Hydro Instruments 250 Series User manual

1
Series 250
Amperometric Residual Chlorine Analyzer
Instruction Manual
RPH-250 Rev. 1/11/2024
The information contained in this manual was current at the time of printing. The most current versions of all
Hydro Instruments manuals can be found on our website: www.hydroinstruments.com

2
Hydro Instruments
Series 250 Residual Analyzer
Table of Contents
I. Functions and Capabilities .....................................................................3
II. Residual Analyzer Components.............................................................6
III. Installation ................................................................................................8
IV. Disinfectant Sensors .............................................................................12
V. pH Electrodes.........................................................................................15
VI. Calibration and Programming ..............................................................16
VII. Explanation of Operation Screens.......................................................19
VIII. Explanation of Configuration Menus...................................................23
IX. Explanation of PID Control Menus.......................................................29
X. Maintenance & Cleaning .......................................................................32
XI. Troubleshooting.....................................................................................35
XII. Data Logger (Optional)..........................................................................39
Figures:
1. Hypochlorous Acid Dissociation Curves ..............................................4
2. Disinfection System Installation Overview............................................9
3. Sample Source Orientation ..................................................................9
4. Sampling Examples ..........................................................................10
5. Operation Menus................................................................................16
6. Configuration Menus ..........................................................................18
7. PID Control Configuration Menus ......................................................24
8. pH Calibration Menus.........................................................................25
9. Disinfectant Sensor Lifespan..............................................................31
10. RPH-250 Circuit Boards.....................................................................43
11. Monitor Internal Wiring and Connections ...........................................44
Tables:
1. Circuit Board Descriptions and Node Numbers .................................35
2. Hydro Instruments RPH-250 Data Log File........................................37
Drawings:
Residual Chlorine Analyzer Parts Diagrams ................................ 38-42

3
I. FUNCTIONS AND CAPABILITIES
1. Basic Concept
The RPH-250 residual analyzer is a multi-parameter instrument that can be used to measure
a variety of disinfectants including: Free Chlorine, Total Chlorine, Chlorine Dioxide and
Chlorite.
Certain chemical species produce an electrical signal in the disinfectant sensor. The strength
of this signal is a function of their concentration. This signal is read by the RPH-250 monitor
as the sample water continuously flows across the disinfectant sensor at a controlled rate.
Parameters that can influence residual readings such as temperature and pH are
compensated for either automatically or manually in software. A temperature sensor is
used to compensate for changes in temperature. An optional pH electrode can be used for
automatic pH compensation or a static pH value can be manually entered. Alternatively,
sample water pH can be chemically adjusted / controlled via a separate chemical feed
system.
The RPH-250 includes two separate PID control loops, which can be enabled or disabled as
desired. The PID control can be setup as flow pacing (i.e. proportional control), residual (i.e.
set-point control) or compound loop (i.e. PID) control. The program accepts a proportional
4-20mA input for the flow pacing and compound loop control and uses its own readings for
the residual and compound loop control.
2. Chlorine Chemistry
When Chlorine dissolves in water it forms Hypochlorous Acid according to the following
reactions:
Chlorine Gas: Cl2
Cl2+ H2O ↔HOCl + HCl
Sodium Hypochlorite: NaOCl
NaOCl + H2O ↔HOCl + Na++ OH–
Calcium Hypochlorite: Ca(OCl)2
Ca(OCl)2 + 2H2O ↔2HOCl + Ca++ + 2OH–
Hypochlorous Acid is a weak acid that partially dissociates into a Hydrogen Ion and a
Hypochlorite Ion as follows:
HOCl
↔H++ OCl–
The degree of dissociation depends on the pH and the Temperature. Regardless of
Temperature, below a pH of 5 the dissociation of HOCl remains virtually zero and above a
pH of 10 the dissociation of HOCl is virtually 100%. Figure 1 shows this dissociation curve at
several Temperatures. The sum of Hypochlorous Acid and Hypochlorite Ion is referred to as
Free Available Chlorine.
When Ammonia Nitrogen is present in the water, some or all of the Free Available Chlorine
will be converted into Chloramine compounds according to the following reactions:
NH3+ HOCl →H2O + NH2Cl (Monochloramine)
NH3+ 2HOCl →2H2O + NHCl2(Dichloramine)
NH3+ 3HOCl →3H2O + NCl3(Nitrogen Trichloride)
The sum of the Chloramine compounds is referred to as “Combined Chlorine”. The sum of
Free Chlorine and Combined Chlorine is referred to as “Total Chlorine”.

