CTI GG-NH3 User manual
Installation and Operation Manual
GG-NH3
AMMONIA GAS SENSOR
2GG-NH3
Warning
Use this product only in the manner described in this manual.
If the equipment is used in a manner not specied by Calibration
Technologies, the protection provided by the equipment may be impaired.
This equipment should be installed by qualied personnel.
GG-NH3 3
Table of Contents
General Description .....................4
Installation .............................4
Locating the Sensor ...................4
Installation Guidelines .................5
Wiring...............................6
Operation ..............................7
Start-Up .............................7
Calibration ...........................7
Maintenance ...........................9
Specications ..........................10
Warranty ..............................11
For technical support, contact:
CTI
920 N Tradewinds Pkwy
Columbia, MO 65201
866-394-5861
www.ctiengineering.com
4GG-NH3
General Description Installation
The GG-NH3 sensor is a +24 VDC, three-wire, 4/20 mA
sensor for ammonia which utilizes proven electro-
chemcial sensor technology for fast and accurate leak
detection. The standard detection range of the GG-
NH3 sensor provides real-time continuous monitoring
of ammonia concentrations accurately down to 5
ppm without false alarms. CTI typically recommends
a 0/100 ppm range for all personnel and product
protection areas. Higher ranges (0/250, 0/500, 0/1000)
are optional for higher alarm setpoint areas such as
Engine Rooms.
The GG-NH3 sensor provides an industrial standard
linear 4/20 mA output signal compatible with most gas
detection systems and PLCs.
This sensor is equipped with SafeCell technology
which checks the electrical viability of the
electrochemical cell every 40 seconds. If it is
determined that the cell is not electrically viable or
missing, the fault (red) LED will blink once per second.
After 6 hours of continued and consecutive test
failures, the 4-20 mA signal output will drop to 0.5 mA
and the fault LED stays on solid. This signal should be
interpreted as a sensor fault at the control panel and
prompt notication to plant personnel to investigate
the sensor. Typically, the cell will need to be replaced
once the SafeCell fault has occurred. Once the cell is
replaced or found to be electrically viable, the fault
condition will clear within 10 seconds.
Locating the sensor
One of the most important considerations when
installing the GG-NH3 sensor is that it must be easily
accessible for calibration and maintenance.
For optimum personnel protection (representative
concentration reading that an employee would be
exposed to), mount the sensor at a height in the
breathing zone of the employees. It would typically
be about ve feet o the ground, which also allows
easy access. As a general rule of thumb, try to mount
sensors within 30 feet of potential leak sources.
Caution: Remove protective label
The GG-NH3 sensor is shipped with a yellow
label installed over the gas diusion port of the
electrochemical cell to preserve cell life. The cell will
not detect ammonia vapors with this label installed.
Remove label and discard during installation.
5
GG-NH3
Installation Guidelines:
• Remove and discard protective cell label.
• Always mount sensor vertically.
• Locate sensor to be easily accessible for calibration
and maintenance.
• Mount sensor close to potential leak source.
• Mount sensor in "breathing zone" (4'-5' above oor)
for optimum personnel protection.
• Take air movement and ventilation patterns into
account.
• Keep sensor and wire runs away from mercury
vapor lights, variable speed drives, and radio
repeaters to prevent electrical interference.
• Protect sensor from physical damage (forklifts, etc).
• Mounting screws should be screwed into studs
when mounting on a wall with studs.
• Never mount the sensor in CA (controlled
atmosphere) rooms. Normal atmospheric levels of
oxygen are required for operation.
• More than one sensor should be installed in each
room for highly critical locations.
• Mount sensor enclosure through the mounting
holes as shown in Figure 1.
2.0"
6.5"
6.8"7.75"
Figure 1: Mounting Dimensions
6GG-NH3
Wiring
Electrical wiring must comply with all applicable codes.
Electrical Power: 24 VDC regulated, 350 mA.
Output: Linear 4/20 mA output. Monitoring
equipment may have a maximum input impedance of
700 ohms.
Cable Recommendation: 20/3 shielded cable
(General Cable C2525A or equivalent). Length of cable
to sensor should be no greater than 1,500 feet.
Monitoring: Monitoring equipment must be
congured to indicate a fault if the signal is below 1
mA. All signals over 20 mA must be considered high
gas concentrations. Alarm setpoints should not be
lower than 10% of full-scale range.
Wiring Guidelines:
• Always use 3-conductor, insulated, stranded,
shielded copper cable.
• Do not pull sensor wiring with AC power cables.
This can cause electrical interference.
• If cable runs cannot be made without a splice, all
splice connections should be soldered.
• Ground the shield at the main control panel.
Connect the shield wire in the sensor terminal
block labeled SHLD.
• Always disconnect power at the controller before
performing any wiring at the sensor.
