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7 Risk Assessment and Management of Chemical Processes
Below, this step of the process risk assessment is illustrated using an example of
establishing safe process conditions concerning fire and explosion hazards for the
use of toluene.
7.4.1 Example: Defining the Safe Use of Toluene
Toluene is planned to be used in a set of manufacturing processes as a solvent.
Using identified fire and explosion hazard data, safe process conditions for the use
of toluene will be defined.
• Flash point: 6 ◦ C
• Lower/upper explosive limit: 1.2/7.1 volume %
• Ignition temperature: 535 ◦ C
• Minimum ignition energy: 0.26 MJ (at 25 ◦ C), easily charged electrostatically
• GHS hazard statement H225: Highly flammable liquid and vapor
• GHS hazard statement H304: May be fatal if swallowed and enters airways
The low flash point indicates that flammable toluene/air mixtures can be formed at
room temperature. Since toluene can be easily electrostatically charged and has low
minimum ignition energy, electrostatic discharges can cause ignition. Since high
electrostatic charge occurs especially in flowing media, careful attention should be
paid to the pouring and transferring of toluene.
These precautions are also reinforced by the relevant GHS precautionary statements for handling toluene, which include:
• P210: Keep away from heat, hot surfaces, sparks, open flames, and other ignition
sources. No smoking.
• P233: Keep container tightly closed.
• P240: Ground/bond container and receiving equipment.
• P243: Take precautionary measures against static discharge.
Considering this collected information, the safe use of toluene as a solvent in a
manufacturing process should include setting the following process conditions:
• Use of a closed and inerted apparatus
• Setting up an explosion protection zone within the manufacturing location
• Earthing the equipment and using conductive tools and clothing
7.5
Risk Identification (Step 3)
This step is arguably the most important of the entire risk assessment since it
identifies the risks that will be assessed. Risks not identified here will miss out on
having measures set to avoid or mitigate them. The key question to answer during
risk identification is: Where and how can systemic conditions become unsafe?
7 Risk Assessment and Management of Chemical Processes
Below, this step of the process risk assessment is illustrated using an example of
establishing safe process conditions concerning fire and explosion hazards for the
use of toluene.
7.4.1 Example: Defining the Safe Use of Toluene
Toluene is planned to be used in a set of manufacturing processes as a solvent.
Using identified fire and explosion hazard data, safe process conditions for the use
of toluene will be defined.
• Flash point: 6 ◦ C
• Lower/upper explosive limit: 1.2/7.1 volume %
• Ignition temperature: 535 ◦ C
• Minimum ignition energy: 0.26 MJ (at 25 ◦ C), easily charged electrostatically
• GHS hazard statement H225: Highly flammable liquid and vapor
• GHS hazard statement H304: May be fatal if swallowed and enters airways
The low flash point indicates that flammable toluene/air mixtures can be formed at
room temperature. Since toluene can be easily electrostatically charged and has low
minimum ignition energy, electrostatic discharges can cause ignition. Since high
electrostatic charge occurs especially in flowing media, careful attention should be
paid to the pouring and transferring of toluene.
These precautions are also reinforced by the relevant GHS precautionary statements for handling toluene, which include:
• P210: Keep away from heat, hot surfaces, sparks, open flames, and other ignition
sources. No smoking.
• P233: Keep container tightly closed.
• P240: Ground/bond container and receiving equipment.
• P243: Take precautionary measures against static discharge.
Considering this collected information, the safe use of toluene as a solvent in a
manufacturing process should include setting the following process conditions:
• Use of a closed and inerted apparatus
• Setting up an explosion protection zone within the manufacturing location
• Earthing the equipment and using conductive tools and clothing
7.5
Risk Identification (Step 3)
This step is arguably the most important of the entire risk assessment since it
identifies the risks that will be assessed. Risks not identified here will miss out on
having measures set to avoid or mitigate them. The key question to answer during
risk identification is: Where and how can systemic conditions become unsafe?