Temperature switches are critical for preventing accidents in hazardous areas across many different industries including oil and gas, chemicals, waste, water and more.
This article delves into the importance of explosion proof and intrinsically safe devices, explaining their features and benefits, and providing a comprehensive guide to help you choose the right switch for your hazardous area needs.
What is a temperature switch?
A temperature switch is a device used to monitor and control temperature levels within a system. It works by detecting temperature changes and activating or deactivating electrical circuits when a predetermined temperature threshold is reached.
This makes temperature switches essential for maintaining safe and optimal operating conditions in various applications, such as heating, cooling, and other industrial processes.
Manufacturing, HVAC, automotive and many other industries use temperature switches to prevent overheating, ensure efficient operation, and protect equipment from damage. To suit these different requirements and environments, they are available in many different designs and types, including mechanical and electronic switch options.
What if a temperature switch is needed in a hazardous area?
In hazardous area environments where there is a risk of explosion, it is imperative that temperature switches have no possibility of becoming a source of ignition. That means the design and build is different, more robust and produced to strict standards. The temperature switches used in these tough applications will often have a 316 Stainless steel or black anodised aluminium switchcase.
In many cases the switches are used as part of a safety system to monitor the temperature and control a system such as in building pumps, compressors, gas turbines, diesel engines and more.
They typically have either a rigid stem or capillary sensor.
Their use in potentially explosive atmospheres is usually associated with the auto ignition temperature of the dangerous substances in the operation. They are used to shut-off other “ATEX rated” equipment before dangerous temperatures are reached. A Pyroban explosion proof engine working offshore for example.
Temperature switches are typically tested and certified in accordance with the international IECEx system or ATEX Directives in Europe with product plates to display authentic certification marks and compliance.
Intrinsically safe vs flameproof (explosion proof) temperature switches
Temperature switches are available as a flameproof (Ex d) option or intrinsically safe (Ex ia). Both can be used in formally classified hazardous areas, but what is the difference?
Intrinsically safe equipment Ex ia
- How it works: Limits the amount of energy in the device to prevent an ignition
- When to use: Low power applications, such as on oil rigs, refineries, or chemical factories
- Advantages: It is lower cost than flameproof equipment and needs no special cabling. Although must be connected via a approved zener barrier or galvanic isolation.
Flameproof / Explosion proof equipment Ex d
- How it works: Contains explosions within a tough protective Ex d enclosure
- When to use: High power devices in explosive environments
When deciding between intrinsically safe or flameproof temperature switches consider the application requirements, cost, regulatory compliance and maintenance.
Key features and benefits of explosion proof temperature switches
Explosion proof, also known as flameproof, temperature switches are specialised safety devices designed to operate specifically in hazardous areas where the risk of explosion is high.
These “IECEx / ATEX rated” temperature switches are constructed to prevent any internal sparks or hot surfaces from igniting the surrounding atmosphere in the event of a release of flammable gases, vapours, or dust where the fine particles in the air can create an explosive mixture.
How They Work: Explosion proof temperature switches function by monitoring temperature levels and activating or deactivating electrical circuits when a set threshold is reached. They are encased in robust, flameproof housings that can withstand and contain any internal explosion, thereby preventing it from spreading to the external environment. That’s if the substance manages to reach the inside of the enclosure.
This is achieved through rigorous sealing and the use of materials that can tolerate extreme conditions without degrading, such as the Perseus™ temperature switch which is flameproof (Ex d) and intrinsically safe (Ex i). It has, for example:
- Robust Design: Made from durable materials that can endure harsh conditions and prevent ignition sources.
- High accuracy: Provides precise temperature monitoring, ensuring reliable performance in critical applications.
- Compliance: Certified to meet stringent safety standards like ATEX, SIL2 and IECEx, ensuring they are safe for use in explosive atmospheres.
- Versatility: Suitable for a variety of industries, including oil and gas, chemical processing, and more.
- Safety: Minimises the risk of explosions, protecting both personnel and equipment, and ensuring compliance with safety regulations.
