Marsh-McBirney Flo-Mate 2000 Manuale utente
FLO-MATE
TM
V2.0, January 1994
Manuel d’Installation & d’Utilisation
Rue J.H. Cool 19a | B-4840 Welkenraedt | Tel.: +32 (0)87 899 799 | Fax: +32 (0)87 899 790 | E-mail: info@flow-tronic.com | www.flow-tronic.com
CONTENTS
General Description........................................................................................................................ 1
Theory of Operation ....................................................................................................................... 2
Design Features .............................................................................................................................. 3
Operation ........................................................................................................................................ 4
Real-Time Operating Mode...................................................................................................... 4
Display ON Sequence............................................................................................................... 4
Units of Measurement/Beeper .................................................................................................. 5
Fixed Point Average/Time Constant Filtering.......................................................................... 5
FPA........................................................................................................................................... 5
rC .............................................................................................................................................. 6
FPA/rC Time ............................................................................................................................ 6
Clearing the Display ................................................................................................................. 7
Storing Velocity Readings........................................................................................................ 7
Recall Operating Mode............................................................................................................. 8
Zero Adjust ..................................................................................................................................... 8
Zero Check ............................................................................................................................... 8
Zero Adjust ............................................................................................................................... 9
Errors ............................................................................................................................................ 10
Error Messages ....................................................................................................................... 10
Error Codes............................................................................................................................. 11
Key Function Summary................................................................................................................ 11
One-Key Functions................................................................................................................. 11
Two-Key Functions ................................................................................................................ 11
Maintenance.................................................................................................................................. 12
Cleaning the Sensor ................................................................................................................ 12
Changing Batteries ................................................................................................................. 12
Battery Life................................................................................................................................... 13
Battery Change Guide ............................................................................................................13
Self Discharge in Storage .......................................................................................................13
Low Battery Flag .................................................................................................................... 13
Options ......................................................................................................................................... 14
Sensor Disconnect .................................................................................................................. 14
Power-In-Signal-Out Connector............................................................................................. 14
Carrying Case ......................................................................................................................... 15
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Sensors.......................................................................................................................................... 15
Open-Channel-Velocity Sensor.............................................................................................. 15
Full-Pipe-Velocity Sensor ...................................................................................................... 16
Sensor Mounting Configurations ................................................................................................. 16
Universal-Sensor Mount......................................................................................................... 16
Standard Wading Rod.............................................................................................................17
Double-End Hanger................................................................................................................ 17
Top-Setting-Wading Rod ....................................................................................................... 18
Suspension Cable.................................................................................................................... 20
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Outputs
Display
31¦2Digit
SignalOutputConnector(Optional)
Analog 0.1 V = 1 ft/sec or 1 m/sec
2 V = Full Scale
Materials
Sensor
Polyurethane
Cable
Polyurethanejacket
ElectronicCase
HighImpactMoldedPlastic
Weight
3 lb 9 oz with case and 20 ft of cable
2 lb 10 oz without sensor and cable
Temperature
Open-Channel-VelocitySensor
32° F to 160° F (0° C to 72° C)
Full-PipeSensor(S/SInsertion Tube)
32° F to 160° F (0° C to 72° C) @ 250 psi
Electronics
32° F to 122° F (0° C to 50° C)
SPECIFICATIONS
VelocityMeasurement
Method
Electromagnetic
ZeroStability
± 0.05 ft/sec
Accuracy
± 2% of reading + zero stability
Range
-0.5 to +19.99 ft/sec
-0.15 m/sec to +6 m/sec
Power Requirements
Batteries
Two D Cells
Battery Life Continuous ON hours
Alkaline25-30
NiCad 10-15 per charge
ExternalPower Supply(Optional)
120 V, 1 W or 220 V, 1 W
WaterResistantElectronic Case
Submersible
One Foot for 30 Seconds
iii
1
GENERAL DESCRIPTION
The Marsh-McBirney Model 2000 Flo-Mate is a portable flowmeter designed for use in both the field
and the laboratory. The unit uses an electromagnetic sensor to measure the velocity in a conductive
liquid such as water. The velocity is in one direction and displayed on a digital display as feet per
second(ft/s)ormetersper second (m/s).
A watertight case protects the electronics from wet weather and accidential submersions. The unit is
powered by two D-size batteries in the bottom of the case. A shoulder strap and 20 feet of sensor cable
are standard. Excess sensor cable is coiled and secured to the shoulder strap by the sensor cable re-
tainer.
Figure 1. Model 2000 Flo-Mate
2
THEORY OF OPERATION
The Flo-Mate measures flow using the Faraday law of electromagnetic induction. This law states that
as a conductor moves through a magnetic field, a voltage is produced. The magnitude of this voltage is
directlyproportional to thevelocity at whichthe conductor movesthrough the magneticfield.
When the flow approaches the sensor from directly in front, then the direction of the flow, the mag-
netic field, and the sensed voltage are mutually perpendicular to each other. Hence, the voltage output
will represent the velocity of the flow at the electrodes.