4
3. Measurement
The information provided in this document focuses on Free Chlorine and Total Chlorine
measurement. Other disinfectant sensors are available and may have their own separate
documentation.
Free Chlorine: Free Chlorine is the sum of Hypochlorous Acid and Hypochlorite Ion. These
two forms exist in equilibrium and their concentration depends on the pH and temperature of
the sample water as shown in Figure 1.
Total Chlorine: The sum of Free Chlorine and Combined Chlorine is Total Chlorine.
pH: Sample water pH is an important consideration and each disinfectant sensor has a pH
range in which it can be reliably used.
The analyzer can be outfitted with an optional pH electrode and set up to monitor sample
water pH or to automatically compensate for pH dissociation via software.
Some disinfectant sensors have a natural pH dependence, meaning the signal tracks with
the dissociation curve of the hypochlorous acid. When using a disinfectant sensor that has a
natural pH dependence, the pH of the sample water must be kept constant or a pH electrode
can be used to automatically compensate.
Some disinfectant sensors have a reduced dependence on pH. These sensors are better
suited for applications that have high and/or varying pH levels.
Temperature: A thermistor is used to continuously measure the sample water temperature.
Significant temperature fluctuations of the sample water can affect readings. The analyzer
software uses the temperature reading to automatically compensate for these effects.
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4. Basic Specifications
Power: 100-250 VAC, 50/60 Hz or 24 VDC, 10 W max.
Inputs: (Qty.1) 4-20mA - PV1 for PID control
(Qty.1) 4-20mA - Sample water pressure sensor (Optional)
(Qty.1) Contact input - Sample water flow switch (Optional)
Outputs: (Qty.4) Isolated 4-20 mA
Digital Communication: Modbus RS-485
Relay Contacts: (Qty.4) SPDT, 10 Amps @ 120 VAC or 24 VDC, resistive load, 5 Amps @
240 VAC, resistive load.
IMPORTANT: When the relay controls an inductive load (e.g. a solenoid
motor), external surge protection must be installed. With no surge
protection the kickback voltage can irreparably damage the relay. The relay
must be protected from this kickback voltage using a diode, metal oxide
varistor (MOV) or transient voltage suppressor (TSV).
A diode is the best protection when powering with a DC power supply.
The diode should be connected directly across the load and must have a
reverse breakdown voltage higher than the power supply being used and
must be rated for a higher current than the maximum load current.
A MOV or TSV is the best protection when powering with an AC power
supply. The surge suppressor should be located as close to the inductive
load as possible. If the suppressor cannot be mounted at the load, it must
be mounted to the relay board terminals.

6
II. RESIDUAL ANALYZER COMPONENTS
1. Monitor
The monitor provides the front end and back end interface for the entire residual analyzer. It
features a 2-line x 20-character alphanumeric display. The residual, temperature and other
readings are displayed here on the main operating screen.
Navigating through the menus is done with the four push-buttons on the face of the monitor.
The buttons functions as follows:
Moves up one menu.
Moves down to the next menu.
Select the flashing option or increase the flashing value.
Decrease the flashing value.
NOTE: When adjusting a parameter, the value displayed is immediately used and
automatically saved.
All I/O connections are made inside the monitor. See Figure 10 for more information.
Data Logger (Optional): Data logger data is written to an internal, removable MicroSDHC
card. The MicroSDHC card is included, but is not installed, when this option is supplied.
2. Sensors & Electrodes
Thermistor: The sample water temperature is continuously measured by the analyzers
thermistor (i.e. temperature sensor).
Disinfectant Sensor: The disinfectant sensor continuously measures the residual
concentration of the target species in the sample water.
pH Electrode (Optional): A pH electrode can be installed into the flow cell and used to
monitor sample water pH and compensate for the effects of pH as described in Section I. If
the pH electrode is included its readings will be displayed on the main operating screen.
3. Flow Cell
For most disinfectant sensors a single piece Open Flow Cell that is open to atmospheric
pressure will be supplied. The open flow cell is designed to maintain a constant pressure
across the disinfectant sensor to minimize readings inaccuracies that occur due to
changing sample water pressure. This flow cell also uses the cross flow insert beneath the
disinfectant sensor to push away air bubbles that could collect on the sensors membrane
cap.
For disinfectant sensors that use a self-cleaning mechanism (e.g. the F3 type), the
analyzer will instead include a two piece Pressurized Flow Cell arrangement that includes
a flow meter with flow adjustment valve. The pressurized flow cell allows for higher flow
rates necessary to activate the disinfectant sensors self-cleaning mechanism.
Drawings for the Open Flow Cell and Pressurized Flow Cell can be found in the back of
this document.

