Hydro GA-180 User manual

1
GA-180 Gas Detector
Operation and Maintenance Manual
GA-180 Rev. 12/20/17
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
GA-180
Gas Detector
Operation Manual
Table of Contents
I. Installation
A. Monitor Installation ..................................................................................3
B. Sensor Installation.....................................................................................3
C. Battery Backup Installation.......................................................................4
II. Operation
A. Navigating the Controller..........................................................................9
B. Operating Screens and Settings ................................................................9
C. Configuring a Sensor Channel ................................................................10
D. Installing and Configuring Temperature .................................................16
E. Alarms and Outputs ................................................................................16
F. Modbus Communication.........................................................................20
G. Response Checks (Bump Testing) ..........................................................20
H. Data Logger ............................................................................................21
III. Troubleshooting
A. Installation Check ...................................................................................22
B. Symptoms, Likely Causes, and Suggested Responses............................22
C. Explanation of Responses.......................................................................23
Figures
1a. Sensor Installation (heavy gases) ............................................................3
1b. Sensor Installation (light gases) ..............................................................3
2. Remove Calibration Cap .........................................................................4
3. Wiring Diagram (inside of door).............................................................5
4. GA-180 Controller Electronics ...............................................................6
5. Pinout Diagrams for MB108 and MB123...............................................7
6. Pinout Diagrams for MB122, MB141, and MB101................................8
7. Calibration Cap .....................................................................................12
8. Sensor and Calibration Kit ....................................................................12
9. GA-180 Operating Screens ...................................................................13
10. GA-180 Configuration Screens .............................................................14
11. GA-180 Modbus Configuration and Node Enable Screens...................15
12. External Alarm Light and Horn.............................................................19
13. Bump Testing (Chlorine Gas Example) ................................................20
Tables
1. Example Controller Configurations ........................................................6
2. Standard Ranges For Hydro Instruments Gas Sensors..........................11
3. Relay Options for Common Relays (33 & 34)......................................17
4. Relay Options for Sensor Relays (1-32) ...............................................17

3
I. INSTALLATION AND OPERATION
A. Monitor Installation
All monitors are able to accept either 120 VAC or 240 VAC single phase power at 50-60 Hz. When
connecting A/C power it is imperative that the power source is well grounded. Improper grounding
will disrupt proper operation of the unit.
Warning: Ensure source power is disconnected from main power, prior to making the instrument
connection.
Monitors are NEMA 4X rated and should be installed at/near eye level and protected from exposure
to direct sunlight and rain. The monitor should be installed near, but outside of the chemical storage
room it is monitoring (see Figure 1a and 1b). Four 5⁄16" DIA through holes are provided on the
enclosure for mounting the monitor against the wall.
FIGURE 1a FIGURE 1b
B. Sensor Installation
Refer to Figures 1a and 1b for more information.
1. Determine a suitable mounting location. For monitoring gases heavier than air, the sensor should
be placed approximately 12-24 inches from the floor. For gases lighter than air, the sensor
should be placed 12-24 inches from the ceiling. Do not place sensor in any location where it
could become wet. This will damage the sensor.
2. Attach the enclosure to the wall using two 1⁄4"-20 mounting screws (recommended).
3. Remove sensor calibration cap. Store this cap in a known location as it is necessary for
calibration when using a span gas. See Figure 2.
GAS ALARM
CONTROLLER
GAS SENSOR
12" - 24"
For gases heavier than air, sensor should be
mounted low.
GAS ALARM
CONTROLLER
GAS SENSOR
12" - 24"
For gases lighter than air, sensor should be
mounted high.

