Teledyne OT-3 User Manual download pdf (Page 28)

Installation OT-3

Teledyne Analytical Instruments 20

The vent line must be installed in a manner which will prevent dirt

and water from accumulating within the line. It must return sample to

atmospheric pressure. The vent line should be 1/4” diameter tubing or

larger and be at least 24” long. This will help to prevent the back

diffusion of O

into the sample system.

3.5 Sample System

The sample system used in the OT-3 Trace Oxygen Analyzer is a

robust gas handling and conditioning system designed for low flow rate

trace oxygen analysis in a natural gas or other low-oxygen gas

environment. It uses stainless steel tubing and fittings throughout and a

special 0-10 psig regulator designed to provide stable sample flow at

low volumes over wide temperature extremes. The incoming sample gas

is conditioned using a coalescing filter and an acid scrubber to remove

moisture and contaminants which would otherwise interfere with the

accurate trace analysis and/or reduce the lifetime of the sensor.

Refer to Figure 3-4 for the following discussion.

Note: Check the front of this manual for any additional

information in the form of addenda that may apply to your

custom system.

Sample gas enters the system at 5-2000 psig. A shut off valve is

installed and is used to switch gas flow on or off. The sample gas is

passed through a horizontal coalescing filter to remove moisture and

debris. This filter is designed to handle inlet gas pressure up to 2000

psig. It is important to periodically drain the condensate by opening the

drain valve. If appropriate, the drain line should be connected to a

suitable receptacle for handling contaminated waste liquid.

A 0-10 psig pressure regulator is installed downstream from the filter

and controls the sample pressure through the analyzer. In conjunction with

the flowmeter, it provides a stable mass flow even at low volume over the

rated temperature range of the instrument. Set the pressure regulator to

provide a flow rate of 0.4 SCFH (approximately 4 psig).

A clear PVC acid gas scrubber is installed between the regulator

and the sample/span gas selector switch. The clear housing permits a

visual analysis regarding the condition of the scrubber medium and

allows the user to predict service intervals.

A switching valve is provided to feed the analysis unit with either

sample or span gas.

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Teledyne OT-3 User Manual Page 28