McMillan 101 Technical Document

Manual 101-M002
June 2007
Revision 2
www.mcmflow.com
© COPYRIGHT 2007 R.D. MCMILLAN COMPANY, INC
MODEL 101
MODEL 102
MODEL 104
MODEL 107
MODEL S-111
MODEL S-112
MODEL S-114
FLO-SENSORS®and FLO-METERS® For Liquids
Installation Manual & Operating Instructions
READ THIS MANUAL COMPLETELY BEFORE ATTEMPTING TO
CONNECT OR OPERATE YOUR FLO-SENSOR. FAILURE TO DO SO
MAY RESULT IN INJURY TO YOU OR DAMAGE TO THE FLO-
SENSOR.
.

101-M002, pg. 2 of 42
TABLE OF CONTENTS
A. Introduction.................................................................................................. 3
1. Unpacking................................................................................................ 3
2. Product Overview And Principle Of Operation............................................... 3
3. Non-Standard Products (Z Suffixes) .............................................................. 4
B. Installation.................................................................................................... 5
1. General Considerations ............................................................................. 5
2. Mounting The FLO-SENSOR®or FLO-METER®.......................................... 6
3. Mounting a FLO-METER®Using an Optional Base Plate (Model S-111 only) ..... 7
4. Tubing Connections................................................................................... 8
5. Electrical Connections................................................................................ 9
a) Overview ..................................................................................... 9
b) Connecting A Cable Assembly............................................................... 10
c) Electrical Connections – Voltage Output Units (Standard Accuracy)............. 11
d) Electrical Connections – Voltage Output Units With Improved Accuracy
(H Suffix Only) ................................................................................... 12
e) Electrical Connections – Units With Both Voltage & Pulse Outputs .............. 13
f) Electrical Connections – Current Output Units (Model 107) ........................ 14
g) Electrical Connections – Current Output Units (Model 107) With
Improved Accuracy .............................................................................. 15
h) Using a 0-5VDC Output Power Adapter Package ..................................... 16
i) Using a 4-20mA Output Power Adapter Package (Model 107).................... 17
j) Using a 4-20mA Output Signal Converter Package (D-24VDC)................... 17
C. Operation .................................................................................................. 18
1. Start-Up ................................................................................................. 18
2. Entrapped Air or Gas ............................................................................... 18
3. Flow Readings......................................................................................... 18
a) 0-5VDC Analog Outputs ...................................................................... 18
b) Pulse Outputs ................................................................................... 20
c) 4-20mA Outputs.................................................................................. 20
d) Units with an Integral Display................................................................. 21
4. Operating at Flow Rates Outside the Calibrated Flow Range ......................... 21
a) Flows Above the Maximum Rated Flow.................................................... 21
b) Flows Below the Maximum Rated Flow .................................................... 22
5. Zero Adjustments..................................................................................... 22
6. Recalibration........................................................................................... 22
7. Calibrating FLO-SENSORS®or FLO-METERS®for different Liquids ................. 24
D. Maintenance And Product Care..................................................................... 25
1. General ................................................................................................. 25
2. Cleaning and Flushing ............................................................................. 25
3. Returning Units For Repair Or Recalibration ................................................ 25
E. Part Number Information.............................................................................. 27
F. Accessories................................................................................................. 28
G. Specifications.............................................................................................. 29
H. Dimensions ................................................................................................ 31
I. Connector Pin And Wire Color Cross Reference............................................... 36
J. Limited Warranty ......................................................................................... 37
K. Trouble Shooting Guide ............................................................................... 40
L. Contacting McMillan ................................................................................... 42

101-M002, pg. 3 of 42
A. Introduction
1. Unpacking
McMillan suitably packages all sensors to prevent damage during shipping.
If external damage is noted upon receipt of the package, please contact
the shipping company immediately. McMillan Company is not liable for
damage to the device once it has left the manufacturing premises.
Open the package from the top, taking care not to cut too deeply into the
package. Remove all the documentation and contents. Take care to
remove all the items and check them against the packing slip. The
products should also be checked for any concealed shipping damage. If
any shortages or damage is noted, please contact the shipping company
and/or McMillan Company to resolve the problem.
Typical Contents of Box
Sensor, Calibration Certificate & Instruction Manual
(Model 101 shown, other models similar).
Caution: Take care not to
drop your sensor or subject it to
sudden impact. Read the installation section of this manual
before providing power or tubing connections to the unit. Any
damage caused by improper installation or careless handling will
not be repaired under warranty (see limited warranty on page 37
for more details).
2. Product Overview and Principle of Operation
McMillan Micro Turbine Wheel FLO-SENSORS®for liquids are capable of
measuring flows as low as 13-100 ml/min or as high as 1.0-10.0 l/min.
Highly repeatable results are achieved using a patented Pelton Turbine
Wheel flow sensor design. This proven design minimizes zero drift while
maintaining fast response and linear outputs with virtually no
maintenance.

