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About Differential Pressure (DP) Level Measurement

Industry-leading DP Level solutions deliver increased accuracy and reliability through continuous technology innovation.

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Differential Pressure Level Measurement

Differential Pressure (DP) Level Measurement uses pressure readings and specific gravity to output level. DP Level is a common measurement technique that is used in a wide variety of applications. Solutions include standard transmitter connections and integrated transmitters with direct or remote mount seals that can be configured in tuned, balanced, and electronic systems. Additional Wireless options are also available.

About DP Level Technology

Direct mount and remote mount connections are engineered to meet a wide variety of measurement needs. Direct mount connections offer simple installation for mounting transmitters directly to the vessel eliminating the need for additional transmitter mounting provisions. Remote mount connections consist of a seal attached to a transmitter via capillary tube and are used in tuned or balanced systems, high temperature installations and remote transmitter mounting applications.

Electronic Remote Sensor (ERS™) Systems provide DP Level measurements by calculating differential pressure using two pressure sensors connected by an electrical cable. This solution eliminates the need for long capillaries and heat tracing, cutting response time by up to 90%. Offering accurate measurements for many applications and conditions, such as tall towers, cold climates, and vacuums, ERS Systems can be independently installed and serviced to reduce installation and maintenance costs.

A Rosemount Tuned-System™ Assembly measures level using capillaries with two different lengths connected to a transmitter which allows the system to improve response time and compensate for temperature induced errors. Typically, one side of the system is directly mounted to the vessel and the other is mounted remotely via a capillary tube. This system saves time and cost during installation by eliminating additional transmitter mounting components and is a great solution for applications with short spans and high pressures.

Balanced Systems are a reliable solution which consists of two, equal-length capillaries connected between the transmitter and seals. The system eliminates the maintenance concerns of wet or dry legs and are good for horizontal flow and indoor applications with little to no temperature variations.

Fill Fluid selection significantly impacts the performance of DP Level systems as they can solidify or vaporize due to harsh process environments leading to inaccurate readings.  Many fill fluids are available for different application needs, such as temperatures down to -105 °C (-157 °F) and up to 410 °C (770 °F) and fluids qualified for hygienic applications.

The Diaphragm Seal System protects transmitters from hot, cold, corrosive, erosive or viscous processes. Seals are available with differential, gage and absolute pressure transmitters. Advanced welding and assembly techniques prevent weld corrosion and improve seal strength to deliver reliability and performance in the toughest applications. 

Thermal Range Expander enables pressure and level measurements in high temperature processes. This seal system uses two different fill fluids, extending the operating range of the transmitter from temperatures ranging from -75 °C (-103 °F) to 410 °C (770 °F). With an improved response time of up to 46%, thermal range expanders simplify installation and reduce cost by eliminating impulse piping and heat tracing.

About 1199 Seal Systems

Extreme Temperatures

Emerson is capable of addressing process and ambient temperatures up to 770°F (410°C) and temperatures as low as -75°C (-103°F) with the use of the:

  • Thermal Range Expander

Corrosive Applications

Emerson provides a wide range of diaphragm materials and seal types. With over 20 isolation diaphragm and fill fluid options, Rosemount can meet your needs.

Clogging and Viscous Process

With Rosemount 1199 seal offering, clogging can be prevented using numerous process connection types.

  • Extended Flushed Flange (EFW)
  • Saddle process connection
  • Flushing Ring

Also, discover agitation loss in your process using Rosemount adcanced diagnotics.

Hygienic Applications

Emerson supplies the most complete hygienic seal offering to meet your needs,

  • 10 published hygienic seal types
  • Custom engineered hygienic seals available upon your request
  • FDA grade fill fluids
  • USP and FDA approved O-Ring
  • Improved surface finish options

Published hygienic offering​​​​​​​

Vacuum Applications

Emerson provides all the tools and methods to specifying the right seal solution for vacuum applications.

Step 1: Specify a high temperature fill fluid

Step 2: Specify All-Welded Vacuum Construction for vacuums below 6 psia (200 mmHgA)
Step 3: Mount transmitter at or below the lower tap (3 feet or 1 meter is a rule of thumb)
Step 4: Use Rosemount Instrument Toolkit® software to validate system in your application

Learn more

Video & Case Studies

This video shows how selecting the right technology and fill fluids for cold climates significantly improves the response time of your DP Level measurements. 

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