Emerson Rosemount 370XA, System Reference Manual

Page: 125 / 209

System Reference Manual 370XA Gas Chromatograph
7P00370-H01 APRIL 2014
4 - 40
4.4.6 Conserve calibration gas
To save calibration gas, the 370XA has a unique feature call Cal-Gas
Saver

that reduces calibration gas usage significantly. During
normal operations, the next stream will start to be purged through the
sample loop from when the sample shut-off valve that is operated by
the back-flush valve timing, at around 25 seconds, is opened, through
to the start of the next analysis. This ensures that the sample lines
and the sample loop are completely purged of the previous stream
and the sample loop is full of the next sample to be analyzed.
A calibration cycle involves running multiple analysis cycles of the
calibration gas. Because there are multiple runs of the same gas,
there is no need to purge the sample lines leading up to the sample
loop after the first analysis run. To conserve the amount of calibration
gas used by the 370XA while still maintaining calibration accuracy, the
calibration gas saver feature turns off the calibration gas stream for a
longer period during the calibration gas analysis cycles to dramatically
reduce the amount of calibration gas consumed.