101-M002, pg. 4 of 42
McMillan’s patented technology measures flow using a miniature turbine
wheel similar in size to a U.S. dime (16 mm diameter, 0.75 mm thick). The
micro-turbine wheel is supported on a very small sapphire shaft that is
held in position by two sapphire bearings. The micro-turbine assembly is
so light that it virtually floats in the liquid. This relieves force on the
bearings and almost eliminates wear.
As flow passes through the FLO-SENSOR®, a precision machined nozzle
directs the fluid onto the very small teeth of the micro-turbine wheel. This
causes the wheel to spin at a speed proportional to the flow rate.
The micro-turbine wheel has alternating white and black sections evenly
spaced on one side of the wheel. An infrared light beam is directed onto
the wheel. As the wheel rotates the infrared beam is reflected off each
white section. The reflected beam is detected by a phototransistor that
converts the reflections into electrical pulses. As the wheel spins faster the
pulse rate increases. Processing circuitry provides analog and/or pulse
output that are linearly proportional to the flow rate
When the wheel stops (under zero flow conditions), no pulses are
generated. Consequently, zero drift is not possible and zero adjustments
are never required.
Every unit is supplied with a calibration certificate detailing the results
obtained during calibration. Units are calibrated using deionized water as
the reference media. Flowing liquids with different specific gravities or
viscosities may effect the calibration.
3. Non-Standard Products (Z Suffixes)
Please note that the installation instructions, operating instructions, and
specifications included within this manual apply to standard production
models only. If your FLO-SENSOR® or FLO-METER®has a “Z” suffix (e.g.
101-
Z0123 ) then your unit is non-standard. Contact the factory to check if
the installation, operation, or specifications of your sensor are different
than detailed in this manual.

101-M002, pg. 5 of 42
B. Installation
CAUTION: Do not flow any gas through a liquid FLO-
SENSOR®or FLO-METER®. This may damage the micro-
turbine assembly and void the warranty. Do not exceed
the pressure, temperature or power operating ranges
detailed in the SPECIFICATIONS section of this manual.
McMillan Company shall not be liable for any damage or
injury caused by incorrect operation of their products.
1. General Considerations
It is recommended that a safety shut-off valve be installed upstream of
(before) the sensor.
All wetted parts should be checked for compatibility with the liquid to be
used. If there are any incompatibilities e.g. highly corrosive liquid, then the
unit may be damaged or fail prematurely. Such damage will not be
repaired under warranty.
Units should be installed in a clean, dry environment with an ambient
temperature that is as stable as possible. Avoid areas with strong magnetic
fields, strong air flows or excessive vibration.
If the liquid to be used may contain particles larger than 25 microns then a
filter (25 microns or less) should be installed upstream of (before) the unit.
The required differential press (or pressure drop across the unit)
decreases exponentially with decreases in flow rate.
Pressure Drop vs. Percentage of the Full Scale
Rated Flow (may vary ±10% of indicated psid)
0
2
4
6
8
10
12
10 20 30 40 50 60 70 80 90 100
% of rated flow
Delta P psid
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Delta P Bar
Range 6
All Other Ranges

