Rosemount 585 Annubar Primary Element

Rosemount 585 Annubar Primary Element

Introduction

In severe service applications—where process temperatures exceed 1000°F, pressures climb above 2500 pounds per square inch, and flow direction may reverse without warning—conventional flow measurement technologies quickly reach their performance limits. Orifice plates cannot withstand sustained high temperatures. Standard averaging pitot tubes lack bidirectional measurement capability. And full-bore meters at large line sizes impose prohibitive capital costs.

The Emerson Rosemount 585 Annubar Primary Element directly addresses these extreme demands. Designed specifically for severe service applications, this averaging pitot tube combines the proven energy efficiency of Annubar technology with high-temperature materials, a symmetrical bidirectional sensor profile, and Flo-Tap mounting for installation and removal under full line pressure. This technical datasheet provides comprehensive specifications and application guidance for engineers requiring flow measurement in the harshest industrial environments.

What Is the Rosemount 585 Annubar Primary Element?

The Rosemount 585 Annubar is a severe-service averaging pitot tube designed for volumetric flow measurement of gases, steam, and liquids under extreme process conditions. It is a member of the Rosemount Annubar family, which includes the Rosemount 485 Annubar Primary Element (general industrial with multivariable measurement), the Rosemount 486 Annubar Primary Element (general industrial averaging pitot tube), and the Rosemount 585 (severe service, high temperature, bidirectional).

Unlike standard averaging pitot tubes that use directional T-shaped sensors, the 585 features a symmetrical sensor design. This geometry allows the 585 Annubar to measure flow in both forward and reverse directions with consistent accuracy, eliminating the need for two separate flowmeter assemblies when bidirectional measurement is required.

The 585 Annubar is manufactured with solid sensor construction that removes structural welds from the process flow path, maximizing mechanical strength and eliminating potential failure points under high thermal cycling. The sensor is available in multiple high-temperature alloys and supports both direct-mount and remote-mount transmitter configurations, including the Rosemount 3051S, 3051S MultiVariable, 4088 MultiVariable, and 2051 pressure transmitter platforms.

The complete 585 flowmeter system consists of the Annubar primary element integrated with a Rosemount pressure transmitter. Factory-assembled configurations include the 585 Annubar Primary Element paired with the 3051SFA Annubar Flowmeter or the 3051CFA Annubar Flowmeter, with each system leak-tested and calibrated prior to shipment.

Key Technical Specifications

The following specifications define the operating envelope and performance capabilities of the Rosemount 585 Annubar Primary Element.

General Specifications

The 585 Annubar provides a 10:1 flow turndown ratio as standard. For applications requiring wider turndown, the flowmeter system can be configured with the Rosemount 3051S MultiVariable transmitter, which offers up to 200:1 rangedown capability.

Pressure and Temperature Limits

The 585 Annubar achieves a maximum process temperature of 1500°F (815°C) when constructed with Alloy 800H wetted materials. For main steam line applications specifically, the sensor can be configured with Chrome-Moly Grade F-11 mounting materials for service up to 1200°F.

Pressure Rating Details

The 585 Annubar Primary Element is rated to ANSI B16.5 Class 2500#. This pressure class corresponds to the following maximum allowable working pressures:

2500# flange rating at 100°F: 6000 psig (413.7 bar)

2500# flange rating at 500°F: 5535 psig (381.7 bar)

2500# flange rating at 750°F: 4965 psig (342.3 bar)

2500# flange rating at 1000°F: 3720 psig (256.5 bar)

Wetted Materials

The Rosemount 585 Annubar is available in multiple material options to accommodate diverse severe service environments:

The solid sensor construction eliminates structural welds within the process flow, ensuring maximum material integrity under sustained high-temperature operation. For main steam line applications, mounting assembly material options include Chrome-Moly Grade F-11 for compatibility with high-pressure steam piping.

Accuracy Performance

The 585 Annubar achieves these accuracy specifications when installed with proper upstream and downstream straight-run conditions. For applications requiring enhanced mass flow accuracy, the Rosemount 3051S MultiVariable transmitter integrates differential pressure, static pressure, and temperature measurement through a single process penetration, delivering fully compensated mass flow with a ±0.04% of reading accuracy for the flow calculation.

