CTI GG-VL2-NH3 User manual

Installation and Operation Manual
GG-VL2-NH3 AMMONIA VENT LINE SENSOR

2GG-VL2-NH3
Warning
Use this product only in the manner described in this manual.
If the equipment is used in a manner not specied by Calibration
Technologies, the protection provided by the equipment may be impaired.
This equipment should be installed by qualied personnel.

GG-VL2-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................................................... 10
Troubleshooting............................................. 11
Specications ................................................. 11
Warranty......................................................... 12 For technical support, contact:
Calibration Technologies
920 N Tradewinds Pkwy
Columbia, MO 65201
866-394-5861
[email protected]
www.ctiengineering.com

4GG-VL2-NH3
General Description Installation
The GG-VL2-NH3 sensor is a +24 VDC, three-wire,
4/20 mA sensor for ammonia. It provides an industry
standard linear 4/20 mA output signal compatible with
most gas detection systems and PLCs.
The GG-VL2-NH3 provides real-time continuous
monitoring of ammonia vapors in refrigeration
system vent lines. Utilizing a long-life ammonia
selective catalytic bead sensor, the GG-VL2-NH3
sensor can withstand occasional exposures to high
concentrations of ammonia without shortening the life
of the sensor.
The sensor element can be accessed from inside
of the stainless steel enclosure, and is sealed from
the vent line to prevent ammonia from entering the
enclosure.
The transmitter circuit board is sealed in potting
compound, protecting sensitive electronic
components and copper tracing from corrosion.
Recommended alarm setpoints for ammonia system
vent lines are typically 0.5% to 1.0% NH3 (12 to 20 mA).
Locating the sensor
Note: The ½” nipple of the supplied mounting kit
should be welded to the relief header to allow airow
to the sensor.
Note: Removing the ½” plug from the mounting
kit usually allows more fresh air to the sensor
and prevents signal rise over time. Since fresh air
promotes longer sensor life and overall long-term
sensor performance, it is recommended that the
sensor is installed outdoors.
Discharging to Atmosphere
The GG-VL2-NH3 sensor assembly should be installed
outdoors three to ve feet above the rooine, where
the relief header discharges to the atmosphere (see
Figure 1).
Discharging to Diusion Tank
The GG-VL2-NH3 sensor assembly should be installed
on the atmospheric vent on top of the water tank (see
Figure 2). This type of installation will not catch the
weeping relief valves, but will detect ammonia vapors
from the water during a release event.
Caution: Installation of the sensor between SRV’s
and the diusion tank will not allow fresh air in, so
any introduction of ammonia gas will stay trapped in
the header, resulting in a continuously high signal.
A compressed air purge may be required for this.
Contact Calibration Technologies for details.

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GG-VL2-NH3
Installation Guidelines:
• Always assume system could discharge at any
moment. Stay clear of discharge path and have
escape route planned.
• Make sure ammonia does not discharge onto
sensor assembly or personnel working on sensor
(i.e. mount sensor opposite side of discharge).
• Install sensor enclosure with conduit hole facing
down.
Figure 1: Discharge to Atmosphere Figure 2: Discharge to Diusion Tank

6GG-VL2-NH3
Wiring
Electrical wiring must comply with all applicable codes.
Electrical Power: 24 VDC regulated, 80 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
congured to indicate a fault if the signal is below
1 mA. All signals over 20 mA must be considered
high gas concentrations.
Wiring Guidelines:
• Use only the existing conduit hole for connections
to the sensor.
• Always use three-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.
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