101-M002, pg. 6 of 42
To calculate the pressure drop at a certain flow rate use the formula
PD = (YourFlow / MaxFlow)2xPDmax
PD = Pressure drop at YourFlow.
YourFLow = flow rate (ml/min or l/min)
MaxFlow = 100% rated flow for the sensor (in same units as
YourFlow)
PDmax = Pressure drop at 100% rated flow (see chart above)
If the pressure available for the flow sensor is BELOW the pressure drop at
the required flow then flow through the unit will not be possible.
For example: You have a sensor with a 50-500ml/min flow range (Range
5) and want to know the pressure drop (or minimum differential pressure
required) at 300ml/min. According to the chart above, the pressure drop
at 100% of flow is approx 10psi. Using the formula above:
PD = (300 / 500)2x 10 = 3.6 psid
Therefore, at 300ml/min the minimum required differential pressure for
this unit is 3.6 psid. This means that if the available pressure is below
3.6psid then flow through the unit may not be possible.
Pressure drop through a system is cumulative. If the total pressure drop
across all the components in a system exceeds the minimum pressure
available then flow will not be possible.
For example: A system has a pressure of 30-40psi. There are several
components and the sum of their pressure drops at the required flow rate
is 32psid. If the system is operating at 30psi flow would not be possible as
the total of the pressure drops would be greater than the pressure
available. The system will only operate if the system pressure is above
32psi.
If there is any possibility that there may be bubbles or entrapped gas in
the system then the outlet tubing should be elevated above the inlet port.
This will enable any gas that may become entrapped in the unit to escape
(see section C2 for details of how to remove entrapped air or gas).
2. Mounting the FLO-SENSOR®or FLO-METER®.
McMillan FLO-SENSORS®and FLO-METERS®have no particular installation
requirements so may be mounted in any convenient position.
It is recommended that units be fixed to a suitable substrate with #4
screws using the two mounting holes provided.

101-M002, pg. 7 of 42
Mounting The Sensor
(mounting hardware not included with sensor)
3. Mounting a FLO-METER®Using an Optional Base-plate (S-111
only).
An optional mounting base-plate (Part Number 110-00-17) is available for
the Model S-111 FLO-METER®. This enables easy installation on flat, level
surfaces.
The FLO-METER®and base-plate should be assembled using the screws
provided.
Assembling the S-111 and Optional Base Plate

101-M002, pg. 8 of 42
4. Tubing Connections
CAUTION: DO NOT FLOW ANY GAS THROUGH A LIQUID
FLO-SENSOR®OR FLO-METER®. THIS WILL DAMAGE THE
MICRO-TURBINE ASSEMBLY AND VOID THE WARRANTY.
All tubing must be clean and without crimps, burrs or scratches.
Only use the fittings factory installed on the unit. If the fittings are
removed the calibration of the unit may be effected and leaking may
occur. If different fittings are required please contact the McMillan
Company Service Department for assistance.
When connecting the sensor to the tubing a wrench should be used to
stop the fitting rotating in the sensor body. Take care not to over tighten
the fittings or leaking may occur.
Connecting and tightening the Fittings
(S Series shown, other models similar)
Caution: DO NOT over tighten the fittings into the FLO-
SENSOR®or FLO-METER®body. Excessive force may
damage the sensor body and will NOT be repaired under
warranty.
The flow direction for the FLO-SENSORS®or FLO-METERS®is clearly
marked on the label. Do not reverse the flow direction or the unit will not
function.

101-M002, pg. 9 of 42
Close Up of Label Showing Flow Directions
(Model 101 shown, other models similar)
For the best results precautions should be taken to minimize the amount
of turbulence in the flow stream. Avoid valves, fittings, curves in the tube,
changes in the internal diameter or any other restrictions close to the inlet
of the sensor. The tubing ID should be as large as possible and preferably
not smaller than the ID of the fittings installed on the sensor.
For 0.2-2.0 L/min (Range 7) units a 10 cm straight length of tube before
the sensor is recommended. For higher flow range units (0.5-5.0 L/min
and 1.0-10.0 L/min), a 20 cm straight length of tubing before the sensor is
recommended. If this is not possible it is recommended that straight
lengths between all connections on the inlet side of the sensor are as long
as possible and 90 degree fittings (with a large enough ID) are used
instead of curves in the tubing.
5. Electrical Connections
Caution: Incorrect wiring may cause severe damage to the unit.
Applying an AC voltage (115VAC or 230VAC) directly to the unit
will cause damage. Read the following instructions carefully
before making any connections.
a) Overview
McMillan FLO-SENSORS®provide a 0-5VDC, or 4-20mA, or 0-5VDC and
pulse output (T option) proportional to the flow rate. This output may be
connected to a display, data acquisition system or voltmeter / current
meter.

101-M002, pg. 10 of 42
The Model S-111, S-112 and S-114 FLO-METERS®feature an integral
display that provides a local flow reading. These units also have a 0-5VDC
analog output available. If required, this may be connected to another
display, data acquisition system or voltmeter.
A stable D.C. power supply is required to operate the unit. The voltage
and current requirements depend on the configuration of the unit. Full
details may be found in the Specification section of this manual.
Connecting wires should be as short as possible to avoid voltage drops.
Twisted 2 pair conductor cable should be used if the length of the power
wires is to be longer than 1 meter.
Units are supplied with an integral 4 pin connector. Connections to the unit
are made using a mating cable assembly or power adapter package as
detailed in the following sections (parts 5.b to 5.h of this manual). A
connector pin and wire color cross reference may also be found in
Appendix I (Page 30) of this manual.
b) Connecting the Cable Assembly
The connector on the end of the cable assembly should be pushed into the
mating socket on the sensor taking care to ensure that it is the correct
way up.
Connecting the Cable Assembly
(Model 101 shown, other models similar)
Electrical Connections are made to the cable assembly as detailed in the
following sections.