Understanding these key aspects is essential for selecting the right explosion proof temperature switch for specific industrial of offshore oil and gas needs.
Applications of Ex d and Ex ia temperature switches
Explosion proof or intrinsically safe temperature switches are indispensable in industries where safety and reliability are paramount.
These ATEX or IECEx switches are designed to operate in hazardous area environments, ensuring that temperature levels are accurately monitored and controlled to prevent accidents, product and equipment damage. There are several applications that require explosion proof temperature switches, including:
Oil and Gas: In the oil and gas industry, Ex temperature switches are used to monitor and control the temperature of various processes, such as refining, drilling, and storage. These switches help prevent overheating and potential explosions, ensuring the safety of personnel and equipment.
Chemical Processing: Chemical plants often deal with flammable and reactive substances. Explosion proof temperature switches are crucial in maintaining safe operating conditions by monitoring temperatures and preventing overheating, which could lead to hazardous reactions.
Pharmaceuticals: In pharmaceutical manufacturing, precise temperature control is essential for producing high-quality products. Explosion proof temperature switches help maintain the required temperature ranges, ensuring product integrity and safety.
Food and Beverage: The food and beverage industry requires strict temperature control to ensure product quality and safety. Explosion proof temperature switches are used in various processes to prevent overheating and maintain consistent temperatures.
Water and Wastewater Treatment: In water and wastewater treatment plants, explosion proof temperature switches monitor and control temperatures to ensure efficient operation and prevent equipment failure. These switches help maintain the quality of treated water and protect the environment.
Defence: The defence sector requires robust and reliable equipment for extreme conditions. Explosion proof temperature switches are used in various military applications to monitor and control temperatures, ensuring the safety and effectiveness of operations.
Pyropress designs and manufactures a wide range of explosion proof temperature switches in the UK, meeting the specific needs of these industries. Products are certified to meet stringent safety standards, such as SIL2, ATEX and IECEx, ensuring they are safe for use in explosive atmospheres with maximum reliability and accuracy.
Key considerations when choosing temperature switches for Zoned hazardous areas
When selecting temperature switches for potentially explosive atmospheres, several crucial factors must be taken into account to ensure optimal performance and safety.
- Firstly, what is the application? Is it Zone 1, 2, 21 or 22 and what are the characteristics of the substance(s)?
- The temperature range of the switch should align with the specific application’s operating conditions. This ensures accurate monitoring and control of temperature levels without risking ignition due to heat. Settings from -10°C to +240°C for example.
- Low power or high power application? This will help decide on flameproof or intrinsically safe option.
- Rigid stem or capillary sensor?
- Certification standards are another vital consideration. It is essential to choose switches that are ATEX and IECEx certified, confirming their compliance with the relevant safety regulations for use in explosive atmospheres.
- Additionally, IP ratings indicate the level of protection against dust and water ingress. Look for IP ratings of IP66 and IP67 to ensure durability and reliability.
- Is the environment outside or exposed on an oil rig offshore? Talk to your supplier about the most suitable casing material.
- Explosion proof temperature switches are much larger than standard temperature switches because of the casing. Check there is space for it.
Selecting the right switch for specific applications is crucial to ensure safety and efficiency.
For instance, oil and gas industries require switches that can handle high temperatures and pressures, as well as corrosion resistant switches for offshore applications.
Matching the switch’s features with the application’s demands minimises downtime, enhances safety, and ensures regulatory compliance. Investing in the right temperature switch ultimately safeguards personnel, equipment, product and processes in hazardous areas.
Explore Pyropress explosion proof and intrinsically safe temperature switches:
- Perseus™ with rigid stem
- Perseus™ with capillary sensor
About the Author
Paul Maddern is an explosion protection instrumentation expert and has been part of the Pyropress team for 35 years.
Pyropress is a leading provider of high-quality instrumentation, specialising in explosion proof and intrinsically safe temperature switches. Pyropress’ expertise ensures safety and efficiency in various industrial applications. The company is a founding member of the Pioneer Safety Group.
