PDF Actual Sample: HJ 915-2017 (PDF-excerpt released/modified date: 2018-11-30/2019-03-24. Translated/reviewed by: Wayne Zheng et al.)
| Standard ID | HJ 915-2017 (HJ915-2017) |
| Description (Translated English) | Technical specifications for automatic monitoring of surface water |
| Sector / Industry | Environmental Protection Industry Standard |
| Word Count Estimation | 39,333 |
| Date of Issue | 2017-12-28 |
| Date of Implementation | 2018-04-01 |
| Drafting Organization | Chinese Academy of Environmental Sciences |
| Administrative Organization | Ministry of Environmental Protection |
| Regulation (derived from) | Ministry of Environmental Protection Bulletin 2017 No. 85 |
ENGLISH: HJ 915-2017 (Translated) HJ 915-2017
HJ
NATIONAL ENVIRONMENTAL PROTECTION STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
Technical specifications for automatic
monitoring of surface water (Trial)
地表水自动检测技术规范
(试行)
ISSUED ON. DECEMBER 28, 2017
IMPLEMENTED ON. APRIL 01, 2018
Issued by. Ministry of Environmental Protection of the PRC
Table of Contents
Foreword ... 3
1 Scope of application ... 4
2 Normative references ... 4
3 Terms and definitions ... 5
4 Construction of automatic water quality monitoring system ... 5
5 Acceptance of automatic water quality monitoring system ... 8
6 Operational maintenance of automatic water quality monitoring system ... 10
7 Quality assurance and quality control ... 15
8 Frequency of data acquisition and effectiveness judgment ... 19
9 Establishment of safeguard system ... 20
Appendix A (Normative) Selection of automatic water quality monitoring item
and requirements for instrument performance ... 21
Appendix B (Informative) Technical requirements for construction of automatic
water quality monitoring system ... 24
Appendix C (Informative) Technical requirements for acceptance of automatic
water quality monitoring system ... 36
Foreword
This standard is formulated for the purpose of implementing the Environmental
Protection Law of the People's Republic of China and the Law of the People's
Republic of China on the Prevention and Control of Water Pollution, protecting
the environment, safeguarding human health, strengthening environmental
management, standardizing the automatic water quality monitoring system.
This standard specifies the technical requirements for the construction,
acceptance, operation and management of the automatic water quality
monitoring system.
Appendix A of this standard is a normative appendix; Appendix B and Appendix
C are informative appendixes.
This standard is the first release.
This standard was formulated under the organization of the Environmental
Monitoring Department and the Science & Technology Standards Department
of the Ministry of Environmental Protection.
Drafting organizations of this standard. China Environmental Monitoring Center,
Jiangsu Environmental Monitoring Center, Liaoning Provincial Environmental
Monitoring Experimental Center, Henan Environmental Monitoring Center, Wuxi
Environmental Monitoring Center Station.
This standard was approved by the Ministry of Environmental Protection on
December 28, 2017.
This standard shall be implemented from April 1, 2018.
For this standard, the Ministry of Environmental Protection is responsible for its
interpretation.
Technical specifications for automatic
monitoring of surface water (Trial)
1 Scope of application
This standard specifies the technical requirements for the construction,
acceptance, operation and management of the automatic water quality
monitoring system (except seawater).
This standard applies to the automatic water quality monitoring system which
is constructed by the environmental protection department.
2 Normative references
The contents of this standard refer to the terms in the following documents. For
undated references, the valid version applies to this standard.
GB 3838 Environmental quality standards for surface water
HJ/T 96 The technical requirement for water quality automatic analyzer of
PH
HJ/T 97 The technical requirement for water quality automatic analyzer of
electroconductivity
HJ/T 98 The technical requirement for water quality automatic analyzer of
turbidity
HJ/T 99 The technical requirement for water quality automatic analyzer of
dissolved oxygen
HJ/T 100 The technical requirement for water quality automatic analyzer of
permanganate index
HJ/T 101 The technical requirement for water quality automatic analyzer of
ammonia
HJ/T 102 The technical requirement for water quality automatic analyzer of
total nitrogen
HJ/T 103 The technical requirement for water quality automatic analyzer of
total phosphorous
HJ/T 104 The technical requirement for water quality automatic analyzer of
total organic carbon
3 Terms and definitions
The following terms and definitions apply to this standard.
3.1
Automatic water quality monitoring
The entire process of automatic collection, processing, analysis and data
transmission of surface water samples.
3.2
Automatic water quality monitoring station
Refers to the on-site part of the automatic water quality monitoring, generally
consisting of all or some of units such as station or house, water collection
and distribution, control, detection, data transmission, etc., abbreviated as
water station.
3.3
Automatic water quality monitoring center
A system for remote monitoring, data transmission statistics and application
of water stations, abbreviated as data platform.
3.4
Automatic water quality monitoring system
An automatic monitoring system consisting of a water station and a data
platform.
3.5
Conventional five parameters
Five conventional items in the monitoring of surface water quality. water
temperature, pH, dissolved oxygen, conductivity and turbidity.
4 Construction of automatic water quality monitoring
system
4.1 General requirements
The construction of automatic water quality monitoring system mainly includes.
the construction of selection of site, construction of station building, water
station units and data platform. Among them, the instrument’s performance
indicators shall meet the requirements of Appendix A.2, the construction of
system refers to the requirements of Appendix B.
4.2 Selection of site
The principles for site selection include feasibility of station construction,
representation of water quality, long-term monitoring, system safety and
operational economy.
In order to ensure the long-term stable operation of the automatic water quality
monitoring system, the selected site shall have good traffic, electricity, clean
water, communication, distance of water collection point, water collection head,
feasibility of water collection in dry season, operation and maintenance safety,
and other basic conditions for the construction of station building.
The monitoring results of the selected sites can represent the water quality
status and changing trends of the monitored water bodies. The river monitoring
section is generally selected in a straight river section where the water quality
is uniformly distributed and the flow rate is relatively stable, more than 1 km
away from the upstream estuary or sewage outlet. In principle, it is consistent
with or similar to the original conventional monitoring section, to ensure
continuity of the monitoring data. The lake reservoir section shall have a good
hydraulic exchange, the location can fully reflect the true state of the water
quality of the lake reservoir in the monitored area, avoid setting it in the
backwater zone, the stagnant water zone, or the place where sedimentation
and watergrass growth are likely to occur.