101-M002, pg. 11 of 42
c) Electrical Connections – Voltage Output Units (Standard
Accuracy)
The cable assembly should be connected to the sensor as detailed in
section 5(b) above. Power should not be applied to the sensor until all the
connections have been made and checked. Electrical connections should
be made as follows:
Wiring Schematic For Voltage Output Units.
The RED wire should be connected to the Positive of the power source.
The BLACK wire should be connected to the Negative ( Ground ) of the
power source.
The WHITE wire provides the signal output and should be connected to
the positive terminal of the display, data acquisition system or voltmeter
with an impedance of greater than 2500Ω(Ohms).
The GREEN wire (if present) is NOT used
Caution: Avoid high voltage static discharges to any of the
connections. Do not short the input/output signal wires or allow
them to contact the power wires at any time. DAMAGE WILL
RESULT!

101-M002, pg. 12 of 42
d) Electrical Connections – Voltage Output Units With Improved
Accuracy (H Suffix Only)
The cable assembly should be connected to the sensor as detailed in
section 5(b) above. Power should not be applied to the sensor until all the
connections have been made and checked. Electrical connections should
be made as follows:
Wiring Schematic For Voltage Output Units (H Suffix ONLY).
The RED wire should be connected to the Positive of the power source.
The BLACK wire should be connected to the Negative ( Ground ) of the
power source.
The WHITE wire provides the signal output and should be connected to
the positive terminal of the display, data acquisition system or voltmeter
with an impedance of greater than 2500Ω(Ohms).
The GREEN wire should be connected to the Negative ( Ground ) of the
display, data acquisition system or voltmeter
For improved accuracy units with both Voltage and Pulse outputs (“T”
suffix) please see section 5(e) below.
Caution: Avoid high voltage static discharges to any of the
connections. Do not short the input/output signal wires or allow
them to contact the power wires at any time. DAMAGE WILL
RESULT!

101-M002, pg. 13 of 42
e) Electrical Connections –Units with Both Voltage and Pulse
Outputs
The cable assembly should be connected to the sensor as detailed in
section 5(b) above. Power should not be applied to the sensor until all the
connections have been made and checked. Electrical connections should
be made as follows:
Wiring Schematic For Voltage and Pulse Output.
The RED wire should be connected to the Positive of the power source.
The BLACK wire should be connected to the Negative ( Ground ) of the
power source.
The WHITE wire provides the signal output and should be connected to
the positive terminal of the display, data acquisition system or voltmeter
with an impedance of greater than 2500Ω(Ohms).
The GREEN wire (“T” option only) is the pulse output and should be
connected to the Positive terminal of the data acquisition system with an
impedance of greater than 10KΩ(Ohms).
The PULSE and VOLTAGE output may be monitored simultaneously.
Caution: Avoid high voltage static discharges to any of the
connections. Do not short the input/output signal wires or allow
them to contact the power wires at any time. DAMAGE WILL
RESULT!

101-M002, pg. 14 of 42
f) Electrical Connections – Current Output Units (Model 107)
The Model 107 provides a 4-20mA active current output proportional to
the flow rate.
The cable assembly should be connected to the sensor as detailed in
section 5(b) above. Power should not be applied to the sensor until all the
connections have been made and checked. Electrical connections should
be made as follows:
Wiring Schematic For Model 107.
The RED wire should be connected to the Positive of the power source.
The BLACK wire should be connected to the Negative ( Ground ) of the
power source.
The WHITE wire provides the signal output (active current) and should be
connected to the positive terminal of the display, data acquisition system
or current meter with an impedance of 0 - 500Ω(Ohms).
The GREEN wire is NOT used.
Caution: Avoid high voltage static discharges to any of the
connections. Do not short the input/output signal wires or allow
them to contact the power wires at any time. DAMAGE WILL
RESULT!

