Emerson Process Management 2051 manual Impulse Piping, Rosemount, Reference Manual

Reference Manual

00809-0200-4101, Rev AA July 2008

Rosemount 2051

Impulse Piping

The piping between the process and the transmitter must accurately transfer the pressure to obtain accurate measurements. There are six possible sources of impulse piping 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./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.

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