4.3 Construction of station building
For the construction of the station building, according to the actual situation of
the site environment, construction period, installation conditions of monitoring
instrument & equipment, and so on of the station site, it adopts the fixed station,
simple station, small station, water fixed platform station, water buoy (ship)
station, etc., for system construction. The design and construction of the station
building is combined with the surrounding environment conditions such as
geological structure, water level and climate. At the same time, it shall take
measures such as lightning protection, earthquake resistance, flood control,
low-temperature resistance, rodent prevention, fire prevention, anti-theft, anti-
power failure, video surveillance, and so on. The station building is designed
with the facilities for waste liquid treatment and domestic sewage collection.
The construction of the fixed station building includes the main building for
carrying the system equipment and the external supporting conditions. The
main building consists of the instrument room, the quality control room, the
living room of the duty guard. External supporting conditions refer to the
introduction of clean water, electricity, communications, building access roads,
flattening, greening, solidifying the land covered.
The simple station building and the small station building are suitable for the
construction of water stations which have limited floor space, complicated
geographical conditions, short project construction period, the need to relocate
or adjust the monitoring section. The design dimensions of the station building
shall meet the installation requirements of the instrument and system integrated
device. The material of the station building should be made of light materials,
which have functions such as constant temperature, heat insulation, rain proof
and alarm, etc.
The water fixed platform station and the water buoy (ship) station are a
monitoring system that integrates monitoring instruments on the platform and
is equipped with power supply equipment such as solar energy and wind energy,
has functions such as warning against collision and alarming, etc.
4.4 Construction of each unit of water station
4.4.1 Water collection & distribution unit
The water distribution & distribution unit is the key part to ensure the normal
operation of the whole system and to obtain the correct data. It must ensure
that the water samples provided are reliable and effective, including the water
collection unit, the pretreatment unit and the water distribution unit. The water
collection unit includes the water collection method, the water collection pump,
the laying of water collection pipeline. The pretreatment unit provides
pretreatment device for different monitoring items, to meet the requirements of
the analytical instrument for the settling time and filtration accuracy of the water
sample. The water distribution unit supplies water directly to the automatic
monitoring instrument, the water quality, water pressure and water quantity
provided by the water distribution unit must meet the requirements of the
automatic monitoring instrument.
4.4.2 Control unit
The control unit is the command center that controls the coordination of the
various units within the system.
4.4.3 Detection unit
The detection unit is the core part of the automatic water quality monitoring
system. It consists of automatic monitoring instruments that meet the
requirements of each detection item. The principles for selecting the instrument
is that the instrument’s measurement accuracy meets the requirements of water
quality analysis and meets the requirements of the analytical methods specified
by the state. The selected instrument has reasonable configuration and stable
performance; the operation and maintenance cost are reasonable, the
maintenance work amount is small, the secondary pollution is small.
4.4.4 Data acquisition and transmission unit
Data acquisition and transmission are required to be automatically executed in
accordance with the analytical cycle, and to enable remote control, automatic
encryption and backup. The acquisition device adopts a unified communication
protocol according to national standards, to realizes transmission of data and
main state parameters in a wired or wireless manner.
4.5 Construction of data platform
The data platform is an operating system that integrates data and state
collection, processing and generation of various types of statements. It has the
collection of field data and main state parameters, conditional back control of
field systems and instruments, data analysis and management, generation and
reporting of statements, alarming, and other business functions. The data
platform software adopts a safe and stable data transmission mode, has
functions such as regular automatic backup, automatic classification alarming,
remote monitoring, and so on, and has expandability.
5 Acceptance of automatic water quality monitoring
system
5.1 General requirements
The acceptance of automatic water quality monitoring system includes the
acceptance of the construction of station building and external supporting
facilities, the acceptance of instrument and equipment, the acceptance of data
transmission and data platform. See Appendix C for details of the acceptance
and corresponding forms.
5.2 Acceptance procedures
a) Carry out instrument performance test and laboratory comparison, entrust
qualified organizations to verify the infrastructure such as station power
supply and lightning protection, conduct trial operation according to the
specified time;
b) Prepare an acceptance report, submit an application for acceptance;
c) Check the completion of the site, organize an acceptance meeting, form
an acceptance opinion;
d) Organize the acceptance data and archive it.
5.3 Basic conditions for acceptance
The acceptance of automatic water quality monitoring system shall meet the
following conditions.
a) The power supply, communication, water supply, traffic, lightning
protection, fire prevention, anti-theft and other infrastructure of the station
building meet the requirements;
b) The monitoring instrument, equipment and accessories are supplied in
accordance with the contract, the appearance is not damaged;
c) Complete the instrument’s performance test, comparison test, the
technical indicators meet the relevant national technical specifications and
contract requirements;
d) Complete the communication test of the automatic water quality
monitoring system, upload the water station’s data to the data platform;
e) Complete the operation of automatic water quality monitoring system for
at least 30 consecutive days;
f) Establish a file for the automatic water quality monitoring system, prepare
an acceptance report.
5.4 Acceptance content
5.4.1 Acceptance of station building and external supporting facilities
The completion acceptance of the station building and external supporting
facilities shall comply with the requirements of national standards, current
quality inspection and evaluation standards, construction acceptance
specifications, design documents approved and relevant laws, regulations,
rules and regulatory documents. Check the entity quality of the project, check
the completion data as provided by the parties involved in the construction,
conduct random inspections and tests on the use functions of the construction
project. If problems are found during the acceptance process and the
completion acceptance criteria are not met, it shall instruct the construction
party to immediately rectify it, meanwhile re-determine the time to organize the
completion acceptance. The technical requirements for the construction of the
station building are as shown in Appendix B and the contract.
5.4.2 Acceptance of instruments and equipment
5.4.2.1 Arrival acceptance
According to the contract, make an inventory of each automatic monitoring
equipment, system integration equipment, data platform hardware system, data
acquisition control system, etc.; check the exit-factory number and quantity of
specific equipment and spare parts according to the packing list; check the
appearance of equipment and spare parts. Take pictures of the parts with
appearance damage and deal with them according to the contract.