7
Sample Water Flow Switch (Optional): The sample water flow switch is a separate
accessory that can be installed into the sample water line at the inlet of the flow cell. It
is used to indicate if sample water flow to the analyzer has stopped. It is a normally
open contact that will close when water flow is applied. Should sample water flow stop,
the switch will open and indicate an alarm on the monitor. An alarm relay can be set to
remotely indicate that sample water flow has stopped.

8
III. INSTALLATION
1. Sample Water Connection and Control
The residual analyzer requires a constant supply of sample water at a controlled rate and
pressure.
Flow: The sample water flow rate should be controlled at a rate appropriate for the flow
cell being used. A flow meter and rate control valve installed upstream of the analyzer
may be necessary to achieve and maintain this flow rate.
Open Flow Cell: 4 to 8 GPH (15 to 30 l/h)
Pressurized Flow Cell: 12 to 24 GPH (45 to 90 l/h)
Pressure: Where the sample point has a high water pressure, a pressure-reducing valve
must be installed to deliver the sample water to the residual analyzer. Alternatively, if the
sample point pressure is too low, then it may be necessary to use a sample pump to deliver
the sample water to the residual analyzer.
Open Flow Cell: 5 PSI (0.3 bar) max.
Pressurized Flow Cell: 15 PSI (1 bar) recommended
Other Considerations: The connection to the sample point should be made in such a way to
avoid receiving air or sediment from the pipe.
Biological growth inside the sample piping will have some disinfectant chemical demand.
This can cause measurement inaccuracies of the sample water (e.g. The chlorine residual
could decrease as the sample water passes through the sample water piping). For this
reason, it may be necessary to periodically disinfect the sample water piping to prevent
biological growth.
It is generally not recommended to use a sample water filter. As the filter collects particles
it can develop a chlorine demand causing the chlorine residual in the sample water to be
reduced, leading to inaccurate readings. However, in certain installations with significant
amounts of solids in the sample water (e.g. iron and manganese) the use of a sample water
filter may be necessary. Where a filter is necessary, it will need to be maintained frequently.
2. Sample Water Disposal
Since no reagent chemical is being injected, the disposal of the water leaving the residual
analyzer is usually not a significant concern.
3. Sample Point Location
There are at least two general concepts to consider when selecting the sample point
location. First, is to select a point that allows reliable determination of the chemical
residual concentration at the most critical point for the installation. Second, is to take into
consideration the chemical injection control timing. A balance between these considerations
must be reached.
Each system is unique, but in general the goal of the chemical injection is to achieve some
result by maintaining a chemical residual concentration in the system (e.g. To maintain a
specific chlorine residual at the exit of the drinking water facility). The location should be
selected so that the injected chemical is already fully mixed so that an accurate sample can
be sent to the residual analyzer.

9
Consideration should be given to the sample point location with regards for use as a control
signal for chemical injection. If there is a long time delay between chemical injection
changes and the change being detected by the measurement cell, then chemical injection
control is adversely affected. The delay time should be kept as short as possible. Less than
5 minutes is recommended.
It is recommended for the analyzers sample point to be 20X the pipe diameter downstream of
chemical injection, but a minimum of 10X the pipe diameter must be observed.
FIGURE 2 - Disinfection System Installation Overview
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10
FIGURE 4 - Sampling Examples
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11
IV. DISINFECTANT SENSORS
1. Commissioning The Disinfectant Sensor
Most disinfectant sensors use a membrane cap and are shipped with the membrane cap
installed. The membrane cap must be removed and filled with electrolyte before use.
For sensors that do not have a membrane cap such as the F3 type, these sensors have an
electrolyte hull that is pre-filled at the factory. For additional information specific to these
sensors see the supplemental F3 & D3 Self-Cleaning Sensor Instructions document.
WARNING: When removing the membrane cap do not touch the electrode finger as this
may irreparably damage the silver chloride coating.
a. Membrane Cap & Electrolyte
Membrane caps are specific to the type of disinfectant sensor. The correct membrane
cap must be used for proper operation. The membrane cap type is stamped into its side.
Electrolyte solutions are specific to the type of disinfectant sensor. The correct electrolyte
must be used for proper operation. The electrolyte type is listed on the bottles label.
NOTE: The electrolyte has an expiration date printed on the bottle. Do not use electrolyte
that has expired.
For membrane cap and electrolyte part numbers and their corresponding disinfectant
sensors, see Dwg. No. RPH-PROBES in this document.
b. Preparation
i. Remove the protective cap offthe membrane cap.
ii. Lift the rubber ring on the membrane cap to expose the vent hole.
iii. Unthread the membrane cap from the disinfectant sensor and place the rubber ring
back into its groove.
iv. Fill the membrane cap with electrolyte to just below the threads.
NOTE: Do not shake the electrolyte before filling the cap. Air bubbles must not be
present in the electrolyte.

