In-situ ChemScan mini UV254 User manual

ChemScan ®
mini UV254 Analyzer
Installation, Operation and
Maintenance Manual
Rev: June 10, 2020
ChemScan, Inc.
2325 Parklawn Drive Suite I
Waukesha WI 53186
PH: 262-717-9500 FAX: [phone]
ChemScan.com
ChemScan
mini
8 9
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ENTER
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CM2CVRF

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Table of Contents
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ChemScan mini UV254 Analyzer
Analyzer Description
Installation and Adjustment
Safety
Installation Diagram
Sample Delivery Suggestions Diagram
Startup Procedure
Verify Fluid Connections
Power-Up
Initial Zero
Configuration Variables
Menu Structure
Menu Table
Analyzer Maintenance
Maintenance Schedule
Maintenance Procedures Interrupting
On-Line Operation
20
Sample Line Screens
Solution Replacement - Zeroing and Cleaning
Manual Instrument Zeroing Procedure
Manual Chemical Cleaning Procedure
Mechanical Cleaning Procedure - Flow-Cell
Flow-Cell Diagram
Retrieving Log Data From the Analyzer
Analyzer Self-Diagnostics and Error Messages
Analyzer Troubleshooting Guide
Appendix "A"
Addendae
Additional Maintenance Diagrams
Cleaning Head Replacement
Cleaning Pump Replacement
Sample Valve Replacement
Simplified Data Download Procedure
Technical Specification
Menu Structure with Comments
Modbus Communication Details
Operator's Screen Guide
Technician's Screen Guide
Maintenance Notes
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3
ChemScan mini UV254 Analyzer
Analyzer Description
The ChemScan UV254 is a photometric analyzer designed to measure light absorbance (or light
transmittance) at 254 nm wavelength in water samples. The sample flows continuously through the
analyzer’s flow-cell except during the auto-zero and auto-cleaning cycles.
Absorbance is a measurement of the change in light intensity after passing through the sample. In
addition to measuring raw absorbance values, absorbance measurements at 254 nm may be correlated
with measurements oforganic matter. Identical samples that are first measured by the ChemScan UV254
Analyzer can be collected and analyzed by a laboratory using the reference method. Those results are
then entered into the UV254 Analyzer to provide a parameter correlation calibration.
Standard measurements of organic content include Total Organic Carbon (TOC-uv), Dissolved Organic
Carbon (DOC-uv), Natural Organic Matter (NOM-uv) and Chemical Oxygen Demand (COD-uv). The
UV254 Analyzer includes the capability to display and communicate raw absorbance values, adjusted
absorbance values or calculated organics values.
Raw absorbance values at 254 nm can also be recalculated and reported as a percent transmittance.
Figure 1
Basic Elements of this Analyzer
1.) Light is emitted by a source LED and directed on a sample.
2.) Chemicals which absorb the emitted light at a specific
wavelength decrease the amount of light transmitted
through the sample.
3.) detector measures the amount of light transmitted through
the sample.
Light SourceSampleDetector
F#254OPDG3

4
Installation and Adjustment
This analyzer is intended for indoor installation in a temperature-controlled
environment. Additional environmental requirements can be found in the technical
specification.
Select an installation location for the analyzer that can accommodate the
pressurized sample required. The installation location should have space for the
zeroing and cleaning containers below the analyzer and allow easy access to the
analyzer for maintenance.
The UV254 Analyzer is supplied with mounting feet as shown in Figure 2. The analyzer
should be mounted securely to an indoor wall or other suitable structure using appropriate
fasteners. Indoor installation is recommended because ambient temperature cycles can
cause optical instability or freeze the zeroing and cleaning solutions.
A power cord is provided for connection to US standard 120 VAC power. Alternatively, the
power cord can be removed and the analyzer connected to 100 to 240V AC 50/60 Hz, single
phase power lines and ground as shown in the Figure 2 (Input Power Terminal Detail View).
The sample line should be connected as shown in Figure 2.
Figure 3 illustrates the required pressurized side stream sample, with a sample pressure of
6 -20 psi (41-138 kPa). A pressure regulator should be installed, if needed, to limit the
pressure. NOTE: Removing the optional 5 psi check-valve from the sample drain will allow
the analyzer to operate with sample pressures as low as 2 psi (14 kPa). A reliable,
pressurized sample that matches the process is critical to the operation of the analyzer.
Analog output wires are connected as shown on the analyzer's internal label. (See menu to
select analog output range.) Analog outputs are in 4-20 mA format.
Safety
Only adequately trained, experienced personnel should operate or maintain this
analyzer.
This analyzer typically uses an acidic, chemical cleaning solution (3% HCl).
Standard chemical handling precautions must be followed. Always wear safety
glasses.
NOTE: HARMFUL UV RADIATION IS PRESENT IN THE FLOW-CELL WHEN THE INSTRUMENT IS
ON! Exposure will cause severe and permanent eye damage!
TURN THE ANALYZER OFF BEFORE REMOVING THE FLOW-CELL OR INSPECTING THE OPTICS.

