Flow - Liquids

Flow measuring of liquids is needed in many industries and in certain applications accurate flow measurement is so important that it can make the difference between profit and loss. Flow is classified into open channel flow and closed conduit flow. Most devices measure flow indirectly and are commonly divided into those that sense or measure velocity and those that measure pressure or head.

The controllers/indicators that Sigma offers are from the first category and are further subdivided in to impeller, electromagnetic, ultrasonic, calorimetric, and micro wave.

flow measuring systems using impeller sensors

200 series

Flow measuring system for closed pipes with “T” mount PVC impellers, that feature a six bladed impeller design with a non magnetic sensing mechanism connected to a 4-20mA transmitter, and an optional remote digital meter/controller with multipple choice of outputs (2/4 transistor relays, 0-10V/4-20mA, RS232/RS485, Profibus, DeviceNet).

Six bladed impeller PVC Tee flow sensors
Also available in brass/bronze, and stainless steel sensors together with the relevant metal Tees,as well as special versions for underground installations.

Accuracy 1% of the max range (0.3-9.0m/sec)
Linearity 1% of the max range
PVC Tee available for 1 ½, 2, 3, 4” pipes
(or threaded fittings for large diameter pipes)


Pulse converter / transmitter 4-20mA
Power supply 15-40 VDC (via panel meter).
Software for adjustment via the PC.
Maximum distance of transmitter from
sensor  500m

Digital Controller
0-20mA or 0-10 VDC  Input
1/8 DIN (48mm x 96mm)
5 Digit, 0.56" (14mm) LED
Voltage 85 to 250 VAC, 50/60 Hz, 15 VA
Field Upgradeable Option Cards (2/4 transistor relays, 0-10V/4-20mA, RS232/RS485, Profibus, DeviceNet)
Power supply :220 VAC

100 series

  • flow ratemeter
  • totalizer /
  • batch controller

for closed pipe flow measuring systems
with “T” mount PVC impellers, that feature a six bladed
impeller design with a non magnetic sensing mechanism.

Six bladed impeller PVC Tee flow sensors
Also available in brass/bronze, and stainless steel sensors
together with the relevant metal Tees,as well as special versions for underground installations.

Accuracy 1% of the max range (0.3-9.0m/sec)
Linearity 1% of the max range
PVC Tee available for 1 ½, 2, 3, 4” pipes
(or threaded fittings for large diameter pipes),

Model 3300
6 Digit Presettable Digital Batch Controller/Counter

An extremely versatile unit that offers the user flexibility in batch counting applications. The unit features three integrated counters in one package; a Process Counter, a Batch Counter, and a Totalizing Counter.

Technical Data

Process, Batch, and Totalizing Counter
69 mm x 133 mm, 6 Digit, 0.56" (14 mm) LED
2 Process Presets, 1 Batch Preset
Input Scaling, Bi-Directional or Quadrature
Solid-State & Relay Outputs
Programmable Decimal Points
Non-Volatile E²PROM Memory
Up to 10 KHz, IP65/NEMA 4

the DAX Flow Meter multi parameter analyser / controller

choice for flow, pH, ORP, or conductivity

The DAX is designed to be an extremely flexible, easy-to-use, multi-paramet er analyser/controller. Just select the parameter you want to measure from the LCD menu on the inside front cover. Choose from conductivity, pH, ORP, or  flow. The DAX gives you access to two displays. A bright LED numeric display with a bargraph on the outside front panel, and a two-line, 16-character LCD display on the inside. The LED readout can be seen from several yards away. The distinctive color-coded bar graph makes diagnosing pump and alarm malfunctions easy. It will immediately indicate if you are within the process parameters you’ve set (green), if the control relays are on (yellow), or if the process is in alarm conditions (red). All configuration and control functions are performed on the LCD menu inside the front panel.

