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

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

The Dangers of CO2

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

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

Gas Monitors – what are the benefits?

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

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

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

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.

 Our Partnership with Point Safety 

Background

Point safety Ltd is one of the UK’s leading gas safety consultants with 20 years of experience, knowledge and background in the instrumentation industry. Founded in 2011, it specialises in sectors such as oil and gas, pharmaceutical, utilities and telecommunication, providing a range of industries, supplying, installing and maintaining bespoke solutions and the service and supply of test equipment. Point Safety provide constancy to their customers as they believe that there is no such thing as ‘one size fits all’ nor does one solution have to be ‘fit for purpose.

Views on Gas Detection

Portable gas detection is an essential piece of equipment when detecting toxic or explosive gasses and measuring gas concentration. Point Safety puts customers at the forefront of gas detection; they believe that it protects their customers’ plants and processes and, more importantly, helps prevent injury, thereby helping to ensure the health, safety, and wellbeing of its workers. 

Through the supply and support of Crowcon, our portable instruments allow Point Safety’s customers to have the freedom to have reliable, efficient service with the confidence and knowledge that the equipment being provided allows for the protection of workers and their employees. Therefore, turnaround is important to Point Safety; ensuring a quick and effective service turnaround for all units is essential, ensuring minimal downtime and increased customer satisfaction.

As Point Safety provide the supply, installation and maintenance of the bespoke solutions, the implementation and servicing of their fixed systems that are provided nationwide are vital to their customers. Point Safety are confident that the continuous monitoring of these systems ensures that our customers’ and their employees’ lives are safe and that of their surroundings.

Working with Crowcon

Through continuous communication of knowledge and expertise with Point Safety, our partnership will allow for the supply of gas detection instruments to ensure the safety of those working within the oil and gas, pharmaceutical, utilities and telecommunication industries.
“We have a long-standing relationship with Point Safety, now a trusted partner in the North. Point Safety offers outstanding service to our end-users and is extremely knowledgeable on Crowcon products” – Katherine Winter, Northern Account Manager. Our partnership, Point Safety, allows for the distributors of Crowcon products throughout the UK in portable and fixed gas detectors/systems. Our partnership has also enabled Point Safety to become a Crowcon calibration site, with all its engineers fully trained and certified to Crowcon standards. “Point Safety Ltd are extremely proud to be associated with Crowcon, the leaders in gas detection systems, not only in the UK but worldwide. Their expertise, knowledge, first-class product range, and total support is second to none.” – Dawn Beever, Head of Sales and Marketing.

Explosion hazards in inerted tanks and how to avoid them

Hydrogen sulphide (H2S) is known for being extremely toxic, as well as highly corrosive. In an inerted tank environment, it poses an additional and serious hazard combustion which, it is suspected, has been the cause of serious explosions in the past.

Hydrogen sulphide can be present in %vol levels in “sour” oil or gas. Fuel can also be turned ‘sour’ by the action of sulphate-reducing bacteria found in sea water, often present in cargo holds of tankers. It is therefore important to continue to monitor the level of H2S, as it can change, particularly at sea. This H2S can increase the likelihood of a fire if the situation is not properly managed.

Tanks are generally lined with iron (sometimes zinc-coated). Iron rusts, creating iron oxide (FeO). In an inerted headspace of a tank, iron oxide can react with H2S to form iron sulphide (FeS). Iron sulphide is a pyrophore; which means that it can spontaneously ignite in the presence of oxygen

Excluding the elements of fire

A tank full of oil or gas is an obvious fire hazard under the right circumstances. The three elements of fire are fuel, oxygen and an ignition source. Without these three things, a fire can’t start. Air is around 21% oxygen. Therefore, a common means to control the risk of a fire in a tank is to remove as much air as possible by flushing the air out of the tank with an inert gas, such as nitrogen or carbon dioxide. During tank unloading, care is taken that fuel is replaced with inert gas rather than air. This removes the oxygen and prevents fire starting.

By definition, there is not enough oxygen in an inerted environment for a fire to start. But at some point, air will have to be let into the tank – for maintenance staff to safety enter, for example. There is now the chance for the three elements of fire coming together. How is it to be controlled?