• To maintain NEMA/IP rating of the enclosure,
conduit ttings of the same rating or better must
be used.
To signal input of monitoring equipment
To +24V terminal of power supply
To ground terminal of power supply
To case (earth) ground of monitoring equipment
Terminal Block Plug (Field Wiring):
SHLD: To case (earth) ground of monitoring equipment
GND: To ground terminal of power supply
+24V: To +24V terminal of power supply
SIG: To signal input of monitoring equipment
7
GG-NH3
Operation
Start-Up
Sensor can be response tested and/or span calibrated
immediately after power up. Allow 60 seconds for
power up time delay of sensor to end (green power
LED will ash during power up).
Start-Up test:
1) One person exposes each sensor to calibration gas.
2) The second person stays at the control panel to
determine that each sensor, when exposed to the
gas, is connected to the proper input and responds,
causing appropriate alarm functions.
LED Functions (see Figure 2 on page 8)
Calibration
The GG-NH3 sensor comes factory calibrated and
should require only minimal adjustment after
installation. There are two pots on the preamp that
are used for calibration (see Figure 2).
Note: Never measure sensor output in mA. Always
use mVDC or VDC voltmeter settings.
Zero Calibration: After the sensor is installed and has
been powered up for a minimum of 8 hours, the unit
can be zero calibrated by the following:
• Be sure the unit is in clean air.
• Adjust the zero pot until the sensor outputs 40 mV
from Test [-] to Test [+] (see Figure 2).Note: To
zero the sensor immediately after power up or cell
replacement, unplug cell from the transmitter and
adjust signal to 40 mV.
Span Calibration: DO NOT ADJUST THE SPAN POT
WITHOUT CERTIFIED CALIBRATION GAS! If span
adjustment is required, use the following procedure:
• To enter calibration mode (disables all ltering and
averaging), turn the Zero pot clockwise 1/4 turn and
then back again. Successful entry into calibration
mode will be indicated by the Power (green) LED
blinking twice per second. Calibration mode will
time out automatically after 4 minutes.
• Apply span gas at 0.5 to 0.8 L/min (span gas must
be in air, not nitrogen or other carrier).
• Sensor should react to gas within 15 seconds.
• Once the output signal has peaked (or 2 minutes
maximum) adjust the Span pot until the correct
output is achieved (see Figure 2). With full-scale
span gas, the calculated span value is 200 mV.
((span gas / sensor range * 16 + 4) (mA output))
Note: Below are a few response characteristics which
may be an indication that the gas sensor is at or near
the end of its useful life. If any of these characteristics
are observed, the cell should be replaced.
• Slow response to / recovery from calibration gas.
• Failure of the output to reach 50% of the calibration
gas value prior to span adjustment.
• Unable to achieve correct output during span.
• Output at 0.5 mA due to SafeCell test failure.
8GG-NH3
Figure 2: Sensor board components and zero/span adjustment
Span adjustment
Zero adjustment
40-200 mV
mVDC
Black Red
-+
Fault (red) LED:
• Blinks once per second if
SafeCell test fails.
• On steady if supply voltage is
less than 10VDC or SafeCell
test fails for six hours.
Status (amber) LED:
• Blinks once per second if RFI is
detected.
Power (green) LED:
• On steady to Indicate Power.
• Blinks once per second for 60
seconds during power-up.
• Blinks once per second
continuously if supply voltage
is too low.
• Blinks twice per second in
calibration mode (4 minute
timeout delay).
Cell
9
GG-NH3
Maintenance
The GG-NH3 sensor is designed for long life and
minimal maintenance. For proper operation, it is
essential that the test and calibration schedule be
adhered to. Calibration Technologies recommends the
following maintenance schedule:
Maintenance Guidelines:
• The sensor is shipped with a factory calibration.
• Sensor should be calibrated 6 months from
purchase date.
• Calibrate the detector at least once every 6 months.
• Calibration should be performed with certied
calibration gas. Calibration kits and replacement
cylinders are available from CTI.
• All tests and calibrations must be logged.
• Always disconnect power at the controller before
performing any wiring at the sensor.
Sensor Life: The electrochemical cells are extremely
reliable, but several things can cause depletion of the
chemistry within the cell including:
• A period of time
• Exposure to high temperatures
• Continuous, long term exposure to ammonia
When the SafeCell test fails, the fault (red) LED will
blink once per second. After six hours of continued
and consecutive test failures, the 4-20 mA signal
output will drop to 0.5 mA and the fault LED stays on
solid. This signal should be interpreted as a sensor
fault at the control panel and prompt notication to
plant personnel to investigate the sensor.
SafeCell technology tests the electrical viability of the
cell, however, it does not conrm proper sensitivity
to gas.There are other factors that could prevent the
cell from detecting gas, such as physical blockage, etc.
