CTI GG-CO2 User Manual

GASGUARD CO2
Carbon Dioxide Sensor
OPERATING & INSTALLATION MANUAL
GasGuard CO2
Operating and Installation Manual
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GasGuard CO2
Operating and Instruction Manual
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
Specifications…………………………………….. 10
Warranty………………………………………….. 11
Calibration Technologies
866-394-5861
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GasGuard CO2
Operating and Installation Manual
General Description
The GasGuard CO2 sensor is a +24 VDC, three-wire,
4/20 mA sensor for carbon dioxide which utilizes proven
infrared sensor technology for accurate and reliable leak
detection. The 0-3% (0-30,000ppm) detection range of
the GasGuard CO2 provides real-time continuous
monitoring of ambient carbon dioxide concentrations. 01% and 0-5% ranges are also available.
The GasGuard CO2 provides an industry standard
linear 4/20 mA output signal compatible with most gas
detection systems and PLCs. The output signal is not
affected by drastic temperature and moisture variations
that occur during washdown, defrost cycles, etc.
The circuit board is forever sealed in potting compound,
completely protecting sensitive electronic components
and copper tracing from corrosion. The specially vented
chemical-resistant polycarbonate enclosure protects the
sensor from accidental damage, weather and direct
hose-hits from cleaning crews.
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Installation
Locating the sensor
One of the most important considerations when
installing GasGuard CO2 sensors is that they 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 five feet off the ground, which also allows easy
access. As a general rule of thumb, try to mount
sensors within 30 feet of potential leak sources.
GasGuard CO2
Operating and Instruction Manual
Installation Guidelines:
• Always mount the sensor vertically.
• Must be easily accessible for calibration and
maintenance.
• Mount the sensor close to the potential leak source.
• For optimum personnel protection, mount sensor in
the “breathing zone” (4’ – 5’ above floor).
• Take air movement and ventilation patterns into
account.
• To prevent electrical interference, keep sensor and
•
•
•
•
wire runs away from mercury vapor lights, variable
speed drives, and radio repeaters.
Protect sensor from physical damage(forklifts, etc.).
If mounting sensor outdoors, consider prevailing
wind direction and proximity to the most likely
source of leaks. Protect the sensor from sun and
rain as much as possible.
Mount sensor enclosures through the mounting
holes as shown in Figure 1. Use the supplied selftapping screws for mounting on sheet metal
surfaces.
Even though the sensor comes from the factory
calibrated, it is always a good idea to calibrate the
sensor to the environment in which it is installed.
This will compensate for any inaccuracies caused
by a change is temperature, altitude, etc.
Figure 1: Mounting dimensions
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GasGuard CO2
Operating and Installation Manual
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 configured
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 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.
• Use only the existing conduit hole for connections
to the sensor.
Figure 2: Wiring diagram
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GasGuard CO2
Operating and Instruction Manual
Operation
Start-up
Before applying power, make a final check of all wiring
for continuity, shorts, grounds, etc. After power-up,
allow at least 2 hours for the system to stabilize before
testing the sensors. Because sensors are normally
located at a distance from the main unit, the test time
required and accuracy of the response checks will be
improved if two people perform the start-up procedures
and use radio contact.
Start-Up Test:
1) One person exposes each sensor to calibration
gas. (breathing on the sensor can also produce a
significant signal rise)
2) The second person stays at the control unit to
determine that each sensor, when exposed to
carbon dioxide, is connected to the proper input
and responds, causing appropriate alarm functions.
Calibration
The GasGuard CO2 Sensor comes factory calibrated
and should require only minimal adjustments after
installation. There are two pots on the preamp that are
used for calibration.
Note: Never measure sensor output in mA. Always
use mVDC (or VDC) voltmeter settings.
Zero Calibration: After the unit is installed and has
been powered up for a minimum of 2 hours, the unit can
be zero calibrated by the following:
• Apply Zero Air gas (or nitrogen) at 0.8 L/min.
• Adjust the zero pot until the sensor outputs 40
mVDC from test points [-] to [+] (see Figure 3).
Span Calibration: DO NOT ADJUST THE SPAN POT
WITHOUT CERTIFIED CALIBRATION GAS! If span
adjustment is required, the following procedure will span
the unit:
• Perform zero calibration prior to spanning.
• Connect tubing to the calibration port of the infrared
tube. (see Figure 3)
• Apply span gas at 0.8 L/min.
• Sensor should react to gas within 10 seconds.
• Once the output signal has peaked (or two minutes
maximum) adjust the span pot until the correct
output is achieved.
Note: The adjustment response is dampened. Make
slight adjustments (no more than ½ turn of the
potentiometer) and wait for output response.
If the correct output cannot be achieved, contact
Calibration Technologies for technical help.
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GasGuard CO2
Operating and Installation Manual
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Figure 3: Sensor output and
zero/span adjustments
GasGuard CO2
Operating and Instruction Manual
Maintenance
The GasGuard CO2 was 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
Sensor Life: Typical sensor life of the GasGuard CO2
is five to seven years. Failure of the infrared sensor
happens normally when the infrared source opens or
breaks, similar to an incandescent light bulb filament. If
this occurs, the sensor will produce a continuous fault
indication signal of 0.5 mA and the fault LED will be lit.
Contact Calibration Technologies for a sensor
replacement.
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 certified
calibration gas. Calibration kits and replacement
cylinders are available from Calibration
Technologies.
• All tests and calibrations must be logged.
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GasGuard CO2
Operating and Installation Manual
Specifications
Detection Principle: Infrared
Detection Method: Diffusion
Gases:
Carbon dioxide (CO2)
Ranges:
0-1% (0-10,000ppm)
0-3% (0-30,000ppm) (standard range)
0-5% (0-50,000ppm)
Output Signal:
Linear 4/20 mA (max input impedance: 700 Ohms)
Power Supply: +24 VDC, 350 mA
Response Time:
T50 = less than 30 seconds
T90 = less than 60 seconds
Accuracy:
+/- 5% of value, but dependent on calibration gas
accuracy
Zero Drift: Less than 0.5% of full-scale per month, noncumulative
Span Drift: Less than 1% per month, non-cumulative
Linearity: +/- 0.5% 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.
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Enclosure: Injection-molded NEMA 4X polycarbonate
sensor housing. Captive screw in hinged lid. For nonclassified areas
Temperature Range: -60°F to +120°F (-51°C to +49°C)
Humidity Range: 5% to 100% condensing
Dimensions: 7.5” high x 6.5” wide x 3.8” deep
Weight: 2 lbs
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 one year, 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.
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GG-CO2 02/2013
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