5.4.2.2 Acceptance of instrument and equipment performance
The acceptance of instrument and equipment performance is mainly for testing
the performance indicators of the instrument and equipment as specified in this
standard. Each equipment shall be accepted in an environment that meets the
requirements. The inspection indicators and judgment criteria meet the relevant
indicators in Table A.2 of Appendix A, the requirements of relevant standards
and contracts. The main contents of the acceptance include, but are not limited
to, the following items. instrument installation, power-on, preheating test,
instrument initialization test, checking of instrument’s basic function, detection
limit, accuracy, precision, checking of standard curve, zero drift, span drift,
checking of response time, checking of repeatability or repeatability error,
comparison of actual water sample. Record the results and make summary.
5.4.3 Acceptance of data transmission and data platform
Under the premise that the automatic monitoring instrument’s performance is
accepted, check whether such indicators as the data transmission of the
automatic monitoring system, the data platform function, the software
performance and so on meet the requirements of national standards and
related technical indicators of the contract.
6 Operational maintenance of automatic water quality
monitoring system
6.1 General requirements
The operational maintenance of the automatic water quality monitoring system
includes routine maintenance of water station at regular interval, maintenance
and repair, troubleshooting, downtime maintenance, daily management and
recording of the data platform, etc.
6.2 Technical requirements for operational maintenance of water station
6.2.1 Routine maintenance
Routine maintenance includes station building’s surrounding inspection,
inspection of instrument and system, replacement of consumables,
replacement of reagent, pipeline cleaning, and so on. The operational
maintenance organization shall conduct regular patrol inspections of the water
station, the frequency of patrol inspection shall not be less than once a week,
the conditions of patrol inspection shall be recorded. The following work is
performed each time performing patrol inspection of the water station.
a) Check the operating status and main technical parameters of each
analytical instrument and auxiliary equipment, to determine whether the
operation is normal; check whether the power supply, process
temperature, stirring motor, sensor, electrode and working sequence are
normal; check whether there is liquid leakage, whether there is air bubble
in the pipeline; regularly clean the conventional five parameters,
chlorophyll and blue-green algae electrodes;
b) According to the operation of the instrument, the water quality of the
section and the environmental conditions of the water station, determine
the replacement cycle of consumables (such as pump tubes, joints,
seals, etc.), ensure finishing replacement before the expiration of the
consumables; if it is necessary to replace the spare parts (such as
electrodes), it shall have inventory to ensure timely replacement;
c) Check the reagent status, add and replace reagents regularly. The pure
water and reagents used must meet the relevant technical requirements.
The replacement period shall not exceed the shelf life of the reagents as
specified in the operating procedures or instrument specifications. It shall
shorten the replacement period when the indoor temperature is high. Each
time the primary reagent is replaced, it shall recalibrate the instrument
according to the appropriate operating procedures or instrument
instructions. Reagent shall be prepared by a qualified laboratory, providing
proof of reagent source and labeling;
d) Timely organize the station building and instrument, complete the
collection of waste liquid, do well in the processing and disposal according
to the relevant requirements, keep the file for future reference; keep the
water station building and all instruments clean and tidy, close the doors
and windows in time, to avoid all kinds of analytical instruments from
exposure to direct sunlight;
e) Check whether the water collection system and the water distribution
system are normal, such as the fixed condition of the water collection buoy,
the operation of the self-priming pump, etc.; regularly clean the water
collection & distribution system, including the water collecting head, the
bucket, the pump body, the grit chamber, the filter head, the water sample
cup, the valves, the related pipelines, etc., it shall timely replace those
which cannot be cleaned;
f) Check whether the power circuit system of the water station is normal,
whether the grounding circuit is reliable; check whether the sampling and
draining pipelines are leaking or blocked, whether the drainage and
exhausting device work normally;
g) Check the air conditioning and thermal insulation measures of the station
building, to keep the temperature stable; check the fixing conditions of the
pump and the air compressor, to avoid vibration of the instrument; check
the operation status of auxiliary facilities such as air compressor,
uninterruptible power supply (UPS), algae removal device, pure water
machine, etc.; replace consumables in time, empty the air compressors;
h) Check the operation status of the industrial personal computer, whether it
is poisoned or not, back up the field data and control software at least
once every quarter; check whether the communication line between the
instrument and the system is normal, whether the data deviation of the
analog transmission meets the requirements;
i) It shall remove timely the weeds and accumulated water around the station
building, check whether the lightning protection facilities are reliable,
whether there is rain leakage in the station, whether other facilities outside
the station are damaged or flooded; if any of the above problems are found,
they shall be handled in time to ensure the safe operation of the system.
Do well in the maintenance of thermal insulation of water collection
pipelines and station before the freezing period comes;
j) Make the work records of daily routine maintenance; take photos for
important work for archiving.
6.2.2 Maintenance and overhauling
According to the environmental conditions of the system operation, overhaul
the instrument and equipment of the system which are in operation within the
specified time to prevent the occurrence of faults. When there is a backup
instrument as a guarantee, it shall use the standby instrument to replace the
monitoring analysis equipment that is running in the water station, send it to the
laboratory for maintenance and overhauling; if there is no backup instrument as
a guarantee, it may carry out maintenance & overhauling at site. The
maintenance & overhauling plan shall be established based on the
configuration of the system instrument and equipment and the requirements of
the equipment manual.
a) The monitoring instrument and equipment of the water station shall be
maintained and overhauled at least once a year;
b) According to the requirements specified by the manufacturer's use and
maintenance manual, based on the service life, replace the key
components such as light source, electrode, peristaltic pump and sensor
in the monitoring instrument;
c) Perform inspection of the leakage and pressure of the liquid path of the
instrument; inspect and clean the optical path, liquid path, circuit board,
various connectors and sockets, etc.;
d) Check and calibrate the output zero and full scale of the instrument, check
the output linearity of the instrument;
e) After completing each overall maintenance and overhauling, or after
replacing the key components such as light source, electrode, peristaltic
pump, sensor, etc. in the instrument, it must calibrate and check the
instruments again, record the overhauling and calibration information.
6.2.3 Troubleshooting
Troubleshooting refers to the targeted inspection and repair of faulty instrument
and equipment. Troubleshooting shall be done as such.
a) According to the characteristics of the instrument used and the
maintenance manual provided by the manufacturer, prepare the work
instructions for judging and repairing common faults;
b) For problems that can be clearly diagnosed at site and can be solved by
replacing spare parts (such as the control failure of solenoid valve, the
rupture of pump tube, the blockage of liquid path, the aging of light source,
etc.), it shall be troubleshooted at site;
c) For other faults that are difficult to diagnose and repair, it shall use the
standby instruments to replace the faulty instruments; send the faulty
instruments or spare parts to the laboratory or the instrument
manufacturer for inspection and maintenance;
d) After each troubleshooting, according to the troubleshooting items and the
replaced parts, calibrate the instruments. For maintenance of the common
consumables (such as replacement of pump tube, cooling fans, fluid path
joints or connectors), it shall perform at least calibration of standard liquid.