Figure 2
5
+ 7 8 9
- 4 5 6
ENTER
1 2 3
120 VAC 60 Hz
Line Cord Provided
6 Feet (1.83 Meters)
Communication Out
per Internal Label
(1/2" Conduit Size Holes)
Minimum Analyzer
Mounting Space
(Latch Access)
12.00"
(305 mm)
7.75"
(197 mm)
0.38" Dia.
(9 mm)
(4 Holes)
L N G
TERMINAL BLOCK
CIRCUIT
BREAKER
AC Power Terminal
(Detail View)
For Conduit Connection:
100 to 240 VAC
Wire per Internal Label
66.00"
(1676 mm)
Communication*
MOUNTING HEIGHT
FROM FLOOR LEVEL
FOR TYPICAL
INSTALLATION
LATCHES
SHOWN
IN OPEN
CUSTOMER
CONNECTIONS
Detail View
4-20 mA
34.00"
(864 mm)
- NOT TO SCALE-
See Auxiliary
I/O Terminal
drawing for
details
. 0
ChemScan
mini
TM
POSITION
23.75"
(603 mm)
4-20 mA +
Return
AUX 4-20
+
1 Alarm 1 Common
2 NC
3 NO
4 Alarm 2 Common
5 NC
6 NO
Shield
Load, <1000 ohm
Load, <1000 ohm
.38" DIA. (9 mm)
(4 HOLES)
SAMPLE OUTLET -
TO OPEN DRAIN
5 PSI
Check-Valve
Optional
Sample Line from
Pressurized Source
SAMPLE LINE INLET ASSEMBLY:
3/8" OD Parker TUBE FITTING
1/4 NPT, ON/OFF VALVE, STRAINER
Additional Y-Strainer
suggested - Supplied by
others or available from
ChemScan.
*Serial Communication Option:
Modbus RTU via RS-232 included
See supplemental file for details.
6-20 psi (41-138 kPa)
(2 psi (14 kPa) w/o
Drain Check Valve)
BLUE LABEL
Continuous, bypass flow is recommended to ensure a
fresh sample is available at the analyzer.
Sample Extraction Accessory
(SEA) - Pump plus Sample
DI
WATER
(ZEROING)
5.0 GALLON
19.0 LITER
CONTAINER
10" x 10" x 17"
RED LABEL
CLEANING
SOLUTION
CONTAINER
2.5 Gallon
(9.5 Liter)
11x14x7"
Pressurization Loop available
from ChemScan
ChemScan mini UV254 Analyzer
WEIGHT: 27 lbs (12.25 kg)
DIMENSIONS: 26.0 x 10.0 x 6.5" DEEP, (660 x 254 x 165 mm)
POWER: 100 - 240 VAC, 50 / 60 Hz, 1 AMP
NEMA TYPE: 4X Fiberglass Enclosure
Intended for Installation Indoors 41-104 F (5-40 C)
ChemScan mini UV254 Analyzer
Installation Diagram / System Plumbing
Details with Auto Clean
R
ChemScan,Inc.
PHONE:[phone]
FAX: [phone]
REV: 7/9/19
FILE # CM2INSTN

