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Mechanical Innovation Opens New Horizons For Pressure Measurement From Rosemount
Oct 12, 2019

With the rapid development of digital technology, all of Emerson's mechanical innovations over the years have ensured that the pressure measurement solutions offered are superior to ever before, and are also easier to design, manufacture, install and maintain. The early success of the Rosemount 1151 Pressure Transmitter stemmed from a dedication to building accurate, rugged, and stable sensors. But in the 1970s, sales of Rosemount 1151 soared, prompting the company's engineers to target a wider range of applications aimed at driving the spread of technology.

For example, applying a conventional orifice primary flow element for differential pressure (DP) flow measurement produces significant pressure loss, which means energy is wasted. Such applications also require longer straight tubes, which complicates the installation. In differential pressure flow and level measurement applications, a long list of fittings, piping, heat traces, and other parts complicates the solution, making design and manufacturing and field assembly difficult and prone to process leaks.

Pressure loss problem?

Emerson discovered the key to solving the pressure loss problem with the “Arkaba Flow Solution”, the first-speed pacing primary flow element first introduced in the early 1970s. The original Annubar flowmeter has a tubular probe that is inserted into a tube and penetrates its diameter, with openings along the upstream and downstream faces of the probe. Accurate flow rate calculation based on differential pressure between upstream and downstream ports – eliminates the higher permanent energy losses of other flow meter technologies.

Emerson acquired Dieterich Standard, the original creator of the Annuuba primary component, and continues to innovate on the basis of the original. In its fifth-generation design (pictured), the current Rosemount Annubar primary component includes an innovative upstream slot for a more comprehensive average, while the sensor's T-design creates a larger back. Stall area to reduce noise. The current model can also specify an integrated thermowell with a single tube penetration to obtain fully compensated real-time mass, volume and energy flow rate information. The product can even be installed with a pressurized opening without shutting down the line and can be installed on pipes up to 96 inches (2400 mm) in diameter.

The permanent pressure loss caused by the Annubar primary component to any flow measuring device, including venturi flowmeters, wedge flowmeters, turbine flowmeters, V-cone flowmeters, and orifice/nozzle flowmeters, is low. Lower pressure losses mean less pumping/compression costs, increased capacity, and lower capital costs to the point of cost of purchasing smaller compressors, pumps or boilers. Lower pressure loss also means that the flow through the existing pipeline increases and the throughput of the gravity feed system can also increase.


Straight pipe length limitation?

It is always challenging to achieve constant pressure measurements that truly represent the complete flow profile within the pipeline. For accurate measurement, a conventional orifice differential pressure flow meter (with a sharp circular hole in the center of the plate) has a long straight tube upstream and downstream for accurate flow measurement. This additional straight tube requires a diameter of 40 or more, which increases the installation cost and space requirements of the flow meter. Rectifiers are sometimes used to provide more constant flow rates with shorter straight tubes, but adding another component (and potential leak points) means increased cost and installation complexity.

Emerson engineers turned their attention to this long-standing fluid mechanical challenge and invented the tuned orifices—four holes instead of one (Figure) on the orifice plate, which greatly reduced the length of the straight tube and reduced 90%. The Rosemount 1595 Adjustable Orifice Plate, introduced in 2003, also increases accuracy by 30%, marking a key breakthrough in flow measurement for differential pressure transmitters for a wider range of applications.


From transmitter to solution

Another important way Emerson can increase the appeal of its pressure measurement solutions is to work together to reduce the complexity of their applications. The “Humanistic Design (HCD) principle, now officially implemented throughout the company, begins with an in-depth understanding of how customers design, purchase and implement on-site installation and maintenance, and strive to reduce complexity throughout the lifecycle.


The Rosemount 3051 Pressure Transmitter for Differential Pressure Flow and Level Measurements allows for smaller, lighter, and easier installations with a unique 50% potential leak through its unique patented Rosemount CoplanarTM connection platform point. It also delivers complete measurement solutions for the plant (including integrated primary components for differential pressure flow measurement applications, instrumentation manifolds for pressure measurement applications, and diaphragm seal assemblies for differential pressure level measurement applications) Paved the way. For example, the Rosemount 405 Series Compact Differential Pressure Flowmeter unifies and simplifies the design and installation of the Annubar flowmeter, orifice and adjustable orifice primary component technology.

In terms of specifications, ordering and installation, a single, seamless process reduces risk and reduces lead times and reduces total acquisition costs by as much as 55%. The flowmeter is fully assembled and factory tested for leaks and ready for installation. The addition of an integrated thermowell for temperature measurement reduces the need for pipe drilling to a lower level. Eliminating the use of a pressure tube can reduce potential leaks by 80%. The integrated centering mechanism for the compact solution ensures that the mechanism is properly installed in the pipeline in accordance with ANSI/API guidelines.

Similarly, in the field of differential pressure level measurement, Emerson's Electronic Remote Sensor (ERS)TM system electronically calculates the differential pressure using two pressure sensors connected together by a power cable instead of a mechanical component. This allows the system to provide faster response and eliminates the need for impulse piping and capillaries, fittings, heat traces and other external components, and potentially maintenance-intensive components. In addition, the Tuned SystemTM assembly eliminates the need for excess capillary and oil - reducing response time by 80% and reducing temperature drift by 20%.