Pyxis ST-774 User manual

ST-774 Porta-Panel
Ultra-Low Dissolved Oxygen
Analyzer User Manual
May 2021

Catalog
Specifications.............................................................................................................................................- 1 -
1.1. Porta-Panel Description, Specifications + Dimensions..............................................................................- 1 -
Unpackaging ..............................................................................................................................................- 5 -
4-20mA Wiring........................................................................................................................................... - 5 -
Sample and Calibration Gas Connection.....................................................................................................- 6 -
4.1. Sample Water Connection ........................................................................................................................- 6 -
4.2. Calibration Gas Connection.......................................................................................................................- 6 -
UC-50 Operation ........................................................................................................................................- 7 -
5.1. Main Screen ..............................................................................................................................................- 7 -
5.2. Button Functions.......................................................................................................................................- 8 -
5.3. System Information...................................................................................................................................- 8 -
5.4. Calibration .................................................................................................................................................- 9 -
5.4.1. Zero Calibration ................................................................................................................................- 9 -
5.4.2. Slope Calibration ..............................................................................................................................- 9 -
5.5. 4-20 mA Output Setting ..........................................................................................................................- 10 -
5.6. Historical Data and Historical Trend ........................................................................................................- 10 -
5.7. USB Operation.........................................................................................................................................- 11 -

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Specifications
Please reference the ST-774 manual for the full specifications on the ultra-low dissolved oxygen sensor.
1.1. ST-774 Porta-Panel Overview + Specification (P/N 42096)
Product Description
The ST-774 Porta-Panel (P/N-42096) is a prefabricated panel ideally
suited for those desiring to use the ST-774 Ultra-Low DO sensor
with local display and data acquisition in a portable fashion for
oxygen measurement (ie. deaerator performance studies). The
Porta-Panel is pre-mounted on an easy-carry self-standing 316L
stainless-steel panel with the ST-774 sensor, flow-cell and
appropriate water sample/calibration gas flow hardware. The
panel comes equipped with an integrated UC-50 Display/Data
Logging Terminal for connected to the ST-774 via RS-485 Modbus
offering live data display, calibration interface and data logging of
the sensor. The UC-50 offers 1x contact relay output and has RS-
485 Modbus and 1x 4-20mA outputs for passing the sensor value
onto another device. The UC-50 also offers Bluetooth 5.0
capability for those desiring to use the uPyxis mobile or desktop
apps for wireless calibration and diagnostics of the Pyxis sensor
connected.
Product Features
•Ideal for Dissolved Oxygen Studies
•Portable Free-Standing Panel –316L SS
•Fully Integrated Plumbing + Flow Cell
•Measurement of Water Sample or Calibration Gas
•Premounted ST-774 Ultra-Low DO Sensor
•0.0-2,000 μg/L measurement range
•0.1 μg/L Lower Limit of Detection
•Built-in temperature and pressure sensors
•Premounted UC-50 Data Logger + Display Panel
•Direct RS-485 Modbus Connection to UC-50 Display
•Fully Integrated Zero + Slope Calibration Interface
•Integrated 4-20mA + RS-485 Output
•1x Contact Alarm Relay and USB Data Logger

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ST-774 Porta-Panel Diagram (mm)
Figure 1 - ST-774 Porta-Panel (P/N-42096)

