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Open Channel Flow Meters
Models BFM001 & BFM002


Open Channel Flow Meters
Models BFM001 & BFM002

Model BFM001
Model BFM001 Model BFM002
Model BFM002 BFM002
BFM002 Wading Set 0012B
Model 0012B Universal Impeller Control Display Unit BFM001
BFM001 Suspension Set FEATURES APPLICATIONS
  • Rugged, low maintenance design
  • Reliable, accurate velocity sensing
  • Wide measuring range
  • Simple in operation
  • Calibrated in accordance with BS3680
  • Stream river gauging
  • Open channel flow
  • Hydrometric studies
  • INTRODUCTION

    The BFM001 & BFM002 Open Channel Flow Meters have been manufactured for over 25 years (formerly under the trade name "Braystoke"), and they are still among our most popular instruments today. Both instruments benefit from the design of impellers and bearings, which give low threshold velocity and consistent performance. In addition the impeller hub design prevents silt and weed entering the bearings, making them suitable for use in a wide variety of environments, including salt water, fresh and effluent water, from shallow streams to tidal waterways. This versatility, their simple yet rugged construction, and their compatibility with the Model 0012B Universal Impeller Control Display Units, make the BFM001 & BFM002 invaluable tools for hydrometric work.

    DESCRIPTION

    The BFM001 & BFM002 are both fitted with a high impact styrene, neutrally buoyant impeller with a jewelled main thrust bearing and PTFE radial guides running on a stainless steel shaft. Durability is achieved using a black Acetal body designed to withstand long periods of operation in silt laden water.

    The principal of operation of the BFM001 and BFM002 is that rotation of the impeller causes magnets mounted in the impeller hub to open and close a reed witch, thus generating pulses. The reed switch contact is housed within a sealed, watertight, quick release adapter, which screws into the end of the signal cable.

    Both BFM001 and 002 may be used with wading rods, hand suspended or with a cableway system. Each wading set contains three 50cm wading rods which are engraved in centimetres and colour coded for 1cm, 5cm and 10cm. The suspension set contains a 35m cable and hanger bar for suspending a sinker weight if necessary. Both systems are supplied with a real time revolution counting control unit, the Model BFM0012B.

    MODEL 0012B

    All of the systems detailed here are supplied as standard with the Model 0012B Universal Impeller Control Display Unit. This unit offers real time and averaged display of velocity and data confidence level for all contact closure current meters, including those of other manufacturers, and is capable of storing calibration coefficients for up to 10 different meters. A data logging facility is also available.

    The display is an LCD Graphics display, with optional backlight. Sealed to IP67 and weighing less than 2kg, it is suitable for all conditions and is a powerful tool in the monitoring of current flow.

    CALIBRATION

    DEFINITION

    The 8011 Series impeller fitted to the BFM001 and the 1178 Series impeller BFM002 have both been group calibrated by HR Wallingford, UK to British Standard BS3680, Part A, 1973. This means that impellers can be changed at any time without the need for recalibration. The group calibration of the 8011 impeller is accurate to 1.5% of measured velocity, and the 1178 impeller to 2.5%. Specific calibration of any impeller can be arranged at HR Wallingford, if necessary.

    ORDERING INFORMATION

    Both the BFM001 and BFM002 may be used with wading rods, hand suspended, or with a cableway system. Each wading set contains three 50cm stainless steel wading rods, which are engraved in centimetres and colour coded for 1cm, 5cm and 10cm. The suspension set contains a 35m cable and hanger bar for suspending a sinker weight if necessary. Both systems are supplied with a real time velocity control display unit, the model 0012B.

    Items may be ordered by their individual part numbers , but the following sets are standard configurations:

    0001001 BFM001 Wading Set, comprising Flow Meter with 125mm diameter impeller, Model 0012B Control Display Unit, 3 x 0.5m stainless steel wading rods (graduated in cm, complete with base plate and direction knob), 2m wading cable carrying case, and operating manual.

    0002001 BFM002 Wading Set. As above, except Flow Meter has 50mm diameter impeller.

    0001002 BFM001 Suspension Set, comprising Flow Meter with 125mm diameter impeller, Model 0012B Control Display Unit, 35m suspension cable, 0.75m tail fin, suspension bar, carrying case and operating manual.

    0002002 BFM002 Suspension Set. As above, except Flow Meter has 50mm diameter impeller.

    0001003 BFM001 Conversion Kit, for converting a wading set to a suspension set, comprising 35m suspension cable, 0.75m tail fin, suspension bar and carrying case.

    0002003 BFM002 Conversion Kit. As above, except 35m suspension cable is for use with BFM002.

    SPECIFICATIONS

    Model

    Velocity Range

    Accuracy

    Impeller

    BFM001

    0.03 to 10 m/sec

    ± 1.5% reading above 0.15 m/sec

    ± 0.004 m/sec below 0.15 m/sec

    125mm diameter by 0.27m pitch

    BFM002

    0.046 to 5 m/sec

    ± 2.5% reading above 0.5 m/sec

    ± 0.01 m/sec below 0.5 m/sec

    50mm diameter by 0.10m pitch