Compact Fixed AV-FlowMeter

Code: FS001

Specify language: English, French, Spanish, Italian, Portuguese

High performance fixed installation Area Velocity flowmeter with a feature set designed for basic open channel and part-filled pipe applications.

This product operates with:

  • Level Sensor standard 10 metre length (varying lengths available upon application) Code: P7001
  • Velocity Sensor standard 10 metre length (varying lengths available upon application) Code:VP002
  • Comms Cable (USB or RS232)
  • Software
  • User Manual


COMPACT Fixed AV-Flowmeter with Velocity and Level Sensor
COMPACT Fixed AV-Flowmeter with Velocity and Level Sensor COMPACT Fixed AV-Flowmeter with Velocity and Level Sensor Enlarge
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system details

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  • Benefits & Features
  • Measurement Principles
  • Product Features
  • Product Hardware
  • Powerful, easy to use PC software simplifies transmitter commissioning
  • Quick to install – no weirs or flumes
  • Velocity measurement from 10mm/S up to 5m/S
  • High sensitivity extends applications to ‘clean’ water
  • Streamlined velocity probe eliminates fouling and reduces flow disturbances
  • High capacity data logger in excess of 1 year when recording at 1 minute intervals; emulates the familiar PC file system
  • 4 M-byte data logger memory is non-volatile (FLASH) giving 20 years data retention without power
  • Real-time processing of velocity signals thereby reducing power consumption
  • Smart power saving mode – intelligent use of power saving which automatically reduces the measurement time for high flow velocities and high signal qualities and increases the measurement time for low velocities and low signal qualities
  • Sophisticated ultrasound processing ignores spurious signals
  • Ultrasound signal quality monitor confirms measurement integrity
  • Specified (constant) silt level taken into account in area calculation
  • Velocity correction factor calibration
  • Automatic recording of velocity signals and histograms for use in performance monitoring or reports
  • Distances up to 500 m from system unit to velocity and level sensor. 300 m for ATEX velocity and level sensor
  • Opto-isolated switch outputs for alarms and controls

Mainstream uses the area-velocity method to give a continuous or time sample measurement of fluid flow.  Mainstream uses a streamlined probe that operates immersed in the flowing liquid. The velocity probe transmits utrasound into the liquid to create a zone of inspection. Bubbles and solid particles carried through this zone by the flow, even when present in only minute quantities, reflect ultrasound back to the probe. Only high quality signals containing verified velocity information is used, thereby ensuring measurement integrity.

This measured frequency shift in the ultrasound signals gives flow velocity.  The verified velocity signals produce a histogram of the flow velocities.  Analysing this histogram gives the mean flow velocity.

Liquid level is measured by a submerged  pressure transmitter or ultrasonic sensor.  The flow cross-sectional area is deduced from the liquid level measurement and the stored description of  the channel or pipe cross section.  The flow rate is the flow velocity multiplied by the flow cross-sectional area.


Transducer Type: Any 4:20 mA current loop level sensor
Method : Pulse activation with configurable sensor warm-up time. Loop current measurement by self-calibrating 16-bit delta-sigma A-D converter
Current Range : 0-30 mA
Resolution : Better than 1 µA
Transducer Calibration : Calibration table (maximum 23 points) with built-in interpolator converts loop current into level measurement. Simple transducer calibration tool included in UI software
Interchangeability : Transducers and calibration data directly interchangeable between Mainstream system units


Transducer Type: Submerged ultrasonic sensor containing signal generator, transmitter, receiver and decoder electronics
Method : Phase Coherence time delay measurement determines the time for tracers carried by the flow to travel a fixed distance (~ 0.75 mm)
Velocity Range : -5 m/s to -10 mm/s and 10 mm/s to 5 m/s
Resolution : Better than 1 mm/s
Measurement Integrity : Ultrasound signal quality monitor gives the percentage of the measurement time that the received ultrasound signal contains useful velocity information
Smart Power Saving : Each velocity measurement is based on the same quantity of information. Automatically reduces the measurement time for high flow velocities and high signal qualities and increases the measurement time for low velocities and low signal qualities


Area : Flow cross-sectional area calculated from the level measurement and the dimensions of the pipe or channel. Calculation can take into account a specified (constant) silt level. Flow cross-section specification tools included in UI software
Flow Rate : Fluid flow rate calculated by multiplying cross-sectional area by flow velocity. Level-to-flow configuration tool included in UI software
Flow Quantity : Three independent flow totalisers calculate forward only, reverse only, and forward-reverse flow quantities. Each totaliser uses separate elements to accumulate hour quantity and total quantity to prevent round-off errors


