Authors:J. Tseng, R. Chang, J. Horng, M. Chang, and C. Shu
ethyl ketone peroxide (MEKPO) possesses complex structures which have caused
many incidents involving fires or explosions by mixing with incompatible substances,
external fires, and others. In this study, reactivities or incompatibilities
of MEKPO with inorganic acids (HCl, HNO3, H3PO4
and H2SO4) were assessed by
differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2).
Parameters obtained by the above-mentioned devices could be readily employed
to discuss the runaway reaction, such as onset temperature (T0),
heat of reaction (ΔHd),
time to maximum rate (TMR), maximum self heat rate (dT/dt)max, adiabatic temperature
maximum pressure of decomposition (Pmax)
and so on.
Mixing MEKPO with hydrochloric acid resulted in the
lowest T0 among
inorganic acids. Nitric acid not only lowered the T0
but also delivered the highest heat releasing rate or self heat rate (dT/dt), which was
concluded to be the worst case in terms of contamination hazards during storage
or transportation of MEKPO.
Authors:G. Kim, H. Woo, J. Kim, T. Yang, and J. Chang
Monochromatic MeV-energy neutron source for secondary reaction was developed utilizing tritium embedded titanium (Ti-3H) thin film via 3H(p,n)3He reaction. We have measured the neutron energies and the energy spread by resonance reactions of 12C(n,tot) and 28Si(n,tot). The available energy was within the range from 0.6 to 2.6 MeV. Energy spread was 1.6% at energy of 2.077 MeV. The
flux in the beam direction was determined to be 3.76·107 n/s/sr by irradiating 197Au by about 2 MeV neutrons. This source was shown to be useful for measurements of nuclear data by measuring the total cross
sections of neutrons on Fe and comparing these data to the data of ENDF-6.
Authors:Y. Chang, J. Lee, J. Chen, H. Liaw, and C. Shu
The flammability characteristics of chemical substances are very important for safety considerations in manufacturing processes.
This study investigated the mixing of toluene and methanol mixtures with five vapor mixing ratios (100/0, 75/25, 50/50, 25/75
and 0/100 vol.%) at initial conditions of 1 atm and 150°C, and determined the flammability properties to identify their potential
fire and explosion hazards. These safety-related parameters included lower explosion limit (LEL), upper explosion limit (UEL),
maximum explosion overpressure (Pmax) and rate of maximum explosion pressure rise ((dP/dt)max); all of them were measured by a 20-L-Apparatus.
In terms of flammability tests for this research, the experimental results indicated that when methanol was increased, which
could induce a higher range of flammability, afterwards the situation could be triggered to a dangerous level, such as fire
or explosion. Based on the above-mentioned, we could obtain a series of flammability properties and provide inherently safer
design in related industrial processes for preventing serious fire and explosion accidents.
Authors:R Chang, J Tseng, J Jehng, C Shu, and H Hou
this study, a mixture of methyl ethyl ketone peroxide (MEKPO) with various
contaminants, such as H2SO4
and NaOH, was prepared in order to elucidate the cause of these accidents
and the results of upset conditions. Thermokinetic parameters were acquired
by both differential scanning calorimetry (DSC) and vent sizing package 2
(VSP2). In addition, we simulated the thermokinetic parameters and created
kinetic models for the specific contaminants. The results indicate that the
thermal hazard of MEKPO is less than that of the mixed MEKPO with the above-mentioned
contaminants. Consequently, the evaluated parameters could be used to prevent
any unexpected exothermic runaway reaction or to alleviate hazards to an acceptable
extent, if such a reaction occurs.
Authors:B. Hsieh, Y. Chang, R. Han, J. Wu, L. Hsieh, and C. Chang
The newly manufactured N-isopropylacrylamide (NIPAM) polymer gel is composed of four components, i.e., gelatin, monomer (NIPAM), crosslinker (N,N’-methylenebisacrylamide, Bis), and antioxidant (tetrakis hydroxymethyl phosphonium chloride, THPC). In this study, we investigated
the effects of gel composition on the dose response of NIPAM polymer gel. A statistical experiment to analyze the contribution
of each composition to the linearity and sensitivity of NIPAM gel was performed. Results indicate that the amount of gelatin,
NIPAM (15.17%), Bis, and THPC have dominant effects on the sensitivity of the gel, with contributions of 59.73, 15.17, 10.64,
and 14.45%, respectively. The amount of gelatin and Bis mainly affected the linearity of the gel, with contributions of 44.70
and 50.99%, respectively. The linearity of most compositions of the gel was greater than 0.99 when (%C)/(%T) was lower than 8.0. Optimal (%C)/(%T) for higher sensitivity should be in the range of 4−9. The temporal stability experiment showed that the dose response curve
attained stability at about 5 h after irradiation and persisted up to 3 months.
