ASTM D3864-96(2000)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D 3864–96 (Reapproved 2000)
Standard Guide for
Continual On-Line Monitoring Systems for Water Analysis
This standard is issued under the fixed designation D 3864; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This guide covers the selection, establishment, applica- 3.1 Definitions—For definitions of terms used in this guide
tion, and validation and verification of monitoring systems for refer to Terminology D1129.
determining water characteristics by continual sampling, auto- 3.2 Definitions of Terms Specific to This Standard:
matic analysis, and recording or otherwise signaling of output 3.2.1 Calibrations:
data.The system chosen will depend on the purpose for which 3.2.1.1 laboratory check sample for flow-through systems—
it is intended: whether it is for regulatory compliance, process calibration curve calculated from withdrawn samples or addi-
monitoring, or to alert the user of adverse trends. If it is to be tional standards that may be spiked or diluted and analyzed
used for regulatory compliance, the method published or using the appropriate laboratory analyzer.
referenced in the regulations should be used in conjunction 3.2.1.2 line sample calibration—coincidental comparison
with this guide and other ASTM methods. ofalinesampleandadjustmentofacontinuousanalyzertothe
1.2 This standard does not purport to address all of the comparedlaboratoryanalyzerorasecondcontinuousanalyzer.
safety concerns, if any, associated with its use. It is the 3.2.1.3 multiple standard calibration—where the calibra-
responsibility of the user of this standard to establish appro- tion curve is calculated from a series of calibration standards
priate safety and health practices and determine the applica- covering the range of the measurements of the sample being
bility of regulatory limitations prior to use. Specific hazard analyzed.
statements are given in Section 7. 3.2.1.4 probe calibration—where the probe is removed
from the sample stream and exposed to a calibration solution
2. Referenced Documents
and the analyzer is adjusted to indicate the appropriate value.
2.1 ASTM Standards: Alternately, two probes are exposed to the same solution and
D1129 Terminology Relating to Water
the on-line analyzer is adjusted to coincide with the pre-
D1193 Specification for Reagent Water
calibrated laboratory instrument.
D2579 Test Methods for Total and Organic Carbon in 3.2.1.5 reference sample calibration—coincidental com-
Water
parison of a reference sample and adjustment of a continuous
D3370 Practices for Sampling Water from Closed Con- analyzer to the compared laboratory analyzer results.
duits
3.2.2 cycle time—the interval between repetitive sample
D4210 Practice for Intralaboratory Quality Control Proce- introductions in a monitoring system with discrete sampling.
dures and a Discussion on Reporting Low-Level Data
3.2.3 drift—the change in system output, with constant
D5540 Practice for Flow Control and Temperature Control input over a stated time period of unadjusted, continuous
for On-line Water Sampling and Analysis
operation; usually expressed as percentage of full scale over a
E178 Practice for Dealing with Outlying Observations 24-h period.
2.2 ASTM Special Technical Publication:
3.2.3.1 span drift—drift when the input is at a constant,
STP 442 Manual on Water stated upscale value.
3.2.3.2 zero drift—drift when the input is at zero.
3.2.4 full scale—the maximum measuring limit of the
This guide is under the jurisdiction ofASTM Committee D19 on Water and is
system for a given range.
the direct responsibility of Subcommittee D19.03 on Sampling of Water and
3.2.5 input—the value of the parameter being measured at
Water-Formed Deposits, Surveillance of Water, and Flow Measurement of Water.
the inlet to the analyzer.
Current edition approved Feb. 10, 1996. Published May 1996. Originally
published as D3864–79. Last previous edition D3864–79 (1990).
3.2.6 interference—an undesired output caused by a sub-
Annual Book of ASTM Standards, Vol 11.01.
stance or substances other than the one being measured. The
Annual Book of ASTM Standards, Vol 14.02.
effect of interfering substance(s) on the measured parameter of
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D 3864–96 (2000)
measured component as the interference varies from 0 to using an appropriate ASTM or other standard laboratory test
100% of the measuring scale. If the interference is nonlinear, method.Bulkquantitiesofthereferencesamplemustbestored
analgebraicexpressionshouldbedeveloped(orcurveplotted) and handled to avoid contamination or degradation. One or
to show the varying effect. more reference samples encompassing the range of the ana-
lyzer may be required.