The sensor is equipped with an electromagnetic coil that produces the magnetic field. A pair of carbon
electrodes measure the voltage produced by the velocity of the conductor, which in this case is the
flowing liquid. The measured voltage is processed by the electronics and output as a linear measure-
mentofvelocity.
Figure 2. Theory of Operation
3
DESIGN FEATURES
The Model 2000 design features are as follows:
• Lightweight (3 lb 9 oz with sensor and 20 ft of cable), water resistant, and rugged. The case is
madeof ahigh impact moldedmaterial which protectsthe electronics fromwet environmentsand
accidentalsubmersions.
• Digitalfiltering.The sensor electronics usesdigitalfiltering.This does a betterjobthananalog
filteringinrejectingelectrical noise that maybepresentinthe flow.
• Noise flag. If there is enough electrical noise present in the flow to interfere with normal operation,
the display will blank out and the noise flag is displayed.
• Conductivitylost detection. Aconductivity lost flagis displayed andthe velocity readingsare
blanked out when conductivity lost is detected. Conductivity lost is usually caused by the sensor
being out of the water.
• Dry sensor power down. The unit stops driving the sensor five seconds after conductivity lost is
detected. This results in a 66% reduction in power consumption, which conserves battery life. If
the sensor is dry for more than 5 minutes, the unit will turn itself OFF.
• Automatic shut off. After five minutes of conductivity lost, the unit will shut itself off thus con-
servingbatterylife.
• Low battery flag. A low battery flag is displayed when the battery voltage drops below a certain
value. The amount of time the batteries will last after the flag is displayed can vary from an hour
(alkaline) to 15 minutes (nicads). The unit will shut itself off if the voltage drops too low.
• Cleardisplayfunction.Theclear display function clearsthedisplayandrestartsthefiltering.
• Data storage and recall ability. There are 19 memory locations in which to store and recall velocity
measurements.
• Unitof measurementselection. The metercan beswitched between English(ft/s) andmetric (m/s)
unitsofmeasurement.
• Selectablefilteringmodes for display output.Fluiddynamicsnear the sensor electrodesmaycause
slightly noisy readings. The output can be stabilized by averaging the velocities over a fixed time
period or by a software algorithm that mimics an RC time constant.
4
OPERATION
The Model 2000 has two operating modes: Real-Time and Recall. In the Real-Time operating mode,
Real-Timevelocitiesfromthesensoraredisplayed. In the Recall operating mode,velocitiesfrom
memoryaredisplayed.
Comment
In the Recall mode, the time bar will be stationary.
Real-Time Operating Mode
The unit will always power up in the real-time operating mode. From the real-time mode you can
change the filter value, store readings in memory, turn the beeper on or off, alternate between feet per
second(ft/s) and metersper second (m/s),alternatebetween fixedpointaveraging and timeconstant
filtering,andswitch to the recalloperatingmode.
Display ON Sequence
When the unit is turned ON, the display output sequence is as follows:
• Software version number. This is the Model 2000 operating software that was burned into the
electronicsatthefactory.
• Displaysegment test. Theunitwilllight all displaysegments.
• Velocity output. The first few readings are not filtered; however, they are accurate.
5
Units of Measurement/Beeper
The Model 2000 can output velocity in ft/s or m/s. When the beeper symbol is shown, the beeper is
active. Press down on the ON/C and OFF keys simultaneously to cycle between:
• FT/S no beeper
• M/S no beeper
• F/S with beeper
• M/S with beeper
Fixed Point Average/Time Constant Filtering
The fluid dynamics around the sensor electrodes may cause the readings to bounce around. To stabi-
lize the readings, the output to the display is dampened. The display can be dampened by Fixed Point
Averaging (FPA) or by time constant filtering (rC).
Fixed Point Averaging is an average of velocities over a fixed period of time. Time constant filtering is
a software algorithm that mimics an RC analog circuit. Press the 5and 6keys simultaneously to
alternate between the FPA and rC displays.
FPA
The display will show the letters FPA when you first switch to the FPA display. Except for the first
period, the display is updated at the end of each averaging period. For example, if the FPA is set to 10
seconds, the display is updated once every ten seconds. The FPA display will have a horizontal time
bar under the velocity output. The time bar provides an indication as to the amount of time left until the
displayisupdated.
6
rC
The display will show the letters rC when you first switch to the time constant mode. The display will
startwithunfiltered full scalevelocities.Thesereadings are accuratebutmaybounce around slightly.
Asthe filteringtakes effect, thereadings will settleout. It takesfive timeconstants to getto maximum
filtering. There is no time bar on the rC display because the display is continually up-
dated.
FPA/rC Time
The FPA and rC time is specified in seconds. The 5key increments time and the 6key decrements
time. The display will show the FPA/rC length in seconds. After you have reached the desired setting,
waitandthedisplay will automatically switchtovelocity.
Comment:
Limits are 2-120 seconds for FPA and 2-30 seconds for rC.Changing FPA and rC time restarts the
filtering.
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