Panametrics CGA 351, User Manual, Page: 84 / 119

Chapter 5.
78 CGA 351 User’s Manual
5.1.4 Calibration Responses
Chapter 4,
Setup and Calibration, describes the procedures for calibrating the CGA 351 in great detail. However, the
response of the unit to the calibration procedures can provide valuable clues to potential problems with the
installation. The three most common situations are described in this section.
5.1.4.1 Everything Is Fine
Calibration of the analyzer at the tagged calibration gas flow rate has been successfully completed. Upon switching
off the calibration gas, the analyzer quickly returns to monitoring and displaying the sample gas concentrations
accurately. This indicates that proper operating conditions have been achieved and the analyzer can be expected to
perform reliably.
5.1.4.2 Forced Flow Problem
If a flow rate higher than the tagged calibration gas flow rate is required to calibrate the analyzer, the sample gas
feed pressure is too high. Under such conditions, the sample is not entering the oxygen sensor by diffusion only, but it
is being forced into the sensor instead. In addition to the calibration problem, sensor life may be shortened and
analyzer plugging may occur. If forced flow is confirmed as the problem, refer to Chapter 2,
Installation, for
instructions on proper installation of the analyzer.
5.1.4.3 Plugging or Dead Space Problem
The analyzer was successfully calibrated at the tagged calibration gas flow rate, and the analyzer responded quickly
to the calibration gas. However, there is a significant delay in reading the correct sample gas concentrations, after
turning off the calibration gas.
When this problem occurs, it is very likely that the sample gas inlet is located in a dead space. After the analyzer is
correctly reading the sample gas concentration, switch on the calibration gas just long enough to get the correct
reading. As soon as the analyzer reads the correct value, quickly shut off the calibration gas. One of two responses
should occur:
1. If the recovery time is still too long, the sample gas path through the oxygen sensor may be plugged with
particulates. Use of a blowback system (contact the factory for assistance) should clear the analyzer and restore
proper operation.
2. If the analyzer reading recovers promptly, dead space is the likely problem. Internal structures can cause dead
spaces that are not evident from an external examination. It may sometimes be necessary to relocate the
analyzer to a more suitable installation site.
Note: If the calibration “Failed”, repeat the calibration procedure on page 62 to page 66. If another failure or any
situations not covered in this chapter are encountered, contact the factory for assistance.
5.1.5 Parts Replacement
The CGA 351 is designed to enable easy and quick servicing, if necessary. This section describes the replacement of
major and minor components of the analyzer. However, before actually replacing any component, carefully read the
complete instructions to become familiar with the procedures.
Each procedure in this section includes a list of the equipment needed to complete the component replacement.
Please make sure that any necessary replacement parts are on hand before dismantling the analyzer. In addition,
the first paragraph of each section gives a description of the function and location of the part to be replaced. refer to
Figure 5 on page 87, while following the step-by-step instructions in this section.
Note: For information regarding component locations and/or wiring connections in an optional enclosure, see
Appendix C.
CAUTION!
If the power must be disconnected to replace a part, perform the replacement as quickly as possible.
The CGA 351 is susceptible to corrosion from acid condensation if it remains without power
for more than thirty minutes.
If service procedures not covered in this chapter become necessary, please contact the factory for assistance.
WARNING!
To ensure safe operation of the CGA 351, it must be installed and operated as described in this
manual.
In addition, be sure to follow all applicable local safety codes and regulations for installing electrical