Warning notices must be observed to ensure personal safety as well as that of others, and to
protect the product and the connected equipment. These warning notices are accompanied
by a clarification of the level of caution to be observed.
Qualified Personne l
This device/system may only be set up and operated in conjunction with this manual.
Qualified personnel are only authorized to install and operate this equipment in accordance
with established safety practices and standards.
Warning: This product can only function properly and safely if it is correctly transported,
stored, installed, set up, operated, and maintained.
Note: Always use product in accordance with specifications.
Copyright Siemens Milltronics Process
Disclaimer of Liability
Instruments Inc. 2003. All Rights Reserved
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Email: techpubs@siemens-milltronics.com
While we have verified the contents of
this manual for agreement with the
instrumentation described, variations
remain possible. Thus we cannot
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contents of this manual are regularly
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in subsequent editions. We welcome
all suggestions for improvement.
Technical data subject to change.
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Material Feed ......................................................................................................................................... 13
Spare Parts ...................................................................................................................................18
i
Page 4
ii
Page 5
Milltronics Millflo S olids Flowmeter
The Milltronics Millflo solids flowmeter is a low to medium-capacity flowmeter for
various product sizes, densities, and fluidities in restricted spaces. This low-cost compact
unit improves processing, increases operating efficiency, and helps provide significant
cost savings.
Operating with a microprocessor-based integrator package, the Millflo provides a display
of flowrate, totalized flow, and alarms. Outputs are 0/4 to 20 mA proportional to rate and
open collector output for remote totalization.
Dry bulk solids enter the flowguide producing a mechanical deflections as they strike the
flowmeter sensing plate before continuing through the process unhindered. A strain
gauge loadcell converts the horizontal force of the deflection into an electrical signal. The
integrator processes this into a display of flowrate and integrated total weight. The
process is immune to the effect of product buildup as only horizontal force is measured.
The Millflo features easy installation into standard pipe sizes, simple operation, and fast
and accurate flow response.
The Millflo is an accurate and repeatable force sensor and its performance depends on
the consistency of the material flow into the flowmeter and the quality of the installation.
The Manual
This manual covers the installation, operation, and maintenance of the Milltronics Millflo
solids flowmeter.
Please refer to this manual for proper installation and operation of any component of the
system to which the Millflo is applied. Adhering to the installation and operating
procedures will ensure a quick and trouble free installation and allows for the maximum
accuracy and reliability of your system. Because the Millflo is used in conjunction with an
integrator, refer to the integrator’s manual also.
If you have any questions, comments, or suggestions about the manual’s contents, please
email us at techpubs@siemens-milltronics.com
For the complete library of Siemens Milltronics manuals,
go to www.siemens-milltronics.com
The Millflo reacts to the horizontal component of force
created by the impact of material on the sensing
plate. The Millflo consists of two physical
components:
• the housing which includes the flowguide and
the outlet. It supports the sensing assembly
and guides the material flow.
• the sensing assembly, which includes the
sensing plate and the load cell.
Horizontal Sensing Plate
The material travels down the flowguide, striking the
sensing plate and discharging through the outlet. The
force exerted on the sensing plate has both a vertical
and horizontal component. The design of the load cell
is such that it reacts to the horizontal component only;
the vertical component is ignored.
material
load cell
flowguide
sensing
plate
outlet
positive
stop
The sensing plate is displaced proportionally to the
material flow and is not susceptible to material build
up, so long as it does not bridge across to the housing.
Positive displacement of the load cell is limited by the
positive stop incorporated in the design of the load cell.
The displacement of the load cell is sensed by its strain
gauges. These convert the excitation signal from the
electronic integrator to produce a signal proportional
to material flow.
A negative stop protects the load cell
against excessive negative displacement
which could functionally destroy it. The
negative stop is factory set so that the
output signal is limited to -20 mV when the
load cell is forced to travel in the negative
direction.
negative
displacement
Under no-flow conditions, the load cell/
sensing plate assembly is at rest at static
zero. Under this condition, the negative
stop should not contact the load cell, and
the output signal from the load cell will be
approximately -5 to 0 mV DC.
Prepare the site in accordance to the Siemens Milltronics drawing(s) provided. If no
drawings were provided or if there is confusion or doubt as to the Milltronics Millflo’s
installation, please consult your Siemens Milltronics representative.