You’ll also be able to perform calibration functions and check temperatures (where applicable) from the front panel LED. Since this routine maintenance doesn’t require opening the front panel to access the main menu on the side, configuration settings can’t be changed by mistake. You can perform process and temperature calibration from the LCD menu, where calibration slope, temperature, and efficiency are displayed.

DAX controller/analysers provide control of external devices using two independent control relays. A third relay is preset to act as an alarm, but can also be used as a process control relay. It has both high and low ON setpoints, with adjustable OFF setpoints.

Factory-set for bidirectional control, both control relays can be set for either rising or falling process with easily programmed On and OFF setpoints. Each control relay has a built-in independent cycle timer, with field-set ON and OFF times. This feature enables tighter control of batch processes by eliminating chemical overshoot.

The DAX is packaged in a rugged NEMA 4X polycarbonate enclosure, making it ideally suited for heavy-duty applications, such as industrial wastewater neutralization, municipal water and wastewater, pulp and paper,and process control.

Each DAX comes complete. There are no extra costs associated with buying boards for different applications, or buying components to achieve NEMA 4X ratings. A universal mounting kit is included with each unit for surface panel and pipe mounting.


  • pH, ORP, conductivity, and flow parameters available as choices.
  • Easy-to-read 4-digit LED display
  • Bright colour-coded bargraph display
  • No extra cards or options required
  • Relay cycle on/off timers
  • Two control relays and high/low alarm relay
  • Two 4-20 mA outputs with range expandability • 1/4 DIN NEMA 4X enclosure
  • Universal mounting hardware provided for surface, panel, and pipe mounting
  • Snap-on terminal connectors

Technical Characteristics

Display: Front Panel: 4x7segment 1/2”LED, 1 LED indicator on line, 7 LED bargraph; Inside: 2 x 16 alphanumeric LCD, access to all parameters of  operations menu
measuring range: 0.01-14.00pH +0.01pH, ORP: -1999/+1999mV
Temperature: 0° to 100°C/32° to 212°F
Conductivity: μS/cm:0 to 2.000,0 to 20.00,
0 to 200.0,  0 to 2000; mS/cm:0 to 20.00, 0 to 200.0
Flow: 0 to 9999,selectable flow rate units (gallons, cubic feet, liters,
cubic meters, custom); Volume:0 to 9999, Φ auto range: Time
units:Hours,minutes, seconds  K factor Input
Power Supply:  240VAC 50/60Hz or 120VAC 50/60Hz (<12VA)
Output: two isolated 4-20mA
Relays: Two Control Relays: 10A/NO, 5A/NC @ 240VAC or 28VDC
Ambient conditions:  temperature -20° to 60°C or -4° to 140°F;
Humidity:  0 to 90% RH (non-condensing)
Mounting: Universal Mounting kit for surface pipe and panel mount


ORDERING INFO                                                ORDER NO.
Multi-parameter Controller/Analyzer, DAX240V      1117 1000
Multi-parameter Controller/Analyzer, DAX120V      1117 1010

Batch Controller Model 515

Α batch controller that covers most fluid batching requirements that use one or two stage control valves. Starting , stopping or setting the preset quantity for each batch can be achieved from the front keypad or further automated via serial communications. The hardware I/O caters for signals such as End Of Batch, Flow Alarm and Pulse Output. The state of the relays can be defaulted to either "open" or "closed".

The 515 Batch Controller is a dual stage batch controller for reliable measurement of preset quantities. Used as a single or dual stage controller it is suitable for fast batch applications. It provides the operator with clear local readout and can be controlled via communications in more automated systems. There is quick access to commonly used preset values directly from the front panel if access has been authorized.
Automatic overrun compensation caters for system delays such as valve closure for precise volumes. The instrument is compatible with a wide range of flowmeter signal outputs, including analogue 4 -20mA, millivolt signals, reed switches, Namur proximity switches and pulse trains via its smart front-panel program selection. Different versions are available for pulse/frequency or analogue outputs.