101-M002, pg. 15 of 42
g) Electrical Connections – Current Output Units (Model 107)
With Improved Accuracy (H Suffix ONLY)
The Model 107 provides a 4-20mA active current output proportional to
the flow rate.
The cable assembly should be connected to the sensor as detailed in
section 5(b) above. Power should not be applied to the sensor until all the
connections have been made and checked. Electrical connections should
be made as follows:
Wiring Schematic For Model 107 With Improved Accuracy Option (H Suffix)
.
The RED wire should be connected to the Positive of the power source.
The BLACK wire should be connected to the Negative ( Ground ) of the
power source.
The WHITE wire provides the signal output (active current) and should be
connected to the positive terminal of the display, data acquisition system
or current meter with an impedance of 0 - 500Ω(Ohms).
The GREEN wire should be connected to the Negative ( Ground ) of the
display, data acquisition system or current meter.
Caution: Avoid high voltage static discharges to any of the
connections. Do not short the input/output signal wires or allow
them to contact the power wires at any time. DAMAGE WILL
RESULT!

101-M002, pg. 16 of 42
h) Using a 0-5VDC Output Power Adapter Package.
An optional 0-5VDC Output Power Adapter Package is available for use
with the Model 101, 102, 104, S-111, S-112 and S-114. This consists of a
power source (115VAC or 230VAC) and cable assembly with pig-tail
(soldered wire) ends for the signal output. This should be assembled as
shown in the following diagram.
Connecting the Power Adapter to the Flow Sensor
(Model 101 shown, other models similar)
Electrical connections to the cable assembly should be made as follows:
YELLOW WIRE: This provides the 0-5VDC signal output and should be
connected to the positive terminal of the display, data acquisition system
or voltmeter with an impedance of greater than 2500Ω(Ohms).
GREEN WIRE: For Pulse output units (“T” suffix only) the green wire
provides the pulse output and should be connected to the positive terminal
of the data acquisition system with an impedance of greater than 10KΩ
(Ohms).
WHITE WIRE: This is the signal negative and should be connected to the
negative (ground) terminal of the voltmeter, display or data acquisition
system.
Caution: Avoid high voltage static discharges to any of the
connections. Do not short the output signal wires or allow them
to contact the power wires at any time. DAMAGE WILL RESULT!

101-M002, pg. 17 of 42
i) Using a 4-20mA Output Power Adapter Package (Model 107).
An optional 4-20mA Output Power Adapter Package is available for use
with the Model 107. This consists of a power source (115VAC or 230VAC)
and cable assembly with pig-tail (soldered wire) ends for the signal output.
This should be assembled in the same way as the 0-5VDC Output Power
Adapter Package shown in Section (f) above. The 4-20mA output may be
connected to a display, data acquisition system or current meter. Wiring
connections should be made as follows:
The YELLOW wire of the cable assembly provides the 4-20mA (active
current) signal output and should be connected to the positive terminal of
a display, data acquisition system or current meter with an impedance of 0
- 500Ω(Ohms).
The GREEN wire of the cable assembly is not used
The WHITE wire of the cable assembly is the signal negative and should
be connected to the negative (ground) terminal of the current meter,
display or data acquisition system.
Caution: Avoid high voltage static discharges to any of the
connections. Do not short the output signal wires or allow them
to contact the power wires at any time. DAMAGE WILL RESULT!
j) Using a 4-20mA Output Signal Converter Package
(D-24 VDC).
An optional 4-20mA Output Signal Converter Package is available for use
with the Model 101, 102, 104, S-111, S-112 and S-114. This consists of a
signal converter, a cable assembly to connect the converter to the sensor
and a cable assembly to connect to the 4-20mA (active current) output
signal. The signal converter requires 24VDC power to operate. This
package should be assembled as shown in the following diagram.
Assembling the D-24VDC 4-20mA Signal Converter Package
(Model 101 shown, other models similar)

