Emerson Rosemount 3051 Reference Manual page 30

Hardware Installation
August 2016
Steam flow measurement
Place taps to the side of the line.
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Mount the transmitter below the taps to ensure that the impulse piping will stay filled
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with condensate.
In steam service above 250 °F (121 °C), fill impulse lines with water to prevent steam from

contacting the transmitter directly and to ensure accurate measurement start-up.
Note
For steam or other elevated temperature services, it is important that temperatures at the
process connection do not exceed the transmitter's process temperature limits.
Figure 3-8. Installation Examples
Flow
Best practices
The piping between the process and the transmitter must accurately transfer the pressure
to obtain accurate measurements. There are five possible sources of error: pressure
transfer, leaks, friction loss (particularly if purging is used), trapped gas in a liquid line, liquid
in a gas line, and density variations between the legs.
The best location for the transmitter in relation to the process pipe is dependent on the
process. Use the following guidelines to determine transmitter location and placement of
impulse piping:
Keep impulse piping as short as possible.

For liquid service, slope the impulse piping at least 1 in/ft (8 cm/m) upward from the

transmitter toward the process connection.
For gas service, slope the impulse piping at least 1 in/ft (8 cm/m) downward from the

transmitter toward the process connection.
Avoid high points in liquid lines and low points in gas lines.

Make sure both impulse legs are the same temperature.
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Use impulse piping large enough to avoid friction effects and blockage.
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Vent all gas from liquid piping legs.
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20
Liquid service
00809-0100-4797, Rev DA
Gas service
Flow
Reference Manual
Steam service
Flow
Hardware Installation