• Tailored for volumetric frequency flow input
• Single or Dual stage control
• Quick access to common batch quantities
• No-flow, leakage and overflow error detection
• Allows for non-linear correction
• Storage of 100 transactions with time and date stamp
• Selection of second language and user tags
• Infra-red communications port on front panel
• Pulse width and scaling of pulse output
• 4-20mA re-transmission
• Sellectable protocols on serial ports including Modbus RTU and Printer output
• Front panel adjustment of 8-24V DC output voltage
• Backlit display
• LCD backup


Power Supply: 95...135 V AC or 190...260 V AC or 12...28 V DC
Consumption: Typically 6W
Temperature: 0°C to +60°C (conformal coating) +5°C to +40°C (no coating)
Humidity: 0 to 95% non condensing (conformal coating) 5% to 85% non condensing (no coating)
Protection: Sealed to IP65 (Nema 4X) when panel mounted
Dimensions 147mm (5.8") width 74mm (2.9") height 167mm (6.6") depth

Type: LCD with 7-digit numeric display and 11-character alphanumeric display (backlit option)
Digits: 15.5mm (0.6") high
Characters: 6mm (0.24") high
LCD Backup: Last data visible for 15min after power down
Update Rate: 0.3 second

Non-volatile Memory
Retention: > 30 years
Data Stored: Setup, Totals and Logs

Interference: CE compliance
Enclosure: ATEX, FM, CSA and SAA approved enclosures
available for hazardous areas

Real Time Clock (Optional)
Battery Type: 3 volts Lithium button cell (CR2032)
Battery Life 5: years (typical)

Frequency Input (General)
Range 0 to 10kHz
Over-voltage 30V maximum
Update Time 0.3 sec
Cutoff frequency Programmable (default at 0.25Hz)
Configuration Pulse, coil or NPS input
Non-linearity Up to 10 correction points

Signal Type CMOS, TTL, open collector, reed switch
Threshold 1.3 volts
Signal Type Turbine and sine wave
Sensitivity 15mV p-p minimum

Signal Type NPS sensor to Namur standard

Remote Logic Inputs
Signal Type Voltage free contact, open collector
Relay Output
No. of Outputs: 2 relays
Voltage: 250 volts AC, 30 volts DC maximum
Current: 3A maximum

Communication Ports
Ports RS-232 port, RS-485 port, Infra-red port (optional)
Baud Rate: 2400 to 19200 baud
Parity: Odd, even or none
Stop Bits: 1 or 2
Protocols: ASCII, Modbus RTU, Printer (RS232)

Transducer Supply

Voltage: 8 to 24 volts DC, programmable
Current: 70mA @ 24V, 120mA @ 12V maximum
Protection: Power limited output

Pulse/Digital Output
Signal Type: Open collector, non-isolated
Switching: 200mA, 30 volts DC maximum
Saturation: 0.8 volts maximum
Pulse Width: Programmable: 10, 20, 50, 100, 200 or 500ms

4-20mA Output (Optional)
Supply: 24 volts DC internal, non-isolated
Resolution: 0.05% full scale
Accuracy: 0.05% full scale (20°C) 0.1% (full temperature range, typical)


  • Tanker Loading
  • Bio-Blending
  • LPG bulk deliveries
  • Chemical IBC filling
  • Additive Injection
  • Weighbridge replacement
  • Edible oil batching
  • Ship bunkering
  • Tanker Unloading
  • Truck Registers
  • Cryogenic metering

Sigma LTF Turbine Flow Meter for full pipes

Designed for performance, this highly accurate with excellent repeatability light weight system, consists of a flow sensor and a signal converter. It is available as compact version and in separate sections version.
Sigma LTF Turbine Flow Meters are ideally suited for low viscosity without impurities industrial fluids.

