Chemistry of fire and explosions Essay Example

  • Category:
    Other
  • Document type:
    Coursework
  • Level:
    Undergraduate
  • Page:
    2
  • Words:
    874

Student:

Q1. What are recommendations that NFPA 654 has for controlling dust to prevent explosions?

The first recommendation is providing access to all the surfaces in a plant to help in assessing the level of dust build-up on these surfaces. The second is regular cleaning of all surfaces in a plant to allow the removal of the dust concurrently with the work cycle thus avoiding dust accumulation. The other is moving dust collectors outside the facility to reduce the risk of further displacement of dust (Amyotte, Paul & Rolf 16).

Q2. Explain what is meant by the Performance-Based Design Option. Why is it necessary?

Performance based design (PBD) refers to a rational approach used in designing a new building or evaluating an existing structure which often engenders superior results (Amyotte, Paul & Rolf 15). It gives an opportunity to improve the design to meet the objectives of the stakeholders.

Q3. What NFPA standard is used for Explosion Protection?

It is the standard for the prevention of fire and dust explosions from processing, manufacturing and the handling of combustible solids.

Q4. What NFPA standard is used to determine the class and group for electrical equipment?

It is the National Electric Code (NEC) for hazardous classes and groups.

Q5. What is Fugitive Dust?

It is defined as the visible emissions that are released from sources such as vents or cyclones.

Q6. What type of detector is required when fire detection is incorporated into the process?

A smoke detector is usually used to sense smoke as an indicator for the existence of fire in the system. The other is thermal detectors which automatically identifies abnormal rise in temperature of the process (Amyotte, Paul & Rolf 19).

Q7. What types of things would go into an Inspection, Testing, and Maintenance Program for facilities that have combustible dust?

These include organic materials such as coal, coke dusts, wood, flour, chemicals, and metals.

The classes include wool, cotton, viscose, polyester, acrylic, polyhaloalkenes, polypropylene, polyaramids and polybenzimidazole. They act as fire passive resistance measures and cause swelling behind the protective char layers thus improving the insulation behind this protective barrier.
Q8. What are the classes of flame retardant chemicals and what are the mechanisms of each in preventing or delaying fire ignition and/or growth?

Q9. What is the mission of the North American Fire Retardant Alliance? Who do they represent? What is their connection to the American Chemistry Council?

NAFRA’s mission include promoting appropriate methods for handling the existing and future flame retardants. Also, expansion of the existing knowledge on flame retardants (Amyotte, Paul & Rolf 21). They represent the global leading users and producers of various flame retardants. The body is related to the American Chemistry Council in that both of them deal with monitoring the development and control of flame retardants.

The concern is that these chemicals are identified as potential ozone depleting substances thus raising the issue of global warming.
Q10. According to the Green Science Policy Institute (and other similar organizations) what is the concern with flame retardant chemicals?

Q11. What classes of flame retardant chemicals pose this concern? Which ones do not present a concern?

The classes that pose depletion of ozone layer is halons and halocarbons and they are comprised of carbon tetrachloride, methyl iodide, dibromodiflouromethane, methyl bromide, bromochlromethane and dibromotetrafluoroethane. The class that do not present this threat is water.

Q12. What are Persistent Organic Pollutants? Why is this a global concern?

These are organic compounds which are resistant to the environmental degradation through biological and chemical processes. It is a global concern since the accumulation of these substances have significant negative health impact on human beings and also affect the environment

Q13. Explain what is meant by the term ‘bioaccumulation’? Why are animals at the top of the food chain most susceptible to hazards?

Bioaccumulation is the accumulation of chemical substances such as pesticides within an organism due to faster rate of intake than its elimination. The increased susceptibility to hazards by animals at the top of food chain is due to biomagnification. Biomagnification refers to toxic concentration in an organism due to ingestion of other animals and plants which possess widely disbursed toxins.

Q14. Using NFPA 2001 and referring to the Clean Agent Fire Suppression presentation, determine the weight of HFC-227ea required to protect an enclosure 20-ft wide, 40-ft long, and 8 ft high at an ambient temperature of 60 F and an elevation of 6000 ft, using a 9% design concentration.

Solution
W = V x C / s x (100-C) s = (k1) + (K2 X T)

W = weight of clean agent

V = net volume of hazard

s = the specific volume of the superheated agent vapor

C= the agent design concentration (volume percent)

T = the minimum estimated temperature of the protected volume.

  • S = 1.885 + 0.0046 T (T in °F) = 1.885 + 0.0046(60) = 2.161

  • V = 20 x 40 x 8n = 6400 ft3

  • W = V x C / s x (100-C)

  • W = V x (C/100-C) x 1/s

= 6400 x (9/100-9) x 1/2.161

=292.9 lbs

Works Cited

Amyotte, Paul R., and Rolf K. Eckhoff. «Dust explosion causation, prevention and mitigation: an overview.» Journal of Chemical Health and Safety 17.1 (2010): 15-28.