For maintenance of critical components (such as maintenance of moving
mechanical parts, optical components, testing components and signal
processing components), follow the requirements of the instrument
standards and specifications to check the standard curve and precision.
All troubleshooting results shall be recorded as required for reference.
6.2.4 Downtime maintenance
Short-term shutdown (downtime less than 24 h). Normal shutdown, the
instrument must be recalibrated when running again.
Long-term downtime (continuous downtime more than 24 h). When the
analyzer needs to be shut down for 24 h or more, turn off the analytical
instrument and injection valve, turn off the power; use pure water to clean the
peristaltic pump and reagent pipeline of the analytical instrument; clean the
measuring chamber and empty it; be sure to remove the measuring electrode
and immerse the electrode tip in the protective solution for preservation. It shall
calibrate the instrument again before running it again.
6.3 Daily management of data platform
For the data platform, it must arrange personnel to understand the equipment
operation and water quality. At every morning and afternoon, remotely observe
the monitoring data of the water station at least once through the data platform
software. Based on actual conditions, organize performing such work as patrol
inspection, verification, maintenance, and so on, to ensure the normal and safe
operation of the water station. The daily management work of the data platform
includes.
a) Check the data transmission, instrument and related system parameter
data of each water station, any problem found shall be handled in time;
b) When the data is found to have persistent outliers, it shall immediately
arrange the technicians to go to the site for investigation; if necessary,
collect the actual water samples for manual analysis;
c) Retrieve and analyze the monitoring data of the water station;
d) Report the monitoring results;
e) Ensure that the hardware and software of the used and backup computer
systems are running normally; regularly update the system software,
water quality’s monitoring software, anti-virus software; back up the
system monitoring data once every quarter;
f) Do a good job in the daily management of the data platform.
6.4 Record
During the operation of the automatic monitoring system, record the verification
and patrol inspection of the instrument performance, the replacement,
calibration and maintenance of spare parts, the preparation of reagents, the
daily work of data platform, etc., to ensure that the records related to the work
are complete, comprehensive and accurate. The descriptions on the problems
found and disposal shall be informative, continuous, conclusive, or has handling
results. See Appendix C for the forms of relevant record.
7 Quality assurance and quality control
7.1 General requirements
After establishing an automatic water quality monitoring system, according to
the automatic monitoring system equipment and its operation characteristics,
as well as the relevant provisions on the monitoring, perform the quality
assurance and quality control work.
7.2 Requirements for standard value transfer
a) Standard samples used to calibrate monitoring instruments, are prepared
using certified standard samples or standard substances;
b) Analytical balances, scales, thermometers, standard multimeters, pipettes,
volumetric flasks, etc. for value transfer shall, in accordance with relevant
regulations, be regularly sent to relevant departments for verification.
7.3 Contents, requirements and methods of verification of instrument
performance
7.3.1 Contents of verification of instrument performance
Verification of instrument performance is the basic guarantee for obtaining valid
data and the key to the normal operation of the automatic monitoring system,
including regular inspection of accuracy, precision, detection limit, standard
curve, spike recovery rate, zero drift, span drift, as well as the calibration work
of instrument before and after each calibration.
7.3.2 Requirements for verification of instrument performance
The requirements for verification of instrument performance are as follows.
a) Check the accuracy, precision, detection limit, standard curve, spike
recovery rate at least once every six months;
b) Check the zero drift and span drift at least once every six months;
c) After updating the detector, check the standard curve and precision once;
d) After updating the instrument, check all instrument performance indicators
in Table A.2 of Appendix A once;
e) Perform instrument calibration at least once a month.
The data acquisition frequency of the verification of instrument performance can
be adjusted to be less than the data acquisition frequency of daily monitoring,
meanwhile it shall ensure that the determination of sample is not affected by
the previous sample.
7.3.3 Methods for verification of instrument performance
7.3.3.1 Accuracy
Accuracy is generally checked according to the relative error of the
determination results of the sample at the specified concentration. The pH,
dissolved oxygen, and temperature are checked according to the absolute error.
When the accuracy is checked based on relative error, the sample’s
concentration is 50% of the range.
The method of checking the relative error. determine 6 times the sample for
concentration determination, calculate the relative error between the mean
value and the true value, compare it with the relevant indicators in Table A.2 of
Appendix A. The relative error (RE) is calculated according to formula (1).
Where.
RE - Relative error;
- Mean value of 6 determinations;
C - Reference value (guaranteed value of standard sample or concentration
value of controlled sample as prepared according to standard methods).
Absolute error checking is applicable to items such as pH, dissolved oxygen,
temperature. The pH accuracy checking is carried out according to the samples
at pH = 4.01, 6.86 and 9.18 (at 25 °C); the dissolved oxygen’s accuracy is
checked according to the determination results at saturation concentration; the
temperature accuracy is checked by two different levels of actual or simulated
samples through the comparison method.
Checking method of absolute error. Determine 6 times the sample of each
magnitude, calculate absolute error of the single determination value and the
reference value, compare the maximum single absolute error with the relevant
indicators in Table A.2 of Appendix A. The absolute error (d) is calculated
according to formula (2).
Where.
d - Absolute error;
ix - The ith determined value;
c - Reference value (guaranteed value of standard sample or value of
controlled sample as prepared according to standard methods).
7.3.3.2 Precision
The precision check is the checking of the determination result of the 50%
concentration (except pH, dissolved oxygen, temperature), it is judged by the
relative standard deviation (see Table A.2 of Appendix A).
Checking method of precision. Calculate the relative standard deviation of the
results of 6 consecutive determinations for each sample, compare it with the
relevant indicators in Table A.2 of Appendix A. The relative standard deviation
(RSD) is calculated according to formula (3).
Where.
RSD - Relative standard deviation;
n - Number of determinations;
ix - The ith determined value;
- Mean value of determinations.
7.3.3.3 Detection limit
The detection limit of the instrument is obtained by the actual test method.
