FEATURE HAZARDOUS AREA / ATEX
Assessing risk from thermal fluid systems
the closed cup flash point of the media; in the presence of a source of ignition, the fluids could ignite. Where such systems operate under high pressure, any leaks from the pipework - at points such as flanged joints, valves and connection points - can create mists or sprays, which result in the creation of an explosive atmosphere outside the system. Thermal fluids operating above their
flash points are classified as hazardous substances, as are those handled below their flash points but under pressure. Whether inside or outside thermal fluid systems, on ignition, volatile atmospheres result in fires and explosions, and European ATEX legislation, implemented in the UK via DSEAR, stipulates requirements for the protection of workers against incidents arising from the presence of hazardous substances in the workplace.
Richard Franklin, managing director of Thermal Fluid Systems, explains why process companies who operate thermal fluid systems need to adopt a continuous risk assessment and management programme
A
n estimated 3,000 companies within the UK’s process industries operate
thermal fluid systems to transfer heat around their plants. Atmosphère Explosible (ATEX) and Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) legislation stipulate that these firms
must proactively manage the risk associated with their systems in order to protect their employees from risk of fire and explosion.
The heat transfer media used in thermal fluid systems is typically mineral or synthetic oil. The systems’ operating temperatures are invariably higher than
THS has reconditioned over 10 million litres of thermal oil across 150 systems in 15 countries, saving customers in excess of £20 million in the cost of replacement oils, excluding cost and disposal downtime
DEGRADING OVER TIME While most companies are aware that thermal fluid systems operating above the flash point of the fluid must be maintained according to DSEAR, many do not appreciate that organic thermal fluids based on mineral oils will degrade over time. Degradation can cause a fluid’s flash point to decrease, as light materials with lower flash points than the heat transfer fluid itself are generated, reducing the flash point of the fluid overall, so that fluids that were not flammable at the operating temperature at installation become flammable. DSEAR demands that the risks inherent
in the use of flammable fluids are assessed and eliminated or reduced. Regular fluid sampling and analysis is required to ensure that flash points are not exceeded. If necessary, oil must be replaced or conditioned so that a safe flash point is restored. The thermal fluid systems themselves also need to be scrutinised, for example to identify and manage potential leak points.
Non-contact temperature monitoring in hazardous areas
Fluke Process Instruments has announced that all models within the MI3 infrared sensor series are now also available as intrinsically safe versions for use in hazardous environments. The intelligent miniature sensors are fully ATEX
and IECEx certified for use in Zones 1 and 2 (gas) and Zones 21 and 22 (dust), to provide a complete intrinsically safe package including the sensor, a communication box, and an Ex power supply. All three components are IP65-rated, and each can be easily exchanged in the field without the need to re-calibrate the entire system. One or two intrinsically safe MI3 sensing heads can be powered by one power supply. The sensor
8 SUMMER 2016 | INDUSTRIAL COMPLIANCE
cables can be up to 30m long, providing high flexibility for setting up safe monitoring scenarios. The MI3 series comprises pyrometers for various spectral ranges and applications, including the 1M and 2M short wavelength models with a 100:1 resolution and 10ms response time, which are suitable for monitoring temperatures up to +1,800°C. The sensors are also said to have good EMC characteristics and can be used in ambient temperatures up to +180°C. Communication boxes are available with
RS485, Modbus, Profibus, Ethernet, and Profinet IO interfaces and with four galvanically isolated analogue outputs.
Fluke
www.fluke.com T: 0207 7942 0708 / INDUST RAL COMPA RI CE
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