Emerson 350, 250 operation manual Transmitter with a Stilling-well

A stilling well may be used along with the transmitter inside the tank. Stilling-well is a pipe external to the sensor probe and float encasing the entire assembly protecting it from surface agitation or from physical damage due to the length of the sensor probe. A depiction of a transmitter with a stilling well is provided below.

Optional Features that are available with the LTM-350 but NOT the LTM-250are:

1.HART Protocol, which enables:

a.A second digital output proportional to an interface level (requires a second float of different specific gravity)

b.A digital temperature output that reflects the liquid temperature.

c.Advanced diagnostics and features highly beneficial for commissioning, troubleshooting or monitoring.

Up to two floats may be used with the LTM-350 only. The second float will typically sense the interface level (the heavier of the two fluids) in the tank. The specific gravity of the second float will be such that it can be totally immersed in the lighter fluid. The drawing below shows a transmitter with dual floats, one for total level and the other for interface level (also available with various process connections).

Figure 4. Transmitter with a Stilling-well

When a stilling well is used, care should be exercised when installing the tube to center it in the chamber so that the float can freely travel the entire length of the probe. Stilling wells are required for transmitters over 10 feet or the instrument cannot be considered under warranty.

Figure 5. Dual Output Transmitter

A dual output transmitter is also available in a gage mount configuration. Consult factory for further details.