Test method. Prepare standard solution or blank sample according to the
instrument method based on concentration of 3 times detection limit; make 8
determinations.
The detection limit (DL) is calculated according to formula (4).
Where.
DL - Detection limit;
S - Standard deviation of the determined values of 8 parallel samples.
7.3.3.4 Standard curve
The checking of standard curve uses the correlation coefficient of standard
curve as the inspection index, follows the Table A.2 of Appendix A to judge the
results.
Test method. According to the range set for the instrument, perform test for the
standard solution of 6 concentrations of 0%, 10%, 20%, 40%, 60% and 80%
according to the sample, calculate the correlation coefficient of the standard
curve.
7.3.3.5 Spike recovery rate
The checking items of the spike recovery rate include. ammonia nitrogen, total
nitrogen, total phosphorus, etc. Use the spike recovery rate as the inspection
index, follow the Table A.2 of Appendix A to judge the results.
Test method. Take 2 sets of same sample; add a certain amount of standard
substance of the tested component (the volume of the spiked sample shall not
exceed 1% of the volume of original sample), the ratio of the difference between
the result of the spiked sample and the result of the un-spiked sample result to
the theoretical value of the standard substance added is the spiked recovery
rate (P), calculated according to formula (5).
Where.
P - Spiked recovery rate;
m2 - Test value of spiked sample;
m1 - Test value of un-spiked sample;
m - Theoretical value of the standard substance added.
7.3.3.6 Zero drift
It is performed according to the technical requirements of the national automatic
water quality analyzer (HJ/T 96 ~ HJ/T 104, etc.), follow the requirements of
Table A.2 of Appendix A to judge the results.
7.3.3.7 Span drift
It is performed according to the technical requirements of the national automatic
water quality analyzer (HJ/T 96 ~ HJ/T 104, etc.), follow the requirements of
Table A.2 of Appendix A to judge the results.
7.3.3.8 Comparison of actual water sample
The comparison test shall use the same water sample as that which is analyzed
by the automatic monitoring instrument. If the instrument needs to filter the
water sample, the comparative experimental water sample can be filtered by
the same filter material (but the composition and concentration of the pollutants
in the water body must not be changed); use the sample division method to split
one sample into 2 ~ 3 sampling bottle, which are then analyzed by the automatic
monitoring instruments and laboratories; follow the Table A.2 of Appendix A to
judge the results.
The relative error of the actual water sample comparison is calculated
according to formula (6).
Where.
xi - Determined value of automatic monitoring instrument;
xl - Determined value of the comparison experiment (average of 2
determinations).
8 Frequency of data acquisition and effectiveness
judgment
8.1 Frequency of data collection
The frequency of collecting the automatic water quality monitoring is generally
4 h. This frequency shall be adjusted based on actual conditions in case of
emergency special circumstances.
8.2 Data validity
The instrument analysis data is divided into valid data and invalid data. The
valid data refers to the data that is confirmed to meet the requirements after the
standard sample test of instrument, manual analysis, online quality control, etc.
The invalid data refers to the data generated by the confirmed instrument fault
through online or offline quality control means. When it cannot be accurately
determined, it can be marked as suspect data, but it must be determined as
valid data or invalid data within 24 hours. Regularly calculate the data efficiency,
that is, the percentage of valid data in the total amount of data, the data
efficiency shall be greater than 90%.
The verification methods are divided into online verification and manual
verification, which uses the standard sample and the comparison of actual
water sample, respectively.
9 Establishment of safeguard system
To ensure the normal operation of the water station and the accuracy and
reliability of the monitoring data, it must establish the corresponding safeguard
system, including but not limited to the following.
a) Management methods of operation of water station;
b) Job responsibilities of the operation management personnel of water
station;
c) Guarantee system of quality management of water station;
d) Operating procedures of instruments of water station;
e) Job training and assessment system of water station;
f) Archives management system for construction, operational maintenance
and quality control of water station.
Appendix A
(Normative)
Selection of automatic water quality monitoring item and requirements
for instrument performance
A.1 Selection of monitoring item
Determine the monitoring items according to the purpose of monitoring and the
characteristics of water quality, they are divided into mandatory test items and
selected test items, as shown in Table A.1. For the selected test items, it shall
be determined according to the water body’s characteristic pollution factor, the
applicability of the instrument and equipment, the comparability of the
monitoring results, the water body’s function. The items where the instrument
is immature or whose performance indicators do not meet local water quality
conditions shall not be used as an automatic monitoring item.
Table A.1 -- Necessary test items and optional test items for automatic
water quality monitoring station
Water body Necessary test items Optional test items
River
Conventional five parameters,
permanganate index, ammonia nitrogen,
total phosphorus, total nitrogen
Volatile phenols, volatile organic compounds,
oils, heavy metals, fecal coliforms, flow, flow
rate, flow direction, water level, etc.
Lake,
reservoir
Conventional five parameters,
permanganate index, ammonia nitrogen,
total phosphorus, total nitrogen,
chlorophyll a
Volatile phenols, volatile organic compounds,
oils, heavy metals, fecal coliforms, algae
density, water level, etc.
A.2 Requirements for instrument performance
The performance indicators of the automatic water quality monitoring system
shall meet or exceed the requirements of Table A.2, the performance of the
instrument shall be verified in accordance with Table A.2.