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ST-774 Description
The Pyxis ST-774 is an ultra-low range dissolved oxygen (DO) sensor with a lower limit of
detection 0.1 ppb (g/L). It is design is based on the principle of fluorescence quenching
to determine the partial pressure of the dissolved oxygen in water and incorporates Pyxis'
advanced technology in the field of fluorescence detection. The Pyxis ST-774 offers the
robustness associated with optical DO sensor technology while achieving the ultra-low
detection limit compatible to an amperometric DO sensor. The ST-774 measures the
oxygen partial pressure that is at equilibrium with the dissolved oxygen in water governed
by Henry’s law (DO/ppb = K PO2) .The embedded process control board within the ST-774
uses the latest USGS equations to convert the built-in partial pressure and temperature
measured to a DO value in ppb (or g/L).
The ST-774 offers an easily replaceable, front loading DO membrane cap that has been
independently developed by Pyxis Lab, with a typical service life of up to two years. The
flat front-end design of the ST-774 makes this platform less prone to contamination or
fouling and is very easy to clean. The sensor body is composed of 316L stainless steel and
is well suited for aggressive industrial application use. The ST-774 sensor is connected via
RS-485 Modbus output when packaged on the ST-774 Porta-Panel (P/N 42096) portable
dissolved oxygen analyzer.
ST-774 Sensor Specifications
Item
ST-774
P/N
53715
Measuring Range
0.00 - 2,000 μg/L (ppb)
Limit of Detection (LOD)
0.1 μg/L (ppb)
Resolution/Repeatability
0.1 μg/L (ppb)
Accuracy
± 0.3 μg/L (ppb) or ± 1%, whichever is greater
Light Source
Blue Light Exc / Red Light Emm
Response Time (90%)
<30s Liquid Phase / <10s Gas Phase
Operational Temperature
0 °C –50 °C (32 - 122° F)
Operating Voltage
22 –26V DC, Power 0.6W
Signal Output
4-20mA analog output / RS-485 digital output
Dimension (L x D)
300 x 60mm (11.8 x 2.36 inches)
Sensor Weight
2150 g (4.74 lb) cable excluded
Total Panel Weight
7257 g (16 lb)
Suggested Flow Range
50 –500 mL/Minute
Sample Connection Format
Sample Line & Inlet Stainless Steel with Compression Fitting
Material
316L stainless steel
Working Pressure
145psi (10Bar)
Wet Material
316L stainless steel / PVC and polycarbonate
Calibration
High = 0.1% O2in N2Gas / Low = 99.9999% N2Gas
DCC-2 Cartridge Life
2 years
Protection / Regulation
IP-67-IP-68 / CE / RoHS
Figure 2
ST-774 DO Sensor
w/Flow Cell

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UC-50
The Pyxis UC-50 is a preconfigured push-button color micro-
display and data logging terminal that can connect any Pyxis
sensor via RS-485, 4-20mA or BlueTooth 5.0 connectivity.
This microprocessor-based display requires no configuration
when connected to Pyxis inline sensors. When Pyxis sensors
are landed via RS-485 modbus, the UC-50 immediately
recognizes the sensor for live sensor value, color trend charts
as well as sensor diagnostics and calibration interface while
logging data for USB download. The UC-50 provides RS-485
and 1x 4-20 mA outputs as well as one Relay output for
connection to additional controllers, PLC or DCS systems.
The UC-50 is premounted as part of the ST-774 Porta-Panel
Dissolved Oxygen Analyzer.
Specifications
Item
UC-50
P/N
43007
Power
110/220VAC 50/60 Hz, 0.6A
Display
2.8” Color 320 x 240 Resolution
Output
1 x 4-20 mA / RS-485 Modbus-RTU
Input
1 x 4-20 mA / RS-485 Modbus-RTU
Relay Output
One channel relay output – 24VDC/10Watt Maximum
Data Storage
32M Flash
USB
1 x USB host for data downloading
Dimension
6.3 inch L x 3.9 inch W x 2.6 inch D
Weight
4.6 lbs / 2.1 kg
Operation Temperature
32 – 122 oF (-0 – 50 oC)
Storage Temperature
-4 – 158 oF (-20 – 70 oC)
Humidity
5 – 95% No Condensation
Protection
IP-65
BlueTooth
BlueTooth 5.0 - Capable of Reading Pyxis Bluetooth Sensors
Regulation
CE, RoHS
Figure 3
UC-50 Display + Data
Logging Terminal

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*As Pyxis technology is continuously updated, this technical parameter may change at any time without notice;
Unpackaging
The package includes the following items mounted on the panel
•ST-774 Porta-Panel Dissolved Oxygen Analyzer System (P/N 42096)
o316L Portable Panel with ¼” SS Tubing Swagelok and Micro Rotameter
oST-774 DO Sensor premounted with flow cell
oPremounted – Prewired – Preconfigured UC-50 Display/Data Logging Terminal
*NOTE* Gas Calibration Cylinders are sold separately.
Optional Accessories –Not Included On Standard Panel
P/N
DCC-3 Pure Nitrogen Gas 99.9999% Cylinder –58L - Replacement
42059
DCC-4 Oxygen Gas 0.1% in Nitrogen Cylinder –58L - Replacement
42060
Order Information P/N
ST-774 Porta-Panel (Portable Panel Mounted ST-774 w/Flow Cell + UC-50 Data Logger) 42096
Optional Accessories Information P/N
ST-774 Flow Cell Assembly (316L Flow Cell w/SwageLok For Spare Use or Replacement) 53718
DCC-2 (Replacement Dissolved Oxygen Membrane Cap for ST-774) 53716
DCC-3 (Replacement Nitrogen Gas Cylinder for Zero Calibration / 99.9999% Pure / 58L) 42059
DCC-4 (Replacement Oxygen Gas Cylinder for Slope Calibration / 0.1% Oxygen / 58L) 42060
UC-50 (UC-50 Micro Display + Data Logging Terminal) 43007
MA-50CR (50-foot Extension Cable w 8Pin Quick Adapters) 50743

