Barton 7000 Liquid Turbine Meters

Models 71xx, 72xx, & 73xx

Barton 7000 series liquid turbine meters are designed for a broad range of precise liquid measurement applications. Based on 35 years of turbine manufacturing, this built-to-order series features a range of sizes, materials, bearing systems, and options.

Features

  • Custody transfer quality:
    • ± 1% of reading over linear flow range of fractional size meters
    • ± 0.25% of reading over linear flow range of meters 1-in. size and above.
  • Repeatability:± 0.02% of reading
  • Compact and efficient: Compared to other metering techniques, Barton® turbine meters are able to handle a larger flow rate in a smaller meter and with a lower pressure drop. With the use of reduced diameter block valves and meter runs,substantial installed cost savings are achieved
  • Self-flushing design:Longer sustained accuracy
  • High frequency digital output: Easy interface with digital equipment
  • Wide rangeability: Eliminates parallel runs and the cost of extra valves and strainers
  • Symmetrical bi-directional design: Ideal for reverse flow applications, where flow capacities are the same in either direction. Electronic options provide instantaneous flow direction sensing
  • Wide temperature and pressure ranges: Measurement options for hot hydrocarbon to cryogenic applications
  • High quality bearings: Wear-resistant tungsten carbide sleeve bearings standard on 71xx/ 73xx meters and self-lubricating, precision stainless steel bearings (dry lubricant impregnated ball separators on 72xx meters)
  • Low mass design: The small lightweight rotor hubs both ensure fast response to process flow changes and reduced bearing load and wear. On meters above 2-in. (50 mm) the hub is either hollow or indented to further reduce the rotating mass
  • Low maintenance: True fluid thrust design hydrodynamically balances the rotor during operation and eliminates the need for mechanical thrust leveling. This low-friction design both improves metering linearity and reduces wear and maintenance

Barton 7000 Series Liquid Turbine MetersRotor Design

All components including the rotors in the 7000 series liquid turbine meters are individually fabricated from industrial bar and sheet stock. A range of housing, bearing, blade, shaft and trim, and shrouded bar (73xx series only) materials assures chemical and wear resistance, as well as pressure containment integrity.

Custom rotor blade pitch angles can be specified if specialized flow capacities are required for a particular meter size. In certain circumstances, this can provide tremendous savings by allowing a metering facility to change its capacity without having to incur the cost to change piping, strainers and valves.

The rotors in the Model 7100 and Model 7200 turbines produce a pulse as each blade passes a fixed point on the turbine housing. On the Model 7300, a shroud or rim is fixed to the outer parameter of the rotor blade tips. In addition to adding strength,closely spaced Hi-Mu metal bars (welded into slots in the shroud) produce many more pulses for each rotor revolution. This high-resolution output is ideal for pipeline custody transfer and leak detection systems. This feature is also valuable when testing a large-capacity turbine with a small volume prover, a situation that would otherwise produce only a few pulses during a calibration run.

All Barton rotors are machined to be both balanced and concentric in the meter-housing bore. By ensuring a constant space between the housing and the rotor, meter linearity is improved though a wide range of process fluid viscosities.

Bearing Choice

The maintenance frequency of any turbine is usually determined by the durability of the bearing. In addition to the hydrodynamic effect (see Unique Design section) that significantly extends the life of bearings on Barton turbines, a choice of styles and materials assures a durable meter fit for the purpose.

Barton Models 7100 and 7300 use a two-piece journal sleeve type bearing:

    • Tungsten carbide is the standard bearing material. Due to its very hard nature, it is ideal for slurry applications or where pipe scale, oxides and other abrasives will be present. The two-piece design makes the bearing resistant to damage by mechanical shock that may tend to crack other types of bearings. In applications where the process temperature may exceed 300°F (150°C), one of the two sleeves should be vacuumbrazed in place. This optional technique secures the bearing for use in temperatures in excess of 990°F (530°C). The mechanical tolerances in the tungsten carbide bearing make it suited for temperatures as low as -160°F (-75°C)
    • For non-lubricating services or applications where tungsten carbide is subject to chemical attack, carbon graphite bearings are available for meter sizes 3-in. and smaller. For larger meters, other materials such as Rulon or Silica are optionally available

Barton Model 7200 meters employ oversized twin ball bearings:

  • Suitable for both lubricating and non-lubricating services, these bearings are the preferred choice when the process piping and fluids are free of solids
  • Each bearing is constructed from 440C stainless steel and includes self-lubricating internal components. This standard bearing is suited for temperatures from -440°F to +570°F (-260°C to +300°C) making it appropriate for a wide range of applications including cryogenics

Operation

As liquid passes over the diffuser section (see Figure 1), it is accelerated onto a multi-blade hydrodynamically balanced turbine rotor. The rotor speed is proportional to the volumetric flow rate. As the rotor turns, a reluctance type pickup coil (mounted on the meter) senses the passage of each blade tip and in turn generates a sine wave output (with frequency directly proportional to the flow rate). Additional coils can be added in-phase for metering redundancy and API level “B” fidelity techniques as defined in API MPMS Chapter 5, Section 5. Coils can also be arranged out-of-phase for flow direction sensing.

The pickup coil can drive a variety of instruments including flow rate indicators, totalizers, pre-amplifiers or flow computers/RTUs. Pre-amplifiers are used to transmit the coil signal over extended distances to remote-mounted instruments. All turbine instruments can be direct or remotemounted and are available with intrinsically safe, explosion/ flame proof, or weatherproof approvals.

Barton 7000 Series Liquid Turbine MetersUnique Design

The unique true fluid thrust bearing design eliminates the need for mechanical thrust bearings by nulling the downstream thrust produced by the flowing stream. This is achieved by developing a differential pressure (DP) across the rotor that opposes the flow, where P2 is greater than P1 (See Fig. 1).

This DP, acting upon the hub area of the rotor, generates a force in the upstream direction. This force lifts the rotor from the downstream diffuser and causes the rotor to float between the diffusers.

The turbine is designed to permit axial movement of the rotor along its axis of rotation over a distance L (L = a + b) where the “L”clearance is minimum at the minimum flow rate and maximum at the maximum flow rate. This axial movement of the rotor is used as a servo feedback mechanism to effect a true balance of forces acting on the turbine.

A counter current flow (Vcc) develops in a series of holes drilled in the hub of the rotor. This patented design creates a null balance component that results in a true force balance. The rotor positions itself some distance “L”as a function of flow rate and total imposed drag upon the rotor.

In addition, a secondary counter current flow is produced that flows through the rotor bearings, cooling them and flushing away any foreign particles.

The result is reduced bearing drag, improved bearing life, greater reliability, and higher performance.

Download Barton 7000 Liquid Turbine Meters Specifications (PDF).
 
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