Table A.2 -- Technical requirements for the performance indicators of
automatic water quality monitoring systems
Monitoring item Testing method
Detectio
n limit
Accurac
Precis
ion
Stability Correlation
coefficient
of standard
curve
Spiked
recover
y rate
Actual
sample
comparis
on
Zero
drift
Span
drift
pH Electrode method - - ± 0.1 - ± 0.1 - - ± 0.1
Water
temperature / °C
Electrode
method - - ± 0.2 - ± 0.2 - - ± 0.2
Dissolved oxygen
/ (mg/L)
Electrode
method - - ± 0.3 ± 0.3 ± 0.3 - - ± 0.3
Conductivity /
(μs/cm)
Electrode
method - ± 1% ± 1% ± 1% ± 1% - - ± 10%
Turbidity / NTU Electrode method - ± 5% ± 5% ± 3% ± 5% - - ± 10%
Ammonia nitrogen
/ (mg/L)
Electrode
method 0.1 ± 5% ± 10% ± 5% ± 5% ≥ 0.995
80% ~
120%
② Spectroph
otometry 0.05 ± 5% ± 5% ± 5% ± 5% ≥ 0.995
80% ~
120%
Permanganate
index / (mg/L)
Electrode
method,
spectropho
tometry
1 ± 5% ± 10% ± 5% ± 5% ≥ 0.995 - ②
Table A.2 (continued)
Monitoring item Testing method
Detectio
n limit
Accurac
Precis
ion
Stability Correlation
coefficient
of standard
curve
Spiked
recover
y rate
Actual
sample
comparis
on
Zero
drift
Span
drift
Total organic
carbon / (mg/L)
Dry, wet
oxidation 0.3 ± 5% ± 5% ± 5% ± 5% ≥ 0.999
80% ~
120% ②
Total nitrogen /
(mg/L)
Spectroph
otometry 0.1 ± 10% ± 10% ± 5%
10% ≥ 0.995
80% ~
120% ②
Total phosphorus /
(mg/L)
Spectroph
otometry 0.01 ± 10% ± 10% ± 5%
10% ≥ 0.995
80% ~
120% ②
Biochemical
oxygen demand /
(mg/L)
Microbial
membrane
method
2 ± 10% ± 10% ± 5% ± 10% ≥ 0.995
80% ~
120% ②
Other pollution
indicators - ① ③
Notes.
① It must be better than the standard limits as specified in GB 3838 (The indicator in Table 1 of GB 3838
must be better than the standard limit of Class I).
② When Cx > BIV, the relative error of the comparison experiment is within 20%;
When BII < Cx ≤ BIV, the relative error of the comparison experiment is within 30%;
When 4DL < Cx ≤ BII, the relative error of the comparison experiment is within 40%;
When it is not detected both in the automatic monitoring data and the laboratory analysis results, or
otherwise it is not detected by either data and the determined value of the other data is less than BI, the
comparison test results are deemed to be qualified;
Where.
Cx - The determined concentration of instrument;
B - The standard limits of the corresponding water quality class in Table 1 of GB 3838;
4DL - The lower limit of determination.
③ It must meet the requirements of the exit-factory technical indicators of instruments.
Appendix B
(Informative)
Technical requirements for construction of automatic water quality
monitoring system
B.1 Basic principles of site selection
Site selection must consider the following basic principles.
a) Feasibility of basic conditions. It has good basic conditions such as land,
traffic, communication, electricity, clean water and geology;
b) Representation of water quality. According to the purpose of monitoring
and the function of the section, it has a good representation of water
quality;
c) The long-term nature of site. It is not affected by the construction of urban,
rural, water conservancy, etc. It has a relatively stable water depth and
river width, which can ensure the long-term operation of the system;
d) Safety of system. The environmental conditions around the water station
are safe and reliable;
e) Economics of operational maintenance. It is convenient for the daily
operation, maintenance and management.
B.2 Basic conditions for the establishment of water station
To ensure long-term stable operation of the system, the selected site location
must meet the following basic conditions.
a) It is convenient for traffic, the time to reach the water station is generally
not more than 4 h;
b) There is reliable power supply and stable voltage, the supply voltage shall
reach 380 V, the equipment voltage shall reach 220 V ± 10%, the capacity
is not less than 15000 W;
c) There is tap water or a self-prepared well water source, the water quality
meets the requirements of domestic water;
d) The communication conditions are good; the quality of the communication
line or wireless network meets the data transmission requirements;
e) The distance between the water collection point and the station building is
generally not more than 300 m; it is not more than 350 m in dry season, it
is conducive to laying pipelines and insulation facilities;
f) The difference between the height of the lowest water surface and the
station building is not more than the maximum lift of the pump;
g) The section has water all year round, the river’s swing shall be less than
30 m, the water depth at the water collection point shall be not less than
1 m, to ensure the possibility of collecting water sample. The maximum
flow rate at the water collection point shall generally be less than 3 m/s,
which is beneficial to the construction and operational maintenance of
water collection facilities, to ensure safety.
B.3 Technical requirements for the construction of main part of station
building
B.3.1 Basic configuration of station building
The area of the instrument room is not less than 60 m2, the net length of the
single-sided continuous wall used for installing the instrument is not less than
10 m, the quality control room is not less than 30 m2, the living room of the duty
guard is not less than 20 m2. Other rooms can be arranged according to actual
needs.
Instrument room. The indoor floor is paved with waterproof and non-slip
materials. The station floor has a certain slope in the direction of the drainage
hole, which can drain the indoor water. There is a special clean water source
pipe in the instrument room. The total pipe diameter of the interface is not less
than DN 20, meanwhile it is equipped with a shut-off valve. Well water is used
where there is no tap water, but it needs to build a high-level water tank and
equip it with automatic water supply system at the top of the station building or
within the station building at a position 2 m above the floor. The volume of the
water tank is about 2 m3. Add water filtering equipment when the well water has
a higher sediment content.
Quality control room. It is equipped with an acid-base-resistant chemical test
bench, it may place the laboratory comparison instruments on the bench and
the work cabinet under the bench, to facilitate the placement of reagents.
Meanwhile it is equipped with a laboratory stool, water supply & drainage, wash
basin, and the like.
Living room of duty guard. To facilitate the work of the duty guard working in the
water station, it shall be provided with a bathroom.
B.3.2 Structural design of the foundation of station building
a) Perform design and construction according to local geological conditions,
make corresponding foundation treatment when encountering weak
foundation;
b) Use brick-concrete structures or frame structures, the endurance life is not
less than 50 years;
c) The ground elevation can withstand the flood of 50-year frequency; the
clearance height in the station building is not less than 2.7 m;
d) Make cement concrete floor around the station building, the ground
outside the station building is flat, the surrounding area is clean and tidy,
which is conducive to drainage, it is properly greened;
e) The shape design of the station building shall be adapted to local
conditions, the appearance is beautiful and generous, the structure is
economical and practical; if located in the scenic area, it shall be
coordinated with the surroundings;
f) There shall be hardened roads leading to the water station, the road width
is not less than 3 m and it is connected with the trunk road, there is a
proper amount of open space in front of the station, to ensure the parking
of vehicles and materials transportation;
g) It shall ensure that the lightning protection system, grounding system,
water collection facilities, water supply and drainage, etc., are
synchronized with the construction of the station building;
h) Dedicated grounding device for station building, instrument, electrical
system, etc., shall have a grounding resistance not more than 4 Ω and be
subjected to equipotential bonding;
i) The area map and plan (1.500 or 1.1000) of the area to be acquired shall
be filed.
