Pyxis CR Series User manual
CR Series LPR Corrosion Sensor
User Manual
June 2, 2020
Rev. 1.51
© 2017 Pyxis Lab, Inc.
Pyxis Lab Proprietary and Condenal
Table of Contents
1 Introducon 2
2 Specicaons 3
3 Unpacking Instrument 4
3.1 StandardAccessories ..................................... 4
3.2 OponalAccessories ..................................... 5
4 Installaon 5
4.1 ElectrodeInstallaon ..................................... 5
4.2 Piping ............................................. 6
4.3 Baery Installaon for CR-200 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.4 WiringforCR-300....................................... 8
4.5 Connecng via Bluetooth for CR-300 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5 Instrument Overview 12
5.1 TestMetalElectrodes..................................... 12
5.2 DefaultSensorSengs .................................... 14
5.3 CalibraonCheckCaps .................................... 14
5.4 CR-200 Funcon Buons and Indicator Lights . . . . . . . . . . . . . . . . . . . . . . . . 15
6 Setup and Calibraon with uPyxis® Mobile App 16
6.1 Download uPyxis® MobileApp................................ 16
6.2 Connecng to uPyxis® MobileApp.............................. 16
6.3 ReadingScreen ........................................ 16
6.4 SengScreen......................................... 16
6.5 DatalogScreenforCR-200 .................................. 17
7 Setup and Calibraon with uPyxis® Desktop App 18
7.1 Install uPyxis® DesktopApp.................................. 18
7.2 Connecng to uPyxis® DesktopApp ............................. 18
7.3 ReadingScreen ........................................ 19
7.4 SengScreen......................................... 20
7.5 DatalogScreenforCR-200 .................................. 20
8 Communicaon using Modbus RTU 21
9 Sensor Maintenance and Precauon 21
10 Regulatory Approval 21
11 Contact Us 22
Warranty Informaon
Condenality
The informaon contained in this manual may be condenal and proprietary and is the property of Pyxis
Lab, Inc. Informaon disclosed herein shall not be used to manufacture, construct, or otherwise reproduce
the goods described. Informaon disclosed herein shall not be disclosed to others or made public in any
manner without the express wrien consent of Pyxis Lab, Inc.
Standard Limited Warranty
Pyxis Lab warrants its products for defects in materials and workmanship. Pyxis Lab will, at its opon, repair
or replace instrument components that prove to be defecve with new or remanufactured components
(i.e., equivalent to new). The warranty set forth is exclusive and no other warranty, whether wrien or oral,
is expressed or implied.
Warranty Term
The Pyxis warranty term is thirteen (13) months ex-works. In no event shall the standard limited warranty
coverage extend beyond thirteen (13) months from original shipment date.
Warranty Service
Damaged or dysfunconal instruments may be returned to Pyxis for repair or r eplacement. In some in-
stances, replacement instruments may be available for short duraon loan or lease.
Pyxis warrants that any labor services provided shall conform to the reasonable standards of technical com-
petency and performance eecve at the me of delivery. All service intervenons are to be reviewed and
authorized as correct and complete at the compleon of the service by a customer representave, or des-
ignate. Pyxis warrants these services for 30 days aer the authorizaon and will correct any qualifying
deciency in labor provided that the labor service deciency is exactly related to the originang event. No
other remedy, other than the provision of labor services, may be applicable.
Repair components (parts and materials), but not consumables, provided during a repair, or purchased
individually, are warranted for 90 days ex-works for materials and workmanship. In no event will the in-
corporaon of a warranted repair component into an instrument extend the whole instrument’s warranty
beyond its original term.
Warranty Shipping
A Repair Authorizaon (RA) Number must be obtained from Pyxis Technical Support before any product can
be returned to the factory. Pyxis will pay freight charges to ship replacement or repaired products to the
customer. The customer shall pay freight charges for returning products to Pyxis. Any product returned to
the factory without an RA number will be returned to the customer.
Chemtrol Technical Support
Contact Chemtrol Technical Support at 1 300 585 820
CR Series User Manual 1
1 Introducon
The Pyxis CR Series corrosion sensor measures the metal corrosion rate in an aqueous environment based
on the principle of linear polarizaon resistance (LPR). A small polarizaon DC voltage is applied to two test
metal electrodes and the resulng current is measured by the sensor. The polarizaon resistance value is
calculated from the measured current and the applied polarizaon voltage. The metal corrosion rate in the
unit of thousandths of inch per year (or mils per year, MPY) is then determined as:
M P Y =B/Rp(1)
where Rpis the polarizaon resistance (LPR) and Bthe proporonal constant.
To calculate Rporiginated from the electrochemical reacon at the metal water interface, the CR Series
sensor subtracts the soluon resistance Rsdue to the test soluon conducvity from the total resistance
measured between the two test electrodes. The CR Series sensor accurately measures the test soluon
conducvity using the two test electrodes and the bipolar pulse technique, which has been successfully
used in other Pyxis conducvity sensors and handheld meters.
