ASTM D3764-92(1998)
(Practice)Standard Practice for Validation of Process Stream Analyzer Systems
Standard Practice for Validation of Process Stream Analyzer Systems
SCOPE
1.1 This practice describes procedures and recommendations for the validation of a total process analyzer system or its subsystems, or both, used in the direct measurement of physical or chemical characteristics of petroleum and petrochemical products. Procedures for initial validation and subsequent continuous quality assurance of system performance are described.
1.2 Validation is achieved by statistical assessment of results generated for common materials by the total analyzer system or its subsystem versus results generated by an ASTM or other established primary test method (PTM).
1.2.1 For analyzers used in product certification, the analyzer system precision determined by the statistical assessment is typically compared to the site precision for the PTM.
1.2.2 For other analyzer applications, analyzer system precision determined by the statistical assessment is compared to prespecified performance criteria based on the intended use.
1.3 Two procedures for validation are described: the line sample procedure and the validation reference material (VRM) injection procedure.
1.4 Only the analyzer system or subsystem downstream of the VRM injection point or the line sample extraction point is being validated by this practice.
1.5 The line sample procedure is limited to applications where material can be safely withdrawn from the sampling point of the analyzer unit without significantly altering the property of interest.
1.6 Validation information obtained in the application of this practice is applicable only to the type and property range of the materials used to perform the validation.
1.7 Procedures for conducting an initial validation are described. These procedures are typically conducted at installation or after major maintenance once the system mechanical fitness-for-use has been established.
1.8 Procedures for the continual validation of system performance are described. These procedures are typically applied at a frequency commensurate with the criticality of the application.
1.9 This practice applies if the process stream analyzer system and the primary test method are based on the same measurement principle(s), or, if the process stream analyzer system uses a direct and well-understood measurement principle that is similar to the measurement principle of the primary test method it is intended to predict.
1.10 This practice is not intended for use if the process stream analyzer system utilizes an indirect or mathematically modeled measurement principle such as chemometric or multivariate analysis techniques. Users should refer to Practice D 6122 for detailed validation procedures for these types of analyzer systems.
1.11 This practice does not address procedures for diagnosing causes of validation failure.
1.12 This practice does not address the methodology for establishing the correlation equation used to generate predicted PTM results using analyzer outputs, nor the expected prediction error. The former is assumed to have been correctly developed as part of the analyzer application development work.
1.13 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or
withdrawn. Contact ASTM International (www.astm.org) for the latest information.
Designation: D 3764 – 92 (Reapproved 1998) An American National Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Practice for
Validation of Process Stream Analyzers
This standard is issued under the fixed designation D 3764; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope F 307 Practice for Sampling Pressurized Gas for Gas Analy-
sis
1.1 This practice serves as a guide for the validation of
process stream analyzers used in determining the physical or
3. Terminology
chemical characteristics of petroleum and petrochemical prod-
3.1 Definitions of Terms Specific to This Standard:
ucts.
Time Units
1.2 Procedures for treating data from automatic process
3.1.1 Lag Time, n—The time interval from a step change in
stream analyzers are outlined. Definitions, terms, calibration
the measured variable at various points in the system to the first
techniques, and applicable statistical tests for validation are
corresponding change in the analyzer signal readout.
described.
3.1.1.1 Discussion—It is a function of system design
1.3 The implementation of this process requires that the
(length and diameter of lines, number of fittings, flow restric-
analyzer be installed in compliance with the principles set forth
tions, etc.) and the flow rate of the process or product stream.
in Part II Process Stream Analyzers of the “Manual on
(See Fig. 1 and Fig. 2.) It consists of the following elements:
Installation of Refinery Instruments and Control Systems”
3.1.2 Sample Loop Lag Time, n—The time required for a
APIRP-550 of the American Petroleum Institute and in agree-
step change in process or product stream quality to traverse the
ment with the supplier’s recommendation. In addition it
distance between the start of the process or product stream
assumes that the analyzer is designed to monitor the specific
sample loop to the inlet of the sample conditioning unit.
quality parameter of interest and at the time of validation the
3.1.3 Sample Conditioning Unit Lag Time, n—The time
analyzer is operating at the conditions specified by the manu-
required for a step change in the process or product stream
facturer.
quality to pass through the sample conditioning unit from the
1.4 The units of measure used in this practice shall be the
junction with the sample loop to the inlet of the analyzer unit.
same as those applicable to the laboratory test standard used as
3.1.4 Analyzer Lag Time, n—A function of the analyzer’s
the reference for analyzer validation.
operating characteristics.