B.3.3 Safety design for station building heating, lightning protection and
earthquake resistance
a) The instrument room is equipped with air conditioning and heating
equipment. The indoor temperature is controlled at 18 ~ 28 °C and the
humidity is within 60%. The air conditioner shall have the function of
automatic reset after power restoration, the heating device is used to
prevent system damage caused by power outage in winter;
b) Perform seismic design based on local seismic fortification intensity;
c) It is equipped with smoke detection, flame alarm, built-in fire extinguishing
equipment;
d) It is equipped with lightning protection system, take safety measures such
as anti-theft and anti-rat.
B.4 Technical requirements for construction of supporting facilities
B.4.1 Power supply facilities
The power supply of the water station is AC 380 V, three-phase four-wire
system, frequency 50 Hz, capacity not less than 15000 W. When the power
supply voltage is connected to the total distribution box in the station room, the
voltage drop is less than 5%, the power supply circuit supplies power stably,
the voltage fluctuations and frequency fluctuations are in line with relevant
national and industry regulations.
The power cord is introduced in a manner that complies with the relevant
national standards. The power cable inside the station building is shielded, the
wall-penetrated tube is buried when the power cable penetrates through walls.
Set up the main distribution box of the station building, which has an electric
meter and an air main switch. Repeat the grounding at the main distribution box,
ensure that the zero and ground lines are separated, the phase difference
between them is zero, meanwhile take the lightning protection measures for the
power supply. Introduce a separate three-phase power supply from the main
distribution box to the instrument room, configure the dedicated power
distribution box for the automatic monitoring system at the designated location.
Lighting, air conditioning and other household electricity (220 V), regulated
power supply and power supply for water collection pump (220 V) use
separated phases. Power capacity. The instrument & equipment and control
power is about 10000 W for two phases (220 V). The air conditioning in the
instrument room, the lighting for station building, the electricity for living is two-
phase (220 V) 5000 W. If there is other electricity demand, it may make
appropriate consideration to increase power supply capacity.
The instrument room is equipped with sufficient lighting equipment, the lighting
equipment is equipped with a control switch; provide a dedicated air-
conditioning socket in the vicinity of the air-conditioning installation, meanwhile
install 2 ~ 3 multi-purpose sockets on each wall of the instrument room
according to requirements, which is convenient for temporary power
consumption. The power supply line, communication line and signal line are
shielded from each other, to avoid electromagnetic interference.
B.4.2 Communication facilities
Water stations are often geographically diverse and the modes of
communication that can be provided are different, it requires communication
systems to have sufficient flexibility. Priority is given to the use of wired
communications; however, if limited by geographical conditions, it may select
wireless communication. When the communication cable is close to the station
building, it has no flying line. When the communication cable passes through
the wall, bury the wall-penetrated tube and do well in grounding.
B.4.3 Water supply and drainage facilities
Sample water. The location where the water collection pipe enters the station
building is close to the lower part of the wall where the instrument is installed,
and provided with the protective sleeve, which is 50 mm higher above the
ground.
Drainage. All water drained from the station building is collected into the trunk
drainage pipe, discharged into the corresponding drainage point through the
external drainage pipe. The total diameter of drainage pipe is not less than DN
150, to ensure smooth drainage. The water outlet of the drainage pipe is higher
than the highest flood level of the river and is located downstream of the water
collection point. A drainage pipe interface for the instrument and equipment is
set in the station building, the pipeline which has the total diameter of pipeline
not less than DN 25 is used. The drainage pipe is 50 mm higher above the
ground. It also needs to pay attention to take antifreeze measures.
Auxiliary water. Tap water or well water is introduced into the station building.
The instantaneous maximum flow of water is not more than 3 m3/h, the pressure
is not less than 0.5 kg/cm2, the water consumed per each cleaning is not more
than 1 m3. There is rainwater drainage system in the region outside the station
building, to avoid water accumulation on the floor outside the station building.
B.4.4 Domestic sewage collection facilities
The station building shall be designed with a domestic sewage septic tank,
which shall be constructed synchronously with the civil work of the station
building.
B.4.5 Uninterruptible power supply facilities
The uninterruptible power supply system shall meet the requirements that the
automatic monitoring instruments, communication equipment, etc., can operate
normally within 2 hours of the power failure mode, including the emptying and
cleaning of the analytical instrument, the operation of the data acquisition
control system. When the backup power supply is used, it shall avoid the air
conditioner from heating operation when the room temperature is relatively low,
to ensure that the monitoring instrument has priority to use electricity.
B.5 Water collection unit
The function of the water collection unit is to ensure that the water sample at
the water collection point is led into the instrument room under any
circumstances and meets the needs of other equipment. The water collection
unit shall have a continuous and intermittent working mode.
Use the alternative water collection mode of double pump/double pipeline, one
in use and the other for standby. In the control system, set the automatic fault
diagnosis and the working function of automatic switching pump. When a fault
occurs in one pipeline, use the control system to timely cut off the power supply
of this water pump, meanwhile it can automatically switch to the other pipeline
to work, to meet the uninterrupted monitoring requirements of the entire system.
The water collection pump selects high-quality submersible pump or self-
priming pump, which is sturdy and durable, easy to maintain and repair, and
can effectively prevent blockage. The flow rate of the water collection pump is
guaranteed to be more than 3 t/h. The water collection amount fully meets the
requirements of the instrument selected by the system and the need to expand
the monitoring parameters in the future. The water collection pump has the
automatic recovery function of restart at power restoration after the power
failure.
The water collection pipelines are all insulated. The sampling pipeline and the
cable are placed in the same casing. The buried part is buried below the frozen
soil layer or installed in the cement gutter. Take the thermal insulation,
antifreeze and anti-icing measures according to the requirements. The thermal
insulation sleeve is provided outside the pipeline to perform thermal insulation
treatment. The protection of the external sleeve shall have excellent
physicochemical stability.