Flange connection type (DN20-DN200)
Thread connection type (DN4-DN50)
Insertion type (DN150-DN1100)
Standard accuracy: 1.0% of Rate, Optional 0.5% of Rate
Output signal: Pulse output, 4-20mA
Display: available with or without LCD Display
Body Material: SS304, Optional SS316
Impeller Material: 2Cr13 or CD4Mcu Stainless Steel

Bearing Material: Tungsten Carbide
Medium teperature: --20-80? 80-150? (High Temperature version
Power Supply: +24VDC±15%
Protection rating: IP60 & IP65 (Ex versions)
Explosion rating: ExdIIBT6 (optional)

Sanitary version for Food & Pharmaceutical Liquids

The sanitary version of LTF flow meter is specifically designed for measurement of food liquids like milk, cream, juice of various fruits and pharmaceutical liquids etc. It is available with compact or remote version of transmitter, with or without display, pulse or 4-20mA output, can be installed either horizontally or vertically with a variety of optional end-fittings to meet your requirements.

Technical data
-Viscosity from 1 to 10 cst
-Pressure resistant to 10 bar
-Communication: Modbus RS485






Operating Principle:
Turbine Flow Meters use the mechanical energy of the liquid to rotate a rotor in the flow stream. Fluid entering the meter first passes through an inlet flow straightener that reduces its turbulent flow pattern. As each turbine blade passes through the magnetic field generated by the meter's magnetic pickup, an AC voltage pulse is generated. These pulses provide an output frequency that is proportional to volumetric flow. The generated signal is converted into engineering units (liters, cubic meters, gallons etc.) on the local display where applicable. Optional accessory modules can be used to export the signal to other equipment.

Ordering Options
Threaded type  (DN4-DN50)
Flanged  type (DN20-DN200)
Insertion type (DN150-DN1100)
No display; 24V DC; Pulse Output
No display; 24V DC; 4-20mA Output
Local display; Lithium Battery Power; No Output
Local display; 24V DC Power; 4-20mA Output, Optional backup power: Lithium Battery
Local display; 24V DC Power; 4-20mA Output;  Modbus RS485 Communication, Optional backup power: Lithium Battery

Low viscosity without impurities diesel; gasoline; water


Ultrasonic in-line flow meter

Ultrasonic stand-alone inline flow meter - 7000 & 8000 series
for flow rate measuring system robust ultrasonic flow rate sensors that offer:-

Flow rate, totalizing, and medium temperature indication suited for water up to a flow rate of 100 l/minute
Binary, analogue and pulse outputs for signal processing
R 1/2 & R 3/4 process connection via adapter fitting


Ultrasonic flow rate sensor DC PNP/NPN, Plug and socket, 4-digit alphanumeric display
Application: water; flow monitoring / temperature monitoring
Operating voltage: 20...28 V DC
Electrical design: DC PNP/NPN
Output: OUT1: normally open / closed programmable or pulse
OUT2: normally open / closed programmable or analogue (4...20 mA / 0...10 V, scaleable)
Current rating: 2 x 250 mA
Flow monitoring:
Measuring range: model 7000: 0...50 l/min; 0,0...3,0 m³/h
model 8000: 0..100 l/min; 0,01..6,0 m³/h
Temperature monitoring:
Temperature range: 5,0...80,0 °C
Pressure rating: 16 bar
Electrical Connection: M12 connector
Process connection: model 7000: G3/4, model 8000: G1
Housing material: housing: AlMgSi0.5 anodised; sealing: Viton; connector housing: brass Optalloy-plated; PA 6.6; cover film: polyamide
Sensor material: gunmetal (2.1096.01); stainless steel (316L); PPR (Hostalen); Viton; PES (Ultrason 2010); Centellen 200
Medium temperature: 5...80 °C
Operating temperature: 5...60 °C
Protection: IP 67, III
Display: Display unit: 4 LED green (l/min, m³/h, m³, °C); Function display: 2 LED yellow; Switching status: 2 LED yellow; Measured values: 4-digit alphanumeric display; Programming: 4-digit alphanumeric display
Accessories (to be ordered separately): Socket, adapter fittings G 3/4~R 1/2, G1 ~ R 1/2, G1 ~ R3/4


A Transit Time Ultrasonic Flow Meter measuring with Clamp-On sensors without contact with the liquids. 

for clean liquids in closed full pipes (< in full pipes with less than 2% solids or gas bubbles at flow velocities from ±0.07 to 39 ft/sec (±0.02 to 12 m/sec).


