Milltronics MMI-2 Instruction Manual

MMI-2

2 IDLER BELT SCALE

Instruction Manual PL-327 January 2001

33453270
Rev. 2.3

Safety Guidelines

Warning notices must be observed to ensur e 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 Personnel

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

Note

This product can only function prope r ly and saf ely if it is correctly transported, stored, installed, set up , operated, and maintained.

:

Always use product in accordance with specifications.

:

Copyright Siemens Milltronics Process

Disclaimer of Liability

Instruments Inc. 2000. All Rights Reserved

This document is available in bou nd version and in
electronic version. We encourage user s to purchase
authorized bound manuals, or t o view electronic versions as
designed and authored by Siemens Milltronics Process
Instruments Inc. Siemens Milltronics Process Instruments
Inc. will not be responsible for the contents of partial or
whole reproductions of either bound or electronic versions.

MILLTRONICS®is a registered trademark of Siemens Milltronics Process Instruments Inc.

While we have verified the contents of this
manual for agreement with the instrumentation
described, variations remain possible. Thus we
cannot guarantee full agreement. The content s of
this manual are regularly reviewed and
corrections are included in subsequent editions.
We welcome all suggestions for improvement.

Technical data subject to change.

Contact SMPI Technical Publications at the following address:

Technical Publications
Siemens Milltronics Process Instruments Inc.
1954 Technology Drive, P.O. Box 4225
Peterborough, Ontario, Canada, K9J 7B1
Email: techpubs@milltronics.c om

For the library of SMPI instruction manuals, visit our Web site:

© Siemens Milltronics Process Instruments Inc. 2001

www.milltronics.com

TABLE OF CONTENTS

Title Page

ABOUT THIS MANUAL 1
ABOUT THE MMI-2 1
SPECIFICATIONS 2
OPERATION 3
INSTALLATION

CALIBRATION

Preamble 4
Welding 4
Load Cell Handling 4
Installation Procedure 5

General 8
Test Load 8
Zero 8
Span 8
Material Test 9
Re-Rating 9

MAINTENANCE AND SPARE PARTS 9

IDLER MOUNTING

Troughed Idler with Channel Spine 10
Troughed Idler with Pipe Spine 11
Flat Idler 12

MSI WIRING 13

OUTLINE DIMENSIONS-CEMA 14

OUTLINE DIMENSIONS-METRIC 15

PL-327 i

ABOUT THIS MANUAL

This instruction manual, PL-327, covers the installation, operation and maintenance of the MMI-2 belt scale.
It is imperative that this manual be read and understood before installation and start up of any component of

the weighing system to which the MMI-2 is being applied. Adhering to the installation and operating
procedures will insure a quick, trouble free installation and allow for the maximum accuracy and reliability of
your weighing system to be achieved.

As the MMI-2 belt scale is used in conjunction with an integrator and optional speed sensor, the instruction
manuals covering these components must be read as well.

ABOUT THE MMI-2

The Milltronics Multiple Idler (MMI-2) is a belt scale application using two Milltronics Single Idler (MSI) belt
scales in succession. The scales are designed to be inserted into belt conveyors for continuous weighing of
dry bulk solids.

Each MSI is comprised of the following: - one weighbridge c/w two load cells with cables run in a

common flexible conduit

- test weight(s)

The addition of an idler (supplied and installed by customer) to each weighbridge completes th e weighing
assembly. The MMI load cells provide an electronic signal, proportional to load, which is fed to the Milltronics
CompuScale series integrator. Thus, weighing is accomplished without disturbing the process and without
affecting the process material.

The MMI-2 is used where conveyor belt speeds or belt loading charactistics result in conditions that
necessitate extending the weighing time beyond the capibilities of a single idler scale. It is also well suited for
applications that require higher sustained accuracies, such as production control inventory accountability or
where certification for trade purposes is required.

It is important to understand that the MMI-2 is an accurate and repeatable force sensor. Its performance is
ultimately dependent upon the conveyor system and the quality of the installation and alignment.

PL-327 1

SPECIFICATIONS

Accuracy: » ± 0.25% of totalization over 5 to 1 operating range

in factory approved installations

Belt Width: » 18" to 96" in CEMA sizes

» 500 to 2000 mm in metric sizes
» refer to Outline and Dimensions

Belt Speed: » up to 4 m/s (800 fpm)

Capacity: » up to 5000 TPH at maximum belt speed

Conveyor Incline: » ± 20° from horizontial, fixed incline

» up to ± 30° with reduced accuracy

Conveyor Idler: » flat to 35°

» up to 45° with reduced accuracy

Idler Diameter: » 50 to 180 mm (2 to 7")

Idler Spacing: » 0.5 to 1.5 m (1.5 to 5.0 ft)

Load Cell: » excitation: » 10 V DC nominal

» 15 V DC maximum
» output: » 2 mV / V excitation at rated load cell capacity
» non-linearity: » 0.02% of rated output
» hysteresis: » 0.02% of rated output
» non-repeatability: » 0.01% of rated output
» capacity: » maximum ranges: 50, 100, 250, 500, 750,1000 lb
» overload: » maximum 1000% of rated capacity
» temperature: » – 40 to 85 °C (– 40 to 185 °F) operating range

» – 15 to 65 ° C ( 5 to 150 °F) internally compensated

Approvals: › CSA certified for general purpose

Hazardous Locations: › with the use of approved intrinsically safe barrier strips

Weight: › see chart, Outline and Dimensions

PL-327 2

OPERATION

Each MSI weighbridge is designed to react to the vertical component of the force being applied to it. Each MSI
consists essentially of a static assembly and a weighing assembly.