The water collection pipeline is removable for washing, has the backwash
function. The pipeline is detachable to prevent the sampling pipeline from being
clogged and to facilitate cleaning after sediment deposition; the water collection
pipeline is provided with the backwash bypass pipeline outlet, it may use the
control system to control the automatic backwash or otherwise use the cleaning
pump or chemical reagent to perform automatic backwash against the whole
path of the sampling pipeline, meanwhile use the switching of the pneumatic
valve to flush the sample injection pipeline by high-pressure vibrated air; the
cleaning process shall not pollute the environment; it is designed with dedicated
double-layer anti-algae structure to prevent the blocked algae from entering the
pipeline or attaching to the water collection head. The pipeline cleaning is
configured with online sediment removal device and the algae removal cleaning
device. After using the chemical reagents to clean the system’s pipeline, it shall
use a large amount of clean water to rinse the pipeline. In case of water
collection, there is no residual chemical liquid in the pipeline, it shall not affect
the monitoring of item, to ensure the measurement accuracy. The turbidity of
the water at the inlet of the colorimetric instrument is controlled below 20 NTU.
The water collection inlet shall be provided with a protective device to prevent
siltation of the water inlet and blockage of floating objects, to prevent damage
to the instrument, equipment and water collection equipment due to impact, or
to affect the operation and anti-theft of the system.
The water collection device takes the water collection buoy as an example. The
buoy shall be made of stainless-steel skeleton and made of surface material of
glass fiber reinforced plastic. There are two cylindrical spaces which is designed
according to the diameter and depth of the submersible pump on the buoy.
When the pump is maintained, it may open the anti-theft lock to easily remove
the water pump, without having to move the buoy. Provide circular pipe guide
rail on both sides of the water collecting installation platform, insert the guide
rail into water, the water collecting buoy can be floated up and down along the
guide rail. No matter how the water level changes, the water collecting buoy
can always ensure that the water collecting depth is always 0.5 ~ 1.0 m below
the water surface, thereby ensuring its normal operation without damage during
the flood season and dry season; it provides with necessary thermal insulation,
antifreeze, anti-corrosion, anti-pressure and anti-sludge, anti-collision and anti-
theft measures, meanwhile makes necessary fixation of water collection
equipment and facilities.
B.6 Water distribution unit
The water distribution unit supplies water directly to the automatic monitoring
instrument; its water quality, water pressure and water volume shall meet the
needs of automatic monitoring instruments.
The automatic monitor of conventional five parameters uses raw water.
According to the requirements of the instruments for the water sample, after the
water sample enters the water distribution unit, a part of the water sample is
directly sent to the conventional five-parameter measuring cell without any
pretreatment according to the principle of the shortest water collecting distance.
The installation of the five-parameter measuring instrument follows the principle
of the minimum distance from the water body. The water flow in the cell is
guaranteed to be stable and the water level is constant.
Reserve multiple instrument expansion interfaces to facilitate system upgrade.
The water distribution pipelines of each instrument adopt parallel water
collection mode. The inner diameter, the lifting-water flow rate and the flow
velocity of the pipeline of each instrument can be separately adjusted and
respectively equipped with pressure gauges. In addition to the water
requirements of the instrument, each branch of the water distribution system
needs to have 2 ~ 3 sets of interfaces for conventional monitoring instruments.
The system is designed with positive & negative cleaning pumps, metering
pumps, high-pressure air scrubbing pipelines, ozone de-algae function, etc. It
may combine a variety of cleaning methods to achieve the best cleaning effect.
The cleaning process will not pollute the environment.
The water distribution pipeline has reasonable design, clear flow direction and
easy maintenance. When the instrument fails, it can be repaired or replaced
without affecting the normal operation of other instruments.
The pipeline has good mechanical strength and chemical stability, long service
life, easy installation and maintenance, it will not affect the water quality of the
water sample.
B.7 Pretreatment unit
Under the premise of ensuring the representativeness of the water sample, the
pretreatment unit performs a series of treatments against the water sample to
eliminate the factors that interfere with the automatic monitoring instrument, so
as to ensure the continuous long-term reliable operation of the analysis system.
It shall not use the interception type filtering device. Since the pretreatment unit
is related to the reliability of the entire analysis system, the valve used in the
pretreatment unit shall be a high-quality electric ball valve.
The pretreatment system adopts a combination of primary filtration and
precision filtration. After the primary filtration, the larger impurities of the water
sample are eliminated, it is further subjected to further natural sedimentation
(sediments deposited by filtration are regularly drained), then filtered through a
precision membrane into the analytical instrument. The precision filtration
adopts the bypass design, which is selected according to the specific
requirements of different instruments, forms the analytical unit together with the
analytical instrument.
The pretreatment system is mainly composed of sedimentation tank, filtration,
safety guarantee, and other parts. The combination of each part can achieve
the ideal sand removal effect. The inner diameter of the pipeline, the lifting-
water flow rate, and the flow rate meet the needs of instrument analysis in the
station, meanwhile it reserves the interfaces for 2 ~ 3 sets of conventional
monitoring instruments. After restoration of the pretreatment system after power
failure, it can be automatically started according to the control timing of the
acquisition controller. It may take appropriate filtration measures according to
different instruments. In special cases, select the precision filter to preform
secondary treatment of the water sample as appropriate.
Under the conditions of not violating the standard analytical method, it may use
the filtration to reach the effect of pre-precipitation; or otherwise use the pre-
precipitation to replace the filtration operation. The treated water sample shall
not only eliminate the influence of debris on the monitoring instrument, but also
cannot lose the representativeness of the water sample. The cleaning
maintenance period of the filtration system is generally 3 months. The filtration
system has the functions of automatic cleaning, sand discharge and algae
removal. The water sample is delivered to the grit chamber through the water
collection pipeline, it is made standing to allow the larger particles to sink to the
bottom of the chamber. The bottom of the chamber is provided with a discharge
valve. At the end of each measurement cycle, the residual water sample in the
precipitation basin is emptied and cleaned, to prepare for the entry of the water
sample of the next period.
The automatic cleaning and algae removal function of the pretreatment unit is
generally completed automatically by the system control, the cleaning process
may be either manual operation on site or remote control. At the end of each
measurement cycle, use the high-pressure gas to backwash the filter, to
remove adherent, algae or sediment attached onto the surface of the filter.
B.8 Control unit
The control unit is the command center system that controls the coordination of
each unit of the system. It adopts an integrated cabinet design; all the
equipment of the control unit is integrated in the cabinet.
The control unit completes the control of the automatic water quality monitoring
system, communicates with the data platf......
(Above excerpt released/modified date: 2018-11-30 / 2019-03-24. Translated/reviewed by: Wayne Zheng et al.)
https://www.chinesestandard.net/PDF.aspx/HJ915-2017