Power Inputs : Connectors for external 12V and 24V supplies
External 12V supply : Connection for external 12V
External 24V supply : Connection for external 24V (required if using 4:20mA output)
Power Supply Monitor : Power monitoring circuits track supply status. Supply voltages can be displayed on LCD, viewed via the UI, stored in the data logger, and used to control switch outputs


File System : Flash file system with 4 Mbyte capacity and data retention of 20 years
File Content : Configurable to record any combination of power supply voltages, level sensor loop current, level, area, ultrasound signal quality, velocity and flow rate, plus forward, reverse and total flow quantities
Recording Mode : Proprietary data compression algorithm for extended logger capacity and rapid data retrieval
Recording Interval : Configurable from 15 seconds to 1 hour
Data Capacity : Logger holds more than one year of data when recording all available measurements at one minute intervals
Retrieval Time : Less than 15 seconds to retrieve one month’s data recorded at 1 minute intervals. File synchronization capability for fast update of previously retrieved data files
Retrieved Data Format : Spreadsheet compatible .csv file with country specific caption text and date/time format for analysis and reports. Flash file image file including complete flowmeter configuration for data archives


Local : RS232 and USB compatible interface with automatic baud rate detection. Supports 1200, 2400, 4800, 9600, 14400, 19200, 38400, 57600 and 115200 baud
Remote : Optional external SDI or MODBUS adapter
Software : Mainstream Communicator UI software for system configuration, diagnostics, real- time measurement display and data retrieval. Mainstream Communicator runs on PC platforms under Windows 2000, XP, Vista, 7, 8, 8.1 and 10 with data transmission from device to PC, for data control, processing and export


Reset Switch : Push to Reset LCD display
LCD : Two line x 16 character LCD. Automatic activation when integral light sensor detects enclosure is open. Configurable display sequence includes date, time, and any combination of measurement data. Country specific caption text and date/time format


Linear (pipe and channel dimensions): Selectable from mm, cm, m, in, ft
Level : Selectable from mm, cm, m, in, ft
Area : Selectable from m2, cm2, mm2, in2, ft2
Velocity : Selectable from mm/s, cm/s, m/s, in/s, ft/s, ft/min
Flow Rate : Selectable from l/s, m3/s, ft3/s, igal/s, USG/s, l/min, m3/min, ft3/min, igal/min, USG/min, m3/h, ft3/h, m3/d, Ml/d.
Quantity : Selectable from l, m3, Ml, ft3, igal, USG
Display Format : Independently configurable display format for each measurement. Options are integer, fixed point with 1 to 6 decimal places, and scientific (E-format). Display defaults to scientific format if data cannot be correctly represented in selected format


Hardware : Two opto-isolated switches rated at 60V ac/dc and 200 mA maximum current. Each switch independently configurable for state output or pulse output operation
State Output : Switch configurable to respond to any item of measured data with separate switch open and switch close settings to provide hysterisis. Applications include power supply monitoring and control, low ultrasound signal quality indication and level, velocity and flow alarms
Pulse Output : Switch configurable to generate a 2.5 second duration switch closure to indicate a defined flow quantity. Flow totaliser can be forward only, reverse only, or forward- reverse. Applications include sampler control and remote flow totaliser operation
4:20mA Outputs : One 4:20 mA output. Configurable to selected measurands


Materials : Titanium, acetal and polyurethane
Dimensions : 185 mm long x 17.5 mm diameter
Cable : 8 mm diameter vented polyurethane cable with Kevlar strain cord
Weight : 1 kg including standard 10 m cable length
Level Range : 0 to 2 m working. Maximum 8m overrange
Resolution : Better than 1mm
Combined Accuracy : Combined effects of non-linearity, hysterisis and repeatability better than 0.25% best straight line. Non-linearity and offsets removed by transducer calibration
Environmental Protection : Fully encapsulated to IP68
Operating Temperature : -20°C to 60°C (temperature compensated 2°C to 30°C)


Materials : Streamlined µPVC moulding and polyurethane cable
Dimensions : 105 mm long x 50 mm wide x 20 mm high
Cable : 8 mm diameter polyurethane cable with Aramid strain cord. Breaking load 45 kg. Minimum static bend radius 52 mm
Weight : 1 kg including standard 10 m cable length
Maximum Cable Length : 500 m; 300 m for ATEX
Environmental Protection : Totally encapsulated to IP 68
Operating Temperature : -10°C to 80°C
Minimum Operating Depth : 30 mm


Materials : Ultra high cast Aluminum housing
Dimensions : 220 mm wide x 120 mm deep x 80 mm high
Weight : 1.9 kg
Environmental Protection : Enclosure is IP67. Electronic assembly is encapsulated to IP68
Operating Temperature : -10°C to 70°C

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