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GG-VL2-NH3
Operation
Start-up
Before applying power, make a nal check of all wiring
for continuity, shorts, grounds, etc. It is usually best
to disconnect external alarms until the initial start-up
procedures are completed. Recommended sensor
stabilization time is 5 minutes before making any
adjustments.
Note: The GG-VL2-NH3 sensor must be zero-
calibrated upon startup. Follow the Zero
Calibration instructions on this page. Sensor can
be response tested immediately after the initial
zeroing.
Note: Do not response test with propane or MAPP
gas, as these can shorten sensor life!
Response Test:
1. One person exposes each sensor to 1% or 2% NH3
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.
The GG-VL2-NH3 is designed with a unique safety
signal latching feature. When the signal reaches 1%
NH3, the signal “latches” until the concentration
drops down below approx 4,000 ppm NH3. This
prevents the possibility of a low reading when the gas
concentration exceeds the Upper Explosion Limit.
Calibration
The GG-VL2-NH3 sensor comes factory calibrated
and should only require zero-calibration adjustment
after installation. Calibration should be performed
every six months. There are two pots on the preamp
that are used for calibration (see Figure 3).
Note: Never measure sensor output in mA.
Always use mVDC or VDC voltmeter settings.
Calibration Mode: Cal mode is required for
calibrating the sensor. It clears the averaging,
latching and deadband (factory set to 8 mA).
Pressing the CAL switch enables cal mode and
the green LED will ash. To exit out of cal mode,
press the CAL switch or after 6 minutes it will
automatically time-out back to normal mode.
Zero Calibration: After the unit is installed and has
been powered up for a minimum of 1 hour, the unit
can be zero calibrated by the following:
• Be sure the unit is in clean air. When in doubt,
apply zero air gas.
• Press the CAL switch to enter cal mode. Do
not adjust the zero pot if the green LED is not
ashing.
• Adjust the zero pot until the sensor outputs 40
mVdc from Test [-] to Test [+] (see Figure 3).

8GG-VL2-NH3
Span Calibration: Do not adjust the span pot
without certied calibration gas! If span adjustment is
required, use the following procedure (see Figure 3):
• Unscrew calibration port cover and connect cal gas
hose to hose barb tting
• Press the CAL switch once to enter cal mode.
• Apply 1% NH3 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 (200 mVdc).
• Shut-o gas, remove hose and replace cover.
• Press the CAL switch to exit cal mode.
• Calibration is now complete.
Note: Allow up to an hour for the signal to return back
to 4 mA after exposure to high concentrations.
Note: If correct output during span adjustment is
unachievable, replace the sensor element. See sensor
replacement procedure on page 10 if a replacement
sensor element is needed.
Note: Gas exposures well above the 0-1% NH3 range
of the sensor can shorten the life of the sensor
element, and typically results in a "zero signal shift",
where the signal is stuck at full-scale levels. Make sure
no ammonia gas is present and simply re-zero the
sensor following the Zero Calibration procedure on
the previous page.
4mA adjustment: Sometimes a ne adjustment of the
4mA signal may be desired to compensate for a slight
positive or negative zero-signal reading on the control
panel.
• Make sure the sensor is NOT in calibration mode.
• Adjust the 4mA pot until the control panel reads
zero.

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GG-VL2-NH3
Figure 3: Transmitter and sensor assembly
Calibration port
Unscrew cap to apply calibration gas
Sensor element assembly
Sensor cable plug Calibration switch
Push to enter cal mode
40-200 mV
mVDC
Black Red
-+

