Teledyne 3000ZA - Trace oxygen analyzer - Manual (Page 75)

Trace Oxygen Analyzer Appendix
Teledyne Analytical Instruments
positive pressure applications as well as vacuum service applications
(see manual for installation instructions).
The standard restrictor (BLUE DOT) is recommended for pressures
between 5 and 50 PSIG. For positive low pressure application (5 psig or
less) the unmarked restrictor is better suited . For unpressurized sample
applications the marked restrictor should be used and configured for
vacuum service.
Note: For extremely low positive pressure applications (less then
2 psig) the vacuum service configuration should provide
higher performance (higher flow rates).
For vacuum service, the end user must supply a vacuum pump and
a by-pass valve for the pump. A vacuum level of 5–10 inches of
mercury should provide the optimum flow rate. CAUTION: flow
restrictors have very small orifices and may be plugged by small
particles (.005” dia or larger) A sample filter must be included in the
sample line prior to the restrictor! (A 60 micron filter is recommended).
3000TA EXAMPLES:
Example 1: With a incoming pressure of 10 psig the std restrictor (blue
dot) will provide a flow rate of 0.76 SLPM. Upstream of the restrictor
the sample line pressure will be 10 psig, while down stream (including
the cell) the pressure will be at atmospheric pressure (analyzer vented to
atmospheric pressure). Note, all other pressure drops in the sample path
are insignificant at these flow rates. This insures that the cell operates at
atmospheric pressure. At very high flow rates (off scale of flow-meter),
pressure drops other than the restriction device could become
significant, and result in pressurizing the cell.
Example 2: A 3000TA is configured for vacuum service as follows. The
unmarked restrictor is placed in the sample vent port. The down stream
end of the restrictor is then connected to a vacuum pump and by-pass
valve. The by-pass valve is adjusted to provide a flow rate of 1 SLPM.
The sample pressure between the pump and the restrictor will be
approximately -7 inches of mercury, while the pressure in the balance
of the sample system including the cell will be approximately at
atmospheric pressure (provided the sample flow into the analyzer is not
blocked).
BY-PASS: