Panametrics CGA 351 User manual

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910-199 Rev. D
Aug 2021
CGA 351
Zirconium Oxide Oxygen Analyzer
User’s Manual

CGA 351 User’s Manual 3
Warranty
Warranty
Each instrument manufactured by Panametrics Sensing, Inc. is warranted to be free from defects in material and
workmanship. Liability under this warranty is limited to restoring the instrument to normal operation or replacing the
instrument, at the sole discretion of Panametrics. Fuses and batteries are specifically excluded from any liability. This
warranty is effective from the date of delivery to the original purchaser. If Panametrics determines that the
equipment was defective, the warranty period is:
•one year for general electronic failures of the instrument
•one year for mechanical failures of the sensor
If Panametrics determines that the equipment was damaged by misuse, improper installation, the use of
unauthorized replacement parts, or operating conditions outside the guidelines specified by Panametrics, the repairs
are not covered under this warranty.
The warranties set forth herein are exclusive and are in lieu of all other warranties whether
statutory, express or implied (including warranties of merchantability and fitness for a particular
purpose, and warranties arising from course of dealing or usage or trade).
Return Policy
If a Panametrics Sensing, Inc. instrument malfunctions within the warranty period, the following procedure must be
completed:
1. Notify Panametrics, giving full details of the problem, and provide the model number and serial number of the
instrument. If the nature of the problem indicates the need for factory service, Panametrics will issue a RETURN
AUTHORIZATION number (RA), and shipping instructions for the return of the instrument to a service center will be
provided.
2. If Panametrics instructs you to send your instrument to a service center, it must be shipped prepaid to the
authorized repair station indicated in the shipping instructions.
3. Upon receipt, Panametrics will evaluate the instrument to determine the cause of the malfunction.
Then, one of the following courses of action will then be taken:
•If the damage is covered under the terms of the warranty, the instrument will be repaired at no cost to the owner
and returned.
•If Panametrics determines that the damage is not covered under the terms of the warranty, or if the warranty has
expired, an estimate for the cost of the repairs at standard rates will be provided. Upon receipt of the owner’s
approval to proceed, the instrument will be repaired and returned.

Warranty
4 CGA 351 User’s Manual
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<Model name> <Manual Type> 5
Contents
Chapter 1.
1.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.1.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.1.2 The Sensor Enclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.1.3 The Sample System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.4 Principles of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.5 The Zirconium Oxide Oxygen Sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1.6 The Heater Control Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Chapter 2.
2.1 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.2 Choosing an Installation Site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1.3 Mounting the CGA 351. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.4 Connecting the Sample System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.5 Wiring the Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Chapter 3.
3.1 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.1.2 Preventing Common Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.1.3 Powering Up the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.1.4 User Program Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.1.5 Configuring the Digital Display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.1.6 Converting mV to Oxygen Concentration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.1.7 Powering Down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Chapter 4.
4.1 Setup and Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.1.2 Accessing the User Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.1.3 The [Cal] Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
4.1.4 Setting Up the Alarm Relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.1.5 Setting the Temperature Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.1.6 Auto Range Analog Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.1.7 The [Opt-User] Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
4.1.8 Setting Fault Alarm Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
4.1.9 Setting Up the Analog Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.1.10 Adjusting the Display Contrast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
4.1.11 Setting the Display Backlight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
4.1.12 Setting Up the Serial Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
4.1.13 Setup and Security Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
4.1.14 Calibrating the CGA 351 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.1.15 Checking the Current Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
Chapter 5.
5.1 Service and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
5.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
5.1.2 General Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
5.1.3 Oxygen Measurement Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
5.1.4 Calibration Responses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.1.5 Parts Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.1.6 Recommended Spare Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85
Chapter 6.
6.1 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89
6.1.1 General Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89
6.1.2 Operating Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90
6.1.3 Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90

Contents
6 <Model name> <Manual Type>
Appendix A.
A.1 The Nernst Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
A.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
A.1.2 Equilibrium Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
A.1.3 The CGA 351 Nernst Equation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94
Appendix B.
B.1 CE Mark Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97
B.1.1 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97
B.1.2 EMC Compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97
B.1.3 LVD Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97
Appendix C.
C.1 Optional Enclosures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99
C.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99
C.1.2 Rack Mount Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99
C.1.3 Rack Mount Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101
C.1.4 Rack Mount Service and Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101