4
4. If necessary, open the sensor enclosure front cover and reconnect the signal wires. Connect
Red to Red and Black to Black on the terminal strip inside the sensor enclosure. Replace
enclosure front cover and be sure to check that the gasket is evenly sealed around the
enclosure. Also tighten the liquid tight fitting.
5. If necessary, connect the signal wire to the appropriate terminals. Refer to Table 1 and Figure 4
so that you can connect the sensor to the right channel. The black wire will connect to AI1 or
AI2 and the red wire will connect to V+ depending on the required channel number.
6. Connect GA-180 main power, allow sensor to stabilize.
7. Configure the sensor channel. See section II.C.
8. Perform a bump test on all sensors installed on the monitor. Confirm sensor has appropriate
response to the test gas.
FIGURE 2
C. Battery Backup Installation
1. Disconnect A/C power before beginning this procedure.
2. Insert the battery into the enclosure by removing the surface protection tape and placing the
Velcro strips on the enclosure back plate. The battery should be installed so that the leads are
facing up.
3. Identify the positive (+) and negative (-) leads on the battery. Remove the plastic protectors
on the battery leads and connect the positive lead of the battery to the “BAT +” terminal on the
battery backup board (MB101). Connect the negative lead of the battery to the “BAT –” terminal
on the battery backup board (MB101).
4. Ensure that the appropriate 24 VDC from the power supply is connected to the appropriate PS +
and PS- terminal. For units with battery backup, the DC power must go into these terminals for
proper operation and detection of A/C power failure.
5. If necessary, enable battery backup on relevant sensor channels. Use the screen tree (Figure 11)
to access the relevant screens. Cycle the power to save the enabled battery backup setting.
Note: Battery 1 will need to be enabled to back up sensors 1-4, Battery 2 will need to be enabled
to back up sensors 5-8, Battery 3 will need to be enabled to back up sensors 9-12, and Battery 4
will need to be enabled to backup sensors 13-16. For example, if a system is ordered with 8
sensors then two batteries will need to be installed (into their respective enclosures). Battery 1
and Battery 2 will need to be enabled. If a unit was purchased at the factory to have battery
backup this will have already been done.
Remove calibration cap
at sensor start-up.
Calibration
Cap
Bottom
Front
Sensor Enclosure

5
FIGURE 3: Wiring Diagram (inside of door)
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6
FIGURE 4: GA-180 Controller Electronics
Date: July 2016
Dwg. No. GA-180-CONTROLLER
GA-180 CONTROLLER
ELECTRONICS
MB220
Display Board
Battery
(CAUTION:
REMOVE BATTERY
BEFORE SHIPPING)
MB141 (CB-THERM)
Thermocouple Board
MB108 (CB-8RELAY)
Eight Relay Board
AC Power
Terminal Block
Power Supply Board MB122 (CB-2X2MA)
Two In, Two Out Board
MB123 (CB-2RELAY)
Two Relay Board
Photo of a GA-180 unit configured for two sensors with a battery backup.
Some other configuration examples are summarized below.
Up To 2 Sensors, No Battery, No Thermocouple 2 No No 1 1 1
Up To 4 Sensors, No Battery, No Thermocouple 4 No No 1 1 2
Up To 4 Sensors, With Battery, No Thermocouple 4 Yes No 1 1 2 1
Up To 4 Sensors, No Battery, With Thermocouple 4 No Yes 1 1 2 1
Up To 2 Sensors, With Battery, With Thermocouple 2 Yes Yes 1 1 1 1 1
MB101 (CB-BAT)
Battery Board
MB141 (CB-THERM)
Thermocouple Board
MB122 (CB-2X2MA)
Two In, Two Out Board
MB123 (CB-2RELAY)
Two Relay Board
MB108 (CB-8RELAY)
Eight Relay Board
Maximum Sensors
Battery?
Thermocouple?
EXAMPLE
TABLE 1: Example
Controller Configurations

