Water Treatment: The Need For Gas Detection In Detecting Chlorine

Water utility companies help provide clean water for drinking, bathing, and industrial and commercial uses. Wastewater treatment plants and sewage systems help keep our waterways clean and sanitary. Throughout the water industry, the risk of gas exposure and gas-associated hazards are considerable. Harmful gases can be found in water tanks, service reservoirs, pumping wells, treatment units, chemical storage and handling areas, sumps, sewers, overflows, boreholes, and manholes.

What Is Chlorine and Why Is It Dangerous

Chlorine (Cl2) gas appears yellow green in colour, used to sterilise drinking water. However, most chlorine is used in the chemical industry with typical applications including water treatment as well as within the plastics and cleaning agents. Chlorine gas can be recognised by its pungent, irritating odour, which is like the odour of bleach. The strong smell may provide adequate warning to people that they are exposed. Cl2 itself is not flammable, but it can react explosively or form flammable compounds with other chemicals such as turpentine and ammonia.

Chlorine gas can be recognised by its pungent, irritating odour, which is like the odour of bleach. The strong smell may provide adequate warning to people that they are exposed. Chlorine is toxic and if inhaled or drunk in concentrated quantities can prove fatal. If chlorine gas is released into the air, people may be exposed through their skin, eyes or through inhalation. Chlorine is not combustible however can react with most combustibles which poses a fire and explosion risk. It also reacts violently with organic compounds such as ammonia and hydrogen, causing potential fire and explosion.

What is Chlorine used for

Water chlorination began in Sweden during the 18th century with the purpose to remove odours from water. This method continued to be used solely to remove odours from water until 1890 when chlorine was identified as an effective substance for disinfection purposes. Chlorine was first used for disinfection purposes in Great Britain in the early 1900’s which over the next century chlorination became the more favoured method used for water treatment and is now used for water treatment in most countries worldwide.

Chlorination is a method that can disinfect water with high levels of microorganisms where either chlorine or substance that contain chlorine is used to oxidise and disinfect the water. Different processes can be used to achieve safe levels of chlorine in drinking water to prevent against waterborne diseases.

Why Do I Need To Detect Chlorine

Chlorine, being denser than air, tends to disperse throughout low-lying zones in poorly ventilated or stagnant areas. Although non-flammable by itself, chlorine can become explosive when in contact with substances like ammonia, hydrogen, natural gas, and turpentine.

The reaction of the human body to chlorine depends on several factors; the concentration of chlorine present in air, the duration and frequency of exposure. Effects are also dependant on the health of an individual and the environmental conditions during exposure. For example, when small amounts of chlorine are breathed in during short time periods, this can affect the respirational system. Other effects vary from coughing and chest pains, to fluid accumulation in the lungs, skin and eye irritations. To note, these effects do not take place under natural conditions.

Our solution

The use of a chlorine gas detector provides detection and measurement of this substance in the air to prevent any accidents. Equipped with an electrochemical chlorine sensor, a fixed, or portable, single gas or multi gas Cl2 detector will monitor chlorine concentration in the ambient air. We have a wide range of gas detection products to help you meet the demands of the water treatment industry.

Fixed gas detectors are ideal to monitor and alert water treatment plant managers and workers to the presence of all the major gas hazards. The fixed gas detectors can be permanently positioned inside water tanks, sewage systems, and any other areas that present a high risk of gas exposure.

Portable gas detectors are lightweight and robust wearable gas detection devices. The portable gas detectors sound and signal an alert to workers when gas levels are reaching dangerous concentrations, allowing action to be taken. Our Gasman, and Gas-Pro portables have reliable chlorine sensor options, for single gas monitoring and multi-gas monitoring.

Control panels can be applied to coordinate numerous fixed gas detection devices and provide a trigger for alarm systems.

For more information about gas detection within water and water treatment, or to explore more of Crowcon’s gas detection range, please get in touch.

Industry Overview: Food and Beverage 

The food and beverage (F&B) industry includes all companies involved in processing raw food materials, as well as those packaging and distributing them. This includes fresh, prepared foods as well as packaged foods, and both alcoholic and non-alcoholic beverages. 

The food and beverage industry is divided into two major segments, which are the production and the distribution of edible goods. The first group, production, includes the processing of meats and cheeses and the creation of soft drinks, alcoholic beverages, packaged foods, and other modified foods. Any product meant for human consumption, aside from pharmaceuticals, passes through this sector. Production also covers the processing of meats, cheeses and packaged foods, dairy and alcoholic beverages. The production sector excludes foods and fresh produce that are directly produced via farming, as these fall under agriculture. 

