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. 

Flue Gas Analyzer Calibration Guide

Ensuring your flue gas analyser (FGA) is regularly maintained goes without saying, however the hows and whys take a little more digging into. This article breaks down the calibration process and highlights handy tips and tricks for maintenance and best practice. 

The Act of Calibration 

Calibrating an FGA involves checking the sensors to ensure accurate measurement of a known concentration of certified calibration gas. To do this, the reading needs to be adjusted to match the gas concentration through an initial sensor calibration of the new or existing unit.

Next up is a calibration drift – this is done using existing instruments to bring the reading back after the drift occurs. Measuring the amount of drift in the gauge is a chance to see how far into inaccurate territory it has moved, and rule out measurement errors moving forward. 

Regularity is key

Sensors degrade over time with each sensor having a different life span of optimum operation, whether it is an electrochemical, catalytic bead and infra-red sensors. Regular calibration raises the gain levels and brings the sensor back in line to avoid dangerous incorrect readings. 

Once the sensor reaches a certain point it cannot be brought back into the correct position and this is the time when a new sensor needs to be installed. 

Explaining the calibration procedure 

The first step of the process is to set the device to calibration mode. This feeds a test gas of a known concentration onto the sensors to see how they respond. The gain levels are adjusted within the sensor to match the readings to the concentration fed in whilst mitigating drop off. 

The new settings are locked into the device’s firmware and a calibration report is produced, creating a PASS or FAIL result. 

Best Practice Tips and Tricks

Here are some best practice recommendations to help you maintain your FGA.

  • Clear out the water trap regularly – moisture is a by-product of combustion and can get sucked into the FGA when a test is undertaken. Water damage is the primary cause of damage in flue gas analysers, so it is imperative to check, empty and replace the unit’s inbuilt water traps and filters to protect from this.
  • Purge the device in clean air before powering down – noxious gases are drawn from the flue and passed over the sensors to gain a reading. After a test is completed and the system closes down some of that gas remains trapped inside. This can cause corrosion damage and shorten the life of the unit, so purging in clean air prior to shut down is a must.
  • Take inside to protect from cold weather conditions – to lessen the chances of condensation build up and water damage within your FGA make sure to remove the unit from your van overnight. This also reduces the risk of theft. 
  • Use approved chargers with outputs tailored for target device – non approved chargers cause damage to the battery and lessen charge retention, or even impairment to the battery and IC chips of the device itself.  
  • Check the devices’ probes and connector pipes – any splits or cracks in the rubber house will cause incorrect readings. Performing periodic checks on your hoses to ensure they are in good operating condition is a useful habit. 

All-Inclusive Service Options 

You have multiple options when sending your device off for it’s annual service and calibration:

Send it direct to us

Crowcon’s innovative Autocal jig system manages the end to end calibration process for Sprint Pro FGA’s. An out-of-calibration unit leads to errors in the combustion reports produced and could disrupt your day to day. 

Autocal servicing is easy. Simply bring your FGA to one of the DPD drop off locations, your unit will be inspected, tested and calibrated within two days and returned to you using DPD’s express return trackable option.

For more information please check out https://shop.crowcon.com/

Send it to your local store

Drop your device in to your local trade counter or specialist servicing centre at a time convenient to you and they will work with us to facilitate the annual calibration.
They will contact you to come and collect your device once the calibration is completed.

The Dangers of Hydrogen

As a fuel, hydrogen is highly flammable and leaks generate a serious risk of fire. However, hydrogen fires are markedly different to fires involving other fuels. When heavier fuels and hydrocarbons, like petrol or diesel, leak they pool close to the ground. In contrast, hydrogen is one of the lightest elements on earth, so when a leak occurs the gas rapidly disperses upwards. This makes ignition less likely, but a further difference is that hydrogen ignites and burns more easily than petrol or diesel. In fact, even a spark of static electricity from a person’s finger is enough to set off an explosion when hydrogen is available. Hydrogen flame is also invisible, so it is hard to pin-point where is the actual ‘fire’ is, but it generates a low radiant heat due to the absence of carbon and tends to burn out quickly.

Hydrogen is odourless, colourless and tasteless, so leaks are hard to detect using human senses alone. Hydrogen is non-toxic, but in indoor environments like battery storage rooms, it may build up and cause asphyxiation by displacing oxygen. This danger can be offset to some extent by adding odorants to hydrogen fuel, giving it an artificial smell and alerting users in case of a leak. But as hydrogen disperses quickly, the odorant is unlikely to travel with it. Hydrogen leaking indoors quickly collects, initially at ceiling level and eventually fills up the room. Therefore, the placement of gas detectors is key in early detection of a leak.