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FIGURE 5: Pinout Diagrams for MB108 and MB123
Date: July 2016
Dwg. No. GA-180-CB1
GA-180 CIRCUIT BOARDS
MB108 & MB123
Normally Closed 8
Common 8
Normally Open 8
Normally Closed 7
Common 7
Normally Open 7
Normally Closed 6
Common 6
Normally Open 6
Normally Closed 5
Common 5
Normally Open 5
Normally Closed 4
Common 4
Normally Open 4
Normally Closed 3
Common 3
Normally Open 3
Normally Closed 2
Common 2
Normally Open 2
Normally Closed 1
Common 1
Normally Open 1
V+
V–
RELAY 8
RELAY 7
RELAY 6
RELAY 5
RELAY 4
RELAY 3
RELAY 2
RELAY 1
MB108 (CB-8RELAY)
EIGHT RELAY BOARD
}
}
}
}
}
}
}
}
Normally Closed 2
Common 2
Normally Open 2
Normally Closed 1
Common 1
Normally Open 1
*Digital Input 1 (Remote Acknowledge)
RELAY 34
RELAY 33
MB123 (CB-2RELAY)
TWO RELAY BOARD
}
}
*Digital Inputs and 4-20mA outputs must also have
appropriate V– (GND) connection. Relays shall be
wired in either a normally open (NO) or normally
closed (NC) arrangement.

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FIGURE 6: Pinout Diagrams for MB122, MB141, and MB101
Date: 2017-12-20-v1
Dwg. No. GA-180-CB2
GA-180 CIRCUIT BOARDS
MB122, MB141, & MB101
SENSOR
4-20mA
OUTPUTS
SENSOR
INPUTS
MB122 (CB-2X2MA)
TWO IN,TWO OUT BOARD
MB141 (CB-THERM)
THERMOCOUPLE BOARD
MB101 (CB-BAT)
BATTERY BOARD
}
}
Normally Closed 1
Common 1
Normally Open 1
Thermocouple Input
To Power Supply
To Battery
HIGH
TEMPERATURE
ALARM
}
*Digital Inputs and 4-20mA outputs must also have
appropriate V– (GND) connection. Relays shall be
wired in either a normally open (NO) or normally
closed (NC) arrangement.
Analog Output
AO1
Analog Output
AO2
Analog Input
AI2
to Horn
Analog Input
AI1
SHIELD
[connect to metal back plate]
SHIELD
[connect to metal back plate]
RED
RED
BLACK
BLACK
RED
RED
BLACK
BLACK
RED
YELLOW

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II. OPERATION
A. Navigating the Controller
The GA-180 is provided with a Nema 4x, 2 line alphanumeric display controller that will display
and output all important features and conditions. Navigating the controller is done by the use of four
push button keys. The push button functions are described below.
key: Cycles to the previous screen.
key: Cycles to the next screen.
key: Increases/changes value, also used to enter screens.
key: Decreases/changes value.
Note: When adjusting parameter values, the number displayed is automatically saved upon leaving
the screen. Thus no “enter” button is needed.
Password: All editable features of the GA-180 are password protected to prevent the unwanted
tampering of the gas detector settings. To access these screens the correct password must be entered
to proceed. The password for the GA-180 is “180”.
B. Operating Screens and Settings
This section gives a description of the operating screens and settings for each channel. To determine
how to access each of these screens, use Figure 9.
1. Sensor Startup: This screen will appear at power on and allows the gas sensors five minutes to
stabilize without the program running to prevent unwanted tripping of alarms and relays. Once,
the five minutes has expired the program will begin. The key can also be pressed to bypass
the countdown and begin the program.
2. Home Screens: These screens display the gas type and current residual level of each active
channel. If one or both channels are activated on a particular screen, then that screen will appear.
The plug and battery symbol represent A/C power and battery power respectively. A solid
symbol represents stable power. A blinking symbol represents loss of, or low power. If the
battery symbol does not appear than the battery backup is not enabled.
3. Temperature: This screen provides a live reading of the room temperature. This screen will
only appear if the thermocouple channel has been enabled.
4. Test Operation: This screen allows the user to test the alarm horn and all enabled relays on the
GA-180. Pressing the key will activate the horn. Pressing the key will trip the relays.
5. Channel Alarm Status: These screens will notify the user of what alarm state a particular
sensor channel is in, if any. Typical statuses would be “Normal”, “Danger”, “Alarm”, or “Error”.
Refer to Sections II.E and III for alarm warning explanations and corrective actions.