A challenge of using the LPR method to measure corrosion rate below 0.01 MPY is to measure electric
current in the range of pico- and nano-amperes. The CR Series sensor adapts a range of techniques that
are pracced in our uorometers where low pico-ampere current is measured. These techniques include
electromagnec interference shielding, special analog circuit designs, and digital signal processing. The
proporonal constant Bhas a theorecal value for a given metal type and size. The CR Series assumes B
equal to 1.24 MPY∙Ω for a 5 cm2mild steel electrode, which is a typical value that has been used in many
LPR corrosion researches. This proporonal constant may be also referred as to the alloy factor of the test
metal and normalized to 1.0 for the steel electrode for convenience. It can be adjusted by the user to ac-
count for variaons in a real applicaon environment.
To determine the corrosion situaon of real process equipment is not a simple maer. The corrosion rates
for various metal surfaces contacng aqueous uids in a process depends on many parameters, including
the corrosivity pertaining to the chemistry of the aqueous uid, physical parameters such as temperature
and the velocity of the uid, and the metallurgical composion of the process equipment itself. Because
of this, the corrosion rate measured by the CR Series sensor should not be used alone to predict or assess
the real corrosion rate of the process equipment. Nevertheless, the science of using the LPR technique to
quanfy the corrosion rate has been well established. The corrosion rate measured by the CR Series sensor
can be used to understand the corrosivity trend of the aqueous uid over a period and its correlaon to
changes in the process parameters.
Measuring corrosion rate using a weight loss corrosion coupon is sll widely pracced in many industry
applicaons. LPR is an instantaneous method compared with the corrosion coupon method. It can indi-
cate a change in corrosion rate in a me scale of a few minutes. In theory, a me-averaged corrosion rate
measured by the Pyxis LPR sensor should agree with that from the weight loss coupon method if both are
pracced according to the common pracces known in the industry. For monitoring mild steel corrosion
rate in an industrial cooling water system, one could also treat the LPR metal electrode itself as the weight
loss corrosion coupon and compare the corrosion rate calculated from the weight loss of the electrode to
the averaged LPR corrosion rate in order to calibrate the LPR corrosion rate by adjusng the alloy factor.
The electrochemical noise measurement has long been used to quanfy the localized corrosion or ping
corrosion rate. The CR Series sensor measures the short circuit electric current owing through the elec-
trodes between the two LPR measurements. The CR Series sensor rst applies a signal process algorithm
CR Series User Manual 2
to remove high frequency noise in the acquired electrochemical current data for a period of 3 minutes
and then calculates the standard deviaon of the processed data set. The standard deviaon calculated is
scaled to generate a localized corrosion index. In such a scaling, the index value for a 304-stainless steel
electrode immersed in a 10% ferric chloride soluon at 72 °F is arbitrarily dened as 100. The real me
electrochemical current noise data are graphically displayed in the Pyxis display panel, an oponal item
that can be purchased separately. With the graphic trend, the noise paern and magnitude can be easily
analyzed visually.
2 Specicaons
Specicaons*CR-200 CR-300
Part Number (P/N) 51006 51007
General Corrosion
Range†0.001–10 MPY
Resoluon 0.001 MPY
Conducvity
Compensaon 10–10,000 µS/cm
Alloy Factor†0–3
Measurement Interval 3–1440 min
Data Storage 6 months‡N/A
Output Bluetooth 4.1, 32 (10 m), Line of
Sight
Two 4–20mA analog outputs,
RS-485 digital output with Modbus
protocol
Installaon Flow cell with 1” NPT
Cable Length N/A 5 (1.5 m)§
Power Supply 3.6 V ER26500 baery 24 VDC, 2 W
Dimensions inch (mm)
Length: 10.3 (260.5), Lower
Diameter: 0.9 (23.0), Upper
Diameter: 1.7 (43.0)
Length: 11.1 (281.5), Lower
Diameter: 0.9 (23.0), Upper
Diameter: 1.7 (43.0)
Weight 1.44 lbs (655 g)|| 1.51 lbs (687 g)
Enclosure Material 304 stainless steel
Sample Temperature -4–122 °F (-20–50 °C)
Operaonal
Temperature 14–122 °F (-10–50 °C)
Storage Temperature -4–158 °F (-20–70 °C)
Pressure Up to 100 psi (0.7 MPa)
Enclosure Rang IP65
Regulaon CE
*With Pyxis’s connuous improvement policy, these specicaons are subject to change without noce.
†Values vary based on metallurgy. See the Test Metal Electrodes secon for a list of these values for commonly
used metals.