When unpacking the Millflo, avoid subjecting the unit to mechanical shock. Excessive
mechanical shock can cause damage to the housing or load cell/sensing plate assembly.
The Millflo is generally shipped assembled with the sensing plate arrested to prevent
damage to the load cell.
The Millflo should be visually inspected for shipping damage. If damage is suspected,
contact your Siemens Milltronics representative and the shipping carrier.
When handling the Millflo, ensure the shipping stop is in place to secure the sensing
plate. Never subject the Millflo to shock by hitting it when trying to position it.
Welding
WARNING: Use extreme caution when arc welding in the area of the flowmeter to
ensure that no welding current flows through the flowmeter, risking destruction of
the load cell.
Remove the sensing plate and load cell before welding.
Load Cell Handling
The load cell tolerates very little negative displacement, or it may be functionally
destroyed. When handling the load cell, care must be taken not to force the gap open.
SUPPORT LOAD CELL THROUGHOUT HANDLING IN NON-VERTICAL POSITIONS.
IMPROPER HANDLING MAY FUNCTIONALLY DESTROY LOAD CELL
Remove the load cell/sensing plate assembly from the housing prior to installation.
1.Remove the access cover, loosen
the shipping rod nuts as shown,
and then remove. Retain
calibration weight cable for use in
the calibration procedure.
2.Secure access door.
3.Remove and hold top cover/
junction box assembly. Avoid
applying stress to the load cell
cable connected through the
cover to the junction box.
4.Hold the load cell by the upper
cross piece. (See
Handling on
Load Cell
page 6).
5.Remove load cell mounting
screws (2 places), and then lift
load cell/sensing plate assembly
up and out of the housing,
keeping the sensing assembly
vertical.
6.Set the assemblies aside in a safe
place.
top cover screws
(4 places)
gasket
load cell
cable
load cell
mounting
screws
(2places)
top cover /
junction box
assembly
top cover
flange
calibration weight
cable
load cell / sensing
plate assembly
access cover
shipping stop
(threaded rod)
loosen 2nd to
remove
shipping stop
loosen first to free
sensing plate
IMPORTANT: While transporting, support the load cell / sensing plate
assembly as shown in Load Cell Handling on page6.
Installation of Shipping Stop
Whenever the unit is to be moved, the
shipping stop should be reinstalled to
prevent damage to the load cell/sensing
plate assembly.
1.With the sensing plate resting in
its static position, insert
threaded rod as shown.
2.Tighten the two end nuts against
the housing to secure the rod in
place.
3.Turn the two opposing sensing
plate locking nuts toward the
sensing plate, maintaining the
sensing plate in its static
position. Tighten nuts to secure
sensing plate.
1.Set the Millflo housing in place ensuring that the flowguide and outlet gaskets are
correctly located.
2.The housing must be vertical within 1° in two planes 90° apart.
3.Bolt the flowguide and outlet flanges to the process piping.
4.If the load cell/sensing plate assembly was not removed prior to beginning the
installation procedure, the shipping stop must be removed. Refer to
page 7 to remove the shipping stop.
If the load cell/sensing plate assembly was removed, reverse the disassembly
procedure to reassemble the load cell/sensing assembly into the housing and to
replace the cover/junction box assembly on to the top access flange. Do not reinstall
the shipping stop. Exercise caution while handling the load cell/sensing plate
assembly. Refer to the diagrams in the
Load Cell Handling
section on page 6.
5.Wire the unit in accordance with Siemens Milltronics supplied connection diagrams
or as described in the integrator instruction manual.
Disassembly
on
(2)
(3) infeed pipe
mounting hardware
(1) gasket
Millflo
mounting hardware
(1) gasket
(3) outfeed pipe
NOTE: All items other than Millflo supplied by customer
After the Millflo has been properly installed, calibration of the solids flowmeter system
should be done in conjunction with the integrator. Refer to the integrator instruction
manual for programming and calibration. The calibration is initially done using a test
weight. Material tests are recommended to achieve maximum accuracy.
Test Rate
The test rate is the material flowrate represented by the test weight. The test weight is
used to simulate the horizontal forces of the material hitting the sensing plate.
CALCULATION OF TEST WEIGHT AND TEST RATE
Select the test weight to represent a calibration point of 60% to 80% of the Design
flowrate based on the Millflo Calibration Constant of 45 g / T/H (tons per hour).