10
6. Communication Status: Whenever a channel is activated, or a different circuit board is enabled
(relays, thermocouples, battery backups) the main display CPU will request information from
the relevant circuit boards to display and operate properly. The GA-180 is able to detect if
any boards on this system are not communicating properly and address the user for immediate
correction. Communication statuses will be “Normal” or “Error”. Refer to Sections II.F for
more details.
7. Temperature Alarm: This screen will indicate if the air temperature in the room has exceeded
the high temperature alarm setting or fallen below the low temperature alarm setting. Status will
indicate one of the following: Normal, Alarm High, Alarm Low or Fail. Refer to Section II.D for
more details.
8. Password: This screen allows access to the adjustable/configuration settings of the GA-180.
Using the and keys, the password may be entered. The password for this unit is “180”.
C. Configuring a Sensor Channel
After the correct password has been entered, press to proceed to the configuration mode. Using
the and keys, select the “sensor” option so that it is blinking and press the key to proceed to
the channel configuration settings.
This section gives a description of the configuration screens and settings for each channel. To
determine how to access each of these settings, use Figure 10.
1. Configure Channel: This screen will allow the user to enable/adjust settings to the relevant
channel. The GA-180 can accept up to 16 separate channel inputs. Use the and keys to
select the relevant channel. Once the relevant channel is blinking, press to enter the sensor
channel settings. All screens will be identical regardless of the channel selected. Settings will be
adjusted and saved to each independent channel.
2. Channel Low and High Set: In the rising alarm configuration; in which the low set is less than
the high set, the channel low set is the point above which the “Danger” alarm will activate. The
high set is the point above which the “Alarm” alarm will activate.
In the falling alarm configuration; in which the low set is greater than the high set, the channel
low set is the point below which the “Danger” alarm will activate. The high set is the point
below which the “Alarm” alarm will activate.
Settings are adjusted using the and keys. Once the alarm levels are set press to proceed
to the next screen.
3. Channel Alarm Type: The high alarm for each channel can be set to latching or non-latching.
0 represents non-latching and 1 represents latching. These values can be adjusted using the
and keys. When latching is selected and a high alarm occurs, the alarm will stay in an alarm
state until the user has acknowledged it, even if the condition has since been alleviated.
The high alarm for each channel can also be set to failsafe or non-failsafe. 0 represents non-
failsafe and 1 represents failsafe. When failsafe is selected, the high alarm relay becomes
energized, in effect making the N.O. contact closed. Therefore should power be lost the relay
will trip/activate.
4. Channel Alarm Delay: This screen allows the user to adjust the amount of time the sensor is
in alarm state before the relays and other alarm features activate. This setting is adjustable from
0-60 seconds, with 5 seconds as the recommended default.

11
5. Zero Calibration: After installation, or throughout the sensor’s lifetime, the sensor signal may
periodically drift from 0.0 ppm even though no gas is present. To reset this press the key to
increase the value and press the key to decrease the value on this screen. The keys must be
pressed one at a time to move the value, pressing and holding will have no effect. Wait at least
10 seconds after a new zero has been entered to confirm signal stability. A bump test should be
performed after calibration.
Warning: The zero calibration should only be adjusted if the sensor is offset by 5% or less from
zero. Confirm that no gas is present prior to recalibration and always ensure adequate safety
procedures are enacted to confirm there is no gas present. If the value is offset by more than 5%
do not recalibrate and consult Hydro Instruments for more information.
6. Channel Gas Type and Units: This screen allows the user to enable the sensor channel by
changing the gas type from “OFF” to one of the following options “NH3”, “O2”, “O3”, “SO2”,
“Cl2”, “ClO2”, “CO”, “H2”, and H2S”. The gas type must match that which the sensor is designed
to detect.
7. Channel Full Scale: This screen allows the user to adjust the full scale of the monitor channel,
so that it will match the full scale of the sensor output connected to the channel. Should the two
outputs be misaligned, improper operation will result. Standard full scales for sensors supplied
by Hydro Instruments can be seen in Table 1. If unsure about the full scale output of a sensor,
please contact Hydro Instruments.
TABLE 2: Standard Ranges For Hydro Instruments Gas Sensors
Gas Type Sensor Range
Chlorine (Cl2) 0-10 ppm
Sulfur Dioxide (SO2) 0-30 ppm
Ammonia (NH3) 0-100 ppm
Other Consult Factory
8. Channel Span Calibration: The gas detector system is factory calibrated and does not require
calibration upon installation setup. Span calibration is rarely required, however, it may be
required or desired to perform span calibrations periodically over the life of the sensor. If
calibration is to be carried out, then the appropriate span gas calibration kit must be purchased
(Figures 7 and 8).
8a. The calibration cap must be installed on the sensor and connected as indicated in Figures 7
and 8. Span gas must be allowed to flow at 500 cc/min for at least 1 or 2 minutes until the
displayed reading stabilizes. The reading on this screen should be adjusted to match the
ppm value of the span gas being used. Use the key to increase the reading of the key
to decrease the reading. Press and release the keys one at a time. Do not press and hold the
keys. After adjusting, wait 10 seconds to confirm that the reading is stable before proceeding
to the next step.

