THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
EPA
U.S. Environmental Protection Agency
ET/
Bairene
The Business of Innovation
ETV Joint Verification Statement
TECHNOLOGY TYPE: MULTI-PARAMETER WATER MONITORS FOR
DISTRIBUTION SYSTEMS
APPLICATION: MONITORING DRINKING WATER QUALITY
TECHNOLOGY NAME: Sentinal™ 500 Series
COMPANY: Clarion Sensing Systems, Inc.
ADDRESS: 3901 West 30th Street PHONE: 317-295-1433
Indianapolis, Indiana 46222 FAX: 317-295-1436
WEB SITE: www.clarionsensing.com
E-MAIL: clarionsystems@earthlink.net
The U.S. Environmental Protection Agency (EPA) supports the Environmental Technology Verification (ETV)
Program to facilitate the deployment of innovative or improved environmental technologies through performance
verification and dissemination of information. The goal of the ETV Program is to further environmental protection
by accelerating the acceptance and use of improved and cost-effective technologies. ETV seeks to achieve this
goal by providing high-quality, peer-reviewed data on technology performance to those involved in the design,
distribution, financing, permitting, purchase, and use of environmental technologies. Information and ETV
documents are available at www.epa.gov/etv.
ETV works in partnership with recognized standards and testing organizations, with stakeholder groups
(consisting of buyers, vendor organizations, and permitters), and with individual technology developers. The
program evaluates the performance of innovative technologies by developing test plans that are responsive to the
needs of stakeholders, conducting field or laboratory tests (as appropriate), collecting and analyzing data, and pre-
paring peer-reviewed reports. All evaluations are conducted in accordance with rigorous quality assurance (QA)
protocols to ensure that data of known and adequate quality are generated and that the results are defensible.
The Advanced Monitoring Systems (AMS) Center, one of six technology areas under ETV, is operated by Battelle
in cooperation with EPA's National Exposure Research Laboratory. The AMS Center evaluated the performance
of the Clarion Sensing Systems, Inc., Sentinal™ 500 Series in continuously measuring free chlorine, temperature,
conductivity, pH, and oxidation-reduction potential (ORP) in drinking water. This verification statement provides
a summary of the test results.
VERIFICATION TEST DESCRIPTION
The performance of the Sentinal™ 500 was assessed in terms of its accuracy, response to injected contaminants,
inter-unit reproducibility, ease of use, and data acquisition. The verification test was conducted between August 9
and October 28, 2004, and consisted of three stages, each designed to evaluate a particular performance
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characteristic of the Sentinal™ 500. All three stages of the test were conducted using a recirculating pipe loop at
the U.S. EPA's Test and Evaluation (T&E) Facility in Cincinnati, Ohio.
In the first stage of this verification test, the accuracy of the measurements made by the Sentinal™ 500 units was
evaluated during nine, 4-hour periods of stable water quality conditions by comparing each Sentinal™ 500 unit
measurement to a grab sample result generated each hour using a standard laboratory reference method and then
calculating the percent difference (%D). The second stage of the verification test involved evaluating the response
of the Sentinal™ 500 units to changes in water quality parameters by injecting contaminants (nicotine, arsenic
trioxide, and aldicarb) into the pipe loop. Two injections of three contaminants were made into the recirculating
pipe loop containing finished Cincinnati drinking water. The response of each water quality parameter, whether it
was an increase, decrease, or no change, was documented and is reported here. In the first phase of Stage 3 of the
verification test, the performance of the Sentinal™ 500 units was evaluated during 52 days of continuous
operation, throughout which references samples were collected once daily. The final phase of Stage 3 (which
immediately followed the first phase of Stage 3 and lasted approximately one week) consisted of a two-step
evaluation of the Sentinal™ 500 performance to determine whether this length of operation would negatively
impact the results from the Sentinal™ 500. First, as during Stage 1, a reference grab sample was collected every
hour during a 4-hour analysis period and analyzed using the standard reference methods. Again, this was done to
define a formal time period of stable water quality conditions over which the accuracy of the Sentinal™ 500 could
be evaluated. Second, to evaluate the response of the Sentinal™ 500 to contaminant injection after the extended
deployment, the duplicate injection of aldicarb, which was also included in the Stage 2 testing, was repeated. In
addition, a pure E. coli culture, including the E. coli and the growth medium, was included as a second injected
contaminant during Stage 3. Inter-unit reproducibility was assessed by comparing the results of two identical units
operating simultaneously. Ease of use was documented by technicians who operated and maintained the units, as
well as the Battelle Verification Test Coordinator.
QA oversight of verification testing was provided by Battelle and EPA. Battelle QA staff conducted a technical
systems audit, a performance evaluation audit, and a data quality audit of 10% of the test data.
This verification statement, the full report on which it is based, and the test/QA plan for this verification test are
all available at www.epa.gov/etv/centers/centerl.html.
