• Measures water level and velocity in partially filled pipes and open channels
  • Works in Irregular Channel Shapes
  • Velocity measurement range: 0.1 to 20 ft/sec and reverse flow to -5 ft/sec
  • Works with water level from 1" to 15 feet
  • Accuracy:
    • Level: ±0.25% of Range
    • Velocity: ±2% of Reading
  • Repeatability and Linearity: ±0.1%
  • No flume or weir required
  • 4-20mA output and 2 control relays for connection to Samplers and SCADA
  • Powered with built-in rechargeable NiMH batteries
  • 2 million point data logger with USB output to flash drives
  • Backlit LCD display for flow rate, totalizer and menu system
  • Simple 5-key Calibration

What's in the Box

  • QZ02L submersible ultrasonic level/velocity sensor
  • 25 ft. shielded tri-coaxial sensor cable
  • Stainless steel sensor mounting bracket
  • Pulsar Greyline Data Logger software for Windows™
  • Installation and operation manual


The Greyline Instruments MantaRay ultrasonic flow meter is a portable instrument designed for flow surveys monitoring stormwater, sewage, industrial effluent, irrigation water and natural streams in open channels, partially filled and surcharged pipes. The MantaRay displays and datalogs flow rate and total flow and connects to samplers, SCADA and telemetry systems.

The MantaRay uses a submerged ultrasonic sensor to continuously measure both velocity and level in the channel. From these measurements, both flow and reverse flow can be calculated. The sensor is a completely sealed ultrasonic unit with no orifices or ports. It is hydrodynamically shaped and designed to shed deposits and stringers for reliable operation in sewage, stormwater and stream flow applications. The QZ02L sensor mounts inside the pipe or at the bottom of an open channel. No special compounds, tools or hardware are required. A stainless steel mounting bracket is included and a size range of optional pipe bands are available for sensor installation in manholes.

The MantaRay has a large, built-in LCD display perfect for realtime viewing of flowrate and total flow. An internal data logger stores up to 2-million data points including level, velocity and water temperature. Pulsar Greyline Logger software is included with each MantaRay. Use this powerful program to open and view data log files in graph and table formats. You can generate flow reports with minimum, maximum average and total flow or export the data to Excel spreadsheets and database programs. 4-20mA output and two control relays allow users to connect to to samplers or SCADA and telemetry systems. Flow log files can be downloaded to a USB memory stick.

The MantaRay's built-in, rechargeable batteries power the flow meter. You can also connect external 12 or 24VDC batteries to extend the MantaRay's operating time indefinitely. Or connect the battery charger (supplied) for continuous operation with 4-20mA and relay operation. For reduced power consumption during flow surveys you can activate the MantaRay's "sleep mode" to conserve energy for extended operation.


This product can be used in the following applications: