Filter
Top Products
Trace Oxygen Analyzer Appendix
Teledyne Analytical Instruments 73
Example 1: With an incoming pressure of 10 psig the standard restrictor
(blue dot) will provide a flow rate of .76 SLPM. Up-stream 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 flowrates. 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
un-marked restrictor is placed in the sample vent port. The downstream
end of the restrictor is then connected to a vacuum pump and bypass
valve. The bypass 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.)
BYPASS:
To improve the system response, a bypass can be added to increase
the sample flow rate to the analyzer by a factor of ten. A bypass
provides a sample flow path around the analyzer of 2-18 scfh, typically.
CALIBRATION GAS:
For 3000 series analyzers r with the Auto-Cal option, the customer
must supply control valves (or restrictors) for any SPAN or ZERO gas
source which is attached to the Auto-Cal ports. The valve should be
adjusted to the same flow rate as the sample gas. When restrictors are
used, the gas pressure must be adjusted to achieve the proper flow rate.
OPERATION WITHOUT A RESTRICTORDEVICE:
Operation without a restrictor device is not recommend as
mentioned above. A 3000TA without any flow restrictor device was
tested on 11-19-97. This results in a flow rate of 2.4 slpm at 1 psig. This
is a cv of 0.023 for the standard sample system.