12
9. Channel 4 mA Output Calibration: Each sensor channel has its own isolated 4-20 mA output
used for remote monitoring/indication of gas residual. Although each channel is calibrated using
NIST certified equipment, it may be necessary to adjust the output of from the controller to
match the input of the remote system. This screen allows the user to adjust the A/D count that
outputs the 4 mA signal. Pressing the key will increase the current output and pressing the
key will decrease the output.
10. Channel 20 mA output Calibration: Similar to screen #9 (4 mA Output Calibration), this
screen allows the user to make minor adjustments to the A/D value that controls the 20 mA
output. Pressing the key will increase the current output and pressing the key will decrease
the output.
11. Channel Filter Time: This filter time is used to eliminate unwanted signal disturbances from
the sensor. The filter time can be set anywhere from 0-60 seconds using the and keys.
The recommended factory default value is 5 seconds.
12. Calibration Diagnostic Screen: This screen allows the user to view the most recent calibration
points and their corresponding A/D values for diagnostic purposes.
13. Live diagnostic Screen: This screen allows the user to see the current sensor value, A/D value
and current output for a particular sensor.
After passing over the sensor
membrane the span gas will
exit through the other port on
the calibration cap.
FIGURE 7: Calibration Cap FIGURE 8: Sensor and Calibration Kit
Note: The sensor is shipped with the calibration
cap already installed. After calibration the
calibration cap should be removed for normal
use. Do not dispose of the calibration cap as
it will have to be reinstalled and used for any
further sensor calibrations.
Ordering Information
Product
Number Description
GA-CK-CL2-10 Calibration Kit – 10 PPM Chlorine Gas
with Regulator
GA-CRS-CL2-10 Replacement Sensor – 0-10 PPM
Chlorine

13
FIGURE 9: GA-180 Operating Screens
03 Cl2---.- ppm
04 Cl2---.- ppm
Sensor Startup 5:00
Press + To Exit 01 Cl2---.- ppm
02 Cl2---.- ppm
15 Cl2---.- ppm
16 Cl2---.- ppm
Temperature 1 = 76F
Test Operation
+ Horn - Relays
01 Status: Error
02 Status: Error
15 Status: Error
16 Status: Error
03 Status: Error
04 Status: Error
...
...
If “Auto Screen Chg” is ON,
screens shown with -
will cycle every X seconds,
where X is defined by
“Cycle Time”
These screens will only appear
if the relevant sensor,
temperature, and/or
communication settings have
been enabled.
*
*
*
*
*
*
*
Enter Password
180
Comm Status
Normal *Normal
Node Error
...

