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The Doppler Clamp-on and Open Channel Flow Metering Technique

Introduction

•Principle of operation.

•Modes of operation.

• Installation guidelines.

 

v = is the speed of waves in the medium

vs = is the velocity of the source

Approximate relationship between fluid velocity and measured time. Does not include clamp on transducer delays.

The general principle of Doppler flow measurement.

Doppler Flow Measurement

• Continuous frequency is transmitted

• Sound bounces off gas bubbles or particles in the fluid• Reflected sound returns at an altered frequency

How it Works:

Doppler Flow Technology

• Doppler Transmit

• Doppler Receive

• Doppler Shift

Modes of operation

• - Single head Transmit and

Receive Crystals in same Head

• - Dual-Head Transmit and

Receive Crystals in separate Heads

Installation guidelines

•Transducer positioning.

• Flow profiles

COUPLINGCOMPOUND

Doppler Sensor Coupling

PIPESENSOR

COMPOUND

CLAMP

RUBBER PAD

Doppler Sensor Mounting

Doppler Sensor Mounting

Doppler Sensor MountingAvoid Turbulent Flow

• Locate the Doppler Sensor 6 to 10 pipe diameters from Pipe Elbows or Tees

• Avoid highly Turbulent Flow locations

FLO W

Doppler Sensor MountingAvoid Laminar Flow

• Viscous or solids-bearing liquids develop a laminar profile

• Take readings at several locations and mount Sensor where flow is evenly distributed

Doppler Sensor MountingAvoid Velocity-Increasing Devices

• Locate the Doppler Sensor 25 to 40 Pipe Diameters from Pumps, Controlling Valves, Orifice Plates, Pipe Discharges or any other Velocity-Increasing Devices

25 - 40 Pipe Diameters

PUMP

Doppler Sensor MountingAvoid Flow in Branch Lines

• Doppler ultrasonic signals can travel long distances in clean, non-aerated liquids

• Mount the Doppler Sensor 25 to 50 diameters from branch lines with flow

Summary

•Principle of operation.

•Modes of operation.

• Installation guidelines.