Teledyne 402REU - Hydrocarbon analyzer - Manual (Page 32)

Chapter 4 Model 402 R-EU
Teledyne Analytical Instruments 4-8
3. After completion of calibration, shut off the main valves on
the zero and span gas tanks to avoid losing gas to minute leaks,
etc.
4.8 Stabilization Period
After the proper gas flow rates have been established and the flame
ignited, the analyzer should be permitted to operate on zero gas until the
isothermal chamber temperature comes to equilibrium, and, more impor-
tantly, until the user is satisfied that the analyzer is operating in a stable
fashion in the absence (or near absence) of hydrocarbons.
Run the analyzer at the span setting found after calibration (and the
selector switch in the low position) on zero gas until a stable recording is
obtained. If time permits, allow the instrument to run for 24 hours. If all
lines are free of hydrocarbons, the recorder should chart a closed circle
from the point where temperature equilibrium was reached. The recording
should have no more than 1% noise, and there should be no more than 2%
diurnal indicated.
4.9 Sampling
After a satisfactory recording is obtained on zero gas (see Calibration,
above), make sure that the process gas sample is in a condition acceptable
to the analyzer, or contamination of the sample system may occur.
The gas must be dry, free of particulates, and at a temperature not to
exceed 120 °F.
Incoming sample pressure should be regulated to 30 psig. In case the
sample pressure is lower than 30 psig, make sure that the incoming sample
pressure exceeds the recommended sample pressure as read on the instru-
ment sample pressure gauge by at least 10 psig and is capable of maintain-
ing a stable bypass flowrate of 0.5-1.0 SCFH. The use of a sample pump is
otherwise indicated.
NOTE: Your analyzer may be designed with a low pressure input option for
sample pressures as low as 5 psig.
If a sample pump is required, one must be selected which does not
emit chemicals visible to the analysis, and should have, if at all possible,
metal bellows and valves. Rubber diaphragms and valves are not ac-
ceptable.