ABB NGC8206, Руководство пользователя

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2101510 Rev. AG Page 2–23
2.7.8 Heat Tracing Sample Lines
If there is a possibility that vapor samples could condense in the sample transport
line, heat tracing the sample line should be considered. This could occur at
ambient temperatures or when a liquid has to be kept warm for transporting or to
keep it from freezing (see
Figure 2-17 ).
To determine heat tracing temperature, a dew point calculation can be performed
based on the worst-case sample composition and transport pressure.
Heat tracing should conform to requirements of national and
local codes.
Figure 2-17 Heat Tracing Sample Line
2.7.9 Tube Corrosion
When designing transport tubing, consider the affect that corrosion has on tubing.
For hydrocarbon service, stainless steel transport tubing type 316SS is
recommended.
For selection of transport tubing for different types of service, refer to reference
information applicable to material applications for corrosive environments.
2.7.10 Tube Preparation
In the course of installing (cutting and fitting) the tubing at an installation, it is
important to dress the ends of any cut tubing and to insure that in the cutting and
deburring process no particles are allowed to remain in the tubing.
2.8 Calculating Lag Time
The following calculations assume that all pressure drops occur across the valves
HV-1, HV-2 and HV-6 and that the Rotameters RM-1, RM-2 and RM-3 are
measuring flow at atmospheric pressure (see
Figure 2-18 ).
Figure 2-18 is for reference purposes only but, it is typical of a
sample conditioning module with liquid separator and liquid
shutoff. It is included for reference only. Refer to the
documentation provided with the unit.
GAS FLOW
SAMPLE TRANSPORT
TUBING
HEAT SOURCE
SAMPLE TRANSPORT
TUBING INSULATION