CGA 351 User’s Manual 1
Chapter 1.
Chapter 1.
1.1 General Information
1.1.1 Introduction
The CGA 351 monitors the oxygen content of any clean and dry gas stream. The analyzer can accurately measure
oxygen levels from 0.1 ppm to 100% O2, and can even measure oxygen content in reducing gases. This is
accomplished with a precision, temperature-controlled, zirconium oxide (zirconia) oxygen sensor.
The standard CGA 351 analyzer is supplied in a pair of stainless steel, NEMA 4X/IP66 enclosures mounted side-by-side
on a metal plate with a 40” flexible conduit connecting the two. This compact, wall-mounted system includes the
following components:
• a
sensor enclosure , which contains the oxygen sensor, sensor furnace, thermocouple, inlet port with needle valve,
outlet port with flowmeter, and interconnecting cable(s), and
• an
electronics enclosure , which contains the temperature control circuitry, output signal processing circuitry,
digital display, user interface, and wiring terminal strips.
The CGA 351 analyzer is also available in optional enclosures. See Appendix C for more information.
Figure 1: Standard CGA 351 Analyzer
1.1.2 The Sensor Enclosure
The sensor enclosure, which is shown in Figure 2 below, houses the sample measurement components. The functions
of these components are as follows:
• a zirconium oxide (zirconia)
oxygen sensor converts the oxygen concentration of the sample gas into a mV
output signal.
• a
sensor furnace heats the oxygen sensor and the sample gas to the optimum temperature of 700°C.

Chapter 1.
2 CGA 351 User’s Manual
• a thermocouple precisely regulates the temperature of the oxygen sensor and the sample gas.
•an inlet needle valve and an outlet flowmeter adjust the sample gas flow to 400 ± 40 cc/min.
Figure 2: Sensor Enclosure
Flowmeter
Furnace Bracket
Flowmeter
Thermocouple
Needle Valve
Sensor Furnace
Oxygen Sensor
Manifold
Electrical Conduit

CGA 351 User’s Manual 3
Chapter 1.
1.1.3 The Sample System
In addition to the components supplied with the CGA 351, an external sample system may be required to ensure that
the analyzer is fed a properly conditioned sample or calibration gas stream. In particular, the gas must be clean and
dry, and it must be delivered to the analyzer at atmospheric pressure.
Note: A suitable sample system, which will be supplied completely assembled on its own mounting plate, may be
ordered directly from the factory.
Commonly used sample system components include filters, pressure regulators, pressure gauges, by-pass loops,
and sample pumps. It is recommended that stainless steel construction be used for all wetted parts of the sample
system. A typical sample system is shown in Figure 3 below.
Figure 3: Typical Sample System
1.1.4 Principles of Operation
A gas sample is drawn into the inlet port of the analyzer by gas diffusion and a forced flow determined by the
external sample system. The sample gas then flows through a ceramic inlet tube and into the annular space
between the inlet tube and the inside of the zirconium oxide oxygen sensor. The flowmeter on the outlet port and the
needle valve on the inlet port are used to adjust the sample flow rate to 400 ± 40 cc/min.
SAMPLE
INLET
SAMPLE
OUTLET
INLET
CAL-GAS
INPUTOUTPUT
To: CGA 351 Inlet
From: CGA 351 Outlet

