SE3310 PROCESS SAFETY & RISK MANAGEMENT
Winter Semester 2022
Assignment #3 – Flammability Properties
Name: Doodnauth Ramnaraine
20160686
1) Complete the flammability diagram.
a. What are the proper labels for the x and y axes?
b. Indicate the LEL, UEL, flash point, auto-ignition point.
c. Identify the regions corresponding to liquids, flammability region, auto-ignition region.
UEL
Concentration
of fuel in air
Liquids
Flammable
region
Auto ignition region
`
LEL
Flash point
Temperature
Auto ignition point
2) A gas test meter, calibrated for methane (LELmethane = 5.3%) indicates 15% LEL. What is the actual
volume % of methane in air?
3) A gas test meter, calibrated for gasoline (LELgasoline = 1.4%) indicates 25% LEL. What is the actual
volume % of gasoline in air?
4) Calculate the flash point of the following (at 1 atm) based on the boiling point.
a. Methanol
b. Hexane
Tb = 64.7°C
Tb = 68.7°C
(a = 230.8
(a = 225.1
b = 390.5
b = 537.6
c = 1780)
c = 2217)
5) Given a mixture of 0.5 vol% hexane, 1.0% methane, 0.5% ethylene, and the balance of air calculate the
LFL and UFL of the mixture. Pure species LFL and UFL data is given below.
Hexane
Methane
Ethylene
Total
Vol %
Fraction combustible Yi LFL (vol %)
0.5
1.0
0.5
2.0
0.5/2.0 = 0.25
1.0/2.0 = 0.50
0.5/2.0 = 0.25
1.2
5.3
3.1
UFL (vol %)
7.5
15
32
6) Calculate the LFL and UFL using the formulas found below for each of the following at 25°C and 1 atm,
based on the stoichiometric air:
C2H4 + _3_ O2 → 2CO2 + 2H2O
a. Ethylene
C6H6 + _7.5_ O2 → 6CO2 + 3H2O
b. Benzene
7) Complete the flammability diagram for the following:
Methyl Alcohol
CH4O + 2 O2 → CO2 + 2H2O
LFL
7.5%
UFL
36%
LOC (N2)
10%
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