Some stability and convergence theorems of the modified Ishikawa iterative sequences with errors for asymptotically nonexpansive
mapping in the intermediate sense and asymptotically pseudo contractive and uniformly Lipschitzian mappings in Banach spaces
Authors:Y. Chang, J. Lee, S. Wu, C. Chen, and C. Shu
Flammable chemicals are frequently encountered in industrial processes. Under the safe operation basis and for fire/explosion
danger prevention, it is imperative to recognize the flammability characteristics of these processes, especially under the
working scenarios for elevated pressure and temperature.
This study was conducted to investigate fire and explosion properties, including the explosion limits (LEL and UEL), maximum
explosion overpressure (Pmax), maximum rate of explosion pressure rise (dP/dt)max, gas or vapor deflagration index (Kg) and explosion class (St) of various acetone/water solutions (100, 75, 50 and 25 vol.%) at higher initial pressure/temperature up to 2 atm and 200°C
via a 20-L-Apparatus. We further discussed the safety-related parameters and fire/explosion damage degree variations in the
above aqueous acetone within 1 atm and 150°C. The results offered a successful solution for evaluating the flammability hazard
effect in such a relevant crucial process with elevated pressure and temperature.
Authors:C. Chang, Y. Chou, J. Tseng, M. Liu, and C. Shu
Many concerns over unsafe or unknown properties of multi-walled carbon nanotubes (MWNTs) have been raised. The thermal characteristics
regarding stability would represent potential hazards during the production or utilization stage and could be determined by
calorimetric tests for various thermokinetic parameters. Differential scanning calorimetry (DSC) was employed to evaluate
the thermokinetic parameters for MWNTs at various compositions.
Thermoanalytical curves showed that the average heat of decomposition (ΔHd) of the MWNTs samples in a manufacturing process was about 31,723 J g−1, by identifying them as an inherently hazardous material. In this study, significant thermal analysis appeared in the presence
of sulfuric acid (H2SO4). From the DSC experiments, the purification process of MWNTs could induce an unexpected reaction in the condition of batch
addition with reactants of H2SO4. The results can be applied for designing emergency relief system and emergency rescue strategies during a perturbed situation
Authors:C. Lin, Y. Chang, J. Lee, S. Lin, and C. Shu
Preventing accidental explosions of flammable liquid/gas mixtures is very important. As far as flammability characteristics
are concerned, we simulated the effects of inert liquid/gas, which was filled with reactors, vessels, or closed space, employed
in the chemical process industries. The inert liquid/gas (H2O) weakened the oxygen concentration and reduced solvent vapor concentration in a 20-L-Apparatus. This study investigated
the flammability characteristics of acetone/water solutions (100/0, 75/25, 50/50, and 25/75 vol.%) that are controlled at
a temperature of 150°C and pressures of 101/202 kPa, respectively. The flammability parameters included flammability limits
(LEL and UEL), maximum explosion pressure (Pmax), maximum explosion pressure rise ((dP dt−1)max), and vapor deflagration index (Kg). The results of a series of experimental tests showed that UEL, Pmax, and Kg all decreased with steam rising under the experimental conditions. The results can be applied to process safety design/operation
for identifying whether the inert liquid/gas (H2O) content has any substantial effects in reducing the fire and explosion hazard of the solution of interest.
Authors:R. Lee, H. Hou, J. Tseng, M. Chang, and C. Shu
Organic peroxides are commonly employed as an initiator for polymerization, a source of free radicals, a hardener, and a linking
agent. Due to its relatively weak oxygen-oxygen bond, di-tert butyl peroxide (DTBP) has been categorized as flammable type or Class III by the National Fire Protection Association (NFPA).
The transport of dangerous goods (TDG) has published a warning against DTBP that it could potentially induce violent heat,
explosion, fire and self-ignition under certain circumstances.
DTBP has been recommended as an international standard sample for estimating the performance of several calorimeters, such
as glass tube tests, differential scanning calorimetry (DSC), and vent sizing package 2 (VSP2). In this study, we measured
the precise temperature changes and heat flow with the above-mentioned testing instruments. However, some runaway incidents
caused by DTBP have demonstrated the reaction temperature could be as low as ambient temperature. The reactivity and the hazardous
incompatibility with sulfuric acid (H2SO4) and hydrochloric acid (HCl) of DTBP have not been evident, and the runaway hazards involved in different processing conditions
were clarified in this study by implementing the two calorimeters. Acid-catalyzed characteristics and reaction hazards of
DTBP could be acquired, such as heat of decomposition (ΔHd) and exothermic onset temperature (T0).