12
v. Hold the sensor vertically and thread the membrane cap on. Make sure to thread the
membrane cap on completely. It will be tight against the sensor body.
NOTE: Some electrolyte will be displaced out of the cap and through the vent hole.
Use water to rinse offany electrolyte residue on the sensor.
vi. The sensor is now prepared to be installed into the flow cell.
2. Installation Into Flow Cell
The Sensor must be installed into the Flow Cell at an appropriate height to allow the sample
water to flow across the membrane as well as prevent air bubble formation.
a. Open Flow Cell
See parts drawing RPH-OFC for details.
i. Install the AFC-INS-CRF Cross Flow Insert into the flow cell.
ii. Install the Probenut and O-Ring into the Threaded Holder but do not fully tighten.
iii. Slide the holder assembly onto body of sensor until it is approximately 3in. (7.6cm) up
from the bottom. Tighten the Probenut and Holder so it stays in place on the sensor.
iv. Place the assembly into top of the flow cell. There should be a small gap, about ¹⁄in.
to ³⁄in., between the tip of the sensor and the recess of the Cross Flow Insert.
b. Pressurized Flow Cell
See parts drawing RPH-PFC for details.
i. Slide the Probenut and O-Ring onto body of sensor until it is approximately 4in.
(10.2cm) up from the bottom.
ii. Place the assembly into top of the flow cell and tighten the Probenut to hold the sensor
in place. There should be a small gap, about ¹⁄in. to ³⁄in., between the tip of the
sensor and the top of the Flow Control Plug, part no. PFC-FCP.

13
3. Cable Connections
Grounding: Analyzers are supplied with a sample water ground pin to prevent electrical
interferences that may be present in the sample water. The sample water ground pin is tied
into the incoming AC ground.
Disinfectant Sensors with mA Outputs: The disinfectant sensor is powered from the
MB129 circuit board with an isolated 24VDC output, terminal (VO+). This isolated output
must be used to power the sensor to prevent electrical interferences and may not be
connected to anything else.
The disinfectant sensor outputs a 4-20mA signal that is received by the MB129 circuit board,
terminal (AI1).
4. Sensor Conditioning
The disinfectant sensor requires conditioning prior to generating stable values.
Before calibration is carried out, the analyzer should be operated with disinfectant in the
sample water for a period of time.
For newly installed disinfectant sensors, allow the sensor to run in for the prescribed start-up
time. This time will vary based on the type of sensor being used and can take 1 to 48 hours.
Startup Times
Sensor Type Start-up Time
F1 Approx. 1 hour
F2 Approx. 2 hours
F3 1 to 48 hours
T1 Approx. 2 hours
NOTE: After membrane cap and/or electrolyte replacement, allow the sensor to run in for the
prescribed start-up time. Refer to the ‘RPH Disinfectant Sensor Selection’ Guide for more
sensor start-up times.
5. Decommissioning and Storage
If the analyzer is going to be taken out of operation for a period of time, the disinfectant
sensor(s) will need to be prepared for storage.
a. Remove the membrane Cap
b. Rinse the electrolyte out of the membrane cap with warm water.
c. Rinse the electrode finger with warm water.
NOTE: The electrolyte must be completely removed from the membrane cap and
electrode finger.
d. Allow to dry in air.
e. Loosely screw the membrane cap onto the sensor to protect the electrode finger during
storage. Make sure that the membrane is not in contact with the electrode finger.
NOTE: If the membrane cap has been in use for a period of time, it is recommended that
a new membrane cap be installed when the sensor is placed back into service.