14
FIGURE 10: GA-180 Configuration Screens
Alarm Delay
5 Secs
Setup: Sensor Temp Display DL Setup: Sensor Temp
Display DL
Configure Channel Ch Setup: Sensor Temp Display DL
Temp: Units = F Alm Delay = 5s
Gas Type= Cl2
Units= ppm
Gas Type= Cl2
Units= ppm
Cl2
ClO2
CO
H2
H2S
OFF
NH3
O2 O3
SO2
ppm
%
Ch1 Ch2
. . .
Ch15 Ch16
Enter Password 180
HOLD
F C
Screens shown with grey border
are hidden screens,
accessed by holding -
at the “Alarm Delay” screen.
On
Off
Temp: Units = F Alm Delay = 5s Temp: Alm Low = 40F Alm High = 120F Temp: Alm Low = 40F Alm High = 120F
Setup: Sensor Temp Display DL Data Log On Data Log Frequency 60 secs Set Time and Date? No Yes Set Time and Date? No Yes Change Time and Date Tue Dec 19 '17 11:13 Time and Date Was Changed!

15
FIGURE 11: GA-180 Modbus Configuration and Node Enable Screens
HOLD
HOLD
Any Low Alarm
Any High Alarm
Sensor/DL/Temp Fail
A/C Power Fail
Battery Low
Temp Low Alarm
Temp High Alarm
Ch1 <Low/High> Alarm
Off
Any Low Alarm
Any High Alarm
Sensor/DL/Temp Fail
A/C Power Fail
Battery Low
Temp Low Alarm
Temp High Alarm
Ch <Low/High> Alarm
Off
Any Low Alarm
Any High Alarm
Sensor/DL/Temp Fail
A/C Power Fail
Battery Low
Temp Low Alarm
Temp High Alarm
Ch16<Low/High> Alarm
Off
Any Low Alarm
Any High Alarm
Sensor/DL/Temp Fail
A/C Power Fail
Battery Low
Temp Low Alarm
Temp High Alarm
2400
4800
9600
19200
38400
57600
115200
250000
Relay 33
Any Low Alarm
Relay 34
Any High Alarm
Relay 1
Ch1 Low Alarm
Relay 2
Ch1 High Alarm
Relay <even #>
Ch High Alarm
**
**
Channel Relay Alarm Relay Alarm
11Ch1Low Alarm 2Ch1HighAlarm
23Ch2Low Alarm 4Ch2HighAlarm
35Ch3Low Alarm 6Ch3HighAlarm
47Ch4Low Alarm 8Ch4HighAlarm
59Ch5Low Alarm 10 Ch5High Alarm
611Ch6Low Alarm 12 Ch6High Alarm
713Ch7Low Alarm 14 Ch7High Alarm
815Ch8Low Alarm 16 Ch8High Alarm
917Ch9Low Alarm 18 Ch9High Alarm
10 19 Ch10Low Alarm 20 Ch10High Alarm
11 21 Ch11Low Alarm 22 Ch11High Alarm
12 23 Ch12Low Alarm 24 Ch12High Alarm
13 25 Ch13Low Alarm 26 Ch13High Alarm
14 27 Ch14Low Alarm 28 Ch14High Alarm
15 29 Ch15Low Alarm 30 Ch15High Alarm
16 31 Ch16Low Alarm 32 Ch16High Alarm
Low and High Alarms for specific
channels can be accessed
according to the table below.
In general, odd numbered relays
can access Low Alarms, and
even numbered relays can
access High Alarms.
**
Relay 1-8 Enable
Yes
Relay 32
Ch16 High Alarm
Relay 31
Ch16 Low Alarm
Relay 33-34 Enable
Yes
Battery 1 Enable
Yes
Relay 9-16 Enable
No
Relay 17-24 Enable
No
Battery 2 Enable
No
Battery 3 Enable
No
Relay 25-32 Enable
No
Battery 4 Enable
No
Modbus Baud=19200
Node= 1 Data=8/N/1
Modbus Baud=19200
Node= 1 Data=8/N/1
Modbus Baud=19200
Node= 1 Data=8/N/1
Enter Password
180
Setup: Sensor Temp
Display DL
Relay <odd #>
Ch Low Alarm
8/N/1
8/N/2
8/E/1
8/O/1
**
**
**