Key Features and Design Advantages

Symmetrical Sensor Design for Bidirectional Flow Measurement

The defining characteristic of the Rosemount 585 Annubar is its symmetrical sensor geometry. Engineered specifically for applications where flow direction may reverse—such as flare gas recovery systems, reversing steam lines, and certain chemical processes—the symmetrical design measures flow accurately in both forward and reverse directions with a single flowmeter assembly. This eliminates the need for two separate flowmeter installations, reducing capital costs, installation labor, and maintenance requirements.

The 585 sensor also includes a symmetrical design for bi-directional flow measurements, providing application flexibility in processes where reverse flow occurs during normal operations or upset conditions. Unlike the directional T-shaped sensors used in the 485 and 486 models, the 585 Annubar can be installed without concern for flow direction labeling.

Solid Sensor Construction for High-Temperature Integrity

The 585 Annubar Primary Element is manufactured with solid sensor construction that removes structural welds from the process flow. This design approach eliminates weld joints as potential failure points under the thermal cycling and mechanical stress characteristic of severe service applications. The result is a primary element with exceptional durability and reliability in main steam lines, superheated gas pipelines, and high-temperature chemical reactors.

Flo-Tap Mounting for Installation Under Pressure

The Rosemount 585 Annubar is available with Flanged Flo-Tap mounting, which enables installation, retraction, and removal without process shutdown. The Flo-Tap assembly can be hot-tapped while the line remains pressurized, allowing flow measurement points to be added without interrupting production. This feature is particularly valuable in refinery, petrochemical, and power generation applications where process downtime carries substantial economic penalties.

The Flo-Tap mechanism uses a gear-assisted mechanism to retract and insert the sensor under pressure. Key steps in the Flo-Tap installation process include:

Welding the mounting hardware to the process pipe

Installing the isolation valve onto the mounting flange

Mounting the drilling machine and drilling the hole through the pipe wall

Removing the drilling machine and installing the Flo-Tap assembly

The 585 Flanged Flo-Tap Annubar is specifically designed for insertion and retraction when the line is pressurized, with no need to depressurize the line for removal. Installation can be completed in less than three hours under typical field conditions.

Lightweight Design at Large Line Sizes

At larger pipe diameters, the 585 Annubar’s insertion design offers substantial weight and cost advantages over full-bore flow meters. A 96-inch Annubar primary element weighs a fraction of an equivalent spool-piece flow meter, reducing shipping costs, installation labor, and structural support requirements. This lightweight design provides a cost-effective primary element solution for large-diameter pipelines common in power generation and refining applications.

Minimal Permanent Pressure Loss

Like all Annubar averaging pitot tubes, the 585 generates significantly lower permanent pressure loss compared to orifice plates, venturis, or other constriction-based DP flow meters. This low pressure drop translates directly into energy savings: reduced compressor work for gases, lower pumping power for liquids, and decreased fuel consumption for steam generation. Over the life of a large steam line or gas pipeline, these energy savings can substantially exceed the initial capital cost of the flowmeter.

Wide Range of Mounting Options

The Rosemount 585 Annubar supports multiple mounting configurations:

Flanged Flo-Tap — For installation and removal under pressure

Direct mount — Transmitter mounts directly to the Annubar primary element

Remote mount — Transmitter mounted separately for high-temperature isolation

Compact design — Installs between raised-face flanges

For main steam line applications, the 585 Annubar can be configured with opposite-side support and an alignment bar for proper sensor positioning. The sensor should be located in the bottom half of the pipe for steam service to ensure proper condensate drainage, with mounting at 45 to 75 degrees above horizontal.

Integral Temperature Measurement (with MultiVariable Transmitter)

When combined with the Rosemount 3051S MultiVariable transmitter, the 585 Annubar system provides differential pressure, static pressure, and temperature measurement through a single process penetration. This eliminates the need for separate thermowell installations, reducing pipe penetrations and potential leak points. The MultiVariable transmitter updates 22 times per second and supports RTD removal without process shutdown.

Transmitter Integration Options

The 585 Annubar Primary Element can be integrated with several Rosemount transmitter platforms:

Each transmitter supports HART, WirelessHART, Foundation Fieldbus, Modbus, or PROFIBUS communication protocols, enabling integration into existing DCS, PLC, and SCADA architectures.