Figure 3
6 F# CM2SAMPJ
66.00"
(1676 mm)
Mounting height
above floor level
for typical installation
- NOT TO SCALE-
IN-LINE
STRAINER
WITH CLEAR
BOWL
.25" DIA. (6.4mm)
(4 HOLES)
MANIFOLD
BLOCK
36.00"
(914 mm)
Sample Outlet to open
drain via optional, 5 psi
(35 kPa) Gray PVC
Check Valve
1/4 NPT Tube Fitting
Manual ON/OFF Valve
SAMPLE OUTLET -
To Drain
0.25 - 0.5 gpm
(0.1 - 2.0 Lpm)
Sample Inlet from
Pressurized Source
Optional Pressure
Regulator 80 psi
Max. (550 kPa)
to Poly Tube Fitting
6 TO 20 PSI
(41-138 kPa)
Sample Inlet:
3/8" OD x 1/4" ID Poly Tube Fitting
(Tubing not provided)
Zeroing Solution Inlet:
3/8" OD x 1/4" ID Blue Poly Tube Provided
Cleaning Solution Inlet:
3/8" OD x 1/4" ID Red Poly Tube Provided
Analyzer Drain:
3/8" OD x 1/4" ID Clear Vinyl Tube Provided
and Gray PVC 5 psi Check Valve Provided
Y-Strainer
OPTION #1 - Pressurized
Sample Recirculation Line
1/2" to 1" ID Typical
(By Others)
or
Tee
Fitting
Manual
Ball Valve
Return to
process
or drain
OPTION #2 -Sample Pump
1-5 gpm (4-20Lpm) Typical
(By Others or ChemScan)
Sample Extraction Accessory
(SEA) - Pump plus Sample
Pressurization Loop available
from ChemScan
ChemScanUV254 Analyzer
Sample Delivery Suggestions
Analyzer Drain
Zeroing Solution (BLUE)
Sample In: 6-20 psi
Cleaning Solution (RED)

7
Startup Procedure
Verify Fluid Connections
Sample, Cleaning and Zeroing connections must be installed as indicated on the installation
drawing. Connections must be firm and vacuum-tight; air drawn into the system will cause
erroneous readings.
Power-Up
With proper connection made to 110/240 VAC, turn the analyzer ON by pressing the red
power switch located behind the front panel. (Access the switch by loosening the two
captive Phillips screws on the right side of the front panel.) The switch should illuminate.
Secure the front panel.
The LCD display will display the default sign-on message. At this point the instrument is
idle. Press the [MAIN MENU] key.
The display will now present four options. These four options are the only selections
available to the operator. The installer has access to several more.
The instrument must be allowed to stabilize for at least 20 minutes before zeroing.
While waiting, you may familiarize yourself with installation tools.
Initial Zero
In normal operation, the instrument automatically cleans, zeros and displays UV254 nm
absorbance. Prior to reading samples the analyzer must measure and record the initial,
(clean) flow-cell value to use for as a reference for autoclean decisions and diagnostics
Allow 20 minutes for the instrument to warm up.
1. Turn off the manual sample ON/OFF valve (the blue handle valve) to stop
sample flow though the instrument.
2. Clean the flow-cell by selecting option [3] CLEAN. Press [2] for MANUAL
cleaning. Press [+] to turn ON the pump, and pump for about 30 seconds.
Press [-] to turn the pump OFF, and allow the cleaning solution to remain in the
flow-cell for about 2 minutes. Press [MAIN MENU] to exit.
3. Press option [2] ZERO, then [1] MANUAL to pump zeroing solution into the flow-cell.
4. The display shows the current (NEW) value and the previous (OLD) zero’s
signal levels in volts. NOTE: The new value will vary as it is displayed in real-
time. We have not entered this data yet, so disregard these values.
5. Press [+] to pump in zeroing solution. Activate pump for about 1 minute, then press [-]
to stop the pump.
6. Observe the NEW value. As air bubbles, formed by the pumping of the zeroing
solution, dissipate the value will stabilize.
7. If the NEW Value is between 1.5 and 4.9 and varying by less than 0.005, the
cell is clean and usable.
8. Press [ENTER] to store the new reference zero. NOTE: The OLD value is now
updated to match the new.
9. Press [MAIN MENU] to exit this procedure.
10. Open the manual ON/OFF valve, closed in step1, to return sample flow to the analyzer.