1.5 This standard does not purport to address all of the
3.1.4.1 Discussion—Where the analyzer is designed to op-
safety concerns, if any, associated with its use. It is the
erate at a specific flow rate, the sum of the elements contrib-
responsibility of the user of this standard to establish appro-
uting to the analyzer lag time 3.1.4.2 (1) and 3.1.4.3 (1) will be
priate safety and health practices and determine the applica-
a constant value. For the analyzer designed for variable flow
bility of regulatory limitations prior to use.
rates the analyzer lag time and its elements must be determined
2. Referenced Documents for each of the flow rates used. These elements are as follows:
3.1.4.2 (1) Analyzer Dead Time, n—The time interval be-
2.1 ASTM Standards:
tween the introduction of a step change in quality at the inlet of
D 1265 Practice for Sampling Liquified Petroleum (LP)
2 the analyzer unit and the initial indication of analyzer response
Gases—Manual Method
to this change at a specific sample flow rate.
D 4057 Practice for Manual Sampling of Petroleum and
3 3.1.4.3 (1) Analyzer Time Constant (See Fig. 2)—The time
Petroleum Products
interval between the initial response of the analyzer unit and
D 4177 Practice for Automatic Sampling of Petroleum and
3 the time required for the analyzer output to reach a value of
Petroleum Products
63 % of the final output value for a step change in sample
quality.
Analyzer Parameters
This practice is under the jurisdiction of ASTM Committee D-2 on Petroleum 3.1.5 Analyzer Output, n—A signal that is proportional to
Products and Lubricants and is the direct responsibility of Subcommittee D02.25 on
the quality parameter being measured and suitable for input to
Validation of Process Analyzers.
readout instrumentation. It can be either a pneumatic, an
Current edition approved Oct. 15, 1992. Published December 1992. Originally
e2
electrical, or a digital signal.
published as D 3764 – 80. Last previous edition D 3764 – 80 (1985).
Annual Book of ASTM Standards, Vol 05.01.
Annual Book of ASTM Standards, Vol 05.02.
Annual Book of ASTM Standards, Vol 10.05.
D 3764
FIG. 1 Total Analyzer System
FIG. 2 Analyzer Time Units
3.1.6 Analyzer Result, n—The measured quality parameter quality parameter being measured that is not masked by
displayed by the analyzer readout instrumentation in terms of background noise as displayed by the readout instrumentation.
the accepted quality units. 3.1.8 Linearity, n—The degree of closeness to which a plot
3.1.6.1 Reference Sample Procedure Result, n—The aver- of the analyzer output, over the analyzer operating range
age of the intermittent or continuous analyzer readings re- approximates a straight line.
corded during a specific time interval after the analyzer is at 3.1.8.1 Discussion—It is expressed as the maximum devia-
equilibrium. tion between an average measured output versus a known input
3.1.6.2 Line Sample Procedure Result, n—The average of and a straight line, where the straight line is drawn through
the intermittent or continuous analyzer readings recorded both terminal points of the known input and measured output
during the time interval required to draw one line sample. This ranges. Linearity of the analyzer over the quality range of
time interval starts at one analyzer dead time after sample port interest must be established and the analyzer output, if nonlin-
valve opening and continues until one analyzer dead time after ear, adjusted manually or automatically so that the analyzer
the required sample has been drawn. The line sample must be result displayed is a true indication of the measured quality.
drawn only when the entire analyzer system is in operation and See Fig. 3.
when there is no significant change in the measured property. Precision Parameters
If a quality change occurs during the sample collection time 3.1.9 Precision, n—The degree of agreement of reported
interval as defined above, the sample must be discarded and a measurements of the same chemical or physical property of a
new sample collected when the measured property is in given material, expressed in terms of dispersion of test results
equilibrium. around the arithmetic mean.
3.1.7 Sensitivity, n—The least discernible change in the 3.1.10 Analyzer Repeatability, n—The difference between
D 3764
NOTE 1—The illustration shows two examples of analyzer output; a linear and a nonlinear system when considering the entire potential analyzer range.
Even though linearity over the entire range is the ideal condition, a nonlinear system can be used effectively when the approximate process or product
quality is known and the operating range of the analyzer can be selected and confined to a small segment of the entire range. By segmentation of the
curvilinearity of the input, output relationship can be considered a constant slope and any deviations from linearity thereby will be insignificant. The
selection of the range segment, however, will require calibration with one or more reference samples representing the minimum, intermediate and
maximum operating range quality to establish the degree of linearity and to institute corrective measures when the deviations from a straight line are
excessive.
FIG. 3 Measured Analyzer Output
two successive analyzer results that would be exceeded in the exceeded in the long run in only 1 case in 20 when the two
long run in only 1 case in 20 when a single analyzer system is
systems are operated at different sites, by different operators,
operated on a flowing sample of uniform quality.
but on identical samples.
3.1.10.1 Discussion—The value is related to the repeatabil-
3.1.11.1 Discussion—The value is related to the reproduc-
ity standard deviation as determined from many sets of
ibility standard deviation as determined from testing the same
successive repeat analyzer results from single analyzers.
samples on many analyzer systems.