Chapter 1.
4 CGA 351 User’s Manual
In the annular sample space, the gas is heated to the same 700°C at which the zirconium oxide oxygen sensor is
maintained. A mV signal is generated. This signal is proportional to the logarithm of the ratio of the oxygen
concentration in the sample gas to the oxygen concentration in a reference gas contacting the outer electrode. In
the display electronics, the logarithmic signal can be read directly in unlinearized form, or it can be converted to a
0/4–20 mA, 0–2 V, or Namur linearized signal before display.
Note: A temperature above 650°C is required for proper operation of the oxygen sensor. Also, ambient air is the
usual reference gas on the outside of the zirconium oxide sensor.
The sensor furnace also generates the convective flow that circulates the sample gas through the sample path.
Pushed from behind by the hot gases still in the furnace, the hot sample gas in the sensor furnace rises out of the
furnace and cools. The cooled sample gases then pass through the outlet port, where they are carried away by the
main gas flow.
A platinum coating on the end of the ceramic tube and the zirconium oxide oxygen sensor ensures that all
oxidation/reduction reactions in the sample gas reach equilibrium. It is therefore possible to measure such
parameters as excess oxygen in air/fuel mixtures and equilibrium oxygen in reducing atmospheres such as
hydrogen.

CGA 351 User’s Manual 5
Chapter 1.
1.1.5 The Zirconium Oxide Oxygen Sensor
The inside and outside of the zirconium oxide oxygen sensor are coated with porous platinum, forming two
electrodes. The sample gas flows past the inside of the sensor, while atmospheric air circulates freely on the outside
of the sensor. This atmospheric air is used as the reference gas for making oxygen measurements. See Figure 4
below.
Figure 4: Oxygen Migration in the Zirconium Oxide Sensor
At the operating temperature of the oxygen sensor, the atmospheric reference oxygen is electrochemically reduced
at the outer electrode, and the resulting oxygen ions seek to equalize with the lower oxygen concentration on the
sample side of the cell by migrating through the porous ceramic toward the inner electrode. At the inner electrode
they give up electrons to become oxygen molecules again, and are swept away by the sample flow.
The lower the concentration of oxygen in the sample gas, the greater the rate of ion migration through the ceramic,
and the higher the cell voltage due to electron exchange at the electrodes. The cell voltage rises logarithmically as
the amount of oxygen in the sample gas falls, allowing the accurate measurement of very low levels of excess
oxygen.
1.1.6 The Heater Control Circuit
The oxygen sensor temperature in the CGA 351 is maintained by a heater, which is part of a complex temperature
control loop. This circuit constantly monitors the temperature input from an RTD, compares it to the set point
temperature, and turns the heater ON or OFF accordingly. The specific type of control circuit, a Proportional Integral
Derivative (PID) loop, is used because of the adjustable parameters involved:
•Proportional Band: Because the system cannot respond instantaneously to temperature changes, the actual
temperature of the oxygen sensor oscillates about the set point. In general, increasing the proportional band
reduces the magnitude of these temperature oscillations.
Volts
O22
O
O2
O2
2
O
O2
Sample O
Inside Cell
Oxygen ions migrate through the zirconium oxide
along the concentration gradient.
From Outside
Electrode From Inside
Electrode
Zirconium Oxide Ceramic
with Lattice Imperfections
Atmospheric O
Outside Cell
When O concentration in sample gas falls, the cell voltage rises
with increased oxygen migration through the zirconium oxide.
2
2
2

Chapter 1.
6 CGA 351 User’s Manual
•Integral Action: A consequence of increasing the proportional band is the introduction of an offset between the
set point and the control point. The integral portion of the control loop acts to move the control point back toward
the set point within a specified period of time. Decreasing this integration time reduces the offset more quickly.
Note: A third parameter, Derivative Action , is not used with the
CGA 351.
The heater control circuit is configured at the factory for optimum performance. Because of the strong interaction
between the parameters involved, properly setting up the PID loop is a very complex matter. As a result, randomly
changing the P, and/or I parameters can seriously degrade the performance of the CGA 351.
IMPORTANT: Always contact the factory before attempting to change the default P and/or I values. The submenu for
performing these changes is password protected to prevent accidental changes.