101-M002, pg. 18 of 42
i) Electrical connections to the FLOW SENSOR cable assembly
The RED wire should be connected to PIN 4 of the signal converter
unit.
The BLACK wire should be connected to PIN 2 of the signal
converter unit.
The WHITE wire should be connected to PIN 3 of the signal
converter unit.
The GREEN wire (if present) is NOT used
ii) Connecting a power supply.
A stable low noise 24 VDC power supply should be connected to the
signal converter as follows:
PIN 1 of the signal converter unit should be connected to the
Positive of the power source.
PIN 2 of the signal converter unit should be connected to the
Negative (Ground) of the power source.
iii) Electrical connections to the 4-20mA FLOW SIGNAL OUTPUT cable
assembly:
The CENTER wire of the cable assembly provides the 4-20mA (active
current) signal output and should be connected to the positive
terminal of the display, data acquisition system or current meter with
an impedance of 0 - 500Ω(Ohms).
The SHIELD wire of the cable assembly is the signal negative and
should be connected to the negative (ground) terminal of the current
meter, display or data acquisition system.
Caution: Avoid high voltage static discharges to any of the
connections. Do not short the output signal wires or allow them
to contact the power wires at any time. DAMAGE WILL RESULT!
C. Operation
CAUTION: USE WITH LIQUIDS ONLY. FLOWING GAS OR
AIR THROUGH YOUR FLO-SENSOR®OR FLO-METER®
WILL DAMAGE THE MICRO-TURBINE ASSEMBLY. THIS
TYPE OF DAMAGE WILL NOT BE REPAIRED UNDER
WARRANTY.

101-M002, pg. 19 of 42
1. Start Up
Before applying power to the unit check all tubing and electrical
connections. Once correct installation is verified switch on the power.
2. Entrapped Air or Gas
There may be a lot of air or gas trapped in your FLO-SENSOR®or FLO-
METER®after installation. This will usually escape the unit when flow
(within the range of the unit) is first started.
Caution: The system should be primed with liquid and flow
started gradually. This will prevent trapped air or gas from being
forced through the sensor at a high velocity that may damage
the sensor.
If gas remains entrapped in the unit it may be necessary to elevate the
outlet tubing above the inlet of the FLO-METER®or FLO-SENSOR®. This
should enable the trapped gas to escape the unit. The FLO-SENSORS®or
FLO-METERS®may be returned to it’s original position once all the gas has
escaped.
If elevating the outlet tubing does not work, block or pinch the outlet tube
whilst there is flow in the system. After approximately 5 seconds, release
the restriction to allow normal flow. Doing this will build up pressure in the
flow path that when released will help remove the entrapped gas. Repeat
this until the entrapped gas is removed form the unit.
3. Flow Readings
McMillan FLO-SENSORS®provide a 0-5VDC, or 4-20mA, or 0-5VDC and
pulse output (T option) proportional to the flow rate. The type of output
signal is detailed in the part number reference and on the calibration
certificate.
The Model S-111, S-112 and S-114 FLO-METERS®feature an integral
display that provides a local flow reading and a 0-5VDC analog output.
Each FLO-SENSOR®or FLO-METER®is factory calibrated for a specific flow
range. The flow range is shown on the unit’s label and calibration
certificate. Units are calibrated using deionized water as the reference
media.
a) 0-5VDC Analog Outputs
By monitoring the voltage output signal it is possible to determine the flow
rate of the liquid. Units are configured so that an output signal of 5.0VDC
is provided when the maximum flow (i.e. Full Scale flow) is passing
through the unit. The output signal is linear and scaleable enabling
calculation of flow rates within the sensor’s range. For example:

101-M002, pg. 20 of 42
For a flow range of 50-500ml/min (Range 5) :
At 500ml/min the output signal would be 5VDC
If the output signal were 3.5VDC then the flow rate would be:
500 ÷ 5 × 3.5 = 350ml/min
If the maximum flow rate is exceeded non-linear and inaccurate readings
will result.
b) Pulse Outputs
By monitoring the Pulse output frequency it is possible to determine the
flow rate of the liquid. The pulse frequency for maximum flow through the
unit (i.e. full scale flow) is detailed on the calibration certificate. This
differs from unit to unit. This output is approximately linear and scaleable
within the sensor’s range. For example:
For a flow range of 1.0-10.0l/min (Range 9) :
The calibration certificate gives the following:
At 10.0l/min the pulse output signal is 312Hz
At 5.0l/min the pulse output signal is 150Hz
At 2.0l/min the pulse output signal is 58Hz
If the output signal were 120Hz then the flow rate would be:
5.0 ÷ 150 × 120 = 4.0 l/min (using the closest calibration point)
c) 4-20mA Outputs
By monitoring the current output signal it is possible to determine the flow
rate of the liquid. Units are configured so that an output signal of 20mA is
provided when the maximum flow (i.e. Full Scale flow) is passing through
the unit. The output signal is 4mA when there is zero flow through the
unit. The output signal is linear and scaleable enabling calculation of flow
rates within the sensor’s range. For example:
For a flow range of 20-200ml/min (Range 4) :
At 200ml/min the output signal would be 20mA
If the output signal were 9mA then the flow rate would be:
200 ÷ (20-4) × 9 = 112.5ml/min