BVT

Wyatt Venturi Tubes
Cast Iron Primary Elements

Features:

  • High Accuracy
  • Reliable Operation
  • Energy Efficient
  • Different Options for a Variety of Applications

Description
The Wyatt VenturiTube is a differential-producing primary flow element that accurately and repeatably measures the flows of liquids or gases in closed, full-pipe conditions. The cast iron Wyatt BVT incorporates an efficient hydraulic shape with static pressure taps in the throat and inlet sections. The BVT can be provided with either 125 or 250 PSI flanges.

Application
The cast iron series is often used in municipal water and wastewater applications. Known for longevity of service with minimal maintenance, BVT meters are ideal for metering potable water, sludge, slurries, as well as gases and clean fluids. The Model BVT-C is uniquely designed for rate-of-flow control applications, while the BVT-S is designed to prevent clog-ging of the pressure taps for appli-cations with solids-bearing fluids.

Flow Measurement Accuracy
For pipe Reynolds numbers greater than 75 000 and with a normalized piping configuration, the Wyatt Venturi Tube provides a flow measurement accuracy of ± 0.50% without flow calibration. With independent flow calibration, Wyatt’s BVTs provide the user with ± 0.25% accuracy.

BVT Technical Specifications

Accuracy

For pipe Reynolds numbers greater than 75 000 and a normalized piping configuration, the Wyatt Venturi Tube provides a flow measurement uncertainty of:

± 0.50% for standard meters and
± 0.25% for flow calibrated meters.

Pressure Loss
The permanent pressure loss of the Wyatt Venturi Tube is shown in Figure 1.

Beta Ratio
Wyatt Venturi Tubes are available with a wide range of diameter ratios (d/D). This provides users with accurate flow measurement over a broad range of flow rates for a given line size.

Temperature Range
Cast iron BVTs can handle process temperatures between -20 °F and +350 °F (-30 °C and +175 °C). Pressure Range/End Connections Flanged end connections per ANSI B16.1 for 125 PSIG and 250 PSIG service are available. A variety of other end connections is also available including: Mechanical joint flanges per AWWA C110 or C111, as well as plain-end designs.

Piping Requirements
Designed for full-pipe flow, BVT flow meters may be mounted either horizontally or vertically. For recommended upstream piping, refer to Wyatt Engineering Technical Manual for the BVT.

Energy Considerations
Figure 1 compares the headloss of the BVT design with that of other primary flow elements. The pressure recovery of the Wyatt Venturi Tube means reduced pumping costs. The Wyatt Venturi has a shorter laying length and exhibits better recovery than typical classical and modified venturi meters.

Design Concepts: The Wyatt Venturi is designed to provide a high degree of accuracy with unquestionable and predictable performance. Key to this design is the following:

Accuracy: Static inlet and throat pressure sensation provides a highly accurate, stable, and predictable flow measurement signal for flow rates with pipe Reynolds numbers as low as
75 000.Reliability: The Wyatt Venturi Tube is free of protrusions and sharp-edged, debris-collecting annuli. Static pressure taps reduce flow noise. The internal contour is designed to minimize the buildup of solids and deter erosion, corrosion, and scaling.

Energy Savings: Wyatt Venturi Tubes operate with minimal headloss. This results in less energy consumption, lower operational costs, and a lower cost of ownership.

BVT Available Options

The cast iron Wyatt Venturi Tube is available in four styles for specific applications.Venturi Tube BVT

Model BVT is a flanged cast iron primary element designed for liquid and gas flow measurement. Typical throat materials are bronze and stainless steel. All valves, except butterfly valves, may be direct-coupled down-stream for control purposes without loss of accuracy. The BVT can be supplied with flanges, mechanical joints, or plain ends. Typical throat materi-als are bronze or stainless steel.

Model BVT-C is a flanged cast iron primary element designed to utilize a butterfly valve for rate-of-flow control in liquid or gas service. The Wyatt Venturi tube is constructed to accept a butterfly valve bolted directly to the downstream flange allowing the BVT-C to be utilized as a rate-of-flow controller. The butterfly valve does not affect the accuracy of the primary element. The meter out-let can be modified to accommodate a valve one or more line sizes smaller than the main piping run.Wyatt Engineering Venturi Tube BVT-SC

Model BVT-S is a flanged primary element designed for wastewater, sludge, slurry, or other fluids with sus-pended solids. Static pressure taps assure stable measure-ment and minimize solids buildup at the tap. Manual vent cleaners are provided as a standard; automatic vent cleaners or a sealed diaphragm system are available as options. An inspection port and water purge systems, either continuous or timed, are also available.

Model BVT-SC is for rate-of-flow controllers used in applications where the line fluid contains suspended solids. The primary element is provided with vent cleaners, sealed diaphragms, or a purge system, and will accept a butterfly valve bolted directly to the downstream flange. This allows the BVT-SC to be used in many applications where other standard venturi or flow tubes cannot be used.Consult your local representative or Wyatt Engineering for information on other materials of construction.

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