8
Configuration Variables
Hidden option, key [9] from the main menu screen, provides the installer a series of configuration
options not visible to the operator. Use the [+] and [-] keys to scroll through the options. The
current value is displayed, and a new value may be entered at the cursor. To store a new value,
press the [ENTER] key. Starting from the beginning, theseare:
MAX CLEAN ATTEMPTS: Number of auto-cleaning cycles in an autozero/clean process before the
operation ceases and flashes a warning message.
MAX ZEROING TIME: Number of seconds the instrument will wait for a stable reading from the
zeroing solution. This is normally set at 120 seconds.
CLEANING PUMP TIME: Number of seconds the cleaning solution is pumped during an autozero/clean
cycle. Normally set to 30 seconds.
ZEROING PUMP TIME: Number of seconds the zeroing solution is pumped during an autozero/clean
cycle. Normally set to 60 seconds.
SAMPLE REFILL TIME: Number of seconds required to fully turn over the cell with fresh process
sample. This time does not include any sample line distance between the instrument and the process.
Normally set to 30 seconds.
CLEAN SOAK TIME: Number of seconds to let the cleaning solution sit in the cell during an
autozero/autoclean cycle. Normally set to 60.
AutoClean FLUSH TIME: Number of seconds to flush the cell with process following the clean
soak. Normally set to 30 seconds.
# of DIGITS after DP: Number of digits displayed after the decimal point - typically set to 1. NOTE: Increasing
the number of digits displayed does not increase the accuracy of the analyzer. Additionally, the resulting,
apparent “variations” in readings may be perceived as erratic operation.
SEND INTERVAL: Minutes and seconds between reports over the serial channel. Default is 1 minute.
ON: ZC4 ZERO5 PUMP6: Controls the ZeroCleanValve, the ZERO valve and the Pump. Pressing key
[4] turns ON the ZeroClean Valve (ZC1); pressing [1] turns OFF the ZeroClean Valve. [5] turns On
the Zero Valve, while [2] turns it OFF. [6] turns ON the Pump, [3] turns it OFF. Not listed on the
screen, [7] turns on alarm relay one; [8] turns on alarm relay two. [CLEAR] turns everything off.
CLEAN IF %T is BELOW: If the transmittance measured during an auto-clean cycle is adequate, we
can omit the cleaning portion, saving on cleaning solution and maintenance. This value is the trigger
point for the auto-clean cycle and is normally set at 95. If organics (slimes) or other contaminants
accumulate on the flow-cell windows, it is recommended to increase this value to 97 to ensure the cell
is cleaned on every auto-zero cycle.
WAIT FOR STABLE HEAD TEMPERATURE: If yes, the analyzer will wait for the source LED to be within
0.05 degrees C of optimum before taking readings. Press [.] (decimal point) to toggle.
SERIAL SETUP MENU: Set baud rate, parity, enable Modbus, set Modbus address
INIT LOG: Press [CLEAR] to clear the internal data log. This may be used if the monitored process had
been shut down for a time or the instrument had been idle for an extended period, making the current log
information irrelevant. Also displayed is the actual number of used log entries. If desired, the log output can
be triggered (to a printer, for example) by pressing the [0] key.
MAX LOG REPORTS: Limits the number of reported (via serial channel) logged events to the most
recent N, where N is between 1 and 15,000. The maximum 15,000 events are always logged, but this
option allows limiting the report size to a lower value. Press [5] to Restore FACTORY DEFAULTS:
Restores settings to factory originals. NOTE: Any user settings will be over-written.
CELL FACTOR: Observe or modify cell factor (effective path length – default is 0.80)
CODE REVISION DATE: The date the software was updated.

