Variable heating rate approach

After all these technical considerations in the variable heating rate approach, Sichinaf highlighted the following ... 

Advantages of the real-time/fast heating approach are in situ analysis of dynamically changing processes and detection of some relatively reactive molecules that are lost to side reactions at slower heating rates or with time delays in the detection step. Thus reaction schemes different from those occurring with slow heating can be studied. Pressure and composition of the atmosphere can be set as desired to gain an additional variable. The small sample size permits studies to be performed safely. A drawback of fast thermolysis techniques is that the sample decomposes under non-isothermal conditions. 

This parameter, the smoke parameter, is based on continuous mass loss measurements, since the specific extinction area is a function of the mass loss rate. A normal OSU calorimeter cannot, thus, be used to measure smoke parameter. An alternative approach is to determine similar properties, based on the same concept, but using variables which can be measured in isolation from the sample mass. The product of the specific extinction area by the mass loss rate per unit area is the rate of smoke release. A smoke factor (SmkFct) can thus be defined as the product of the total smoke released (time integral of the rate of smoke release) by the maximum rate of heat release [19], In order to test the validity of this magnitude, it is important to verify its correlation with the smoke parameter measured in the Cone calorimeter. 

The unified approach adopted by Ma ek assumed that all initiations are ultimately thermal. More precisely every initiating stimulus (shock, impact, electric discharge, friction, etc) serves to heat up the explosive or a portion thereof, initially at a temperature T to an elevated temperature T. It is assumed that T and the length of time t the explosive is exposed to T are the two variables sufficient to account for initiation. The 3rd factor influencing the reaction rate, density p, is important in gaseous combustions and explosions where it varies considerably with temperature and pressure in homogeneous solids and liquids it is nearly constant... 

Apply full heat to the liquid bath and when the temperature of the sample reaches 190 F (87.S C), adjust the heat input so that the temp of the sample increases at a rate of 2 tO. 5 F (11 0.25 C)/min Note 6 The heaters on some testers do not have sufficient capacity to maintain the proper rate of heating when the temperature approaches 250 F (121.1 C) or above. The heat input to the liquid bath may be increased if necessary by using a variable transformer to increase the voltage on the heater or by wrapping the bath with electrical heating tape. The application of suitable insulation to the outdide of the bath to prevent heat loss is also permissible. The important factor is to maintain the rate of temp increase of the sample at 2i 0.5F (1—0.25 C)/min... 

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