14
V. PH ELECTRODES
1. Commissioning The pH Electrode
The pH electrode is shipped in a cap containing a solution of pH buffer and potassium
chloride. The electrode should only be removed from this solution when it is ready to be
installed and used.
2. Installation Into Flow Cell
a. Mounting
See parts drawing RPH-OFC or RPH-PFC for details.
i. Remove the electrode from its buffer cap and place it into its mounting gland. Secure it
into place by gently threading it into the gland, rotating clockwise until it stops.
b. Wiring
Analyzers ordered with a pH electrode will have its connection pre-wired and only the
electrode needs to be connected to its quick-disconnect cap & cable assembly after
mounting.
i. Connect the quick-disconnect cap & cable assembly to the top of the pH electrode by
gently threading the cap on, rotating clockwise until it stops.
3. Cable Connections
If a pH electrode is not being used a jumper wire must be connected between the AI3 &
AIC terminals on the MB128 circuit board. Failure to install the jumper will cause the A/D
converter to be inaccurate.
NOTE: If a pH electrode is being used for automatic pH compensation, it is normal for the
chlorine residual reading to be effected when the pH probe is removed from the flow cell.
5. Decommissioning and Storage
If the analyzer is going to be taken out of operation for a period of time, the pH electrode
should be store in pH storage solution or in a pH 4 buffer if storage solution is not available.
NOTE: Do not store the pH electrode in deionized (DI) water as this will damage the
electrode.
6. Additional Information
For additional information see the pH & ORP Electrode - General Instructions document.

15
VI. CALIBRATION AND PROGRAMMING
1. Modes of the RPH-250 Residual Analyzer
a. Operation Mode: This is the mode used during normal operation of the RPH-250
Analyzer. It provides a display of the current residual reading, water temperature reading,
pH and any alarm conditions that may exist.
b. Configuration and Calibration Mode (Programming): This mode is used to set up the
display options, operational parameters and other features.
c. PID Control Mode: This mode enables and configures the PID Control program in the
software. The program can perform proportional, set-point (residual) or compound loop
control. One or more of the analog outputs (AO1 to AO4) can be programmed to transmit
a 4-20 mA control signal.
2. Switching Between Modes
a. Operation Mode: This is the standard mode, which appears during initial powering
of the device. To return to this mode from any other screen simply press the button
repeatedly.
b. Configuration and Calibration Mode: This mode is accessed from the Operation Mode
by pressing the button until the password screen is reached. Then enter the password
“250” and then press the button.
c. PID Control Mode: When enabled, this program will display several general status and
control screens in the Operation Mode. To access the screens, which allow this program
to be set-up, press the button (in the Operation Mode) until the password screen is
reached. Then enter the password “220” and press the button.
3. Operating the Keypad
1. Navigation: To move from one screen to another, simply press the and buttons to
reach the desired screen. Navigation between screens is possible in either direction.
2. Adjustment of Displayed Parameters: To adjust a displayed parameter in the
Configuration Mode, simply use the and buttons to increase or decrease. Once a
parameter has been set to the desired position, pressing either or button to leave
the screen will cause the new parameter to be stored. To select a blinking option (such
as “Temperature Cal – Yes/No”), use the arrow buttons as needed to make the desired
selection blink then press the button.

