Emerson Rosemount 3051 Reference Manual page 25

Reference Manual
00809-0100-4001, Rev JA
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:
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Mounting requirements
Impulse piping configurations depend on specific measurement conditions. Refer to
for examples of the following mounting configurations:
Liquid flow measurement
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Gas flow measurement
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Steam flow measurement
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Installation
Keep impulse piping as short as possible.
For liquid service, slope the impulse piping at least 1 in./foot (8 cm/m) upward from the
transmitter toward the process connection.
For gas service, slope the impulse piping at least 1 in./foot (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.
Use impulse piping large enough to avoid friction effects and blockage.
Vent all gas from liquid piping legs.
When using a sealing fluid, fill both piping legs to the same level.
When purging, make the purge connection close to the process taps and purge
through equal lengths of the same size pipe. Avoid purging through the transmitter.
Keep corrosive or hot (above 250 °F [121 °C]) process material out of direct contact
with the sensor module and flanges.
Prevent sediment deposits in the impulse piping.
Maintain equal leg of head pressure on both legs of the impulse piping.
Avoid conditions that might allow process fluid to freeze within the process flange.
Place taps to the side of the line to prevent sediment deposits on the transmitter's
process isolators.
Mount the transmitter beside or below the taps so gases can vent into the process line.
Mount drain/vent valve upward to allow gases to vent.
Place taps in the top or side of the line.
Mount the transmitter beside or above the taps so liquid will drain into the process line.
Place taps to the side of the line.
Mount the transmitter below the taps to ensure that the impulse piping will stay filled
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.
Section 2: Installation
November 2012
Figure 2-8
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