CGA 351 User’s Manual 7
Chapter 2.
Chapter 2.
2.1 Installation
2.1.1 Introduction
This chapter provides a general description of the standard CGA 351 and gives directions on how to install and wire
the analyzer for proper operation.
Note: For information regarding component locations and/or wiring connections in an optional enclosure, see
Appendix C.
IMPORTANT: For compliance with the European Union’s Low Voltage Directive (73/23/EEC), the CGA 351 requires an
external power disconnect device such as a switch or circuit breaker. The disconnect device must be
marked as such, clearly visible, directly accessible, and located within 1.8 m (6 ft) of the unit.
WARNING! Power up the CGA 351 as quickly as possible after introduction of the sample gas. If the analyzer is left
installed without power, the unit’s components become susceptible to acid condensation that will
cause corrosion.
Be sure to observe all installation limits and precautions described in this chapter. Pay particular attention to the
ambient temperature range of –25 to +50°C (–13 to +122°F) specified for the instrument.
WARNING! To ensure safe operation of the CGA 351, the unit must be installed and operated as described in this
manual. Also,
be sure to follow all applicable local safety codes and regulations for installing electrical equipment.
In addition, all procedures should be performed
by trained service personnel.

Chapter 2.
8 CGA 351 User’s Manual
2.1.2 Choosing an Installation Site
All environmental and installation factors should have been discussed with a Panametrics Sensing applications
engineer or field sales person at the time the CGA 351 was ordered. Thus, the equipment should be suited to the
application and the planned installation site. Before installing the unit, however, read the following guidelines to verify
that the best installation site has been chosen for optimum instrument accuracy and reliability. Make sure that:
• the CGA 351 enclosures are suitable for the environmental conditions at the installation site.
• the analyzer system will be installed in a location with little or no vibration.
• the ambient temperature at the installation site is between –25° and 50°C (–13° and 122°F).
• there are no restrictions in the discharge line (i.e. flow control valves downstream of the meter).
• the CGA 351 system is installed in a location that provides ready access for programming, testing, and servicing
the unit.
• the cables will be protected from excessive physical strain (bending, pulling, twisting, etc.). Do not subject the
cables to temperatures above 65°C (149°F) or below –50°C (–58°F).
• the line voltage used at the planned installation site corresponds to the factory preset line voltage rating for the
meter.

CGA 351 User’s Manual 9
Chapter 2.
2.1.3 Mounting the CGA 351
This section explains how to mount the analyzer components at the installation site and how to connect the sample
system to the analyzer.
Note: If more than one analyzer system is being installed, be aware that each system is a matched set (i.e., each
sensor enclosure must be matched to a specific electronics enclosure). Refer to the identification tags on the
enclosures to match the systems correctly.
IMPORTANT: For compliance with the European Union’s Low Voltage Directive (73/23/EEC), the CGA 351 requires an
external power disconnect device such as a switch or circuit breaker. The disconnect device must be
marked as such, clearly visible, directly accessible, and located within 1.8 m (6 ft) of the unit.
IMPORTANT: This symbol indicates Caution - risk of electric shock:
Refer to Figure 5 on page 13, and complete the following steps to mount the CGA 351:
1. Select a flat surface on a vertical wall or instrument panel with sufficient space to hold the mounting plate with
both of the CGA 351 enclosures.
Note: Mount the system in an upright position, so that the sample inlet and outlet fittings are on the bottom of the
sensor enclosure.
2. Using the mounting dimensions shown in Figure 5 on page 13, locate and prepare four (4) mounting holes or two
(2) horizontal mounting rails on the vertical surface.
3. Secure the system to the mounting surface with four (4) sets of mounting hardware. Be sure that the enclosures
are in a vertical position, with the inlet/outlet connectors on the bottom.
4. The flowmeter, which is fastened to the right side of the sensor enclosure, is connected to the discharge port on
the bottom of the unit with a length of 6mm stainless steel tubing. Make sure that the factory-installed Swagelok
fittings are secure.
5. A flow control valve is attached to the inlet port on the bottom of the sensor enclosure with 6mm stainless steel
tubing and Swagelok fittings. Point the valve in the proper direction to receive the inlet piping from the sample
system, and securely tighten the fittings.
2.1.4 Connecting the Sample System
The sample system should be located so that it is able to deliver a sample at a flow rate of 400 ±40 cc/min. For best
results, mount the sample system as close as possible to the CGA 351. An ideal location would be on the same panel,
just below the analyzer. If there are questions, consult with an applications engineer at the factory.
See Figure 5 on page 13, and complete the following steps to connect the sample system to the analyzer:
1. Using 6mm stainless steel tubing (or ¼” stainless steel tubing with adaptors), connect the gas source from the
sample system to the Swagelok fitting on the flow control valve at the inlet port on the analyzer.
2. Using 6 mm stainless steel tubing (or ¼” stainless steel tubing with adaptors), connect the Swagelok outlet fitting
at the top of the flowmeter on the analyzer to the gas discharge connection on the sample system.
Note: If desired, a suitable sample system may be ordered directly from the factory. The sample system would be
supplied fully assembled on a flat plate with four (4) mounting holes.