9
Menu Structure
The analyzer is equipped with an operator interface consisting of a display and keypad. The
operational parameters can be adjusted through the operator interface. NOTE: Whenever a
“+” is displayed in the lower right of the display, use the [+] key to display more menu choices.
A complete menu structure table can be found at the end of this section.
The keypad is used to enter numerical values and to select menu choices for the analyzer. There
are four main menu paths:
1) ONLINE
2) ZERO
3) CLEAN
4) SETUP
NOTE: Data from the analyzer is frequently used by process control algorithms. Incorrect
analyzer readings due to calibration, testing, or monitoring activities could severely disrupt these
control loops. For this reason, the analyzer 4-20 ma communication outputs remain frozen at the
most recent ONLINE data in all but the force-output modes when the analyzer is taken offline.
ONLINE selection
Pressing [1] from the MAIN MENU screen places the analyzer in the ON-LINE mode. The flowing
sample is continuously analyzed, and the resulting readings are displayed on the front panel.
Simultaneously, the same data is sent to the 4-20mA-output channel and to the serial port.
Pressing the [MAIN MENU] key will return to the [MAIN MENU]; if a security code is set, the
operator will be prompted to enter the code (default is “0”) before the analyzer will exit the
ONLINE mode. Upon leaving the ONLINE mode, the 4-20 outputs will be frozen at the last
measured value and the serial output will stop updating.
ZERO menu
Pressing [2] opens a menu, which offers the option of manual zeroing or triggering the automatic
clean/zero cycle. Pressing the [MAIN MENU] key will return to the MAIN MENU screen.
CLEAN menu
Pressing [3] opens another menu layer where the cleaning and zeroing solutions can be
manually pumped into the instrument. Select either, then press [+] to start the flow and [–] to
stop the flow. Pressing the [MAIN MENU] key will return to the MAIN MENU.
SETUP menu
Provides options for configuration of the analyzer and the various output channels.

UV254 Menu Structure
MAIN MENU
1) ONLINE
1) MANUAL ZERO
2) MANUAL
1) ZERO
2) ZERO
3) CLEAN
4) SETUP
2) AUTO ZERO
1) ZERO TIME
2) ZERO INTERVAL
1) AUTO
2) PARAM
3) CLOCK
4) OUTPUT
5) ALARM
6) SECURITY
7) LOGS
1) SETUP OUTPUTS
2) FORCE OUTPUTS
1) INTERVAL MINsec
2) READING CHANGE
8) RESPONSE(TIME) (# of seconds to average)
2) % T
1) 254 ABS
10

11
Analyzer Maintenance
The analyzer has been designed to minimize the total amount of maintenance time. Typically, the
analyzer requires less than 2 hours of maintenance per month. Always use safe practices when
handling chemicals and avoid exposure to analyzer's UV light.
Maintenance Schedule
Routine maintenance of the UV254 Analyzer is limited to a few periodic procedures as follows:
Daily
- Observe operation looking for abnormal operation
Weekly (or as needed*)
- Fill Zeroing and Cleaning solution containers.
- Inspect and clean Inlet Strainer (required schedule varies with site)
Monthly
- Perform Manual Zero Operation and Log Indicator Numbers (optional)
Quarterly – Every Three Months (or as needed)
- Perform a Calibration Verification and Adjustment
Two Years (or as needed - varies with site / application*)
- Replace Cleaning Solution peristaltic pump
assembly. (see Appendix "A" Additional
Maintenance Items)
*NOTE 1: Replacement interval may require adjustment if cleaning solution container
requires refilling more frequently than once per week.
NOTE 2: The Zeroing Pump requires no periodic maintenance.

12
ENTER SECURITY CODE
INVALID SECURITY CODE
STRAINER
BOWL
STRAINER
SCREEN
RED O-RING
Maintenance Procedures
The following pages describe the routine maintenance procedures. Additional maintenance
details can be found in Appendix "A".
Interrupting On-Line Operation
To interrupt on-line operation the “Main Menu” key is pressed. If a security code is
programmed, the following message will appear:
Enter the security code followed by the ENTER key. The display will to return to the Main Menu. If
an invalid security code is entered or if the entry of the code takes longer than 30 seconds, the
following message will be displayed for 5 seconds:
The instrument will then return to the on-line mode.
Sample Line Screens
The sample line inlet is equipped with a small mesh screen to prevent the entry of large particles
and debris into the system. This screen must be inspected, periodically cleaned or replaced as
required. To clean the strainer, INTERRUPT on-line mode and close the sample line valve.
Unscrew the strainer bowl and remove the screen. If algae is growing on the screen clean it with a
bleach solution. Rinse the screen and bowl thoroughly with tap water. Reinstall the screen into the
strainer bowl. Be sure the o-ring is installed and screw the bowl onto the housing. Open the sample
line valve and check for leaks. After the strainer have been cleaned, return the analyzer to the on-
line mode.

