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Risk-based DSEAR assessment of high flashpoint “Class III” fuels

Author : Tony Ennis, Director, Haztech Consultants Ltd

08 November 2019

Class III fuels are defined as those having a flashpoint at or above 37.8°C (100°F) and below 60°C under the CLP Regulations. The upper flashpoint for these materials was previously 55°C under CHIP. The change has resulted in many common fuels with flashpoints specified as ">56°C" (i.e. between 55-60°C) falling into Class III. The objective of the paper is to clarify issues raised by the reclassification of Diesel and similar fuels.

The DSEAR assessment of fuels having flashpoints >50°C has been the subject of much research and several pieces of guidance, not all of which are entirely helpful or practical to implement. With this in mind, consideration has been given to how the risks of storage and handling these fuels can be assessed appropriately without excessive costs being incurred and whilst ensuring that risks to persons are As Low As Reasonably Practicable (ALARP).

This paper considers the fundamental physical and flammability properties of the materials and assesses how these factors affects the hazardous area classification and the associated risk of fire and explosion. In particular, the effect of flashpoint on the requirement for hazardous area classification are taken into consideration.

The potential risk of misting is examined under common situations of pumping and filling of tanks from typical fuel dispensing operations. The nature of fuel mist is explored and the difference between “mists” and “sprays” is clarified. The risk of the heating of liquid fuels by hot surfaces creating a flammable vapour is also considered.

The relevant guidance for hazardous area classification is considered, including BS EN 60079-10-1, EI15 and the APEA Blue Book. Research carried out by the HSL into formation of mists is considered.

Guidelines are proposed for hazardous area classification of fuels based on the flashpoint and expected range of ambient temperatures. Several misconceptions are explored with regards to the requirement for zoning of materials with flashpoints of >55°C. Several examples are considered with respect to the risk of fuel handling in common operations.

Tony Ennis

Tony Ennis is a Chemical Engineer with a degree from Leeds University and a Masters in Computer Simulation of batch Reactors from Nottingham. He has worked for a variety of companies including Shell, Air Products and ICI and in a variety of roles including production management, project engineering and process design.

Tony Joined ICI Engineering in 1993 and has been a full-time process safety specialist since that time. He specialised in fire, explosion and gas dispersion and pressure relief systems. Leaving ICI in 2000, he joined Haztech Consultants as Technical Director working in broadly similar areas.

Tony has specialised in fire and explosion hazards especially relating to DSEAR for some years. He previously sat on the committee of the UK Explosion Liaison Group and is currently on the committee responsible for the updating of EI15 Model Code of Safe Practice. Recently, he has been involved in the assessment of the hazards relating to high-flashpoint fuels.

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