Chapter 2.
10 CGA 351 User’s Manual
2.1.5 Wiring the Analyzer
The system components which are housed in the sensor enclosure have already been wired at the factory. These
include:
• oxygen sensor (TB2)
• thermocouple (TB2)
• sensor furnace (TB2)
To completely wire the CGA 351 zirconium oxide oxygen analyzer, the following items must be connected:
• serial port (TB1)
• analog output (TB1)
• alarm relays (TB1)
• line power (TB3)
Refer to the wiring diagram shown in Figure 6 on page 14, while completing the instructions presented in this section.
WARNING! In order to meet CE Mark requirements, all cables must installed as described in Appendix B,
CE Mark
Compliance
.
IMPORTANT: For compliance with the European Union’s Low Voltage Directive (73/23/EEC), the CGA 351 requires an
external power disconnect device such as a switch or circuit breaker. The disconnect device must be
marked as such, clearly visible, directly accessible, and located within 1.8 m (6 ft) of the unit.
WARNING! To ensure safe operation of the CGA 351, the unit must be installed and operated as described in this
manual. Also, be sure to follow all applicable local safety codes and regulations for installing
electrical equipment. In addition, all procedures should be performed by trained service personnel.
To access the terminal printed circuit board, remove the cover below the digital display panel, which is fastened with
six (6) Phillips head screws. The PC Board has terminal blocks TB1 (12 connections), TB2 (8 connections), and TB3 (3
connections) mounted on it. Proceed to the appropriate sub-section to wire each of these terminal blocks.
2.1.5.1 Wiring the Outputs (TB1)
Terminal block TB1 contains connections for the CGA 351’s output signals. Specifically, the following signals are
available at this terminal block:
• serial port
• 0/4–20 mA, 0–2 V, or Namur analog output
• alarm relays
To wire any or all of these output signals, complete the following steps:
1. Attach a cable or conduit with the appropriate number of conductors to an entry port on the bottom of the
electronics enclosure.
2. To connect a serial port from a personal computer, use the
COMM pins on terminal block TB1 as follows:
a. Connect the
transmit wire to pin 1.
b. Connect the receive wire to pin 2.
c. Connect the
ground/return wire to pin C.
3. To connect an analog output device, use the
4-20mA pins on terminal block TB1 as follows:
a. Connect the
input wire to the external device to pin +.
b. Connect the output wire from the external device to pin –.
4. To connect alarm device(s), use the
ALARM 1 and/or ALARM 2 pins on terminal block TB1 as follows:
a. Connect the
input wire to the alarm-1 device to pin NO.
b. Connect the output wire from the alarm-1 device to pin C.

CGA 351 User’s Manual 11
Chapter 2.
c. If desired, repeat sub-steps a and b to connect alarm-2.
5. Connect any shields to pin G.
Proceed to the next section to continue wiring the CGA 351.
2.1.5.2 Wiring the Inputs (TB2)
Terminal block TB2 contains connections for the CGA 351’s sample measurement signals. Specifically, the following
signals are routed to this terminal block:
• zirconium oxide oxygen sensor
• thermocouple
• sensor furnace
All of the connections on terminal block TB2 have already been wired at the factory. In the event that one or more of
these wires must be reconnected, complete the following steps:
1. Locate the leads from the
zirconium oxide oxygen sensor . Connect these leads to terminal block TB2 as follows:
a. Connect the
positive sensor wire (white - #1) to pin +.
b. Connect the negative sensor wire (white - #2) to pin –.
2. Locate the leads from the
thermocouple . Connect these leads to terminal block TB2 as follows:
a. Connect the
positive thermocouple wire (yellow - no number) to pin +.
b. Connect the negative thermocouple wire (red - no number) to pin –.
Note: The two thermocouple wires (red and yellow) are bound together in a brown sheath.
3. Locate the leads from the sensor furnace . Connect these leads to terminal block TB2 as follows:
a. Connect one furnace wire (white - #5) to pin 1.
b. Connect the other furnace wire (white - #6) to pin 2.
Note: The polarity of the sensor furnace leads is not important.
4. Connect the ground wire (white - #G) and any shields to either of the pins labeled G.
This completes the wiring of terminal block TB2. Proceed to the next section to continue wiring the CGA 351.