Model 6.1 Transit Time Flowmeter

  • Non-Contacting Clamp-on Ultrasonic Transducers
  • accuracy of ±1% of reading or 0.1 ft/sec (0.03 m/sec), whichever is greater
  • Works on Metal and Plastic Pipes
  • Large Backlit Flow Rate Display and Totalizer
  • Isolated 4-20mA Output
  • Built-in 5-Key Calibrator
  • 2 Programmable Control Relays
  • 128mb Data Logger

Accurately measure the flow rate of clean, non-aerated liquids like water, chemicals, and oils in full pipes. Ultrasonic transducers mount on the outside of a pipe without shutting down flow. Flow rate is displayed on the large, backlit display along with totalizer and signal strength. Use the built-in control relays for flow alarms or flow proportionate pulse. Connect the isolated 4-20mA output to PLC's or controllers.

Model 6.1 works on a wide range of pipe sizes and materials including carbon steel, stainless steel, ductile iron, cast iron, PVC, PVDF, fiberglass, copper, brass, aluminum and pipes with bonded liners including epoxy, rubber and Teflon.

Model 6.1 Transit Time Flowmeter operates by measuring the “transit time” or “time of flight” for ultrasonic sound pulses transmitted from one transducer to another. Depending on the mounting configuration, the signal may cross the pipe once, twice or four times. To measure flow the transit time is compared between ultrasonic signals travelling upstream and downstream.

Standard Features Include:
pair SE16B ultrasonic transducers - clamp-on for 1/2” to 48” (12 mm to 1200 mm) pipes and rated non-incendive for Class I, Division 2, Groups A, B, C & D locations
sensor cables - pair 25 ft / 7.6 m coaxial with BNC connectors
flow rate range: ± 0.07 to 39 ft/sec (± 0.02 to 12 m/sec)
installation - stainless steel transducer mounting brackets and clamps, alignment bar and silicone coupling compound kit
enclosure - watertight, NEMA4X (IP66) polyester and polycarbonate
display - white, backlit matrix
totalizer - 14 digits
calibration - built-in 5-key programmer
output - isolated 4-20mA (1000 ohm)
2 control relays - 5 amp, SPDT - programmable for flow proportional pulse output, and/or flow alarm
plug-and-play options including data logger and extra control relays
power input - 100-240VAC 50/60Hz, 4 Watts maximum (optional 9-32VDC 10W)
electrical surge protection and RFI filters - AC, sensor, 4-20mA

How it works

Transit Time transducers typically operate in the 1-2 MHz frequencies. Higher frequency designs are normally used in smaller pipes and lower frequencies for large pipes up to several meters in diameter. So operators must select transducer pairs/frequencies according to the application. Doppler transducers usually operate at 640 kHz to 1 MHz frequencies and work on a wide range of pipe diameters.
Transit Time Flowmeter with Two Ultrasonic Sensors     Transit Time flowmeters must have a pair of transducers, each containing a piezo-electric crystal. One transducer transmits sound while the other acts as a receiver.
As the name suggests, Transit Time flowmeters measure the time it takes for an ultrasonic signal transmitted from one sensor, to cross a pipe and be received by a second sensor. Upstream and downstream time measurements are compared. With no flow, the transit time would be equal in both directions. With flow, sound will travel faster in the direction of flow and slower against the flow. Because the ultrasonic signal must cross the pipe to a receiving transducer, the fluid must not contain a significant concentration of bubbles or solids. Otherwise the high frequency sound will be attenuated and too weak to traverse the pipe.