16
D. Installing and Configuring Temperature
1. Determine adequate mounting location for thermocouple and support bracket. Mount the support
bracket to a wall or fixture using appropriate hardware (hardware not supplied with GA-180).
2. If necessary, connect the thermocouple to the thermocouple circuit board using the TI + and TI-
terminals. Connect the Red wire to TI- and the Yellow wire to TI+. Only type K thermocouples
can be used on the GA-180.
3. If necessary, connect the thermocouple board (MB141) to the display through the Modbus connector.
4. If necessary, enable the thermocouple communication. Follow the screen tree (Figure 11) to
navigate to the screen “thermocouple enable”. Change to yes by pressing the key and cycle
the power. Unless you turn the power off and back on, the change will not take effect.
5. Check communication by confirming that the appropriate live temperature screen and
temperature alarm screen have appeared in the correct area (Figure 9).
6. Using the screen tree (Figure 10), navigate to the “Temperature Units” screen. Units can be
adjusted between “F” for Fahrenheit and “C” for Celsius. Select the appropriate unit using the
and keys.
7. Press
and select the high and low temperature alarm points. Values can be selected anywhere
from 0-255 F/C. Hydro Instruments recommends the high temperature alarm setting be at least
20ºF lower than the fusible plug melting point of gas cylinders and/or ton containers. Contact
your chemical supplier to confirm the temperature for the fusible plug melting point. Other
equipment or local restrictions may apply. Each value is adjusted using the and keys.
8. Press
and select the alarm delay time. This setting sets the amount of time the temperature
must remain above the high temp. alarm setting or below the low temp. alarm setting before the
alarm will activate. Values can be set in the range of 0-60 seconds. Values are adjusted using the
and keys. Press to exit the thermocouple configuration.
E. Alarms and Outputs
1. Alarm Status Definitions:
a. Normal – The sensor is operating normally and is below the “Danger” set point.
b. Danger – The sensor reading has reached or exceeded the “Lo Set” level, but is lower than the
“Hi Set” level. Refer to Section II.C and Figure 10 Screen 2 for additional details.
c. Alarm – The sensor reading has reached or exceeded the “Hi Set” level. Refer to Section II.C
and Figure 10 Screen 2 for additional details.
d. Error – The sensor signal has been lost.
Alarms: The GA-180 comes with two common relays and eight sensor relays to every four sen-
sors ordered. The two common relays (relay 33 and relay 34) can be configured to any of the alarm
conditions outlined in Table 2. The sensor relays can be configured to any of the alarm conditions
outlined in Table 2. All relays are dry contacts with a maximum power rating of 10 A.
To change any alarm relay to an alarm condition outlined in Tables 2 & 3. Follow the configuration
sceen layout screen tree. Once at the appropriate relay, change the alarm condition by pressing the
key. Cycle the power to save the new condition.

17
TABLE 3: Relay Options for Common Relays (33 & 34)
Relay Options
Odd Numbered Ch_ low alarm
Any sensor low
Any sensor high
Any sensor signal loss
Loss of A/C Power (must have battery backup)
Loss of / Low Battery Power (must have battery backup)
Even Numbered Ch_ High alarm
Any sensor low
Any sensor high
Any sensor signal loss
Loss of AC Power (must have battery backup)
Loss of / Low Battery Power (must have battery backup)
Relay Options
Relay 33 & 34 Any Sensor High
Any Sensor Low
Any Sensor Signal Loss
Loss of AC Power (must have battery backup)
Loss of / Low Battery Power (must have battery backup
TABLE 4: Relay Options for Sensor Relays (1-32)