Test Weight = Design Flowrate x Calibration Point x Calibration Constant
1
Test Rate = Test Weight
Calibration Constant
For Example:
If the Design Flowrate is 6 T/H, then
Test Weight 60%
Test Weight 80%
Therefore the test weight should be between 162 g and 216 g.
If an available test weight of 200 g is used, then
Test Rate = 200g
= 6 T/H x 60% x 45 g / T/H
=162 g
= 6 T/H x 80% x 45 g / T/H
= 216 g
45 g T/H
= 4.444 T/H
1.
The Calibration Constant represents an average of a range of values covering
various material flow arrangements and materials handled by the Millflo. It is an
approximate value to be used in the calculation of the Test Rate. Through the
running of material tests, the Test Rate may be factored to obtain an optimum
value which should lie in the range of 50% to 100% of the Design Rate. The Test
Rate should never exceed 100% of the Design Rate.
Perform the zero calibration as described in the Calibration section of the integrator
instruction manual.
Span
1.Install the calibration pulley and bracket assembly to the flowmeter housing.
2.Hang the test weight over the calibration pulley using the test weight cable.
3.Perform the span calibration as described in the calibration section of the integrator
instruction manual.
4.After the span calibration has been completed, remove the test weight and pulley
assembly and store them.
hook
sensing plate
calibration access hole (remove plug
to access hook during calibration)
calibration
bracket
calibration pulley
mount bracket
using bolts
threaded into
Millflo wall
Millflo
housing
cable
test
weight
Material Test
Calibration of the flowmeter by test weight is not a dynamic simulation and yields only an
approximate span calibration. Effective material flow, friction, and velocity can only be
reproduced by running actual material tests.
At least two 5 minute samples should be taken to ensure repeatability.
Refer to
Material Test
integrator manual.
Re-Rating
After material tests have been done and a decision is made to re-rate the Millflo at a
higher or lower capacity, (with 20% of the design rate specified at the time of purchase)
only the design rate parameter of the integrator needs to be changed. Following that, a
recalibration of the zero and span can be performed using the old test weight and test
rate. New material tests will not be required.
Note: For best performance and limited maintenance requirements, keep in mind
material compatability and flow patterns.
Ideal material characteristics:
•low cohesion (flows well through chutes, similar to a liquid)
•low adhesion (does not stick to surfaces)
•low abrasion (will not wear out chutes, flowguide, or sensing plate)
•low causticity (will not damage internal flowmeter components)
Location
Materials with low moisture content generally have excellent flow and adhesion
characteristics. In processes where material moisture content varies, select a flowmeter
location where the moisture content is lowest.
Linings
•Sensing plate and flowguide non-stick linings are often used for flour (wheat),
starch, and material with similar characteristics.
•Sensing plate and flowguide abrasion resistant linings are often used for barley,
corn, soya beans, wheat, and material with similar hardness and particle mass.
Abrasive materials are best monitored at low velocity.
Material Feed
Ideal material in-feed characteristics
•constant and relatively low material velocity
•uniform material flowrate (not pulsing)
•negligible air flow through the flowmeter
•flowguide 17% to 50% full during operation
Feed Conditions
•A gravity-fed flowmeter generally provides accurate readings.
•A mechanically fed flowmeter may not provide a consistent feed, affecting
flowmeter performance. A consistent feed provides the most accurate readings.
•A reverse flowguide transition is preferred for high or variable velocity feeder
material discharges. (Refer to
•A larger loadcell compensates for slight to moderate material pulsing at greater
than 1 pulse per second. If heavily pulsing feeder discharges at less than 1 pulse per
second, consult Siemens Milltronics or your local distributor.
•Use a flowmeter discharge chute suitable so that material cannot backup into the
flowmeter housing.
•Short pitch and/or double flight screws are
preferred. They reduce the batch size (and
increase the frequency) of the material
discharge pulses. Alternatively, the flights of a
standard screw may be cut back, ending before
the discharge opening.
•A reverse flowguide transition should be
considered for variable operating speeds or
constant speeds above 40 rpm.
•Provides an air seal between the upstream and/or
downstream process, and the flowmeter
•Required when the material is pneumatically
conveyed or flowmeter/process isolation is
required.
•Use a reverse flowguide transition for variable
operating speeds or constant speeds above 10
rpm.