‡With measurement interval set to 30 minutes
§Extension cables available
|| Baery included
CR Series User Manual 3
3 Unpacking Instrument
Remove the instrument and nd the standard accessories from the shipping container as listed b elow. In-
spect each item for any damage that may have occurred during shipping. Verify that all accessory items are
included. If any item is missing or damaged, please contact Chemtrol Customer Service
3.1 Standard Accessories
3.1.1 CR-200 Package (P/N: 51006)
• One CR-200 sensor
• One 3.6V ER26500 battery
• One pair of mild steel electrodes (P/N: 51002)
• One pair of copper electrodes (P/N: 51003)
• One 2.0 MPY steel calibration check cap (P/N: 51010)
• One 0.1 MPY copper calibration check cap (P/N: 51011)
• One Bluetooth adapter for PC (P/N: MA-NEB)
• Operation Manual is also available for download at Chemtrol website
3.1.2 CR-300 Package (P/N: 51007)
• One CR-300 sensor
• One 5- extension cable terminated with connectors
• One 2- cable with one end terminated with a connector
• One pair of mild steel electrodes (P/N: 51002)
• One pair of copper electrodes (P/N: 51003)
• One 2.0 MPY steel calibration check cap (P/N: 51010)
• One 0.1 MPY copper calibration check cap (P/N: 51011)
• One Bluetooth Adapter for CR-300 (P/N: MA-CR)
• One Bluetooth adapter for PC (P/N: MA-NEB)
•Operation Manual is also available for download at Chemtrol website
CR Series User Manual 4
3.2 Optional Accessories
The following optional accessories can be purchased via your Regional Sales distributer.
Figure 1.
*NOTE* Pyxis Lab does not manufacture LPR electrodes. Some electrodes are provided by
Pyxis Lab from Metal Samples as a convenience. UNS Codes for each electrode format are
provided in the Test Metal Electrodes section.
4 Installaon
4.1 Electrode Installaon
The CR Series sensor is shipped without the electrodes installed. A pair of copper and mild steel electrodes
are included in the package. Follow the steps below to install either pair of electrodes:
1. Remove the O-rings in the electrode package.
2. Place an O-ring to each threaded rod on the sensor.
3. Fasten the electrodes to the threaded rods to slightly compress the O-ring on the boom of the
threaded rod.
4. Clean the electrodes with isopropanol to remove any oil or other foreign materials on the electrode
surfaces.
CR Series User Manual 5
4.2 Piping
Figure 2. CR Series installaon into the sample ow line
The CR Series should be inserted into a pipe via a 1-inch threaded tee. The corrosion rate measured by the
CR Series sensor may be aected by the posion of the two-test metal electrodes in relaon to the water
ow. The electrodes should be fully immersed in the water sample and away from any turbulence. The
sensor body has three O-ring grooves to allow the 1-inch male NPT thread to be locked at three posions
on the sensor with a compression nut. Thus, the depth of the sensor inseron in the pipe can be adjusted.
For the best performance, the two-test metal electrodes should be installed to be parallel to the ow and
maintain a symmetry between the electrodes with respect to the ow environment as much as possible as
seen in Figure 2. Figures 3 and 4 show the dimensions of the CR-200 and CR-300, respecvely.
Figure 3. CR-200 dimensions in inch (mm)
CR Series User Manual 6
Figure 4. CR-300 dimensions in inch (mm)
4.3 Baery Installaon for CR-200
The 3.6 V ER26500 baery should be used and is available from Pyxis (P/N: 50730).
Figure 5. ER26500 baery (P/N: 50730)
WARNING
Do NOT use type C alkaline baeries for CR-200. Although type C alkaline baeries are in the same
dimensions as ER26500 lithium, they are 1.5 V nominal voltage baeries. CR-200 will NOT work with
type C alkaline baeries.
See detailed instruconal video (hps://www.youtube.com/watch?v=8LHabJX8Sx0) or follow the steps be-
low to install the ER26500 baery into the CR-200:
1. Loosen the two screws that fasten the baery cover plate (Figure 6).
2. Separate the cover plate from the CR-200 body (Figure 7).
*NOTE*Do NOT twist the cover plate
3. Place an ER26500 baery to the CR-200. Make sure that the posive terminal of the baery is facing
outward (Figure 8).
4. Place the baery cover plate back and fasten the two screws. Please make sure that the at cable
has been fully pushed inside the CR-200 baery compartment and avoid pinching the cable between
the CR-200 body and the cover plate (Figure 9).
CR Series User Manual 7
Figure 6. Figure 7.
Figure 8. Figure 9.
4.4 Wiring for CR-300
If the power ground terminal and the negave 4–20mA terminal in the controller are internally connected
(non-isolated 4–20mA input), it is unnecessary to connect the 4–20mA negave wire (Gray) to the 4–20mA
negave terminal in the controller. If a separate DC power supply other than that from the controller is
used, make sure that the output from the power supply is rated for 22–26 VDC @ 65mA.
*NOTE*The negave 24V power terminal (power ground) and the negave 4–20mA ter-
minal on the CR-300 sensor are internally connected.
Follow the wiring table below to connect the CR-300 sensor to a controller:
Wire Color Designaon
Red 24V +
Brown 24V Power ground
White General corrosion rate, 4–20mA +
Pink Localized corrosion rate, 4–20mA +
Gray*4–20mA -
Blue RS-485 A
Yellow RS-485 B
Green Shield, earth ground
*Internally connected to the power ground
CR Series User Manual 8
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