Model 9060Z Manual
downwards with the filter removed. Probes can also be mounted horizontally with no filter with some dusts. An occasional automatic back purge is helpful in this case.
Normally heated probes are supplied with filters for applications with particulates in the flue gas. The probe response time should be tested when the probe is first installed, and then regularly until it remains constant for a significant period. Filter purging should be set up on the time periods determined by these tests. To test the probe response time, use a stopwatch to obtain the time for a probe to achieve a 63 % change from one reading to another. If a probe filter blocks completely in a short period of time, then there is no option but to use the probe without the filter. A trial probe with filter can be installed to test whether a filter blockage is likely to occur.
4.20 STRATIFICATION
If the transmitter and probe have been fully tested and the oxygen readings in the flue gas are incorrect, gas stratification may be occurring. The phenomena cannot be anticipated for any particular installation. Generally, large flues have oxygen differences of approximately one percent across the flue. Occasionally an oxygen error of several percent may occur in a flue of any size. Moving the probe to a new location normally solves this problem. The effects of stratification can be reduced by using two probes and averaging the two oxygen readings. This can be achieved within a Teledyne Analytical Instruments 9060Z transmitter controlling two probes.
4.21 CONNECTING A PRESSURE TRANSDUCER
If the process gas pressure varies more than 4" WG and therefore requires automatic compensation, connect a pressure transducer as shown below. Place a link across LK2, near to the input terminals 24
&25. If the link is not populated, you can achieve the same thing connecting a 120Ω resistor across the two terminals. A pressure change of 4" WG will cause a change in the calculated oxygen reading of approximately 1%.
There are no calibration adjustments for the zero or span of the pressure transducer input. Set the transducer scale range in the commissioning menu ‐ See Section 7.2.8. The pressure can be displayed on the lower line by enabling the corresponding option. See Section 6.3.2.
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