3.2.7 laboratory analyzer—a device that measures the
chemical composition or a specific physical, chemical, or
NOTE 1—It is essential that the laboratory analyzer be checked care-
biological property of a sample.
fully before these tests are performed to ensure compliance with the
3.2.8 limit of detection—a concentration of twice the crite-
requirements of the standard test procedure. To further ensure proper
rion of detection when it has been decided that the risk of operationitisrecommendedthatapreviouslycalibratedreferencesample
or an in-house control standard of known concentration be tested to
making a Type II error is equal to a Type I error as described
validate the operations of the laboratory analyzer.
in Practice D4210.
3.2.18 validations—a one-time comprehensive examination
3.2.9 linearity—the extent to which an actual analyzer
of analytical results.
reading agrees with the reading predicted by a straight line
3.2.18.1 reference sample validations—a reference sample
drawn between upper and lower calibration points—generally
zero and full-scale. (The maximum deviation from linearity is is analyzed a minimum of seven times by an appropriate
continuousanalyzerandbyanappropriatelaboratoryanalyzer.
frequently expressed as a percentage of full-scale.)
A comparison is made between the average continuous ana-
3.2.10 monitoring system—the integrated equipment pack-
lyzer results and the average laboratory results using the
age comprising sampling system, analyzer, and data output
Student’s t test at 95% confidence coefficient, two-tailed test
equipment, required to perform water quality analysis auto-
as described in 14.1. Passing the Student’s t test signifies the
matically.
continuousanalyzer’saverageanalysisofthereferencesample
3.2.10.1 analyzer—a device that continually measures the
is not statistically significantly different from the laboratory
specific physical, chemical, or biological property of a sample.
analyzer’s average analysis of the same reference sample
3.2.10.2 data acquisition equipment—analog or digital de-
(validation test acceptable). Failing the 88t” test signifies a
vices for acquiring, processing, or recording, or a combination
statistically significant difference exists (validation test not
thereof, the output signals from the analyzer.
acceptable).
3.2.10.3 sampling system—equipment necessary to deliver
3.2.18.2 line sample validations—a line sample is analyzed
a continual representative sample to the analyzer.
coincidentally a minimum of seven times by an appropriate
3.2.11 output—a signal, usually electrical, that is related to
continuous analyzer and an appropriate laboratory analyzer or
the parametric measurement and is the intended input to data
a second continuous analyzer. A comparison is made on the
acquisition equipment.
differencesbetweenthecoincidentalresultsusingtheStudent’s
3.2.12 range—the region defined by the minimum and
ttestat95%confidencecoefficient,two-tailedtest,toevaluate
maximum measurable limits.
whether the average difference is statistically significantly
3.2.13 repeatability—a measure of the precision of one
different from zero difference as described in 14.2.
analyzertorepeatitsresultsonindependentintroductionofthe
3.2.19 verification—a periodic or routine procedure to en-
same sample at different time intervals.
sure reliability of analytical results.
3.2.14 reproducibility—ameasureoftheprecisionofdiffer-
3.2.19.1 line sample verification—a line sample is analyzed
ent analyzers to repeat results on the same sample.
as described in 3.2.18.2, and the results of the difference
3.2.15 response time—the time interval from a step change
betweenthecontinuousanalyzerandthelaboratoryanalyzeror
in the input or output reading to 90% of the ultimate reading.
a second continuous analyzer is plotted on a control chart. If
3.2.15.1 lag time—the time interval from a step change in
the calculated difference between the continuous analyzer and
input to the first corresponding change in output.
the laboratory analyzer or a second continuous analyzer is
3.2.15.2 total time—the time interval from a step change in
within 63 S ,thecontinuousanalyzerisconsideredverified.If
d
the input to a constant analyzer signal output.
the calculated difference is outside 63 S the continuous
d
3.2.16 sample port—that point in the sampling system
analyzer is considered out of control (not verified).
located between the sample conditioning unit and the analyzer
3.2.19.2 reference sample verification—a reference sample
or at the outlet of the analyzer from which samples for
is analyzed as described in 3.2.18.1 and the results of the
laboratory analysis are taken.
differencesbetweenthecontinuousanalyzerandthelaboratory
3.2.17 samples:
analyzer are plotted on a control chart. If the calculated
3.2.17.1 line sample—aprocesssamplewithdrawnfromthe
difference between the continuous analyzer and the laboratory
sample port (3.2.16) during a period when the process stream
analyzer is within 63 S the continuous analyzer is considered
d
flowing through the continuous analyzer is of uniform quality
verified. If the calculated difference is outside 63 S the
d
and the analyzer result displayed is essentially constant.
continuous analyzer is considered out of control (not verified).