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4-20mA Output Wiring
Figure 4. 4-20mA Output Wiring
Sample and Calibration Gas Connection
4.1. Sample Water Connection
Connect the sample to the water inlet port via a ¼ Swagelok tubing fitting and operate at a flow of 50-
500mL/minute for optimum accuracy. To ensure a sample free of oxygen ingress, only compression style
fittings (ie. Swagelok) and stainless steel sample tubing should be used. Never use plastic tubing for the
sample line or threaded fittings or oxygen ingress may occur. With proper installation using stainless steel
sample lines and thoroughly tightened compression fittings, the ST-774 should stabilize to a low level
within a few hours after startup. Once this has occurred, you may proceed with the oxygen
study/evaluation. If stabilization of the sensor takes a longer period of hours or days, please evaluate your
installation for oxygen ingress into the sample line and other on-site application parameters (ie. deaerator
operating temperature, pressure, feedwater flow rates, loss of oxygen scavenger feed etc.)
Tightly connect the cooled sample water inlet to the bottom sample in line. Connect the outlet flow line
to drain. Note, the outlet flow line can utilized poly tubing if desired. Ensure the pre-inlet valve is in the
open position. Slowly open the inlet valve allowing cooled sample to enter the inline rotameter. Adjust
inlet sample flow to a range of 50-500mL/minute on the rotameter. Allow your ST-774 sensor to stabilize
by observing the display value on the UC-50 display/data logging terminal. Your ST-774 comes
precalibrated from the Pyxis production facility and should not need calibration or maintenance for a
period of up to one year with proper use.
4.2. Calibration Gas Connection
Before connecting the calibration gas to the gas inlet port on the bottom right of the panel via a ¼ inch
Swagelok fitting, open the pre-sensor valve to allow gas flow to drain. Adjust rotameter to the open
position allowing calibration gas to pass by the ST-774 sensor.

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Ultrapure nitrogen gas (Pyxis DCC-3 P/N 42059) is recommend for the zero calibration. The slope calibration
requires 0.02% to 0.1% (or 200 to 1000 ppm) oxygen in nitrogen gas (Pyxis DCC-4 P/N 42060). The user can
connect the gas source to the gas inlet port. Portable standard calibration gas cylinders can be purchased
from Pyxis if desired. *NOTE* Pyxis does not provide the C-10 regulating valve for gas cylinders.
For low pressure applications users may also conduct ZERO calibration of the ST-774 sensor with 5% cobalt
catalyzed sodium sulfite solution.
As an alternative and far faster/easier option, Pyxis Lab offers ST-774 SERVICE SWAP (P/N ST-774 SWAP).
This service provides the user with a new or reconditioned ST-774 sensor calibrated and ready for service
in exchange for the unit in need for calibration/service removed from the system. Contact Pyxis Lab for
details at [email protected]om .
UC-50 Operation
5.1. Main Screen
The UC-50 is configuraed to read and display measurement data from the Pyxis ST-774 dissolved oxygen
probe. The system time, ST-774 DO ppb reading and the sample temperature measured by the ST-774 are
displayed on the main screen. The green dot on the upper right of the screen indicates normal
communication between the UC-50 and the ST-774 probe. In the bottom of the screen, the analog input
(AI) value, the analog output (AO) value, and the relay status are shown.
Figure 5. Main Screen

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5.2. Button Functions
The house button on the left is for returing to the main screen from any screens. The left arrow button
(second from the left) is for returing to the previous screens. The up and down buttons are for selecting
items on the screen by moving the selection focus up, down, left, or right. The up and down buttons are
also used to enter a numerical input. Single click or hold on these two buttons will increase or descrease
the numerical value in the selected input fields. The OK button is for the selection confirmation, like the
enter key on a computer keyboard.
5.3. System Information
Click the left arrow button to launch the system settings screen. Use the down button to select System
Information. The UC-50 serial number, the hardware version and software version are shown in the System
Information screen. Use the down button to hightlight the Time field. Reset date or time if necessary.
Figure 6. Settings
Figure 7. System Information