10 GG-VL2-NH3
The GG-VL2-NH3 was designed for long life and
minimal maintenance. For proper operation it is
essential that the calibration schedule be adhered to.
Calibration Technologies recommends the following
maintenance schedule:
Maintenance Guidelines:
• Sensor should be calibrated at 6 month intervals.
• Calibration should be performed with certied
calibration gas. Calibration kits and replacement
cylinders are available from Calibration
Technologies.
• All tests and calibrations must be logged.
• Always disconnect power at the controller before
performing any wiring at the sensor.
Sensor Life: This catalytic bead sensor exhibits long
life and is very reliable. Typical sensor life is 5-7 years.
As with all gas detectors, regular 6-month calibration
intervals are essential to correct for sensor aging
characteristics. A few conditions can cause the sensor
to become faulty, including:
• a long period of time.
• exposure to liquid ammonia.
• poisoning due to silicon-based oils or lubricants,
sulfur compounds or high concentrations of
chlorine gas.
Maintenance Sensor Replacement: (part #: GG-VL2-NH3-RS)
When the sensor becomes faulty, a replacement
sensor element can be obtained from Calibration
Technologies.
To replace the sensor, refer to Figure 3 and the
following procedure.
Caution: Always assume the system could
discharge at any moment. Stay clear of discharge
path and have an escape route planned.
1. Be prepared for fault/alarm conditions during this
process.
2. Remove power from sensor. This can be done by
simply unplugging the 4-position power plug from the
transmitter.
3. Unplug sensor cable from transmitter.
4. Unscrew the sensor element assembly and discard
old sensor.
5. A replacement O-ring is included in case existing
O-ring is damaged or lost.
6. Screw in new replacement sensor assembly (do not
overtighten).
7. Plug in sensor cable to transmitter.
8. Re-apply power to sensor
9. The sensor can be response-tested immediately
after replacement but allow 12-hour warm-up time
before performing zero/span calibration.

GG-VL2-NH3 11
Specications
Input Power: +24 VDC, 80 mA
Detection Principle: Catalytic bead
Detection Method: Diusion
Gas: Ammonia (NH3)
Range: 0-1% (10,000 ppm) with 0.25% NH3 deadband
Output Signal:
Linear 4/20 mA (max input impedance: 700 Ohms)
Response Time: T90 = less than 30 seconds
Accuracy: +/- 2% of full-scale
Zero Drift: Less than 0.1% of full-scale per month
Span Drift: Less than 2% of full-scale per month
Linearity: +/- 1% of full-scale
Repeatability: +/- 1% of full-scale
Wiring Connections:
3-conductor, shielded, stranded, 20 AWG cable
(General Cable C2525A or equivalent) up to 1500 ft.
Terminal Block Plug (Field Wiring): 26-16 AWG,
torque 4 lbs-in.
Enclosure: 18 gauge stainless steel housing. Captive
screw in hinged lid. For non-classied areas.
Mounting Kit: Schedule 80 NPT pipe ttings
Temperature Range:
-40°F to +140°F (-40°C to +60°C)
Dimensions: 4.8” high x 4.72” wide x 3.35” deep
Weight: 4 lbs (includes mounting kit)
Certication:
ETL Listed: Conforms to UL 61010-1
Certied to CSA C22.2 No. 61010-1
Troubleshooting
Sensor Fault: (0.5 mA signal output)
Indications: (any or all)
• Red LED on transmitter lit and voltage signal at
testpoints is 5 mVdc (.5 mA output).
• PLC displays negative value (i.e. -2200 ppm).
• Controller indicates sensor fault or sensor failure
Possible Cause / Solution:
• Sensor exposed to liquid. Replace sensor element
(see page 10 for more info).
• Loose connection. Check all sensor wires.
Constant or Intermittent high signal or alarms:
Possible Cause / Solution:
• Gas exposures well above the 0-1% NH3 range
of the sensor can shorten the life of the sensor
element, and typically results in a "zero signal
shift", where the signal is stuck at full-scale level.
Make sure no ammonia gas is present and simply
re-zero the sensor following the Zero Calibration
procedure.
• Weeping relief valve. Check valve by drawing a
sample from the header with an accurate portable
ammonia detector. Be sure to sample 1’ to 3’ from
inside the header to ensure a good reading.
• Or loosen union nut and remove sensor assembly
from header. If signal returns to normal in fresh air,
investigate relief valve(s) and replace if necessary.

12 GG-VL2-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 2 years (including 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) gas sensors that have been wetted by liquid ammonia, oil or water;
b) routine replacement of parts due to the normal wear and tear of the product arising from use;
c) any product which in CTI’s opinion, has been misused, altered, neglected or damaged by accident or abnormal
conditions of operation, handling or use;
d) 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.

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ctiengineering.com | 866-394-5861
GG-VL2-DOC1-4
20180808