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15:40:36 Page 30
Test Standards and Codes
The term ‘‘standard’’ is also applied in other ways in engineering. Test standards refer to welldefined test procedures, technical terminology, methods to construct test specimens or test devices,
and/or methods for data reduction. The goal of a test standard is to provide consistency in the
conduct and reporting of a certain type of measurement between test facilities. Similarly, test codes
refer to procedures for the manufacture, installation, calibration, performance specification, and safe
operation of equipment.
Diverse examples of test standards and codes are illustrated in readily available documents
(13–16) from professional societies, such as the American Society of Mechanical Engineers
(ASME), the American Society of Testing and Materials (ASTM), and the International Standards
Organization (ISO). For example, ASME Power Test Code 19.5 provides detailed designs and
operation procedures for flow meters, while ASTM Test Standard F558-88 provides detailed
procedures for evaluating vacuum cleaner cleaning effectiveness and controls the language for
product performance claims. Engineering standards and codes are consensus documents agreed on
by knowledgeable parties interested in establishing, for example, some common basis for
comparing equipment performance between manufacturers. These are not binding legal documents
unless specifically adopted and implemented as such by a government agency. Still, they present a
convincing argument for best practice.
1.6 PRESENTING DATA
Since we use several plotting formats throughout this text to present data, it is best to introduce these
formats here. Data presentation conveys significant information about the relationship between
variables. Software is readily available to assist in providing high-quality plots, or plots can be
generated manually using graph paper. Several forms of plotting formats are discussed next.
Rectangular Coordinate Format
In rectangular grid format, both the ordinate and the abscissa have uniformly sized divisions
providing a linear scale. This is the most common format used for constructing plots and
establishing the form of the relationship between the independent and dependent variable.
Semilog Coordinate Format
In a semilog format, one coordinate has a linear scale and one coordinate has a logarithmic scale.
Plotting values on a logarithmic scale performs a logarithmic operation on those values, for
example, plotting y ¼ f(x) on a logarithmic x-axis is the same as plotting y ¼ log f(x) on rectangular
axes. Logarithmic scales are advantageous when one of the variables spans more than one order of
magnitude. In particular, the semilog format may be convenient when the data approximately follow
a relationship of the form y ¼ ae
x or y ¼ a10
x as a linear curve will result in each case. A natural
logarithmic operation can also be conveyed on a logarithmic scale, as the relation ln y ¼ 2.3 log y is
just a scaling operation.
Full-Log Coordinate Format
The full-log or log-log format has logarithmic scales for both axes and is equivalent to plotting log y
vs. log x on rectangular axes. Such a format is preferred when both variables contain data values that
30 Chapter 1 Basic Concepts of Measurement Methods
15:40:36 Page 30
Test Standards and Codes
The term ‘‘standard’’ is also applied in other ways in engineering. Test standards refer to welldefined test procedures, technical terminology, methods to construct test specimens or test devices,
and/or methods for data reduction. The goal of a test standard is to provide consistency in the
conduct and reporting of a certain type of measurement between test facilities. Similarly, test codes
refer to procedures for the manufacture, installation, calibration, performance specification, and safe
operation of equipment.
Diverse examples of test standards and codes are illustrated in readily available documents
(13–16) from professional societies, such as the American Society of Mechanical Engineers
(ASME), the American Society of Testing and Materials (ASTM), and the International Standards
Organization (ISO). For example, ASME Power Test Code 19.5 provides detailed designs and
operation procedures for flow meters, while ASTM Test Standard F558-88 provides detailed
procedures for evaluating vacuum cleaner cleaning effectiveness and controls the language for
product performance claims. Engineering standards and codes are consensus documents agreed on
by knowledgeable parties interested in establishing, for example, some common basis for
comparing equipment performance between manufacturers. These are not binding legal documents
unless specifically adopted and implemented as such by a government agency. Still, they present a
convincing argument for best practice.
1.6 PRESENTING DATA
Since we use several plotting formats throughout this text to present data, it is best to introduce these
formats here. Data presentation conveys significant information about the relationship between
variables. Software is readily available to assist in providing high-quality plots, or plots can be
generated manually using graph paper. Several forms of plotting formats are discussed next.
Rectangular Coordinate Format
In rectangular grid format, both the ordinate and the abscissa have uniformly sized divisions
providing a linear scale. This is the most common format used for constructing plots and
establishing the form of the relationship between the independent and dependent variable.
Semilog Coordinate Format
In a semilog format, one coordinate has a linear scale and one coordinate has a logarithmic scale.
Plotting values on a logarithmic scale performs a logarithmic operation on those values, for
example, plotting y ¼ f(x) on a logarithmic x-axis is the same as plotting y ¼ log f(x) on rectangular
axes. Logarithmic scales are advantageous when one of the variables spans more than one order of
magnitude. In particular, the semilog format may be convenient when the data approximately follow
a relationship of the form y ¼ ae
x or y ¼ a10
x as a linear curve will result in each case. A natural
logarithmic operation can also be conveyed on a logarithmic scale, as the relation ln y ¼ 2.3 log y is
just a scaling operation.
Full-Log Coordinate Format
The full-log or log-log format has logarithmic scales for both axes and is equivalent to plotting log y
vs. log x on rectangular axes. Such a format is preferred when both variables contain data values that
30 Chapter 1 Basic Concepts of Measurement Methods