Hydrogen is usually stored and transported in liquified hydrogen tanks. The last concern is that because it is compressed, liquid hydrogen is extremely cold. If hydrogen should escape from its tank and come in contact with skin it can cause severe frostbite, or even the loss of extremities.

Which sensor technology is best for detecting hydrogen?

Crowcon has a wide range of products for the detection of hydrogen. The traditional sensor technologies for flammable gas detection are pellistors and infrared (IR). Pellistor gas sensors (also called catalytic bead gas sensors) have been the primary technology for detecting flammable gases since the 1960s and you can read more about pellistor sensors on our solution page. However, their key disadvantage is that in low oxygen environments, pellistor sensors will not function properly and may even fail. In some installations, pellistors are at risk of being poisoned or inhibited, which leaves workers unprotected. Also, pellistor sensors are not fail-safe, and a sensor failure will not be detected unless test gas is applied.

Infrared-type sensors are a reliable way to detect flammable hydrocarbons in low oxygen environments. They are not susceptible to being poisoned, so IR can significantly enhance safety in these conditions. Read more about IR sensors on our solution page, and the differences between pellistors and IR sensors in the following blog.

Just as pellistors are susceptible to poisoning, IR sensors are susceptible to severe mechanical and thermal shock and are also strongly affected by gross pressure changes. Additionally, IR sensors cannot be used to detect hydrogen. So the best option for hydrogen flammable gas detection is molecular property spectrometer (MPS™) sensor technology. This does not require calibration throughout the life cycle of the sensor, and since MPS detects flammable gases without the risk of poisoning or false alarms, it can significantly save on total cost of ownership and reduce interaction with units, resulting in peace of mind and less risk for operators. Molecular property spectrometer gas detection was developed at the University of Nevada and is currently the only gas detection technology able to detect multiple flammable gases, including hydrogen, simultaneously, very accurately and with a single sensor.

Read our white paper to find out more about our MPS sensor technology, and for more info on hydrogen gas detection visit our  industry page and have a look at some of our other hydrogen resources:

What do you need to know about Hydrogen?

Green Hydrogen – An Overview

Blue Hydrogen – An Overview

Xgard Bright MPS provides hydrogen detection in energy storage application

Keeping your gas monitors clean during COVID-19

During this challenging time, keeping your gas monitor clean is more important than ever to ensure you’re keeping yourself, and others, safe.

Cleaning your monitor

The following procedure and precautions should be noted if you intend to clean your Crowcon gas monitor to protect against COVID-19 transmission.

Gas monitors contain sensors that may be affected by the chemicals in cleaning compounds. In general Crowcon recommends cleaning with mild soap and a soft cloth taking care not to introduce excessive amounts of liquid into the product/sensors.

Alcohol-based cleaning products may cause a temporary response on some electrochemical sensors; potentially leading to false-alarms. It is recommended monitors are switched-off before cleaning and not switched back on until the alcohol has fully evaporated.

Cleaning agents that contain chlorine and/or silicones must be avoided, especially on monitors that contain pellistor-type flammable gas sensors as these compounds will ‘poison’ the sensor leading to permanent loss of sensitivity to gas.

Where gas monitor cleaning regimes are introduced or increased Crowcon strongly recommends that sensors are bump tested with the target gas periodically to ensure that sensors remain operational. Pellistor-type sensors in portable monitors should be tested every day before use as prescribed in the European standard EN60079-29 Part 1.

It is extremely likely that any viral agent could get trapped within the pump or filters within an instrument. Maintenance procedures should continue to be performed as described in the Operation and Maintenance Manual for the product and in-line with operating company policy.

For more information on how to keep you or your business safe during the COVID19 pandemic, get in touch and we’d be more than happy to help.

What is the life expectancy of my sensors?

Given the critical nature of gas detectors, it is important to know they are working correctly at all times. Many factors can affect the performance of gas detection sensors, and all sensors will fail eventually, so users must be vigilant and prepared to change their sensors when required. But changing sensors too early, when they actually have plenty of life left, can be a waste of time and money.

A further issue arises with purchasing and storing spares. Replacement sensors have a finite shelf life, which begins from the moment they are made. As time passes, they can degrade even if kept in ideal conditions (i.e. in a contaminant-free, temperature and humidity controlled environment  so the period between purchase and first use should be brief.

So, what should users do to extend the life of their sensors without putting people at risk?

Factors affecting sensor life

The life and/or performance of gas detection sensors can be affected by various factors, including:

  • Temperature
  • Humidity
  • Interfering gases
  • Physical factors, e.g. excessive vibration or impact
  • Contamination of or damage to the sensor e.g. by incorrect cleaning products
  • Contamination of filters or sinters e.g. by dust, sand or pests (yes spiders!)
  • Exposure to poisoning/inhibiting compounds even when the sensor is not powered.

