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: Q45WQ Series
COMPANY: Analytical Technology, Inc.
ADDRESS: 6 Iron Bridge Drive PHONE: 610-917-0991
Collegeville, Pennsylvania 19426 FAX: 610-917-0992
WEB SITE: www.analyticaltechnology.com
E-MAIL: sales @ analyticaltechnology.com
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 Analytical Technology, Inc., (ATI) Q45WQ Series water quality monitor in continuously measuring free
chlorine, turbidity, 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 Q45WQ 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 characteristic
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of the Q45WQ. All three stages of the test were conducted using a recirculating pipe loop at the U.S. EPA's Test
and Evaluation Facility in Cincinnati, Ohio.
In the first stage of this verification test, the accuracy of the measurements made by the Q45WQ units was
evaluated during eight, 4-hour periods of stable water quality conditions by comparing each Q45WQ 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 Q45WQ 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 Q45WQ 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
Q45 WQ performance to determine whether this length of operation would negatively impact the results from the
Q45 WQ. 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 Q45WQ could be evaluated. Second, to evaluate
the response of the Q45WQ 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 Q45WQ unit was provided by the vendor and does not represent verified
information.
The Q45WQ unit can be customized based on users' needs to include various monitoring devices. The unit
verified during this test included sensors for pH, conductivity, free chlorine, ORP, temperature, and turbidity. The
purpose of the unit is to provide an integrated package of monitors that can be deployed throughout water
distribution systems to collect general water quality data and transmit it to remote locations, giving water
companies access to real-time data from throughout their systems.
In this verification test, pH was measured using a differential pH sensor containing two glass pH electrodes, one
for sensing and another in buffer to serve as a reference electrode. ATI informed Battelle that, during the same
time period as this verification test, several users of its pH sensors reported a drift in the pH measurement similar
to that observed during testing. ATI stated that it determined that a problem with the salt bridge assembly was
causing the downward drift, which impacted not only the accuracy of the pH measurement, but also of the
chlorine measurement. According to ATI, the problem was subsequently corrected. Conductivity was measured
with a four-electrode conductivity sensor that measures the current-carrying capacity of the water. ORP was
measured in millivolts with a differential ORP sensor containing a platinum sensing electrode and separate glass
electrode in buffer to serve as a reference electrode. A membrane-covered amperometric (polarographic) sensor
provided direct chlorine response without the need for chemical reagents. The conductivity sensor provided the
output for both the conductivity and temperature measurements. Turbidity was measured with a 90-degree scatter
nephelometer, using an infrared light source for stability and a sealed flow chamber to reduce bubble formation.
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The Q45WQ unit that was tested was 24 inches wide by 47 inches high. The units normally provide 4-20 mA
outputs for each parameter and can be connected to virtually any type of user-specified data acquisition system.
During this verification test, ATI provided HOBO® data loggers from Onset Computer Corp. (Bourne,
Massachusetts) to collect the data. Data points were collected every 30 seconds. The data logger generated a file
with a .dtf suffix that required conversion to a delimited text file using software from Onset. This file was then
imported into Microsoft Excel prior to further data analysis. These data loggers were downloaded daily using a
serial port on a personal computer and Onset's Boxcar® software. The cost of the unit as configured for the
verification test is $1 1,500. In addition, ATI estimates that the total cost of replacement parts is approximately
$150 per year. This includes replacement membranes, electrolytes, O-rings on the chlorine sensor, and the salt
bridge on the pH and ORP electrodes. Total labor required for preventive maintenance is approximately one hour
per month.
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
Aldi-
carb
Reference
Q45WQ
Reference
Q45WQ
Reference
Q45WQ
Units 1 and 2,
range of %D
(median)
Unit 1, %D
Unit 2, %D
E. coli
Aldi-
carb
Reference
Q45WQ
Reference
Q45WQ
Free
Chlorine
-4 1.5 to
54.3 (-15.7)
-
-
-
-
-
-
-33.7 to
29.7 (-7.3)
1.1
-1.1
-
-
-
-
Turbidity
-47.2 to
-16.9 (-24.9)
(b)
+
(b)
+
(b)
+
-88.0 to
18.2 (-42.3)
-5.9
11.8
+
+
+
+
Tem-
perature
-5.5 to
1.3 (-1.4)
NC
NC
NC
NC
NC
NC
-4.9 to
1.5 (-1.4)
0.0
-0.9
NC
NC
NC
NC
Conduc-
tivity
-19.7 to
-2.6 (-12.7)
NC
NC
+
+
NC
NC
-19.4 to
-5.3 (-13.6)
-14.0
-7.9
+(0
NC
NC
NC
pH
-11.8 to
-0.9 (-5.0)
NC
NC
+
+
NC
NC
-8.3 to
1.5 (-3.5)
0.1
-2.2
-
-
-
(c)
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)
r2
p-value
0.88 (0.10)
0.77
0.59
0.97 (0.028)
0.99
0.76
0.97(0.31)
1.00
0.41
1.09 (-1.1)
0.97
0.00020
0.71 (2.4)
0.85
0.48
0.89 (40)
0.96
0.0093
The ORP and conductivity sensor generated results that were significantly different from one another.
Each unit's results were highly correlated with one another; but, because of the small degree of
variability in each sensor's results, they were significantly different.
Based on the performance of the free chlorine and pH sensors, the pH sensor may have to be adjusted
periodically to maintain the accuracy of both measurements. No other maintenance was necessary
during the test.
(a) ORP was not included in the accuracy evaluation because of the lack of an appropriate reference method.
(b) Relatively large uncertainty in the reference measurements made it difficult to determine a significant change.
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Original signed by Gregory A. Mack 10/17/05 Original signed by Andrew P. Avel 1/17/06
Gregory A. Mack Date Andrew P. Avel Date
Assistant Division Manager Acting Director
Energy, Transportation, and Environment Division National Homeland Security Research Center
Battelle U.S. Environmental Protection Agency
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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