Rosemount Thermal Range Expander: Proper Use And Applications - Emerson Rosemount 1199 Reference Manual

Remote Seal Systems
May 2020
2.9 Rosemount Thermal Range Expander: proper
use and applications
Figure 2-8: Rosemount Thermal Range Expander
A. Intermediate diaphragm
B. High temperature fill fluid (viscous)
C. Ambient temperature fill fluid
The Rosemount Thermal Range Expander increases the application range where DP Level
technology can be used by expanding the ambient and process temperature ranges of the
system.
Traditional remote seal systems are filled with a single fill fluid to operate in applications
with varying ambient and process conditions. Silicone 704 and 705 are commonly used
fluids for hot process applications going above 570 °F (300 °C); these fluids must be kept
above 32 °F (0 °C) and 68 °F (20 °C), respectively, in order to properly transmit the pressure
signal to the transmitter. This can prove to be difficult for outdoor installations where
extremely cold ambient conditions cause these fill fluids to gel.
The Rosemount Thermal Range Expander is a seal system that uses two different fill fluids
to extend the operating temperature range of the system. A high temperature fill fluid,
which is next to the hot process, is kept warm enough to stay responsive. A second fill
fluid, located on the other side of the intermediate diaphragm, operates over a wide
ambient temperature range. The Rosemount Thermal Range Expander can operate in
ambient temperatures as low as –103 °F (–75 °C), and process temperatures up to 770 °F
(410 °C) and 850 °F (454 °C) design temperature
percent and eliminates the need for mechanical heat tracing.
The Rosemount Thermal Range Expander can be used with any Rosemount 3051S DP
Level configuration including Balanced Systems, Tuned-System Assembles, Electronic
Remote Sensors (ERS), or direct mounted to a transmitter.
(1) UltraTherm 805 supports maximum design temperature of 850 °F (454 °C). Design temperature rating is for non-
continuous use with a cumulative exposure time less of than 12 hours. Continuous use temperature is rated to 770 °F (410
°C).
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Reference Manual
(1)
. This improves response time up to 46
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