  • Oxygen has to be allowed in
  • There may be present FeS, which the oxygen will cause to spark
  • The element that can be controlled is fuel.

If all the fuel has been removed and the combination of air and FeS causes a spark, it can’t do any harm.

Monitoring the elements

From the above, it is obvious how important it is to keep track of all the elements that could cause a fire in these fuel tanks. Oxygen and fuel can be directly monitored using an appropriate gas detector, like Gas-Pro TK. Designed for these specialist environments, Gas-Pro TK automatically copes with measuring a tank full of gas (measured in %vol) and a tank nearly empty of gas (measured in %LEL). Gas-Pro TK can tell you when oxygen levels are low enough to be safe to load fuel or high enough for staff to safely enter the tank. Another important use for Gas-Pro TK is to monitor for H2S, to allow you judge the likely presence of the pryophore, iron sulphide.

Working together for safety at sea

Crowcon Detection Instruments is working together with Solent University’s Warsash School of Maritime Science and Engineering – all in the name of teaching engineering cadets, senior Merchant Navy officers, and Superyacht crews.

Solent delivers world-renowned yacht and powerboat design degree programmes, a suite of international maritime studies courses and a wide range of specialist support services for the maritime industry. It is also conducting a large number of research studies that make a real impact on industry thought leadership.

Their partnership with Crowcon makes good sense!  The marine environment is a dangerous one – and not just the more obvious hazards like high seas, storms, or rocks and coral reefs.  Confined spaces on ships, high-risk cargo, and on-ship processes all present potential gas hazards.

To keep mariners safe, gas monitoring equipment is essential.  Gas detection equipment requires specific marine environment testing and certification to ensure suitability to the extreme environments it operates in.  The European Marine Equipment Directive (MED) approval is internationally recognised. Gas detectors used by mariners onboard a vessel registered in an EU country must hold MED approval, and show the wheel mark to demonstrate compliance.

Crowcon has provided the university with demonstration T4 portable multi gas detectors.  T4 provides effective protection against the four most common gas hazards experienced in the marine industry, and is robust and tough enough to deal with the demanding marine environments.  T4 is ideally suited to help vessels comply with multiple SOLAS requirements which dictate the need for gas detection onboard vessels.

John Gouch, lecturer at  Solent University, said: “I have used Crowcon instruments in industry for many years, and know how reliable and trustworthy their gas detectors are. Since joining Warsash 18 months ago, I have been keen to ensure students understand the important part gas detection plays within the on-board safety system.”

“By using demo units of these detectors within our marine engineering courses, we can show the importance of gas detection in a marine environment to hundreds of seafarers and mariners, keeping as many people as possible aware and safe.”

Louise Early, Head of Marketing at Crowcon, said: “We’re really pleased with our partnership with Solent University.  By developing our relationship with training establishments, our safety message gets out to the people who will benefit most. We are always keen to learn from industry and this programme also offers Crowcon further insight into the way in which our equipment is used.”

For more information, visit the Solent University website, or the marine section of our industries page.

Hydrogen Sulphide: toxic and deadly – Chris explains more about this dangerous gas

Many of you will have come across hydrogen sulphide (H2S). If you have ever cracked a rotten egg the distinctive smell is H2S.

H2S is a hazardous gas that is found in many work environments, and even at low concentrations it is toxic. It can be a product of man-made process or a by-product of natural decomposition. From offshore oil production to sewerage works, petrochemical plants to farms and fishing vessels, H2S presents a real hazard to workers.

Continue reading “Hydrogen Sulphide: toxic and deadly – Chris explains more about this dangerous gas”

Chris’ quick guide to bump testing

Following on from last week’s article, ‘Why do I need to bump test my instrument?’, I thought I’d give you a little more detailed information about what is a bump test and how to carry one out.

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Why do I need to bump test my instrument?

Crowcon’s expert, Chris is here to answer your question

There are lots of reasons why a portable gas detector may not react to gas, some of which may not be obvious when you pick up a unit. The safest way to make sure your gas monitor is working is to ‘bump’ test it.

Continue reading “Why do I need to bump test my instrument?”