operations and greatly improve safety.

To find out more about Crowcon Connect and cloud storage, please have a look at our white paper on the subject, which you can access by clicking here.

How Long will my Gas Sensor Last?

Gas detectors are used extensively within many industries (such as water treatment, refinery, petrochemical, steel and construction to name a few) to protect personnel and equipment from dangerous gases and their effects. Users of portable and fixed devices will be familiar with the potentially significant costs of keeping their instruments operating safely over their operational life. Gas sensors are understood to provide a measurement of the concentration of some analyte of interest, such as CO (carbon monoxide), CO2 (carbon dioxide), or NOx (nitrogen oxide). There are two most used gas sensors within industrial applications: electrochemical for toxic gases and oxygen measurement, and pellistors (or catalytic beads) for flammable gases. In recent years, the introduction of both Oxygen and MPS (Molecular Property Spectrometer) sensors have allowed for improved safety.  

How do I know when my sensor has failed? 

There have been several patents and techniques applied to gas detectors over the past few decades which claim to be able to determine when an electrochemical sensor has failed. Most of these however, only infer that the sensor is operating through some form of electrode stimulation and might provide a false sense of security. The only sure method of demonstrating that a sensor is working is to apply test gas and measure the response: a bump test or full calibration. 

Electrochemical Sensor  

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. 

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. 

Pellistor Sensor 

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 500˚C. 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. 

Factors affecting Pellistor Sensor Life 

The two main factors that affect the sensor life include exposure to high gas concentration and poising 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 life more than ten years is common in applications where inhibiting or poisoning compounds are not present. Higher power pellistors have greater catalytic activity and are less vulnerable to poisoning. More porous beads also have greater catalytic activity as their surface volume in increased. Skilled initial design and sophisticated manufacturing processes ensure maximum bead porosity. Exposure to high gas concentrations (>100%LEL) may also compromise sensor performance and create an offset in the zero/base-line signal. Incomplete combustion results in carbon deposits on the bead: the carbon ‘grows’ in the pores and creates mechanical damage. The carbon may however be burned off over time to re-reveal catalytic sites. Extreme mechanical shock or vibration can in rare cases also 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. 

How do I know when my sensor has failed? 

A pellistor that has been poisoned remains electrically operational but may fail to respond to gas. Hence the gas detector and control system may appear to be in a healthy state, but a flammable gas leak may not be detected. 

Oxygen Sensor 

Long Life 02 Icon

Our new lead-free, long-lasting oxygen sensor does not have compressed strands of lead the electrolyte has to penetrate, allowing a thick electrolyte to be used which means no leaks, no leak induced corrosion, and improved safety. The additional robustness of this sensor allows us to confidently offer a 5-year warranty for added piece of mind. 

Long life-oxygen sensors have an extensive lifespan of 5-years, with less downtime, lower cost of ownership, and reduced environmental impact. They accurately measure oxygen over a broad range of concentrations from 0 to 30% volume and are the next generation of O2 gas detection. 

MPS Sensor  

MPS sensor provides advanced technology that removes the need to calibrate and provides a ‘True LEL (lower explosive limit)’ for reading for fifteen flammable gases but can detect all flammable gases in a multi-species environment, resulting in lower ongoing maintenance costs and reduced interaction with the unit. This reduces risk to personnel and avoids costly downtime. The MPS sensor is also immune to sensor poisoning.  

Sensor failure due to poisoning can be a frustrating and costly experience. The technology in the MPS™ sensor is not affected by contaminates in the environment. Processes that have contaminates now have access to a solution that operates reliably with fail safe design to alert operator to offer a peace of mind for personnel and assets located in hazardous environment. It is now possible to detect multiple flammable gases, even in harsh environments, using just one sensor that does not require calibration and has an expected lifespan of at least 5 years.