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5.4. Calibration
5.4.1. Zero Calibration
Select Probe Calibration from the screen shown in figure 6. Select Zero cal. Establish the zero calibration
gas (Pyxis DCC-3 Cylinder = 99.9999% Nitrogen Gas) flow for 15 minutes or until the ppb reading to be
stablized. Press OK on the Zero cal to start the zero calibration. If the zero calibration is complete, a
calibration succeed message will be prompted.
Figure 8. Zero Calibration Figure 9. Zero Calibration waiting
5.4.2. Slope Calibration
Select Probe Calibration from the screen shown in figure 6. Select High cal. Establish an oxygen containing
calibration gas (Pyxis DCC4 = 99.9% Nitrogen / 0.1% Oxygen Gas Cylinder) flow for 15 minutes or until the
ppb reading has stablized. Press OK on the High cal to start the slope calibration. Use the up/down button
and OK button to focus on the oxygen percentage value. Use the up and down button to change this value
to the oxygen percentage concentration in the calibration gas being used. If the slope calibration is
complete, a calibration succeed message will be prompted.
*NOTE* - the value shown in figure 10 is the oxygen percentage in the calibration gas, not the dissolved
oxygen concentration in ppb or ppm. The ST-774 probe will automically convert the oxygen percentage
concentration along with the measured barometric pressure and temperature to the precise dissolved
oxygen concentration in ppb or ppm during the calibration process.

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Figure 10. High (slope) Calibration
Figure 11. Calibration succeed
5.5. 4-20 mA Output Setting
Select Probe Settings from the Settings screen. Change the 4-20 mA scale via interface shown in figure
13. The unit for DO is ppb (g/L).
Figure 12. Probe Setting
Figure 13. Setup 4-20 mA output scale
5.6. Historical Data and Historical Trend
Use the left arrow button to launch the Settings screen. Select Historial Data or Historical Trend to view
screen shown in figures 14 and 15. The historical data is recored every minute. The Trend card is not in real-
time. When the trend card screen is launched, the recorded data is charted with a 6 minute delay. The
historical data can be uploaded to a USB driver in CSV format.

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Figure 14. Recorded Historical Data
Figure 15. Historical Trend Chart
The ppb range of the trend chart can be configured via interface shown in figures 16 and 17.
Figure 16. Trend Chart Setup
Figure 17. Y-Axis Range Setup
5.7. USB Operation
UC-50 has a built-in USB interface to support historical data export and firmware upgrade function. Before
accessing USB functions, please make sure USB thumb drive is properly plugged into UC-50 USB interface.

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5.7.1. Export Historical Data
Select USB Settings from the Settings screen. In the USB settings screen, historical data can be downloaded
to a USB thumb driver by selecting Data Export function. Make sure a USB thumb drive is plugged into UC-
50 before exporting historical data.
Figure 18. Select USB Settings Figure 19. Select Data Export
Further select the historical data date and time range or simply choose All Export to export all historical
data. Once data export 100% completed, you can safely unplug the USB thumb drive.
Figure 20. Specify Date & Time Range Figure 21. Export Historical Data

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5.7.2. Upgrade UC-50 Firmware
Copy the target UC-50 firmware file (.bin) to the root directory of USB thumb drive, plug the thumb drive
to UC-50 USB interface, select USB Settings in Settings page and select Progam Upgrade function in USB
Settings page. UC-50 will automatically start firmware upgrading procedure and reboot itself once the
procedure completed.
5.7.3. Adjust Historical Data Interval
By default, UC-50 will save sensor value every 60 seconds to its internal data storage, if an application
requires 3 months historical data export, UC-50 will generate over 10,000 lines of historical data if the
historical data interval is set to 60 seconds. However, UC-50 allows cutomer to adjust historical data interval
to
1) Reduce exported historical data file size if high resolution data is not required
2) Capture high resolution data if sensor value changes rapidly
Figure 22. Adjusting Set Data Storage – Steps 1 and 2

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Figure 23. Adjusting Set Data Storage (Data Log Frequency in Seconds)
Contact us
Contact us if you have questions about the use or maintenance of the ST-774 sensor:
Pyxis Lab, Inc.
1729 Majestic Dr. Suite 5
Lafayette, CO 80026 USA
1-866-203-8397
www.pyxis-lab.com
[e-mail]