Α flowmeter for difficult liquids, corrosive chemicals, viscus liquids, wastewater, slurries, sludge, etc

Non Intrusive - Doppler Model 6.1

Doppler Model 6.1 is ideal for "difficult liquids" that would damage regular flow meters - wastewater, slurries, sludge, chemicals, viscous liquids and abrasives. There is no obstruction to flow and no pressure drop. The standard, strap-on ultrasonic sensor fits any pipe 1/2" (12.5 mm) Inside Diameter or larger. The electronics/display enclosure can be mounted nearby.

Use the isolated 4-20mA to transmit flow to remote displays, recorders or controllers. The 2 programmable relays can be used for flow control, pump protection or flow proportionate pulse. Calibration is easy with the built-in 5-key calibrator. Display and totalize flow in your choice of engineering units (gallons, liters etc.)

Sensor cable can be extended up to 500 ft. (152 m) with no loss of signal. Model 6.1 can be equipped with intrinsic safety barriers for sensor installation in hazardous rated locations. Other options include high temperature sensors.

Doppler Model 6.1 includes a new digital signal processor to filter background noise and interference and to measure flow rates between 0.2 to 40 ft/sec (0.06 to 12.2 m/sec) with accuracy of ±2% of full scale on liquids with entrained particles or gases of 100 microns or larger and minimum concentrations of 75 ppm. The flow meter operates with a single-head flow sensor mounted externally on any contiguous pipe material that conducts sound including: carbon steel, stainless steel, ductile iron, copper, FRP, PVC, ABS, or cement lined pipe from 1/2" to 180" (12.5 mm to 4.5 m) ID.

Main Features

  • Non-Contacting Ultrasonic Sensor
  • Large, Backlit LCD Display
  • 12-Digit Totalizer
  • power input - 100-240VAC 50/60Hz
  • Isolated 4-20mA (1000 ohm)
  • 2 control relays programmable for flow
  • reverse flow measurement
  • backflow rejection - external, voltage-free relay input
  • Automatic Sensitivity Adjustment
  • New Signal Processing System
  • Built-in 5-Key Calibrator
  • RFI Rejection Filters
  • Built-in 26-million point data logger with USB data transfer
  • sensor - strap-on, single head ultrasonic for 1/2" to 180" (12.5 mm to 4.5 m) ID pipes
  • sensor operational temperature: from -40°F to 200°F (-40°C to 93°C) High temperature optional
  • sensor cable - 20ft / 6m shielded coaxial pair
  • enclosure - watertight NEMA4X (IP66) polycarbonate

optional: Intrinsic Safety Barriers for Sensor mounting in hazardous locations,
SE3H High Temperature model rated up to 302°F (150°C),
ISE Insertion type for special applications

How it Works

Doppler Model 6.1 Ultrasonic flow meters measure flow from outside a pipe with a strap-on sensor. Doppler Model 6.1 meters continuously transmit high frequency sound (640 kHz) that travels through the pipe wall and into the flowing liquid. Sound is reflected back to the sensor from solids or bubbles in the fluid. If the fluid is in motion, the echoes return at an altered frequency proportionate to flow velocity. Model 6.1 flow meters continuously measure this frequency shift to calculate flow.

The Doppler technique only works on liquids which contain solids or gas bubbles to reflect its signal. These are "difficult" liquids that may damage regular flow meters: slurries, sludge, wastewater, abrasives, viscous and corrosive chemicals. Because the sensor mounts on the outside of the pipe, there is no pressure drop and no obstruction to flow.

For best performance Doppler sensors should be mounted away from turbulence creating devices like pipe elbows and tees, and away from velocity increasing devices like controlling valves and pumps. Typical accuracy is ±2% of full scale.