Bucket Elevator
Conveyor Belt
material
discharge
baffle
•Common to grain applications
•Slow elevators (typically chain drive) often
produce heavily pulsing material discharge,
requiring feeder discharge damping. Generally not
suitable for the Millflo.
•Fast elevators (typically reinforced belt drive) often
require a deadbox to reduce material velocity. High
frequency of pulses make it suitable for the Millflo.
•Conveyor belts generally produce a non-pulsing
material discharge, ideal for flowmeter operation.
•A reverse flowguide transition (and/or material
discharge baffle) is often required for variable belt
speeds or constant speeds in excess of 1 m/s (200
feet/minute).
•Vibratory (pan) feeders produce a non-pulsing
material discharge.
•A reverse flowguide transition should be
considered for variable speed varieties.
Flowmeter In-Feed Chutes
The flowmeter in-feed chute delivers the material from the bin or feeder discharge to the
flowmeter flowguide. For optimal performance, in-feed chute is set to condition the
material flow to minimize the following:
•abrasion
•velocity variation
•feeder discharge trajectory variation
•pulsing
Feeder/Flowguide Transition
•A reverse flowguide transition reverses the
direction of the bin or feeder material discharge
before the material enters the flowmeter
flowguide.
•Reversing direction forces the material into a
desirable flow pattern, as opposed to permitting
material to be flung from the feeder directly into
the flowguide. This transition is especially
important for high or variable speed feeders.
•A forward flowguide transition maintains the
material in the same direction between the bin or
feeder discharge and the flowmeter flowguide.
•This transition is acceptable for a low and
constant velocity feeder.
•To use a forward flowguide transition for a high or
variable speed feeder application, install a baffle
plate.
Page 20
Short Fall Chute
<0.6 m (2ft)
Long Fall Chute
>0.6m (2ft)
•A short fall chute is when the bin or feeder
discharge to flowmeter flowguide fall is less than
0.6 m (2 ft) from the material infeed.
•The short fall chute present ideal measurement
conditions because material velocity due to gravity
is minimum.
•The chute center line and angle should coincide
with that of the flowguide for a distance greater
than or equal to the flowguide diameter (before
the flowguide inlet).
•A long fall chute is when the bin or feeder
discharge/flowguide fall is more than 0.6 m (2 ft)
from the material infeed.
•The long fall chute presents problematic
conditions because material velocity is increased,
increasing flowmeter component abrasion.
•Increased distances after chute-angle changes (to
settle material into desirable flow patterns) are
also required.
Dogleg
Deadbox
•Use a dogleg to reduce the detrimental effect of
high or variable material velocity, and when a long
fall chute is used.
•For abrasive material, line the chute with an
abrasion resistant material or use an in-feed
deadbox.
•Install a deadbox where the chute angle changes,
causing the material to strike upon itself, rather
than on the chute surface
•Deadboxes conditions:
•high feeder discharge velocity
•variable discharge
•abrasive material
•Locate deadboxes where long-fall chute angles
change.
If the flowmeter is properly installed, the zero and span calibrations will require limited
attention. However, to maintain the accuracy of your flowmeter’s operation, the zero and
span should be periodically redone. The frequency of recalibration is highly dependent
upon the application in which the flowmeter is being used and the severity of its
operating conditions. Initially frequent recalibrations should be performed (noting the
deviations), then tapering off in frequency as time and experience dictate.
Refer to the
Programming
and
Calibration
sections of the integrator manual.
Checks
If material sticks to the sensing plate, incorporate a program to ensure that the
impingement area remains clean. If sticking of the material persists, contact your
Siemens Milltronics representative.
Check for material bridging across the load cell or sensing plate to the housing which can
restrict the free movement of either component.
Do not strike the flowmeter, its components, or adjacent piping to dislodge material.
Check for wearing of the sensing plate. If wear is excessive contact your Siemens
Milltronics representative.
Spare P arts
The following are the recommended spare parts. As each may be available in more than
one option, consult Siemens Milltronics for assistance in ordering spare parts. In all
correspondence please quote the Milltronics Serial Number of the unit for which the
parts are required.
•load cell
•sensing plate
Unit Repair and Excluded Liability
All changes and repairs must be done by qualified personnel and applicable safety
regulations must be followed. Please note the following:
•The user is responsible for all changes and repairs made to the device.
•All new components must be provided by the Siemens Milltronics Process
Instruments Inc.