Teledyne TurbO2 - Portable trace oxygen analyzer - Manual (Page 13)

9
Portable Trace Oxygen Analyzer TURBO
2
Teledyne Analytical Instruments
If the instrument is to be used for sampling after the calibration proce-
dure has been completed, follow the decreasing oxygen reading by position-
ing the Range Selector Switch so that the meter gives the best possible
resolution of the oxygen. Do not attempt to actually take a reading until
the meter indication stabilizes.
If, on the other hand, the instrument is not to be used immediately after
calibration, and a low PPM oxygen gas is being employed as a purge, allow
the manifold to be purged overnight, and then disconnect both male fittings.
Always disconnect the source fitting first and then the vent fitting
immediately after.
Positive Pressure Sampling
When connecting the instrument to a positive pressure sample source,
always proceed as follows:
1) Before making any connections to the instrument, establish a
flowrate in the sample line of from 0.1 to 10 liters/min. Allow the
sample to vent to atmosphere long enough to purge the line free
of air.
2) Install the vent fitting first, and then the sample source fitting. Be
prepared to make the connections in rapid order, so that
atmospheric diffusion time through the vent fitting is held to a
minimum.
When disconnecting the instrument, reverse the procedure: source
fitting first, and then vent fitting.
The objective of the connection–disconnection procedure is to obviate
the possibility of pressurizing the manifold. If a flowing sample is connected
to the manifold without the vent fitting in place, the pressure in the manifold
will rise and equal the sample pressure immediately, possibly causing a
manifold leak.