Induction time period

Experience has shown that fuels with induction period times reported to be <240 minutes are unstable. These fuels tend to perform poorly in the field under long-term storage conditions. 

It is known that ignition and expln of dangerous coal mine atmosphere depends on many factors, such as compn of mine atm, wt of charge of expl, induction period (time elapsed betw expln of charge and ignition of mine atm), temp of products of expln, presence of hot solid particles in products of expln, duration of flame, heating of mine atm due to adiabatic compression created by incident and reflected shock waves, etc. 

Absorption of polar degradation products is noticed immediately. Whereas the AOM method determines the time for the triglyceride to reach a specific level of oxidation (100 meq peroxide value), OSI determines the induction period (time required to exhaust the antioxidant properties), but not oxidation progress in the oil. OSI values always are lower (less time) than AOM values. 

Ap/t = p = rate of change of pressure, (Ap)max = maximum pressure increase, p ax maximum rate of change of pressure, = Induction period = time delay from admission of reactants to attainment of Pmax, AT = Reactant temperature excess, T = wall temperature, T) = Compressed gas temperature, T, = ignition delay, / = light emission intensity, Iw-ai = period of maximum rate of reaction given that (I20-60) = kp", Q = heat release rate. 

Induction period = time for emulsions to achieve a conjugated diene content of 0.4%. 

The adsorption of linoleic acid onto silica gel from petroleum ether solution conformed to a Langmuir isotherm, consistent with the formation of a monolayer (Porter etal. 1972). Confirming the finding of Honn etal. (1951) with soybean oil, it was found that the most rapid uptake of oxygen occmred at a linoleic acid-silica ratio close to that for the monolayer. Without included antioxidant, oxidation commenced at a nearly linear rate without observable induction period. Time for consumption of one-half mole of oxygen per mole of linoleic acid was ca. 60 min on acid-washed silica. If very small amounts of a-tocopherol were included in the layer, virtually no oxygen uptake measurable in this system occurred during the induction pe-... 

The KDIE value normally is expressed as a ratio between reaction rate constants of the normal C—H compound and its C—D labeled analogue. While kh/ka rate constants are most often used, inverse induction period times ta/th > critical temperature Tch/Tca burn rates rbh/rbd, s id impact sensitivity Va/Vh > can be used since they all are dependent upon the global decomposition rate of the given energetic compound. This is especially important in chemical reactions or processes when one cannot directly obtain an experimental rate constant (k).5,7-10 There are three characteristics regarding the KDIE which one must remember, especially as it might apply to the complex thermochemical decomposition process of an energetic material ... 

The conditions relating the system size and material characteristics under which such behavior can occur are clearly of paramount interest, along with the induction period (time from initial heating to the onset of ignition) and the final temperature the system can reach. 

Finally, the determination of the induction period (NF M 07-012) also reveals the potential of gum formation during storage. The fuei sampie is contained in a bomb filled with oxygen at 100°C, under a pressure of 7 bar and the oxygen pressure is monitored with time. The time corresponding to the first drop in pressure is noted, symptomatic of incipient oxidation. If no further events take place, the test is stopped after 960 minutes. This time corresponds thus to the maximum induction period. 

Oxidation stability (gasoline) (induction period) NFM 07-012 ISO/DlS 7536 ASTM D 525 Time necessary for a sample bomb under oxygen pressure to reach the critical induction point... 

The bromate-ferroin reaction has a quadratic autocatalytic sequence, but in this case the induction period is detennined primarily by the time required for the concentration of the hiliibitor bromide ion to fall to a critical low value tlirough the reactions... 

Experimental results are in general conformity with the Avrami equation, but the interpretation of various observations is still complicated in many instances. One intriguing observation is that the induction period for nucleation is inversely proportional to the length of time the liquid is held in the liquid state after previous melting. This dependence on prior history may be qualitatively understood... 

The free radicals initially formed are neutralized by the quinone stabilizers, temporarily delaying the cross-linking reaction between the styrene and the fumarate sites in the polyester polymer. This temporary induction period between catalysis and the change to a semisoHd gelatinous mass is referred to as gelation time and can be controUed precisely between 1—60 min by varying stabilizer and catalyst levels. 

The reaction time depends on the quality of the potassium hydroxide employed. An induction period is often observed when older potassium hydroxide samples are used, possibly because surface formation of carbonates reduces the solubility of the salt in acetonitrile. An attempt was made to monitor the cinnamonitrile reaction by GLC, following loss of starting... 

At t = 0, Cg = 0, but after a short time, relative to the duration of the reaction, the difference - e 2t reaches the value of unity. The concentration of B is then C gk/kj, which is much less than C, g. After this short induction period, the concentration of B remains almost... 

Kinetic studies involving enzymes can principally be classified into steady and transient state kinetics. In tlie former, tlie enzyme concentration is much lower tlian that of tlie substrate in tlie latter much higher enzyme concentration is used to allow detection of reaction intennediates. In steady state kinetics, the high efficiency of enzymes as a catalyst implies that very low concentrations are adequate to enable reactions to proceed at measurable rates (i.e., reaction times of a few seconds or more). Typical enzyme concentrations are in the range of 10 M to 10 ], while substrate concentrations usually exceed lO M. Consequently, tlie concentrations of enzyme-substrate intermediates are low witli respect to tlie total substrate (reactant) concentrations, even when tlie enzyme is fully saturated. The reaction is considered to be in a steady state after a very short induction period, which greatly simplifies the rate laws. 

Adiabatic induction time Induction period or time to an event (spontaneous ignition, explosion, etc.) under adiabatic conditions, starting at operating conditions. 

Induction period measurements can also be used to determine interfacial tensions. To validate the values inferred, however, it is necessary to compare the results with an independent source. Hurley etal. (1995) achieved this for Cyanazine using a dynamic contact angle analyser (Calm DCA312). Solid-liquid interfacial tensions estimated from contact angle measurements were in the range 5-12 mJ/m which showed closest agreement with values (4—20mJ/m ) obtained from the log-log plots of induction time versus supersaturation based on the assumption of — tg. 

Figure 3-8 is a plot of Ca, Cb, Cq, and Cd for a hypothetical system of the Scheme X type. An interesting feature is the time delay after the start of the reaction before the final product, D, appears in significant concentrations. This delay in product appearance is called an induction period or lagtime. In order to observe an induction period it is only necessary that the system include several relatively stable intermediates, so that the bulk of the material balance is temporarily stored in these prior forms. An experimental measurement of the induction period requires an arbitrary definition of its length. 

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