16
FIGURE 5 - Operation Menus
(Operation Menu Flow Chart) (Control Type Dependent Operation Screens)
Residual= 1.20PPM
Temp= 72F pH= 7.00
Alarm Status
Normal
Skip to RES Span Cal
No Yes
Skip to RES Span Cal
No Yes
Enter Password
250
T=72F
pH=7.00 MF=1.00
Input/Output HOLD
Time= 10 min HOLD=Off
Input/Output HOLD
Time=10min HOLD= Off
Resl Filter= 30 secs
pH Filter= 60 secs
Flow Stop = 00 %
Com Errors = 0
pH 7.00 4.00 10.00
mV 0 177 -177
pH TC=291.6 S=-59.0
Offset 7pH=0mV
Probe mA = 3.81
ReslAdc = 572
HOLD
Turb1 = 0.74 NTU
Turb2 = 46 NTU
This screen is only present
if Turb1 and/or Turb2 are
enabled.
AUTO FLO 24.9 %
¹¹¹¹ PO1 0.0KG/H
Set Dosage
1.00
Alarm Status
None
Enter Password
220
AUTO > MANL >
increments of 1
0.01 increments
MANL FLO 24.9 %
¹¹¹¹ PO1 0.0KG/H
Set PO1(Valve)
¹¹¹¹ 0.0KG/H
Alarm Status
None
Enter Password
220
MANL > AUTO >
increments of 1
0.1 increments
Set Dosage
1.00 0.01 increments
“Flow Pacing” AUTO “Flow Pacing” MANL
AUTO RES 1.24 PPM
¹¹¹¹ PO1 0.0KG/H
Set Point Res/ORP
2.00 PPM
Alarm Status
None
Enter Password
220
AUTO > MANL >
increments of 1
0.01 increments
MANL RES 1.24 PPM
¹¹¹¹ PO1 0.0KG/H
Set PO1(Valve)
¹¹¹¹ 0.0KG/H
Alarm Status
None
Enter Password
220
MANL > AUTO >
increments of 1
0.1 increments
Set Point Res/ORP
2.00 PPM 0.01 increments
“Residual/ORP” AUTO “Residual/ORP” MANL
Enter Password
220
AUTO RES 1.24 PPM
¹¹¹¹ PO1 0.0KG/H
AUTO FLO 24.9 %
¹¹¹¹ PO1 0.0KG/H
Set Point Res/ORP
2.00 PPM
Set Dosage
1.00
Alarm Status
None
AUTO > MANL >
AUTO > MANL >
0.01 increments
increments of 1
0.01 increments
MANL RES 1.24 PPM
¹¹¹¹ PO1 0.0KG/H
MANL FLO 24.9 %
¹¹¹¹ PO1 0.0KG/H
Set Point Res/ORP
2.00 PPM
Set PO1(Valve)
¹¹¹¹ 0.0KG/H
Alarm Status
None
Enter Password
220
MANL > AUTO >
MANL > AUTO >
0.01 increments
increments of 1
0.1 increments
Set Dosage
1.00 0.01 increments
“Compound Loop” AUTO “Compound Loop” MANL
Resl Span Cal
8.0PPM ( 796 )
AUTO FLO 24.9 %
¹¹¹¹ PO1 0.0KG/H
This screen is not present
if Control Type
is set to OFF.
Screens shown with grey border
are hidden screens,
accessed by holding -
at the appropriate screen
(typically 2nd to last in the branch)
ReslAdc0 = 599
ReslCal0 = 0
ReslAdc1 = 543
ReslCal1 = 796
Probe mA Cal Values
C0=3.99 C1=12.62
Temp = 72F
Therm = 101511 ohms
On
Off
Modbus Baud= 19200
Node= 1 Data= 8/N/1
Sensor= Probe F1
Probe F1
Probe F2
Probe T1
Probe F3

17
VII. EXPLANATION OF OPERATION SCREENS
Main: This screen will display the residual value as well as the sample water temperature. If
“Manual”, “Auto” or “Monitor” is selected as the “pH Compensation Mode”, the main screen will also
display the pH value.
Alarm Status: Displays any existing alarm conditions.
Turbidity: This screen is present when one or more of the two Turbidity channels is enabled. It
displays Turbidity reading(s).
Control Operational: This menu appears when the PID Control program is enabled. It displays the
PID Control Status (Manual or Auto), the Process Variable(s) and the Process Output. To change
between “Auto” and “Manual” control status, press the button. When Compound Loop Control is
in use, there will be two Control Operation screens.
Set Dosage: This menu appears when the PID Control program is enabled and the Control Mode
is selected as either Proportional or Compound Loop Control. This is an adjustable factor that is
multiplied to the incoming flow signal.
Set Point RES/ORP: This menu appears when the PID Control program is enabled and the
Control Mode is selected as either Residual or Compound Loop Control. This is an adjustable
factor that represents the desired value for residual (or ORP).
Set PO1: This menu appears when the PID Control program is enabled and the control status
is set to “Manual”. On this screen, the control output can be changed by pressing the and
buttons.
Skip to RES Span Cal?: This screen allows a direct jump to the residual span cal screen
(bypassing the password). To pass this screen, press the button twice or press the button
when the word “No” is blinking.
Enter Password: This screen allows access to the configuration or PID Control menus. Enter the
desired password and then press the button.