Chapter 2.
12 CGA 351 User’s Manual
2.1.5.3 Wiring the Line Power (TB3)
Terminal block TB3 contains connections for the line power to the CGA 351. To wire the line power, complete the
following steps:
WARNING! Before proceeding with the section, verify that the line power has been turned off at the external
disconnect device.
1. Attach a cable or conduit with the three line power conductors to an entry port on the bottom of the electronics
enclosure.
CAUTION! Be sure that the input voltage to the CGA 351 complies with the value specified at the time of
purchase. If the voltage is incorrect, contact the factory immediately.
2. Connect the line power leads to terminal block TB3 as follows:
a. Connect the
line power lead (black) to pin L.
b. Connect the neutral power lead (white) to pin N.
c. Connect the
ground power lead (green) to pin G.
This completes the wiring of the CGA 351 analyzer. Proceed to Chapter 3,
Operation , for instructions on using the
meter.

CGA 351 User’s Manual 13
16
(406)
11 1/2
(292)
9 1/2
(241)
3 1/2
(89)
6 3/4 (171)
7 3/8 (187)
6 3/8 (162)
SIDE VIEW
FRONT VIEW
16
(406)
14 1/4
(362)
7/8 (22)
7/8 (22)
8 1/4 (208)
3 7/8 (98)15 1/4 (387)
17 (432)
Ø1/2 (Ø12.7) 4pl
Mounting Hole
Mounting
Note: Dimensions are in inches (millimeters).
Plate
Figure 5: CGA 351 Mounting Dimensions

CGA 351 User’s Manual 14
FUSE
TB3
TB2
TB1
COMM 4-20mA ALARM 1 ALARM 2 O2 TC HEATER 90-265 VAC
Group
COMM
4-20mA
ALARM 1
ALARM 2
Pin #
1
2
C
G
+
-
NO
C
NC
NO
C
NC
ALL
Description
RS232 Transmit (TX)
RS232 Receive (RX)
RS232 Return (RTN)
Any Shield or Ground
Analog Output (SIG+)
Analog Output (SIG-)
Normally Open (Standard Mode)
Common
Normally Closed (Failsafe Mode)
Normally Open (Standard Mode)
Common
Normally Closed (Failsafe Mode)
TB1 - OUTPUTS
HEATER
TC Thermocouple (-)
Furnace (+)
Any Gnd/Shield
1
2 Furnace (-)
G
-
G
+
Any Gnd/Shield
Thermocouple (+)
O2
Group Description
TB2 - INPUTS
-
+
Pin #
Sensor (-)
Sensor (+)
ALL
ALL
6 (White)
5 (White)
N.A.
G (White)
N.A. (Red)
N.A.(Yellow)
2 (White)
1 (White)
Wire # (Color)
G
TB3 - POWER*
N
L
Pin #
5 x 20 mm
Size:
3 A
FUSE
Type:
Rating:
Anti-Surge
*90-265 VAC, 50/60 Hz, 250 W
NOTE: For proper operation,
the unit must be powered by
the voltage specified at the
time of purchase.
Description
Line
Neutral
Ground
Color
Black
White
Green
Outputs/PowerInputs Conduit
CCG+ C21 -21G
-
+
G
-
+LNGNC NCNO NO
DS1
Conduit
Figure 6: CGA 351 Wiring Connections