The manufacture and processing of food and beverages create substantial risks of fire and toxic gas exposure. Many gases are used for baking, processing and refrigerating foods. These gases can be highly hazardous – either toxic, flammable, or both. 

Gas Hazards 

Food Processing

Secondary food processing methods includes fermentation, heating, chilling, dehydration or cooking of some kind. Many types of commercial food processing consist of cooking, especially industrial steam boilers. Steam boilers are usually gas-fired (natural gas or LPG) or use a combination of gas and fuel oil. For gas-fired steam boilers, natural gas consists mainly of methane (CH4), a highly combustible gas, lighter than air, which is piped directly into boilers. In contrast, LPG consists mainly of propane (C3H8), and usually requires an on-site fuel storage tank. Whenever flammable gases are used on site, forced mechanical ventilation must be included in storage areas, in case of leakage. Such ventilation is usually triggered by gas detectors that are installed near boilers and in storage rooms. 

Chemical Disinfection 

The F&B industry takes hygiene very seriously, as the slightest contamination of surfaces and equipment can provide an ideal breeding ground for all kinds of germs. The F&B sector therefore demands rigorous cleaning and disinfection, which must meet industry standards. 

There are three methods of disinfection commonly used in F&B: thermal, radiation and chemical. Chemical disinfection with chlorine-based compounds is by far the most common and effective way to disinfect equipment or other surfaces. This is because chlorine-based compounds are inexpensive, fast acting and effective against a variety of microorganisms. Several different chlorine compounds are commonly used, of which include hypochlorite, organic and inorganic chloramines, and chlorine dioxide. Sodium hypochlorite solution (NaOCl) is stored in tanks while chlorine dioxide (ClO2) gas is usually generated on site.  

In any combination, chlorine compounds are hazardous and exposure to high concentrations of chlorine can cause severe health issues. Chlorine gases are usually stored on site and a gas detection system should be installed, with a relay output to trigger ventilation fans once a high level of chlorine is detected. 

Food Packaging 

Food packaging serves many purposes; it allows food to be transported and stored safely, protects food, indicates portion sizes and provides information about the product. To keep food items safe for a long time, it is necessary to remove oxygen from the container because otherwise, oxidation will occur when the food comes into contact with oxygen. The presence of oxygen also promotes bacterial growth, which is harmful when consumed. However, if the package is flushed with nitrogen, the shelf life of packaged food can be extended. 

Packagers often use nitrogen (N2) flushing methods for preserving and storing their products. Nitrogen is a non-reactive gas, non-odorous and non-toxic. It prevents oxidation of fresh food with sugars or fats, stops the growth of dangerous bacteria and inhibits spoilage. Lastly, it prevents packages from collapsing by creating a pressurized atmosphere. Nitrogen can be generated on site using generators or delivered in cylinders. Gas generators are cost effective and provide an uninterrupted supply of gas. Nitrogen is an asphyxiant, capable of displacing oxygen in air. Because it has no smell and is non-toxic, workers may not become aware of low oxygen conditions before it is too late.  

Oxygen levels below 19% will cause dizziness and loss of consciousness. To prevent this, oxygen content should be monitored with an electrochemical sensor. Installing oxygen detectors in packaging areas ensures the safety of workers and early detection of leaks. 

Refrigeration Facilities 

Refrigeration facilities in the F&B industry are used to keep food cool for long periods of time. Large-scale food storage facilities often use cooling systems based on ammonia (> 50% NH3), as it is efficient and economical. However, ammonia is both toxic and flammable; it is also lighter than air and fills up enclosed spaces rapidly. Ammonia can become flammable if released in an enclosed space where a source of ignition is present, or if a vessel of anhydrous ammonia is exposed to fire.   

Ammonia is detected with electro-chemical (toxic) and catalytic (flammable) sensor technology. Portable detection, including single- or multi-gas detectors, can monitor instantaneous and TWA exposure to toxic levels of NH3. Multi-gas personal monitors have been shown to improve workers’ safety where a low-range ppm for routine system surveys and flammable range is used during system maintenance. Fixed detection systems include a combination of toxic- and flammable-level detectors connected to local control panels – these are usually supplied as part of a cooling system. Fixed systems can also be used for process over-rides and ventilation control. 