18
FIGURE 6 - Configuration Menus
HOLD
HOLD
Setup: Resl Temp pH Turbid Aout Alarm DL
Setup: Resl Temp pH Turbid Aout Alarm DL
Setup: Resl Temp pH Turbid Aout Alarm DL
Residual Units PPM
PPM
MG/L
Resl Decimal Posn 00.00
000.0 00.00 0.000 00000
Residual Full Scale 5.00 PPM Residual Low Alarm
0.00 PPM (0=Off)
Residual High Alarm
5.00 PPM
Sample Flow Stop Alm Off
On
Off
Begin Resl Span Cal? Skip Hold/Begin
Resl Span Cal 5.00PPM (5000 )
Temp Sample Cal 38F
pH Low Alarm
6.00
pH High Alarm 9.00 pH Compensation Mode AUTO
AUTO
MANUAL
MONITOR
NONE
Setup: Resl Temp pH Turbid Aout Alarm DL Turbidity 1 = Off Turbidity 2 = Off Turbidity 1 = Off Turbidity 2 = Off Turb 1 Decimal Posn 00.00
000.0 00.00 0.000 00000
Turb 1 Full Scale 10.0 NTU Turb 1 High Alarm 1.00 NTU Turb 2 Decimal Posn 00.00 Turb 2 Full Scale 10.0 NTU Turb 2 High Alarm 1.00 NTU Turb 1 Span Cal? Skip Hold/Begin Turb 1 Span Cal? Skip Hold/Begin Turb 2 Span Cal? Skip Hold/Begin Turb 2 Span Cal? Skip Hold/Begin
Turb 1 Span Cal 10.00 NTU Turb 2 Span Cal 10.00 NTU
Begin Resl Zero Cal? Skip Hold/Begin
Resl Zero Cal 0.00PPM (0 )
Begin Resl Span Cal? Skip Hold/Begin
Resl Span Cal 0.00PPM (5000 )
Turb 1 Zero Cal? Skip Hold/Begin Turb 1 Span Cal? Skip Hold/Begin
Turb 1 Zero Cal 0.00 NTU Turb 1 Span Cal 50.00 NTU
Turb 2 Zero Cal? Skip Hold/Begin Turb 2 Span Cal? Skip Hold/Begin
Turb 2 Zero Cal 0.00 NTU Turb 2 Span Cal 50.00 NTU
000.0 00.00 0.000 00000
Residual Temperature pH Turbidity
Data Logger = On
Setup: Res1 Temp pH Turbid Aout Alarm DL
Setup: Res1 Temp pH Turbid Aout Alarm DL
Setup: Res1 Temp pH Turbid Aout Alarm DL
Select AO1 Resl
Resl Temp
pH
Turb 1 Turb 2
PO1
Select AO2 Resl Select AO3 Resl Select AO4 Resl
Alarm Mode Non-latching
Non-latching
Latching
Alarm Delay Time 10 secs Select Relay 1 Resl High Alarm
Data Log Frequency 60 secs Set Time and Date? No Yes
On
Off
Set Time and Date? No Yes Change Time and Date Thu Feb 22 ,18 14:43 Time and Date Was Changed!
Resl High Alarm
Resl Low Alarm
Turbid 1 High Alarm Turbid 2 High Alarm
pH High/Low Alarm
Any Alarm
Sample Flow Stop Alm
Select Relay 2 Resl High Alarm Select Relay 3 Resl High Alarm Select Relay 4 Resl High Alarm
Analog Outputs Relays Data Logger
AO1 Cal: 4mA= 795 20mA=3986 AO2 Cal: 4mA= 802 20mA=4005 AO3 Cal: 4mA= 794 20mA=3979 AO4 Cal: 4mA= 798 20mA=3988
HOLD
Begin pH 7.0 Cal? 520mV Skip Begin Begin pH 7.0 Cal? 520mV Skip Begin pH 7.0 Buffer Cal Wait…25 Begin pH 10.0 Cal? 520mV Skip Begin Begin pH 10.0 Cal? 520mV Skip Begin pH 10.0 Buffer Cal Wait…25
pH Calibration Type
7.0 and 10.0
Sample
4.0 and 7.0
4.0 and 10.0 7.0 and 10.0
Temperature Mode AUTO
AUTO MANL
Temperature Units
F
F C
Screens shown with grey border
are hidden screens,
accessed by holding -
at the appropriate screen
(typically 2nd to last in the branch)
Screens shown with grey border
are hidden screens,
accessed by holding -
at the appropriate screen
(typically 2nd to last in the branch)

