The Dow Fire and Explosion Index (F&EI) is a hazard classification guide that assesses the potential fire and explosion risks in chemical processes. It provides a systematic approach for evaluating risks based on various factors like material properties and process conditions, and is meant for early project stages as well as auditing existing plants. A case study of a nitroaniline reactor revealed a severe hazard level with a F&EI score of 182 due to critical process failures and conditions.

1. DOW FIRE AND
EXPLOSION HAZARD
AND ITS CASE STUDY
BY:
GAURAV SINGH RAJPUT
@gauravkrsrajput

2. WHAT IS DOW FIRE AND
EXPLOSION INDEX?
 The hazard classification guide developed by Dow
Chemical Company.
 Published by the American Institute of Chemical
Engineering, Dow (1994).
 It gives a method of evaluating the potential risk
from process, and assessing the potential loss.

3. OBJECTIVES OF DOW F&EI
Quantify:
The expected damage of potential fire & explosion
incidents in realistic terms
Identify:
Equipment that would likely contribute to the
creation or escalation of an incident
Communicate:
The fire & explosion potential to design teams and
plant personnel

4.  It is tailored for storage, handling and processing of
explosive and flammable material in chemical
process industry. It uses systematic approach based
on rating form.
 Suitable to be used at an early stage of a project and
for auditing existing plant.
 Final rating number (i.e. F&EI) provided a relative
ranking of hazard.
 It is also used for estimating damage radius (using
Dow correlation) and estimate dollar losses in the
event of accident (using consequences analysis form).

5. Quantative measurement based on
 Historic loss data
 Energy potential of material
 Effectiveness of loss prevention practises

6. Application
 Flammable( Combustible) and reactive materials
 Material stored handled or processed
 Material quantity > 2200 kg or 2.2 cubic meter
 Recommended for pilot plant( >450 kg)
 Should state point in time of operation
 Relative ranking of risk of various process

7. Factors in selecting pertinent
process units
 Chemical energy potential
 Quantity of material in process unit
 Capital density ($/unit area)
 Process temperature and pressure
 Loss history
 Criticality to plant operation

8. FEI Hazard
1-60 Light
61-96 Moderate
97-127 Intermediate
128-158 Heavy
>158 Severe
FEI > 128 – Further risk review

9. Procedure
To develop the DOW FEI study, the following
documents are required:
-An accurate plot plan.
- A process flow sheet.
-Data sheets of the main process units.
-A fire & Explosion Index Hazard classification guide.
-A complete Fire & Explosion Index form.
-Replacement cost data for the installed process
equipment under study.

10. 1. The first step of the study, is the identification of
the critical process unit.
Only those items, or units, with a critical role
inside the process should be studied, and to
simplify the identification of those units.
- Storage tank
- Process stem storage tank
- Reactor feed tank
- Reactors
- Recovery vessels
- others

11. 2. Calculation of The Material Factor:
The Material Factor, it is the first parameter of the FEI
calculation. The MF is the measure of the intrinsic
potential energy released by the combustion,
explosion or chemical reaction of the substances.
Those parameters are NFPA rating expressing the
flammability and reactivity of the substance
respectively.
The MF for the particular material in the process unit
is to be obtain from table 1.

14. 3. General Process Hazards Factor (F1):
The general Process Hazard Factors are six different
elements, playing a primary role in the hazardous
scenario like explosions of fires.
- Material Handling and Transfer
- Process Units
- Access to the area
- Drainage and Spill Control

15. For each of this parameters, a different grade of penalty
must be chosen.
General Process Hazards Penalty Factor
Range
Base Factor 1.00
A. Exothermic Reactions 0.30 to 1.25
B. Endothermic Processes 0.20 to 0.40
C. Mat’l Handling and Transfer 0.25 to 1.05
D. Enclosed/ Indoor Process 0.25 to 0.90
E. Access 0.20 to 0.35
F. Drainage and Spill Control 0.25 to 0.50
Add them up =
General Process Hazards Factor = F1

16. 4. Special Process Hazards Factor (F2):
The special process hazard are factors that contribute
primarily to the probability of a loss incident. There
are twelve factors:
- Toxic Materials
- Sub Atmospheric Pressure (Under 500 mmHg)
- Operation IN or NEAR Flammable Range
- Toxic Materials
- Sub Atmospheric Pressure (Under 500 mmHg)
- Operation IN or NEAR Flammable Range
- Dust Explosion
- Relief Pressure

17. - Relief Pressure
- Low Temperature
- Quantity of Flammable/Unstable Material
- Corrosion and Erosion
- Leakage
- Use of Fire Equipment
- Hot Oil Heat Exchanger System
- Rotating Equipment
Each factor have contributes with a penalty range. The
choice of the correct value is related to the type and
condition of the substance, process design, and grade
of maintenance.

18. 5. Process Unit Hazard Factor (F3):
The process Unit Hazard Factor is the product of the
General Process Hazard Factor (F1) and the Special
Process Hazard Factor (F2).
(F3 = F1 X F2)
6. Determination of Fire and Explosion Index (FEI):
Fire & Explosion Index = (Process Unit Factor) x
(Material Factor)

20. 7. Determination of the Area of Exposure surrounding the
Process Unit being evaluated is to be performed based
on Radius of Exposure.
8. Determination of the replacement value of all
equipment within the Area of Exposure and the
inventory is to be done.
9. Determination of the Damage Factor, which represents
the degree of loss exposure, is to be done, based on the
MF and the Process Unit Hazards Factor (F3).
10. Determination of the Base Maximum Probable
Property Damage (Base MPPD) is to be made
multiplying the Value of the Area of Exposure by the
Damage Factor.
11. When developing the F&EI, it is recommended that
people with a working knowledge of the plant's history
experiences be contacted to discuss probable incident
scenarios to assure the most viable F&EIs are developed.

23. CASE STUDY ON DOW’S FIRE AND
EXPLOSION INDEX
 UNIT: Nitroaniline Reactor
 LOCATION: Monsanto’s Krummrich Chemical
Plant
 SPECIFICATION:
 Reactor is located indoor
 2.5 inch steel reactor designed to handle pressure of 500
to 550 psig easily.
 3350 gallon reactor with pressure relief valve in series
with rupture disk

24.  Due to long time leak in rupture disk and the relief valve
was corroded (no pressure indicator present b/w rupture
disk and r/v )
 Absence of dyke (p.f0.5 ).
 No computer control and reactor was not inerted.
 Reactor was operating at 175 °c.
 On the day of accident ,the reactor was charged with
1867 kg h2o, 733 kg NH3 and 1425 kg aniline.

25. Nitroanline Synthesis Reaction

29. THANK YOU….!

30. The Dow Fire and Explosion Index of the case under
study was found to be 182 which implied the case under
study had severe degree of hazard.