Brewing and Drinks Industry 

The risk involved in the manufacture of alcohol involves sizable manufacturing equipment which can be potentially harmful, both to operate and because of the fumes and vapours that can be emitted into the atmosphere and subsequently impact the environment. Ethanol is the main combustible hazard found within distilleries and breweries is the fumes and vapours produced by ethanol. With the capacity to be emitted from leaks in tanks, casks, transfer pumps, pipes and flexible hoses, ethanol vapour is a very real fire and explosion hazard faced by those in the distillery industry. Once the gas and vapour is released into the atmosphere, it can quickly build and pose a danger to the health of workers. It is worth noting here however, that the concentration required to cause harm to workers’ health has to be very high. With this in mind, the more significant risk from ethanol in the air is that of explosion. This fact reinforces the importance of gas detection equipment to recognise and remedy any leaks straight away, so as to avoid disastrous consequences. 

Packaging, Transport and Dispensing 

Once wine is bottled and beer is packaged, they must be delivered to the relevant outlets. This commonly includes distribution companies, warehousing and in the case of breweries, draymen. Beer and soft drinks use carbon dioxide or a mix of carbon dioxide and nitrogen as a way of delivering a beverage to the ‘tap’. These gases also give beer a longer-lasting head and improve the quality and taste. 

Even when the beverage is ready to deliver, gas-related hazards remain. Those arise in any activity at premises that contain compressed gas cylinders, due to the risk of increased carbon dioxide levels or depleted oxygen levels (due to high levels of nitrogen). Carbon dioxide (CO2) occurs naturally in the atmosphere (0.04%). CO2  is colourless and odourless, heavier than air and if it escapes, will tend to sink to the floor. CO2 collects in cellars and at the bottom of containers and confined spaces such as tanks and silos. CO2  is generated in large amounts during fermentation. It is also injected into beverages during carbonation. 

To find out more on the gas hazards in food and beverage production visit our industry page for more information. 

Gas Safety Protocols in Water Treatment

Water is vital to our daily lives, both for personal and domestic use and industrial/commercial applications. It is everywhere, promoting some chemical reactions and inhibiting others. Being used to clean surfaces, carry chemicals to where they are used and to carry unwanted chemicals away. Do anything and you create a gas somewhere in some quantity. Do anything with water there are so many permutations of things that can come together and react, dissolved gases that can come out of solution, dissolved liquids and solids that can react to generate gases. Additionally, you must determine what gases you generate when you collect, clean, store, transport or use water. Gas detectors must be chosen to suit the specific environment in which they operate, in this case highly humid, often dirty, but rarely outside the temperature range 4 to 30 degrees C. All the risks are present in these complex environments, with multiple toxic and flammable gas hazards and often the additional risk of oxygen depletion.

Gas Hazards

Apart from common gas hazards known in the industry; methane, hydrogen sulphide, and oxygen, there are bi-product gas hazards and cleaning material gas hazards that occur from purifying chemicals such as ammonia, chlorine, chlorine dioxide or ozone that are used in the decontamination of the waste and effluent water, or to remove microbes from clean water. There is great potential for many toxic or explosive gases to exist as a result of the chemicals used in the water industry. And added to these are chemicals that may be spilled or dumped into the waste system from industry, farming or building work.

Chlorine (Cl2) gas appears yellow green in colour, used to sterilise drinking water. However, most chlorine is used in the chemical industry with typical applications including water treatment as well as within the plastics and cleaning agents. Chlorine gas can be recognised by its pungent, irritating odour, which is like the odour of bleach. The strong smell may provide adequate warning to people that they are exposed. Cl2 itself is not flammable, but it can react explosively or form flammable compounds with other chemicals such as turpentine and ammonia.

Ammonia (NH3) is a compound of nitrogen and hydrogen and is a colourless and pungent gas, also known to be highly soluble when in contact with water. This means that NH3 dissolves quickly into the water supply. Found at very low levels in humans and in nature. It is also often used in some household cleaning solutions. Although NH3 has many benefits, it can be corrosive and dangerous in certain circumstances. Ammonia can enter wastewater from several different sources, including urine, manure, cleaning chemicals, process chemicals and amino acid products. If NH3 enters a copper piping system, it can cause extensive corrosion. If NH3 enters water, its toxicity varies depending on the exact pH of the water. It is possible for ammonia to break down into ammonium ions, which can react with other compounds present.