13
Solution Replacement
Zeroing Solution
The analyzer will automatically perform a zeroing operation at a preset interval. The zeroing
solution is typically deionized or distilled water. The zeroing solution must contain no nitrate,
nitrite, iron or organics. A 5 gallon (19.5 liter) zeroing solution container is provided with the
analyzer.
Cleaning Solution
While the analyzer is performing an autozero, it will test the need for cleaning the flow-cell. Over time
“fouling” of the flow-cell windows can occur due to an accumulation of organic bacteria or non-organic
compounds. If the light level falls below a preset level, the cleaning solution is pumped into the flow-
cell using the analyzer’s dedicated “cleaning pump”.
The typical cleaning solution is 1 liter of Muriatic acid (32% HCl) into 9 liters of DI water. This creates
a cleaning solution with 3.2% hydrochloric acid concentration. A 2.5 gallon (10 liter) cleaning solution
container is provided with the analyzer.
Alternative cleaning solutions may be recommended for site-specific conditions. Please call
ChemScan Service if cleaning solution usage is excessive. (refilling required more than once per
week)

14
ENTER SECURITY CODE
1) ONLINE 3) CLEAN
2) SAMPLE 4) SETUP
1) MANUAL
2) AUTO
NEW: [XXXX] OLD [XXXX]
+ OR -, Zeroing Pump On/Off
Manual Instrument Zeroing Procedure
The ChemScan UV254 Analyzer must be zeroed occasionally to correct for drift and flow-cell
fouling. The analyzer will automatically perform an Auto-Zeroing Operation on a preset interval (as
set in the SETUP menu). However, it is important to periodically perform a Manual Zero Operation
to track the indicator numbers. This procedure simply involves rinsing the flow-cell with deionized
water, initiating a zero reading and testing the zero.
Items Required:
1 gallon of deionized water
Interrupt on-line mode:
Press the Main Menu key on the keypad. If a security code is programmed, the following message
will appear:
Enter the current security code followed by the ENTER key and the Main Menu will be displayed:
Instrument Zeroing:
Press 2 for ZERO. The following message will be displayed:
Selection of 2) AUTO will cause the system to immediately initiate an auto zero cycle. The
instrument will automatically flush with DI water, take a reading, compare the values to certain set
points, determine if cleaning is necessary, auto clean, re-zero and re-test. For details concerning
the autozero cycle, refer to the Selection of 1) MANUAL ZERO will require the operator to manage
the zeroing procedure and to interpret the indicator results. This zero once saved, serves as a
point of reference for internal diagnostics.
Press 1 for MANUAL ZERO. The following message will be displayed:
Using the + key to begin flushing the deionized water. Allow the water to flush for 2 minutes and
press the - key to stop flushing; wait 30 seconds for the water to settle. Press ENTER to take the
reading. The instrument will read the deionized water and store the reading as a zero. The new
zero value will be displayed on the right left of the top line. The previous zero displayed to the left.
Using the + and - keys to control the pump, allow deionized water to flush for 8-10 seconds.
The Zero Value should be above 0.500. If not, manually clean the flow-cell. If the reading varies
by more than 0.005, flush again, pause for 10 seconds, and observe again. Continued noisy zero
indicates there may be loose material in the flow-cell, which must be removed by following the
cleaning procedure.

15
Manual Chemical Cleaning Procedure
Over time the windows in the flow-cell may foul, reducing the light level. For most applications the flow-
cell windows must be cleaned occasionally to insure adequate light through the sample. This is typically
handled automatically with the analyzer's auto-clean feature. However, the process can be performed
manually from the keypad by flushing the flow-cell and tubes with the cleaning solution, (dilute HCl) and
rezeroing the instrument.
Interrupt On-Line Mode:
If the instrument is in the ON-LINE mode, press the Main Menu key on the keypad. If a security code is
programmed, the following message will appear:
ENTER SECURITY CODE
Enter the current security code (default is 0) and the instrument will display the MAIN MENU.
Acid Flush:
Note: The Cleaning solution can cause permanent damage to eyes, skin and clothing. Take proper
precautions while handling. If the cleaning solution contacts eyes, skin or clothing, rinse
immediately and heavily with cold water. Note that the typical cleaning solution is ~3%
Hydrochloric Acid (HCl). This information is important for any subsequent treatment that may be
required.
On the instrument keypad, press [3]for CLEAN. The CLEAN MENU will be displayed:
Press [2]for MANUAL.
Press the [+]key to begin pumping the cleaning solution. Allow the pump to run for 30 seconds.
Press the [-]key to stop the pump. Allow the cleaning solution to stay in the flow-cell and tubes for
2 minutes, THEN PRESS Main Menu to exit.
Instrument Zeroing:
Zero the instrument using the MANUAL INSTRUMENT ZEROING PROCEDURE.
Following the zeroing procedure, note the Zero instability. If greater than 0.005, the flow-cell must be
disassembled and cleaned.
Returning to On-Line Mode:
From the MAIN MENU, press [1]for ON-LINE.