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2. Acknowledgement of Alarms: If an alarm condition occurs, the alarm (red) LED will
illuminate and the relay will be activated. To acknowledge an alarm (and deactivate the relay) for
all sensors in the “Alarm” condition press the key. Pressing the key once will inactivate
the horn, pressing the key twice will inactivate the relay. Alarms can also be acknowledged
remotely through the use of a SCADA system / PLC. To do this, connect a contact input to the
DI1 input terminal on the 2 relay board (MB123) and to a relevant ground. Connecting the input
once will inactivate the horn, connecting the input twice will inactivate the relay.
Note: Even after acknowledging the alarm, both LEDs will remain illuminated until the alarm
condition has been removed.
3. Alarm Explanation: Rising and Falling Alarms
a. Rising: If the Danger (low level alarm) is set to a lower value than the Alarm (high
level alarm), then the GA-180 will automatically configure the channel as a rising alarm.
Therefore, if the sensor reading is higher than the Danger or Alarm setting the GA-180 will
activate the appropriate alarm(s). To configure a sensor rising/falling alarm, follow the steps
outlined in Section II-C.
b. Falling: If the Danger (low level alarm) is set to a higher value than the Alarm (high
level alarm), then the GA-180 will automatically configure the channel as a falling alarm.
Therefore if the sensor reading is lower than the Danger or Alarm setting the GA-180 will
activate the appropriate alarm(s). To configure a sensor rising/falling alarm, follow the steps
outlined in Section II-C.
c. Failsafe Alarms: If a sensor channel is set to failsafe, then the corresponding Alarm (high
level alarm) relay will become normally energized. This will cause a reversal of the NC/
NO connections. Therefore, the normally closed connection will be open unless an alarm
condition is present or power is lost. To configure a sensor failsafe alarm, follow the steps
outlined in Section II-C.
4. 4-20 mA Outputs: The GA-180 also includes isolated 4-20 mA outputs for each channel
ordered. This output signal will represent the current gas residual value. See Figure 6 for
4-20mA output wiring locations.

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FIGURE 12
Available Models
Features
An external alarm light with combination audible horn is an electronic device
designed to alert operators and other personnel both visually and audibly to a
specific danger.
Most commonly an external alarm light and horn is used with a gas leak detector
to warn of gas leaks before entering a structure or room.
Single compact unit
Wall mounting
Rotating strobe light with red lens
90 dB Audible horn
Weather resistant
GA-AL-110 (110VAC)
GA-AL-220 (220VAC)
The external alarm light & horn is an optional accessory for use with all Hydro
Instruments gas leak detection equipment. The alarm light connects to a relay
inside the gas detector monitor. This can be a sensor specific relay or a common
relay.
PWR
L
N
NO CO
LN
Relay
Light
L = Line
N = Neutral
NO = Normally Open
CO = Common
NC = Normally Closed
NC
Alarm Light Wiring—Normally Open Relay Circuit

20
FIGURE 13: Bump Testing (Chlorine Gas Example)
F. Modbus Communication:
Modbus RS-485 communication. The GA-180 is equipped for remote display and communication
using the modbus RS-485 standard. To do this, you must define the node, baud rate and parity
of the system. For more information on how to setup modbus refer to the Modbus Installation
and Instruction manual. The Modbus Installation manual can be downloaded from the Hydro
Instruments website (www.hydroinstruments.com). Printed copies are available upon request.
G. Bump Testing
To verify responsiveness, the gas sensors can be bump tested (exposed to a small amount of the
target gas) in order to test the reaction of the sensor. A plastic squeeze bottle is provided with each
gas detector for this purpose (Figure 13). It is suggested that bump testing be done at quarterly
intervals, however required frequency is determined by environment, conditions, number of and
severity of leaks. Proper bump testing will not substantially degrade the sensor or shorten sensor
life. Figure 13 diagrams a bump testing procedure for chlorine gas. Contact Hydro Instruments for
other bump testing procedures should the sensor be for something other than chlorine gas.
Gas
Fumes
Gas
Liquid
For Chlorine sensors
bottle contains 2 parts
NaClO solution (bleach)
and 1 part vinegar
WARNING: Do NOT
allow the liquid solution
to directly contact the
sensor membrane.
Bump Test Bottle
GAS SENSOR
1 (888) 38-HYDRO
www.hydroinstruments.com
GAS SENSOR