There are multiple sensing technologies available and the life expectancy of a sensor is commonly linked to the technology employed. Electrochemical sensors tend to have a shorter life expectancy as compared to Infrared (IR) or catalytic sensors. The type of gas being detected can also have an impact of the life expectancy,  the more ‘exotic’ gases (for example chlorine or ozone) tends to be shorter than that of sensors monitoring the more common gases (carbon monoxide, hydrogen sulphide for example).

Most sensors will also suffer general wear and tear, and the damage caused is not always easy to detect, so the first rule for keeping sensors safe and in good working order is to undertake regular maintenance. This should include scheduled bump testing (also known as a gas or functional test) and calibration; while exposure to substantial volumes of gas may harm some sensors, the small amounts used in bump testing and calibration are absolutely fine

It is not always easy to tell that a sensor has failed; some of the techniques suggested are unreliable and this is not an area in which to take risks. The only sure-fire way to know a sensor is working correctly is through application of the target gas(es) in bump testing/calibration.

Planning gas sensor replacement

It makes sense for users to extend the life of their sensors as far as possible; they cost time and money to replace, after all. The ability to forward-plan and predict sensor consumption also makes sensor purchasing more efficient and helps to reduce the time spare sensors are kept in storage.

To predict and plan sensor replacement, users must understand the factors that influence their sensors’ performance. These will be specific to their own setting, which is why users must also be able to draw upon knowledge and experience built up through regular testing and calibration of sensors in their particular environment and applications.

Good quality sensors will come with a warranty, but while this may indicate a general life expectancy there are too many variables and too much at stake for it to stand alone. There really is no substitute for user knowledge and regular maintenance: with these in place, gas detector sensors are far more likely to live long and prosper.

What’s the difference between a pellistor and an IR sensor?

Sensors play a key role when it comes to monitoring flammable gases and vapours. Environment, response time and temperature range are just some of the things to consider when deciding which technology is best.

In this blog, we’re highlighting the differences between pellistor (catalytic) sensors and infrared (IR) sensors, why there are pros and cons to both technologies, and how to know which is best to suit different environments.

Pellistor sensor

A pellistor gas sensor is a device used to detect combustible gases or vapours that fall within the explosive range to warn of rising gas levels. The sensor is a coil of platinum wire with a catalyst inserted inside to form a small active bead which lowers the temperature at which gas ignites around it. When a combustible gas is present the temperature and resistance of the bead increases in relation to the resistance of the inert reference bead. The difference in resistance can be measured, allowing measurement of gas present. Because of the catalysts and beads, a pellistor sensor is also known as a catalytic or catalytic bead sensor.

Originally created in the 1960’s by British scientist and inventor, Alan Baker, pellistor sensors were initially designed as a solution to the long-running flame safety lamp and canary techniques. More recently, the devices are used in industrial and underground applications such as mines or tunnelling, oil refineries and oil rigs.

Pellistor sensors are relatively lower in cost due to differences in the level of technology in comparison to 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 vapours present.

Not only this but pellistors within fixed detectors with mV bridge outputs such as the Xgard type 3 are highly suited to areas that are hard to reach as calibration adjustments can take place at the local control panel.

On the other hand, pellistors struggle in environments where there is low or little oxygen, as the combustion process by which they work, requires oxygen. For this reason, confined space instruments which contain catalytic pellistor type LEL sensors often include a sensor for measuring oxygen.

In environments where compounds contain silicon, lead, sulphur and phosphates the sensor is susceptible to poisoning (irreversible loss of sensitivity) or inhibition (reversible loss of sensitivity), which can be a hazard to people in the workplace.

If exposed to high gas concentrations, pellistor sensors can be damaged. In such situations, pellistors do not ‘fail safe’, meaning no notification is given when an instrument fault is detected. Any fault can only be identified through bump testing prior to each use to ensure that performance is not being degraded.

 

IR sensor

Infrared sensor technology is based on the principle that Infrared (IR) light of a particular wavelength will be absorbed by the target gas. Typically there are two emitters within a sensor generating beams of IR light: a measurement beam with a wavelength that will be absorbed by the target gas, and a reference beam which will not be absorbed. Each beam is of equal intensity and is deflected by a mirror inside the sensor onto a photo-receiver. The resulting difference in intensity, between the reference and measurement beam, in the presence of the target gas is used to measure the concentration of gas present.