Therefore, it is absolutely essential that the sensor be
calibrated every six months.
Typical cell life is 2 to 5 years. When the cell becomes
depleted, a replacement cell can be obtained from
CTI. Simply unplug the cell's ribbon cable from the
transmitter, pull the old cell from the spring clip,
discard the old cell and replace with a new one.
The new cell can be span-calibrated immediately.
However, an 8 hour warm-up period is required
before zeroing, if necessary.
Replacement cell order#: GG-NH3-RC
10 GG-NH3
Specications
Input Power: +24 VDC, 350 mA
Detection Principle: Electrochemical
Detection Method: Diusion
Gases: Ammonia (NH3)
Ranges:
0/100 (standard)
0/250
0/300
0/500
0/1000
Custom ranges available. Call for more information
Output Signal: Linear 4/20 mA (max input impedance:
700 Ohms)
Response Time:
T50 = less than 30 seconds
T90 = less than 60 seconds
Accuracy: +/- 5% of full-scale, but dependent on
calibration gas accuracy and time since last calibration
Zero Drift: Less than 0.1% of full-scale per month,
non-cumulative
Span Drift: Application dependent, but generally less
than 3% per month
Linearity: +/- 0.5% of full-scale
Repeatability: +/- 1% of full scale
SafeCell Viability Check: Automatic electrical viability
test of the electrochemical cell every 40 seconds.
Failure of the test results in 0.5 mA output after 6
hours of continued and consecutive test failures.
Power (green) LED: Blinks once per second for 60
seconds during power-up. If supply voltage is too
low (<10 VDC) or improperly grounded, green LED
will blink once per second continuously. Stays steady
on to indicate power. Blinks twice per second in
calibration mode (4-minute timeout delay)
Status (amber) LED: Blinks once per second if RFI
(radio frequency interference) is detected
Fault (red) LED: Stays on steady if supply voltage is
too low (<10 VDC)
Wiring Connections: 3-conductor, shielded,
stranded, ≥ 20 AWG cable (General Cable C2525A or
equivalent) up to 1500 ft
Terminal Block Plug (Field Wiring): 26-12 AWG,
torque 4.5 lbs-in
Enclosure: Injection-molded, NEMA 3RX washdown-
duty, polycarbonate sensor housing with hinged lid
and captive screw. For non-classified areas.
Optional 18 GA, NEMA 3RX washdown-duty stainless
steel enclosure with hinged lid and captive screw. For
non-classified areas
Temperature Range: -50˚F to +122˚F (-46˚C to
+50˚C)
Humidity Range: 5% to 100% condensing
Dimensions: 7.7" high x 6.7: wide x 3.8" deep
Weight: 3.0 lbs
Certification: ETL Listed: Conforms to UL 61010-1
Certified to CSA C22.2 No. 61010-1
11
GG-NH3
Limited Warranty & Limitation of Liability
Calibration Technologies, Inc. (CTI) warrants this product to be free from defects in material and workmanship
under normal use and service for a period of two years (including the sensor element), beginning on the date of
shipment to the buyer. This warranty extends only to the sale of new and unused products to the original buyer.
CTI's warranty obligation is limited, at CTI's option, to refund of the purchase price, repair, or replacement of a
defective product that is returned to a CTI authorized service center within the warranty period. In no event shall
CTI's liability hereunder exceed the purchase price actually paid by the buyer for the product.
This warranty does not include:
a) routine replacement of parts due to the normal wear and tear of the product arising from use;
b) any product which in CTI's opinion, has been misused, altered, neglected or damaged by accident or
abnormal conditions of operation, handling or use;
c) any damage or defects attributable to repair of the product by any person other than an authorized dealer or
contractor, or the installation of unapproved parts on the product
The obligations set forth in this warranty are conditional on:
a) proper storage, installation, calibration, use, maintenance and compliance with the product manual
instructions and any other applicable recommendations of CTI;
b) the buyer promptly notifying CTI of any defect and, if required, promptly making the product available for
correction. No goods shall be returned to CTI until receipt by the buyer of shipping instructions from CTI; and
c) the right of CTI to require that the buyer provide proof of purchase such as the original invoice, bill of sale or
packing slip to establish that the product is within the warranty period.
THE BUYER AGREES THAT THIS WARRANTY IS THE BUYER'S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF
ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY
OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. CTI SHALL NOT BE LIABLE FOR ANY SPECIAL,
INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSSES, INCLUDING LOSS OF DATA, WHETHER
ARISING FROM BREACH OF WARRANTY OR BASED ON CONTRACT, TORT OR RELIANCE OR ANY OTHER THEORY.
ctiengineering.com | 866-394-5861
GG-NH3-DOC1-3
20190605
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