16
(l) MANUAL (2) AUTO
Mechanical Cleaning Procedure
Occasionally the automatic cleaning of the flow-cell will not remove enough of the fouling on the
flow-cell windows. If the analyzer readings are erratic or the chemical cleaning solution is being
consumed more rapidly than normal, perform the MANUAL ZEROING PROCEDURE. If the zero
reading is below the specified range, perform a mechanical cleaning procedure.
Items Required:
One #2 Phillips screwdriver.
One wide mouth liquid container 50 - 100 ml.
One box of laboratory lens wipes.
One gallon of deionized water for
zeroing.
Turn off the manual sample valve.
Flush the Flow-Cell:
From the MAIN MENU, press [2] for ZERO.
The ZEROING menu will be displayed:
Press [1] for MANUAL.
Using the + and - keys to control the pump, allow deionized water to flush for 60 seconds. Press
the - key to stop the flow. Press the MAIN MENU key to return to the Main Menu.
Turn off the analyzer using the red power switch behind the front panel. (Phillips screwdriver)
NOTE: HARMFUL UV RADIATION IS PRESENT IN THE FLOW-CELL WHEN
THE INSTRUMENT IS ON! Exposure will cause severe and permanent eye damage!
Removing the Flow-Cell Assembly
1) Hold a small container under the flow-cell sample inlet fitting. Loosen the fitting and
capture the deionized water into the container. Remove the tubing from the fitting.
2) Remove the tubing from the top of the flow-cell.
3) Remove the two thumbscrews securing the flow-cell.
4) Carefully remove the flow-cell assembly by sliding it out the front of the flow-cellmount.
Disassembling and Cleaning the Flow-Cell Assembly
1) Remove the two Phillips head screws securing the mounting plate.
2) Remove the four window plate mounting screws.
3) Clean the windows using laboratory lens wipes dipped in water or cleaning solution.
4) Wipe the windows and flow-cell completely dry and inspect in good lighting to verify they are clean.

17
Figure 5

18
Assembling and Mounting the Flow-Cell Assembly
1) Mount the window plates to the flow-cell body with the larger window against the o-rings and
the cover plate mounting holes facing the same direction. Use care to ensure the o-ring is
installed and fully seated in the o-ring groove prior to reassembling the window plates.
Note: Tighten the four window plate screws in an alternating sequence to evenly compress
the o-ring and avoid breakage of the windows.
2) Wipe the outside of the flow-cell. Use laboratory wipes and isopropyl alcohol to remove anyfingerprints.
3) Mount the cover plate to the window plates.
4) Carefully slide the flow-cell assembly into the flow-cell mount and secure using thethumbscrews.
5) Attach the fluid tubing and tighten the fittings.
Turn on the instrument. Allow 20 minutes for warm-up.
Testing the Flow-Cell Assembly
1) Perform the MANUAL ZEROING PROCEDURE.
Following the zeroing procedure, note the zeroing value. If the value is less than 5000, call
ChemScan Service for further instructions.