TECHNOLOGY DESCRIPTION
The following description of the Sentinal™ 500 unit was provided by the vendor and does not represent verified
information.
The Sentinal™ 500 is designed to remotely monitor and report drinking water quality. The Sentinal™ 500 uses a
sensor array to acquire information about drinking water quality on site in near-real time by analyzing the water
quality and comparing it to its normal baseline values and notifies utility/security personnel if water quality
changes significantly from its baseline. The Sentinal™ 500 used in this verification test measured free chlorine,
temperature, conductivity, pH, and GKP in drinking water. The sensors measured these parameters by
potentiometric, amperometric, and conductance methods.
The Sentinal™ 500 consists of sensors and their respective meters with digital displays; a data acquisition,
analysis, and management microprocessor; a communications link such as radio, cellular networks, satellite
networks, wireless Ethernet or LANs (as configured during this test), and a receiving station where the data are
presented and alarms are distributed. The systems can serve up their own Web pages to the network, and other
monitoring sites can be accessed through each site. The system could be configured to actuate valves and pumps
to shut off or divert water for on-site treatment.
For this verification test, the continuous data were stored on the on-board computer and downloaded daily by
plugging an Ethernet cable into a laptop and entering an IP address into Microsoft Explorer. A Web page was
called up, and the data could be easily downloaded as an Excel spreadsheet. System software (the Sentinal™ Data
Acquisition and Management Device) could be configured to average all of the data over time to determine site-
specific normal baselines. The software also can be programmed to recognize when deviations (threshold set by
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the user) from the baseline occur and either triggers "alerts" or "alarms," depending on the degree of deviation.
All aspects of the data acquisition could be configured for remote observation and data collection.
The Sentinal™ 500 is 30 inches by 36 inches and weighs about 30 pounds. Prices for Sentinal™ systems range
from $12,600 to $24,500. The cost of the system as configured for the verification test is $17,000. Other costs
include $800 annually for replacement chlorine sensor gel caps and electrolyte gel and a one-time purchase of a
calibration kit for $540.
VERIFICATION OF PERFORMANCE
Evaluation Parameter
Stage 1—
Accuracy
Stage 2—
Response to
Injected
Contaminants
Stage 3—
Accuracy During
Extended
Deployment
Stage 3 —
Accuracy After
Extended
Deployment
Stage 3 —
Response to
Injected
Contaminants
Injection
Summary
Inter-unit
Reproducibility
(Unit 2 vs. Unit 1)
Ease of Use
and Data
Acquisition
Units 1 and 2,
range of %D (median)
Nicotine
Arsenic
trioxide
Aldicarb
Reference
Sentinal™ 500
Reference
Sentinal™ 500
Reference
Sentinal™ 500
Units 1 and 2,
range of %D (median)
Unit 1, %D
Unit 2, %D
E. colt
Aldicarb
Reference
Sentinal™ 500
Reference
Sentinal™ 500
Free Chlorine
3.4 to 117.1
(26.2)
-
-
-
-
-
-
-54.8 to 50.0
(-21.5)
-10.9
-18.5
-
-
-
-
Temperature
-18.4 to 2.7
(-3.7)
NC
NC
NC
NC
NC
NC
-7.8 to 2.7
(-2.7)
-0.5
-3.1
NC
NC
NC
NC
Conductivity
-26.8 to -22.4
(-24.6)
NC
NC
+
+
NC
NC
-0.8 to 5.5
(2.1)
2.5
0.3
+
+
NC
NC
pH
-6.1 to 0.5
(-1.9)
NC
NC
+
+
NC
NC
-7.2 to 1.6
(0.3)
0.0
1.2
-
-
-
-
ORP
(a)
-
-
-
-
-
-
(a)
(a)
(a)
-
-
-
-
For a reason that is not clear, aldicarb altered the pH, as measured by the reference method, during the
Stage 3 injections, but not during the Stage 2 injections.
Slope (intercept)
9
r
p-value
0.86(0.10)
0.87
0.92
0.98 (-0.04)
1.00
0.23
1.01 (-4.13)
0.98
0.74
1.05 (-0.3)
0.95
0.17
0.89 (72)
0.98
0.87
All sensors generated results that were similar according to the results of the t-test. However, the slopes
of the ORP and free chlorine sensor data plotted against one another suggest that the results from each
unit were somewhat different from one another.
Based on the performance of the free chlorine sensors, they may have to be adjusted periodically to
maintain the accuracy of the measurements. The memory module in Unit 1 had to be replaced and,
twice, each unit had to be rebooted before data could be downloaded.
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NOTICE: ETV verifications are based on an evaluation of technology performance under specific,
predetermined criteria and the appropriate quality assurance procedures. EPA and Battelle make no expressed or
implied warranties as to the performance of the technology and do not certify that a technology will always
operate as verified. The end user is solely responsible for complying with any and all applicable federal, state,
and local requirements. Mention of commercial product names does not imply endorsement.
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