Volatility of a material is not an equilibrium thermodynamic property but is a characteristic of a material related to a thermodynamic property that is vapor pressure. It is influenced by such factors as surface area, temperature, particle size, and purge gas flow rate; that is, it is diffusion controlled.
The extent of containment achieved for specimens in this test method by means of a pinhole opening between 0.33 to 0.38 mm allows for measurement circumstances that are relatively insensitive to experimental variables other than temperature. Decreasing the extent of containment by use of pinholes larger than 0.38 mm will increase the magnitude of the observed rate of mass loss but will also reduce the measurement precision by increasing the sensitivity to variations in other experimental variables.
Results obtained by this test method are not strictly equivalent to those experienced in processing or handling conditions but may be used to rank materials for their volatility in such circumstances. Therefore, the volatility rates determined by this test method should be considered as index values only.
The volatility rate may be used to estimate such quantifiable values as drying interval or the extent of volatile release from a process.
DESIG: E 2281 08a ^TITLE: Standard Practice for Process and Measurement Capability Indices ^SIGNUSE:Process Capability8212;Process capability can be defined as the natural or inherent behavior of a stable process that is in a state of statistical control (1). A “state of statistical control” is achieved when the process exhibits no detectable patterns or trends, such that the variation seen in the data is believed to be random and inherent to the process. Process capability is linked to the use of control charts and the state of statistical control. A process must be studied to evaluate its state of control before evaluating process capability.
Process Control8212;There are many ways to implement control charts, but the most popular choice is to achieve a state of statistical control for the process under study. Special causes are identified by a set of rules based on probability theory. The process is investigated whenever the chart signals the occurrence of special causes. Taking appropriate actions to eliminate identified special causes and preventing their reappearance will ultimately obtain a state of statistical control. In this state, a minimum level of variation may be reached, which is referred to as common cause or inherent variation. For the purpose of this standard, this variation is a measure of the uniformity of process output, typically a product characteristic.
Process Capability Indices8212;The behavior of a process (as related to inherent variability) in the state of statistical control is used to describe its capability. To compare a process with customer requirements (or specifications), it is common practice to think of capability in terms of the proportion of the process output that is within product specifications or tolerances. The metric of this proportion is the percentage of the process spread used up by the specification. This comparison becomes the essence of all process capability measures. The manner in which these measures are calculated defines the different types of capability indices and their use. Two process capability indices are defined in 5.2 and 5.3. In practice, these indices are used to drive process improvement through continuous improvement efforts. These indices may be used to identify the need for management actions required to reduce common cause variation, compare products from different sources, and to compare processe......
Copyright ©2024 All Rights Reserved