Open Channel Ultrasonic Flow Measuring Systems

Open Channel Flow Monitor - Model OC5

Continuously monitor, display, totalize and data log flow through any flume or weir. The OC 5.0 includes a non-contacting ultrasonic sensor that mounts just 8" (203.2 mm) above the flowing water. It is accurate (±0.25%) and reliable. There is no obstruction to flow and no fouling. Use the built-in Keypad/menu system to select your flume or weir from the Menu and to choose measurement units (gallons, liters etc.)

The OC 5.0 includes built-in 2-million point Data Logger and flow reporting system. Connect a flash memory stick to the flowmeter's USB output to download log files and then view your data in graph and table formats with 'Logger' software – supplied free with each OC 5.0. Daily flow reports including minimum, maximum, average and total daily flow can be viewed directly on the backlit OC 5.0 LCD display.

Use the isolated 4-20mA to transmit flow to remote chart recorders or displays, and the control relays are programmable for level/flow alarm, and flow proportionate pulse (for samplers, chlorinators or remote totalizers). An Intrinsic Safety Barrier is optional for sensor and cable installation in hazardous rated locations. The separate, watertight electronics/display enclosure is mounted at a convenient location within 500 ft (150 m) of the sensor.


  •  Non-Contacting Ultrasonic Sensor
  •  Accurate and Verifiable
  •  Built-in 2 million point Data Logger
  •  USB and RS232 Outputs
  •  4-20mA/0-5V Output
  •  2 Programmable Control Relays
  •  Simple 5-key Calibration

Area-Velocity Flow Monitor- Model-5.0

Monitor flow through open channels, partially full sewer pipes and surcharged pipes without a flume or weir. Ideal for stormwater, combined effluent, raw sewage, irrigation water and streams.
Model 5,0 uses a submerged ultrasonic sensor to continuously measure both Velocity and Level in the channel. The sensor is a completely sealed ultrasonic unit with no orifices or ports. It mounts inside a pipe or at the bottom of a rectangular, trapezoid or egg-shaped channel. Calibration is simple: enter the pipe diameter or channel width and Model-5 computes the flow volume and displays the flow rate.


  • For Open Channels and Pipes
  • Ultrasonic - Measures Velocity + Level to Calculate Flow
  • No Flume or Weir required
  • 3 Isolated 4-20mA Outputs (Flow, Level and Velocity)
  • Totalizer and 2 Programmable Control Relays
  • Simple 3-key Calibration - Password Protected
  • Optional Intrinsically Safe Sensor
  • Optional built-in 2 million point Data Logger and Software

This flow meter is recommended for pipe diameters greater than 6" (150 mm). Maximum pipe diameter or channel width should not exceed 10 ft (3 m) unless flow velocity is evenly distributed across the channel width. Avoid sensor mounting locations where sediment builds up and locations where there is an elevation drop or bend immediately upstream from the sensor. Maximum pipe or channel slope should not exceed 3%.

The flow meter  measures flow velocity from 0.1 to 20 ft/sec (0.03 to 6.2 m/sec) and reverse flow up to 5 ft/sec (1.5 m/sec)

How it Works

The ultrasonic sensor is installed at the bottom of a pipe or channel. To measure water level the sensor transmits ultrasonic pulses that travel through the water and reflect off the liquid surface. The instrument precisely measures the time it takes for echoes to return to the sensor. Based on the speed of sound in water, the level is measured with accuracy of ±0.25%.

Flow velocity is measured with an ultrasonic Doppler signal continuously injected into the water. This high frequency sound (640 KHz) is reflected back to the sensor from particles or bubbles suspended in the liquid. If the fluid is in motion, the echoes return at an altered frequency proportionate to flow velocity. With this technique the instrument measures flow velocity with accuracy of ±2%.

A separate down-looking ultrasonic sensor can be used for highly aerated or turbulent flow applications. It measures level by transmitting ultrasonic pulses through the air to the liquid surface with accuracy of ±0.25%. Along with the level sensor, a submerged Doppler velocity sensor is used to measure the water velocity.