Chlorine dioxide (ClO2) is an oxidising gas commonly used to disinfect drinking water. When used in very small quantities, it is safe and does not lead to significant health risks. But ClO2 is a strong disinfectant that kills bacteria, viruses, and fungi, and when used in high doses, it can be dangerous to people since it can damage red blood cells and the lining of the gastrointestinal (GI) tract.

Ozone (O3) is a gas with an antiseptic smell and no colour that, mostly, forms naturally in the environment. When inhaled, ozone can have a range of harmful effects on the body. As it is colourless gas it is difficult to trace without an effective detection system in place. Even when relatively small amounts are inhaled, the gas can have a damaging impact on the respiratory tract, causing inflammation and chest pain, alongside coughing, shortness of breath and throat irritation. It can also act as a trigger causing diseases such as asthma to worsen.

Confined Space Entry

The pipelines used to transport water require regular cleaning and safety checks; during these operations, portable multi-gas monitors are used to protect the workforce. Pre-entry checks must be completed prior to entering any confined space and commonly O2, CO, H2S and CH4 are monitored. Confined spaces are small, so portable monitors must be compact and unobtrusive for the user, yet able to withstand the wet and dirty environments in which they must perform. Clear and prompt indication of any increase in gas monitored (or any decrease for oxygen) is of paramount importance – loud and bright alarms are effective in raising the alarm to the user.

Legislation

European Commission Directive 2017/164 established an increased list of indicative occupational exposure limit values (IOELVs). IOELV are health-based, non-binding values, derived from the most recent scientific data available and considering the availability of reliable measurement techniques. Non-binding but best practice. The list includes carbon monoxide, nitrogen monoxide, nitrogen dioxide, sulphur dioxide, hydrogen cyanide, manganese, diacetyl and many other chemicals. The list is based on Council Directive 98/24/EC that considers the protection of the health and safety of workers from the risks related to chemical agents in the workplace. For any chemical agent for which an IOELV has been set at Union level, Member States are required to establish a national occupational exposure limit value. They also are required to take into account the Union limit value, determining the nature of the national limit value in accordance with national legislation and practice. Member States will be able to benefit from a transitional period ending at the latest on 21 August 2023.

The Health and Safety Executive (HSE) state that each year several workers will suffer from at least one episode of work-related illness. Although, most illnesses are relatively mild cases of gastroenteritis, there is also a risk for potentially fatal diseases, such as leptospirosis (Weil’s disease) and hepatitis. Even though these are reported to the HSE, there could be significant under-reporting as there is often failure to recognise the link between illness and work.

Under domestic law of the Health and Safety at Work etc Act 1974, employers are responsible for ensuring the safety of their employees and others. This responsibility is reinforced by regulations.

The Confined Spaces Regulations 1997 applies where the assessment identifies risks of serious injury from work in confined spaces. These regulations contain the following key duties:

  • Avoid entry to confined spaces, e.g., by doing the work from the outside.
  • If entry to a confined space is unavoidable, follow a safe system of work.
  • Put in place adequate emergency arrangements before the work start.

The Management of Health and Safety at Work Regulations 1999 requires employers and self-employed people to carry out a suitable and sufficient assessment of the risks for all work activities for the purpose of deciding what measures are necessary for safety. For work in confined spaces this means identifying the hazards present, assessing the risks and determining what precautions to take.

Our solution

Elimination of these gas hazards is virtually impossible, so permanent workers and contractors must depend on reliable gas detection equipment to protect them. Gas detection can be provided in both fixed and portable forms. Our portable gas detectors protect people against a wide range of gas hazards, and include T4x, Clip SGD, Gasman, Tetra 3, Gas-Pro, T4 and Detective+. Our fixed gas detectors are used where reliability, dependability and lack of false alarms are instrumental to efficient and effective protection of assets and areas, and include the Xgard, Xgard Bright and IRmax product ranges. Combined with a variety of our fixed detectors, our gas detection control panels offer a flexible range of solutions that measure flammable, toxic and oxygen gases, report their presence and activate alarms or associated equipment, for the wastewater industry we often recommend our Gasmaster panel.

To find out more on the gas hazards in wastewater visit our industry page for more information.

Cross sensitivity of toxic sensors: Chris investigates the gases that the sensor is exposed to

Working in Technical Support, one of the most common questions from customers is for bespoke configurations of toxic gas sensors. This frequently leads to an investigation into the cross sensitivity of the different gases that the sensor will be exposed to.

Cross sensitivity responses will vary from sensor type to sensor type, and suppliers often express the cross sensitivity in percentages while others will specify in actual parts-per-million (ppm) levels.

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