Laboratory tests or results from a second continuous analyzer
4. Summary of Guide
are obtained from each sample and compared with the con-
tinuous analyzer results obtained at the time of sampling.
4.1 This guide provides a unified approach to the use of
3.2.17.2 reference sample—can be a primary standard or a on-line monitoring systems for water quality analysis. It
dilution of a primary standard of known reference value. The presentsdefinitionsofterms,safetyprecautions,systemdesign
reference value must be established through multiple testing and installation considerations, calibration techniques, general
D 3864–96 (2000)
operating procedures, and comments relating to validation and 7.2.4 The metallic framework of the analyzer shall be at
verification procedures. ground potential.
7.2.5 Consider additional protection in the form of properly
5. Significance and Use
sized ground fault interrupters for each individual application.
7.2.6 Analyzerscontainingelectricallyheatedsectionsshall
5.1 Many of the manual and automated laboratory methods
have a temperature-limit device.
for measurement of physical, chemical, and biological param-
7.2.7 Theanalyzer,andanyrelatedelectricalequipment(the
eters in water and waste water are adaptable to on-line
system), shall have a properly sized power cutoff switch and a
sampling and analysis. The resulting real-time data output can
fuse or breaker on the “hot” side of the line(s) of each device.
have a variety of uses, including confirming regulatory com-
7.3 Givefullconsiderationtosafedisposaloftheanalyzer’s
pliance, controlling process operations, or detecting leaks or
spent samples and reagents.
spills.
7.4 Provide pressure relief valves, if applicable, to protect
5.2 This guide is intended to be a common reference that
both the analyzer and monitoring system.
can be applied to all water quality monitoring systems.
7.5 Take precautions when using cylinders containing gases
However, calibration, validation, and verification sections may
or liquids under pressure. Helpful guidance may be obtained
be inappropriate for certain tests since the act of removing a
from Refs (1–4).
sample from a flowing stream may change the sample.
7.5.1 Gas cylinders must be handled by trained personnel
5.3 Technical details of the specific methodology are con-
only.
tainedinthepertinentASTMstandardtestmethods,whichwill
7.5.2 Fasten gas cylinders to a rigid structure.
referencethispracticeforguidanceinselectionofsystemsand
7.5.3 Take special safety precautions when using or storing
their proper implementation.
combustibleortoxicgasestoensurethatthesystemissafeand
5.4 This guide complements descriptive information on this
free from leaks.
subject found in the ASTM Manual on Water.
7.6 Gas piping, where possible, shall be metallic, especially
inside the analyzer housing.
6. Reagents
6.1 Purity of Reagents—Reagent grade chemicals shall be
8. Measurement Objectives
used in all tests. Unless otherwise indicated, it is intended that
8.1 Carefully define the measurement objective for the
all reagents shall conform to the specifications of the Commit-
monitoring system before selecting components of the system
tee on Analytical Reagents of the American Chemical Soci-
5 andsetspecificationsrealistically,tomeettheobjective.Terms
ety. Other grades may be used, provided it is first ascertained
used as specifications shall be consistent with the terminology
that the reagent is of sufficiently high purity to permit its use
in Section 3.
without lessening the accuracy of the determination.
8.2 If the monitoring system is intended primarily to deter-
6.2 Purity of Water— Unless otherwise indicated, refer-
mine compliance with regulatory standards, the accuracy,
ences to water shall be understood to mean reagent water
precision, frequency of sampling, and response time may be
conforming to Specification D1193, Type II.
dictated by the requirements of the regulations.Ahigh degree
of stability and on-line reliability is generally required. The
7. Hazards
analyzer response for a specific parameter must be referenced
7.1 Each analyzer installation shall be given a thorough
toarecognizedorspecifiedlaboratorymethodapprovedbythe
safety engineering study.
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