19
VIII. EXPLANATION OF CONFIGURATION MENUS
Main: The Configuration Mode is structured as a “tree branch” program. The main screen is the
trunk from which each branch can be accessed (Figure 6). Seven options appear on this screen,
with one option blinking. To change which option is blinking, press the button. To select the
blinking option, press the button. To access the configuration mode from the operation mode
scroll down and enter “250” as the password when prompted.
Res: This branch accesses the settings for the residual (as related only to the analyzer). To
calibrate the instrument residual, follow the steps below.
• Residual Units: Select PPM or MG/L.
• Residual Decimal Position: Select desired decimal place for residual.
• Residual Full Scale: Enter desired full scale (range). This setting is what a 20 mA residual
output signal represents. An output of 4mA always represents a residual of zero.
• Residual Low Alarm: Enter low residual alarm trip-point (if desired).
• Residual High Alarm: Enter high residual alarm trip-point (if desired).
• Sample Flow Stop Alarm: Enable (On) or Disable (Off) the flow stop alarm. If the optional
sample flow stop switch is installed this option can be enabled. If the optional sample flow
stop switch is not installed this option should be disabled. In the event that the analyzers
sample water flow stops the analyzer will indicate a “Sample Flow Stop” alarm. An alarm
relay can be set to remotely indicate this alarm status.
NOTE: While the “Sample Flow Stop” alarm is active all 4-20mA outputs will be frozen and
will only return to a live reading once the “Flow Stop” alarm is no longer active.
• Begin Residual Zero Cal?: The residual zero calibration has been performed at the factory
prior to shipment and generally should not be required in the field. To access this calibration
menu, follow the steps noted on Figure 6. To pass by this screen, press the button twice
or press the button when the word “Skip” is blinking. To perform a residual zero cal, press
the button to make the word “Begin” blink. Then press the button.
• Residual Zero Cal: Enter residual value of “zero” sample water. When the residual value
on the screen matches the known residual of the “zero” sample water, press the button. A
confirmation screen should appear indicating that the calibration was performed.
• Begin Residual Span Cal?: To pass by this screen, press the button twice or press the
button when the word “Skip” is blinking. To perform a residual span cal, press the button
to make the word “Begin” blink. Then press the button.
• Residual Span Cal: Enter residual value of “span” sample water. When the residual value
on the screen matches the known residual of the “span” sample water, press the button. A
confirmation screen should appear indicating that the calibration was performed.
Temp: This branch accesses the settings for the temperature. To calibrate the temperature, follow
the steps below.
• Temperature Units: Select “F” (Fahrenheit) or “C” (Celsius).
• Temperature Mode: Select “Manual” or “Auto”. Automatic enables the temperature to be
automatically detected via the thermistor.
• Manual Temperature: This screen appears when Temperature Mode “Manual” has been
selected. Enter the sample water temperature using the and buttons.

20
• Temp Sample Cal: This screen appears when Temperature Mode “Auto” has been selected.
The temperature displayed represents what the program interprets the current temperature
reading to be. If necessary, adjust the displayed temperature using the and buttons.
NOTE: Displaying the temperature on the main operating screen is optional and can be
changed by accessing a hidden menu as detailed in the note on Figure 6.
pH: This branch accesses the pH compensation settings and pH electrode calibration.
• pH Compensation Mode: Choose your pH compensation method by pressing the plus key
until the desired pH compensation method is displayed. Your choices of pH compensation
are:
◦None: In this mode, the analyzer will assume the pH of the sample water is either stable
or has been buffered low enough such that dissociation is not a concern. Note that in this
mode, the pH value is not displayed on the main operations mode screen. If this mode is
chosen, no pH electrode is needed.
◦Auto: In this mode, the pH value of the sample water is monitored using a pH electrode
(available through Hydro Instruments) and compensation is performed automatically in
the controller’s software.
◦Manual: In this mode, the pH value of the sample water can be entered and will remain
fixed unless changed.
◦Monitor: In this mode, the sample water pH will be continuously monitored by the pH
electrode but it will have no effect on the residual reading.
If Auto or Monitor modes have been chosen; on the following screen you can select your
calibration type. Select the calibration method based on recommendations below.
• pH Calibration Type: The residual analyzer allows the user to select from four different
calibration methods including: (‘Sample’, ‘4.0 and 7.0’, ‘4.0 and 10.0’, ‘7.0 and 10.0’).
The calibration type to use is completely up to the user. However Hydro Instruments
recommends using the following selection criteria:
◦If pH buffers are not available, then use the “Sample” calibration. This is only a one point
calibration (your sample) and will automatically calculate an ideal calibration slope. This
provides reasonable accuracy if the sample pH is close to seven and pH of the process is
relatively stable.
◦If sample pH is less than seven, use the ‘4.0 and 7.0’ calibration method.
◦If sample pH is greater than seven, use the ‘7.0 and 10.0’ calibration method.
◦If sample stream is subject to wide swings in pH, use the ‘4.0 and 10.0’ calibration
method.