PerkinElmer TGA 8000, Installation And Hardware Manual

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20 . TGA 8000 Installation and Hardware Guide
Overview
Thermogravimetry is a branch of thermal analysis that examines the mass change of a
sample as function of temperature or time as it is subjected to a controlled temperature
program in a controlled atmosphere. Not all thermal events cause a change in the sample
mass (for example, melting, crystallization, glass transition), but there are some important
exceptions such as desorption, absorption, oxidation, decomposition. Thermogravimetry
characterizes the decomposition and thermal stability of materials under a variety of
conditions and examines the kinetics of the physico-chemical processes occurring in the
sample.
The TGA 8000 is a computer-controlled analyzer that has been designed to take advantage
of the enhanced features of Pyris Software. It is made up of two major components: a
microbalance and a furnace element.
About the Microbalance
The microbalance of the TGA 8000 operates as a high gain electromechanical servo system that
permits detection of weight changes as small as 0.1 g, with a maximum capacity of 1300 mg.
The null balance design uses a servo-controlled torque motor to automatically compensate for
weight changes in the sample material. When a sample is placed in a sample pan and the pan is
on the hangdown wire, the beam that supports the sample pan deflects. A beam position
detector measures the deflection with an optical sensor and uses current to return the beam to
its original position. The amount of current necessary to maintain the system in the "null" state
is directly proportional to the weight change in the sample. The current is amplified and filtered
and then displayed in the display panel of the instrument in mg.
About the Furnace
The furnace allows operation of the TGA 8000 from subambient to 1200°C. The furnace uses
a microfurnace that has a low thermal mass for quick cooling and equilibration. Accurate
program temperature control reduces overshoot to 0.2°C at 100°C/minute which results in
stepwise analysis precision. The sample temperature is sensed by a chromel–alumel
thermocouple.
Features
Some of the features of the TGA 8000 are:
1. Faster furnace cool-down with the cooling fan above the furnace instead of underneath.
This creates positive upward ventilation of the furnace during cool-down.
2. iPad control.
3. The sample gas interface has been repositioned for easier access.
4. Controlled balance environment gives the TGA 8000 long-term ordinate stability. The
weighing balance is housed in a thermally-isolated enclosure that eliminates thermal
gradient effects.
5. An anti-convection iris prevents decomposition products and heat from the furnace
from backstreaming into the balance chamber.
6. The "quick release" furnace tube makes furnace tube cleanup easy. The furnace tube
is attached to the furnace base by a clamp.
7. Temperature control of the segmented furnace is optimized by the heater/sensor
furnace technology.