LINE 7: PPM – Parts Per Million is the volume concentration referenced to standard temperature and
pressure and is computed from lines 5, 8 and 13. There are 2 figures given. The first (annotated by
a B) is the actual PPM at the IR branch. The second is a PPM reading normalized to standard
temperature and pressure.
LINE 8: Zero Temperature – This line contains the sensor and enclosure temperature measured and
stored during the last purge cycle in degrees C.
LINE 9: Bench Temperature – This is the current IR sensor temperature in degrees C as well as the
raw voltage coming from the temperature sensor itself. This value can range from ambient to
ambient +15 degrees C.
LINE 10: Box Temperature – This is the current internal enclosure temperature along with the raw
voltage from the temperature sensor, and has the same range as line 9.
LINE 11: Pressure – This is the current absolute manifold pressure in PSIA along with the output
voltage of the pressure sensor. This value should always be 0.2 to 1.0 PSIA below ambient (line 13).
LINE 12: Vacuum – The vacuum pressure is measured every purge cycle by closing all sample
valves. Its’ value is typically 2.5 to 4.0 PSIA below ambient (line 13).
LINE 13: Ambient – Ambient pressure is measured every purge cycle with the sample pump off and
the manifold open. Its’ value is weather and altitude dependent and can range from 10.0 to
15.5 PSIA.
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