Chemical Reactivity. Chapter 8: Crowl & Louvar. Chemical Reactive Hazard. Chemical reactivity hazard: situation with potential for an uncontrolled chemical reaction, resulting in harm to people, equipment, or environment. Result could be:
Chapter 8: Crowl & Louvar
Chemical reactivity hazard: situation with potential for an uncontrolled chemical reaction, resulting in harm to people, equipment, or environment.
Figure 8-1 Screening flowchart for reactive chemical hazards. An answer of “yes” at any decision point moves more toward reactive chemisty. See Section 8.2 for more details. (Source: R.W. Johnson, S.W. Rudy, and S. D. Unwin, Essential Practices for Managing Chemical Reactivity Hazards (New York: AIChE Center for Chemical Process Safety, 2003.))
Why important: Common problem with exothermic reactions.
1. Loss of coolant.
2. Increased temperature.
3. Increased energy generation.
High pressure due to: Vapor pressure of liquid.
Vapor decomposition products.
Larger vessels respond faster - less heat transfer thru walls!!!
Some chemicals can achieve self heat rates of 100’s deg. C/min! Styrene, Acrylic Acid
Most reactive runaways result in 2-phase flow thru relief and require a relief area 2 to 10 times larger than single phase relief.
A company had a spray painting operation to paint automotive parts. The spray painting was done in a paint booth to reduce worker’s exposure and to collect any paint droplets that might be entrained in the exhaust air. The paint droplets were collected by fibrous filters. At the end of each day, the filters were removed, placed in plastic bags, and stored for disposal in a separate building.
Due to environmental concerns over volatile emissions from paint solvents, the paint supplier reformulated the paint to use a less volatile solvent. This change was done in consultation with the paint company. Several test were done to ensure the reformulated paint worked well with the existing spray equipment and that the quality was satisfactory.
The company switched to the reformulated paint. Several days later the disposal building caught on fire, apparently due to a fire started by the paint filters. Can you explain how this might have happened. Any suggestions for prevention?
A university lab expansion includes installation of a distribution system to provide gaseous oxygen from manifolded cylinders to a biochemical engineering laboratory. No chemical reactivity hazards have been previously identified for the lab facilities.
Apply the screening method of Figure 8-1 to determine if any chemical reactivity hazards are expected.