19
Retrieving Log Data from the Analyzer *(alternative, simplified procedure follows on page 26)
The analyzer stores approximately 5,000 log entries. Log entries are made up of events (online,
offline, zeroing operations, data readings, etc.), which are time-stamped and stored in non-volatile memory.
Memory retention time without power applied is approximately 100 years. Log entries
may be read using the analyzer’s serial channel.
Communications settings:
9600 baud
8 bit data
2 stop bits
No parity
No handshaking
Procedure for using a computer running a terminal emulator program
(HyperTerminal, PCPlus, etc.):
Connect a straight through (no crossover) DB9 - to – DB9 serial cable between the computer and
the female DB9 connector located in the center of the analyzer’s circuit board (found behind the
control panel).
Open a serial channel, with the above settings.
The Following Detailed Description Applies to “HyperTerminal” Found in Most Windows
Operating Systems:
Click on “Start”, “Programs”, “Accessories”, “Communication” and “HyperTerminal”.
A “Connection Description” dialog box will open. Enter a file name, naming it as you wish, where
you wish, on the computer. (For this example “ChemScan” is the file name.) A “ChemScan –
HyperTerminal” communication box will open with the file name you specified.
When the “Connect To” dialog box appears select “COM 1” (or other suitable COM channel)
under the “Connect Using” heading and select “OK”. There is no need to specify
“Country/Region, Area Code, or Phone Number” information.
A “Com 1 Properties” box will open. Specify “Port Settings” as indicated above, (Bits Per
Second: 9600, Data Bits: 8, Parity: None, Stop Bits: 2, Flow Control: None), then select “OK”.
The cursor prompt should appear inside the “ChemScan – HyperTerminal” box.
This concludes the detailed description relevant to the Windows OS HyperTerminal Software.
The following text is also relevant for other terminal emulator programs.
On the computer keyboard, enter the command to initiate download: GETLOG.
The command should echo to the computer’s display. If you cannot see what you type, there is a
problem with the serial channel or the cable.
After you press the ENTER key, the instrument will send its internal log. When the data transfer is
finished, close the file you opened, and terminate the terminal emulator.
15,000 entries is perhaps too much information. You can limit the amount reported to any value
you wish. For example, to receive the last 100 entries, type GETLOG 100.
Perhaps you wish to put the log data into a spreadsheet. In that case, the non-reading events
such as power up, cleaning, etc., would need to be removed. To eliminate the need to remove the
non-reading events manually you can tell the analyzer to report only readings by typing GETLOG
READINGS 500. This will return the last 500 stored readings without operational information.
Or if you want to see what’s been happening with the operation, type GETLOG EVENTS 100 to
get the last 100 events without any reading data. If you want all the data included, you can type
GETLOG ALL 1000 to get all of the last 1000 log entries.
When the internal log reaches the end of its storage space it begins overwriting the earliest data,
so there is no need to manually erase the log file. Should you wish to do so, however, use the
command RESET LOG.
GETLOG [ ALL] [value]
[READINGS][value]
[EVENTS][value]
RESET LOG

20
Analyzer Self-Diagnostics and Error Messages
MAINTENANCE REQUIRED message:
The UV254 Analyzer performs an autozero at predetermined intervals. As the deionized water is
measured, the light intensity values are monitored. If the light intensity values fall below the preset
value, the system will attempt to chemically clean the flow-cell. This process will be repeated up to
3 times. If the intensity values are still too low, the ALL CYCLE FAILED CLEAN CELL MANUALLY
message will be flashed on the display. The flow-cell will need to be mechanically cleaned to
correct the problem.
Analyzer Error Messages:
MODE: ANALYZER ON-LINE
MESSAGE: [ ]
[ALARM TRIPPED]: Flashing message indicating that the concentration set point has been
reached, triggering the alarm relay.
[ AZC CYCLE FAILED]
[CLEAN CELL MANUALLY]: Auto Zero, Clean Cycle Failed – Displayed following an
unsuccessful AZC Cycle
[AUTOCLEAN FAILED]
[AUTOZERO FAILED]: Flashing error messages, indicating a previous clean/zero failure.
Messages remain until system is taken off-line or a successful AZC Cycle concludes.
MODE: ANALYZER OFF-LINE
[UNABLE TO ZERO]
[PLEASE CLEAN CELL] : Manually triggered autozero cycle failed because the cell
transmittance is too low compared to the stored reading from when the cell was clean.
[ZERO ATTEMPT FAILED]: Manually triggered autozero cycle failed because the light level was
unstable. The system may retry if it has been programmed by the user to do so. If the error
continues, check for good zero solution, air bubbles in the cell and/or tubes, loose particulate in
the cell. Make sure the analyzer is warmed up (20 minutes) and the environment is stable.