Installation Guidelines

Straight Pipe Requirements

To achieve specified accuracy, the 585 Annubar requires the following minimum straight-run lengths:

Sensor Positioning for Steam Service

For steam applications, proper sensor orientation is critical. The Rosemount Annubar should be mounted 45 to 75 degrees above horizontal to allow condensate to drain efficiently back into the process pipe. The sensor should be located in the bottom half of the pipe. The flow arrow on the sensor head must be aligned with the direction of flow using the supplied gaskets and flange bolts.

Flo-Tap Installation

For the Flanged Flo-Tap configuration, alignment of the flow arrow on the head with the direction of flow is the first step. The Flo-Tap assembly is then fastened to the isolation valve using supplied gaskets and flange bolts, with nuts tightened in a cross pattern to compress the gasket evenly.

Top Mounting Recommendation

For steam applications, top mounting of DP flowmeters is recommended to prevent condensate accumulation in impulse lines. The 585 Annubar with remote mount transmitter configuration allows the transmitter to be positioned above the pipe for optimal condensate drainage.

Comparison: Rosemount 485 vs. 486 vs. 585

Within the Rosemount Annubar product family, three primary models serve distinct application needs:

Comparison: Rosemount 585 vs. Other Flow Meter Technologies

Industry Applications

The Emerson Rosemount 585 Annubar Primary Element is suitable for severe service flow measurement across demanding industries:

Ordering Information

The Rosemount 585 Annubar Primary Element is configured based on specific application parameters. A Configuration Data Sheet must be completed prior to order for application verification and sensor sizing.

Key ordering parameters include:

Line size — 4 to 96 inches (100 to 2400 mm)

Process fluid — Liquid, gas, or steam with complete properties

Operating pressure and temperature — Minimum, normal, maximum (especially maximum temperature for material selection)

Flow rate range — Minimum, normal, maximum flow rates

Pipe schedule/wall thickness

Mounting type — Flanged Flo-Tap, direct mount, remote mount, compact

Process connection — Flanged, threaded, weld-in

Wetted material — 316/316L SS, Alloy C-276, Alloy 800H

Mounting assembly material — Carbon Steel (A105), 316/316L Stainless Steel, Carbon Steel (A350 LF2), Chrome-Moly Grade F-11 (for main steam)

Transmitter integration — 3051S, 3051S MultiVariable, 4088 MultiVariable, 3051C, 2051, or customer-supplied

Frequently Asked Questions

Q: What is the maximum temperature for the Rosemount 585 Annubar?

A: The 585 Annubar Primary Element is rated for process temperatures up to 1500°F (815°C) when constructed with Alloy 800H wetted materials. For main steam line applications, service up to 1200°F (649°C) is recommended with Chrome-Moly Grade F-11 mounting materials.

Q: Can the Rosemount 585 measure bidirectional flow?

A: Yes. The 585 features a symmetrical sensor design specifically engineered for bi-directional flow measurements, eliminating the need for two flowmeter assemblies.

Q: Can the 585 Annubar be installed without process shutdown?

A: Yes. The Flanged Flo-Tap configuration enables hot-tap installation, insertion, and retraction under full line pressure without interrupting process flow.

Q: What is the minimum line size for the 585 Annubar?

A: The Rosemount 585 Annubar supports line sizes from 4 inches (100 mm) up to 96 inches (2400 mm).

Q: How does the 585 differ from the 485 Annubar?

A: The 585 offers higher temperature capability (1500°F vs. 850°F), symmetrical bidirectional sensor design, and solid sensor construction without structural welds. The 485 provides integral temperature measurement as standard but is limited to 850°F maximum.

Q: What transmitter should I use with the 585 Annubar for mass flow measurement?

A: For fully compensated mass flow measurement, the Rosemount 3051S MultiVariable transmitter integrates differential pressure, static pressure, and temperature measurement through a single process penetration.

Q: Is the 585 Annubar suitable for superheated steam?

A: Yes. The 585 Annubar is specifically engineered for main steam line applications, including superheated steam up to 1200°F.

Q: Does the 585 Annubar require conductive fluids?

A: No. Unlike magnetic flow meters, the 585 Annubar can measure any fluid—conductive or non-conductive—including gases, steam, hydrocarbons, and non-conductive liquids.

Q: What is the recommended calibration interval?

A: Under normal severe service operating conditions with clean fluids, calibration intervals of up to 10 years are achievable. For steam or erosive applications, more frequent verification may be required.