Product data

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Rosemount 5300 Series
October 2014
Interface measurements
Considerations
The Rosemount 5302 is a good choice for measuring the interface of oil and water, or other
liquids with significant dielectric differences. It is also possible to measure interfaces with a
Rosemount 5301 in applications where the probe is fully submerged in the liquid.
If interface is to be measured, follow these criteria:
 The dielectric constant of the upper product must be known and should not vary. The Radar
Master software has a built-in dielectric constant calculator to help the user estimate the
upper product dielectric constant.
 The dielectric constant of the upper product must have a smaller dielectric constant than the
lower product.
 The difference between the dielectric constants for the two products must be larger than 6.
 The maximum dielectric constant for the upper product is 8 for the single lead probes, 10 for
the coaxial, and 7 for the twin lead probes.
 The upper product thickness must be larger than 5.1 in. (0.13 m) for all probes, except the
HTHP coaxial probe, which requires 8 in. (0.2 m) to distinguish echoes from the two liquids.
 Sometimes there is an emulsion layer (mix of the products) between the two products which
can affect interface measurements. For guidelines on emulsion situations, consult your local
Emerson Process Management representative.
For information on the maximum allowable product thickness and measuring range, see
“Interface Measuring Range” on page 41.
Interface Measurement
Product Level
Interface Level
Interface Level
5302 5301
Interface Measurement with
fully submerged probe