3.1.11 Analyzer Reproducibility, n—The difference between
3.1.12 Historical Standard Deviation, n—A test method
a single result from each of two analyzer systems that would be
D 3764
standard deviation established by averaging the standard de- 5.3 This practice addresses analyzer calibration in the range
viations of many samples tested by many laboratories. of interest and in accordance with the manufacturer’s instruc-
3.1.13 Line Sample, n—A process or product sample with- tions so that the sensitivity and linearity to process or product
drawn from the sample port (6.1.3.3) in accordance with quality change are established and adjusted to produce a
Practices D 1265, D 4057, D 4177, and F 307, whichever is meaningful analyzer result.
applicable during a period when the material flowing through
the analyzer is of uniform quality and the analyzer result 6. System Components
displayed (3.1.6) is essentially constant.
6.1 Fig. 1 illustrates a total analyzer system incorporating a
3.1.13.1 Discussion—The laboratory tests are obtained for
selection and arrangement of components that are typical but
each sample of this material and compared with the analyzer
not specific for any particular analyzer system. A total analyzer
result obtained (3.1.6) at the time of sampling.
system design must consider the chemical and physical prop-
3.1.14 Reference Sample, n—A pure compound or a mixture
erties of the process or product stream in selecting the
of compounds of known properties that have a reference value
components required. These must meet the requirements of the
for the quality to be measured.
analyzer, and provide a representative sample, without ad-
3.1.14.1 Discussion—It can also be an isolated batch of
versely affecting the value of the specific quality parameter of
process or product with chemical or physical properties ap-
interest (1.3).
proximating the quality level to be monitored by the analyzer.
6.1.1 Total Analyzer System consists of all piping, hard-
In this event a reference sample value (3.1.15) for the moni-
ware, and instrumentation required to automatically perform
tored property must be established through multiple testing by
on-stream analysis of a process or product stream including the
an appropriate ASTM or other standard laboratory test method.
analyzer unit, readout instrumentation, sampling conditioning
Bulk quantities of the reference sample must be stored and
devices, sample stream, and sampling port.
handled with care to avoid contamination or degradation of the
6.1.2 Analyzer Unit is the instrumental hardware necessary
quality of interest. One or more reference samples encompass-
to automatically measure the physical or chemical property of
ing the minimum, intermediate, and maximum range of the
a process or product stream and to provide either an intermit-
expected operating range of the analyzer will be required for
tent or a continuous output signal.
both the reference sample and line sample procedures.
6.1.2.1 Intermittent Analyzer is an analyzer that tests the
3.1.15 Reference Sample Value, n—The quality value estab-
sample and produces the prime output signal at discrete time
lished by appropriate ASTM or other standard laboratory test
intervals.
methods on representative pure compounds, mixtures thereof
6.1.2.2 Continuous Analyzer is an analyzer that tests the
and process or product samples.
sample and produces the prime output signal on an instanta-
3.1.15.1 Discussion—The laboratory apparatus shall be
neous or continuously updated basis.
checked carefully before these tests are run to assure compli-
6.1.3 Sampling System is that assembly of valves, lines,
ance with the requirements of the standard test procedure. To
containers, regulator, and gages which constitutes the equip-
further assure proper operation it is recommended that a
ment employed to obtain a proper sample from the sample loop
previously calibrated reference sample or an in-house control
or to introduce a reference sample into the analyzer, or both.
standard of known quality be tested to validate the operation of
6.1.3.1 Sample Loop is that portion of the sampling system
the laboratory equipment.
which takes the sample from the process or product line to the
sample conditioning unit and returns most of the flow back to
4. Summary of Practice
the line of origin or to waste.
4.1 Two procedures have been included; either or both can
6.1.3.2 Sample Conditioning Unit is one or more devices
be applicable in a given situation.
that properly prepare a portion of the sample from the sample
4.1.1 Reference Sample Procedure covers the use of a
loop for testing by the process analyzer consistent with the
laboratory calibrated reference sample, which is introduced
requirements of the analyzer. This preparation can consist of
into the analyzer, and the analyzer result compared with the
temperature or pressure adjustment, change of state (liquid,
reference value.
vapor), or removal of contaminates to assure consistent treat-
4.1.2 Line Sample Procedure covers withdrawal of samples
ment of the sample prior to testing by the analyzer.
from the analyzer system in accordance with Practices D 1265,
6.1.3.3 Sample Port is that point on the sampling system,
D 4057, D 4177, and F 307, whichever is appropriate. Ana-
located between the sample conditioning unit and the analyzer
lyzer results obtained at the time of sampling are compared
or at the outlet of the analyzer from which samples for
with laboratory analyses of the samples using the applicable
laboratory analysis are taken. A sample port location at the
ASTM or other test method.
outlet of the analyzer can be used only if the properties of the
5. Significance and Use
sample are unchanged as it passes through the analyzer or if the
sample is a slip stream identical to the sample tested. It is
5.1 This practice can be used to establish the valid
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