In many cases, infrared (IR) sensor technology can have a number of advantages over pellistors or be more reliable in areas where pellistor-based sensor performance can be impaired- including low oxygen and inert environments. Just the beam of infrared interacts with the surrounding gas molecules, giving the sensor the advantage of not facing the threat of poisoning or inhibition.

IR technology provides fail-safe testing. This means that if the infrared beam was to fail, the user would be notified of this fault.

Gas-Pro TK uses a dual IR sensor – the best technology for the specialist environments where standard gas detectors just won’t work, whether tank purging or gas freeing.

An example of one of our IR based detectors is the Crowcon Gas-Pro IR, ideal for the oil and gas industry, with the availability to detect methane, pentane or propane in potentially explosive, low oxygen environments where pellistor sensors may struggle. We also use a dual range %LEL and %Volume sensor in our Gas-Pro TK, which is suitable for measuring and switching between both measurements so it’s always safely operating to the correct parameter.

However, IR sensors aren’t all perfect as they only have a linear output to target gas; the response of an IR sensor to other flammable vapours then the target gas will be non-linear.

Like pellistors are susceptible to poisoning, IR sensors are susceptible to severe mechanical and thermal shock and also strongly affected by gross pressure changes. Additionally, infrared sensors cannot be used to detect Hydrogen gas, therefore we suggest using pellistors or electromechanical sensors in this circumstance.

The prime objective for safety is to select the best detection technology to minimise hazards in the workplace. We hope that by clearly identifying the differences between these two sensors we can raise awareness on how various industrial and hazardous environments can remain safe.

For further guidance on pellistor and IR sensors, you can download our whitepaper which includes illustrations and diagrams to help determine the best technology for your application.

You won’t find Crowcon sensors sleeping on the job

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

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

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

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

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

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

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

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

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

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

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

An ingenious solution to the problem of high temperature H2S

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

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

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

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

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

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

 

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

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

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

Why monitoring oxygen doesn’t protect from carbon dioxide

Carbon dioxide (CO2) is gas used or produced in many industries, if not directly in the products, in cooling and refrigeration systems. Possibly because of its association with breathing (we breathe in oxygen and breathe out CO2), the toxic nature of CO2 is not always appreciated. As a result, some believe that the level of oxygen (O2) in the air is a suitable indicator of safe CO2 levels. However, while monitoring O2 concentrations protects you from asphyxiation, it can’t be relied upon to protect against CO2 poisoning. Making a link between safe levels of CO2 and safe levels of O2 can be a fatal error.

Continue reading “Why monitoring oxygen doesn’t protect from carbon dioxide”

What you need to be aware of when…

…zeroing your CO2 detector

Without wishing to sound accusing, where were you the last time you zeroed your CO2 detector?  In your vehicle?  In the office before you travelled to the location you were working in?

It might not have caused you problems so far, but the air around you can make a big difference to the performance of your CO2 detector.

What is zeroing?

Zeroing your detector means calibrating it so its ‘clean air’ gas level indication is correct.

When is zero not really zero?

Many CO2 detectors are programmed to zero at 0.04% CO2 rather than 0%, because 0.04% is the normal volume of CO2 in fresh air.  In this case, when you zero your detector, it automatically sets the baseline level to 0.04%.

What happens if you zero your CO2 monitor where you shouldn’t?

If you zero your detector where you shouldn’t, the actual CO2 concentration could be much higher than the standard 0.04% – up to ten times higher, in some cases.

The end result?  An inaccurate reading, and no true way of knowing how much CO2 you’re actually exposed to.

What are the dangers of CO2?

CO2 is already in the earth’s atmosphere, but it doesn’t take much for it to reach dangerous levels.

  • 1% toxicity can cause drowsiness with prolonged exposure
  • 2% toxicity is mildly narcotic and causes increased blood pleasure, pulse rate, and reduced hearing
  • 5% toxicity causes dizziness, confusion, difficulty in breathing, and panic attacks
  • 8% toxicity causes headaches, sweating and tremors. You’ll lose consciousness after five to ten minutes of exposure.

What can I do to make sure I’m safe?

Only zero your instruments if you really have to, and make sure you zero your detector in fresh air – away from buildings and CO2 emissions, and at arm’s length to make sure your own breath doesn’t affect the reading.

What if I think my zero reading is incorrect?

It’s best to test the instrument with 100% nitrogen to check the real zero point, and then with a known level of CO2 test gas. If the zero gas reading is incorrect, or any other gas reading for that matter, the detector will need a full service calibration – contact your local service provider for help.

If you have a Crowcon detector, you can use our Portables Pro software to correct its zero reading.  For further information, call Crowcon customer support on +44 (0)1235 557711.