The static assembly is used to mount each MSI between the conveyor stringers and supports the weighing
assembly via its load cells.

The weighing assembly supports the scale idler and transfers the weight of the material to the load cells.
These are the active components in the weighing assembly.

As the material travels along the conveyor, a force is exerted through the suspended idler onto the weighing
assembly. The weighing assembly is forced down proportionally. The movement in each load cell is sensed
by its strain gauges. These modulate the excitiation signal from the electronic integrator to produce a signal
proportional to weight, which is returned to the integrator. The movement in the load cell is limited by the
positive stop incorporated in the design of the load cell.

idler bracket

test weight bar

Force

idler clip

idler frame

scale mounting bracket

dynamic beam

static beam

weigh
bridge

PL-327 3

INSTALLATION

PREAMBLE

The MMI-2 is shipped from the factory, attached to a frame for protection. Each MSI weighbridge must be
removed from its shipping frame and inspected for physical damage.

Insure that the conveyor design meets the installation requirements for the Milltronics MMI-2 scale. The
conveyor stringers must be rigid, straight, parallel to and square with the belt line in the area of the scale
installation. The idlers to be used on the scale and at least the next two approach and retreat idlers must be
of the same style and manufacture and in good condition.

Prepare the site in accordance with the Milltronics drawing(s) provided or by reference to Milltronics
instruction manual PL-328, Applications Guidelines.

WELDING

Extreme caution should be used when arc welding in the area of the belt scale. Insure that no welding current
can flow through the belt scale. Welding currents through the scale are sufficient to functionally destroy the
load cells.

LOAD CELL HANDLING

The load cell can tolerate very little negative displacement, otherwise the load cell will be functionally destroyed.
When handling the individual MSI’s install both shipping stops to their vertical position to protect the load cells.

Do not lift the MSI’s by the weighing assembly or subject it to shock from blows of a hammer when trying to
position it.

DO NOT STAND OR WALK ON THE SCALE.

OVERLOADING, SHOCK AND TWISTING OF THE SCALE CAN ALL

FUNCTIONALLY DESTROY THE LOAD CELLS.

PL-327 4

INSTALLATION PROCEDURE

1. Remove the conveyor idlers currently at the desired points of installation.

2. Remove the foot plates and modify the idler frame at both ends of the idlers as shown .

customer’s idler

12.7 mm
(0.5")

100 mm
(4")

before

after

3. Insert the MSI’s in the place of the removed idlers. The MSI is designed to use the existing holes in the
stringer and should not require further drilling. Install the mounting bolts and nuts, but do not tighten .
Remove the idler clips. Refer to Outline and Dimensions.

location of
removed idlers

material flow

test weight(s)

test weight(s)

MSI belt scales

Insure that there is sufficient clearance between the return belt and the MSI and test weight (when used
during the calibration procedure).

PL-327 5

4. Position the individual MSI’s such that they are centered and square to the stringer. Mount the modified
idlers such that they are centered onto the scale using the idler clips. Tighten all mounting hardware.
Refer to Idler Mounting for alternate idler mounting arrangements.

Orient the scale so that the large arrow on the scale mounting brackets is pointing in the direction
of material flow.

idler clips

conveyor stringer
(typical)

5. Release the shipping stops on each MSI in order to free the weighing mechanism. Loosen screws ‘A’ and
rotate both shipping stops inward until the underside slots slide around the shoulder bolts ‘B’. Tighten
screws ‘A’ to secure in place.

‘A’ screws

shipping stop

‘B’ shoulder bolts

PL-327 6

shipping stop

6. The idlers in the weighing area must be properly aligned and leveled by shimming the scale idler (S#), the
two approach (A#) and the two retreat idlers (R#) until they are within ± 0.8 mm (1/32") of each other.
Be sure to check that the idlers are centered and squared to the conveyor during the shimming process.

Center of
idlers to
be in line

90°

CC

idlers must be square to stringers

R 1

R 2

alignment of idlers
A 2 to R 2 to be within

±

0.8 mm (1/32")

A 2

material flow

S 1

S 2A 1

7. Precise idler alignment is very important if maximum accuracy of the weighing system is to be achieved.
Misaligned idlers will result in unequal forces being applied on each idler in the weighing area, causing
calibration and measurement errors. Use a good quality wire or string to check for alignment. The wire
or string must be able to withstand sufficient tension as to eliminate any sag. By shimming, make the
necessary adjustments to bring all the rolls of the A2 through to the R2 idlers in line within 0.8 mm(1/32").

A 2

approach idlers

A 1

S 1

S 2

MSI with modified scale idler

wire or string
(for alignment)

PL-327 7

R 1

retreat idlers

R 2

Although the accepted tolerance for idler alignement is ±0.8 mm (1/32"), the scale mounted idlers should
never be lower than the adjacent idlers. Establishing good idler alignment is the most important part of the
installation procedure. Scale accuracy is directly affected by alignment. Proper attention must be given here.

CALIBRATION

GENERAL

After the MMI-2 has been properly installed, calibration of the weighing system must be done in conjunction
with the integrator. Refer to the integrator instruction manual for programming and calibration. The
calibration is initially done using the supplied test load. Material tests are recommended to achieve maximum
accuracy.

TEST LOAD

The test load value for each MSI is the same and is given on the accompanying data sheet. The value is to
be entered into the dedicated programming parameter of the integrator, in kilograms per meter or pounds per
feet. An equal number and mass of weights must be applied to each suspension during the span calibration
function.

If the actual idler spacing differs from that recorded on the design data sheet, the test load must be
recalculated as follows. Failure to do so will cause the design test load value to be in error.

test load = total weight of all test weights per MSI kg lb

idler spacing m ft

ZERO

Perform the zero calibration as described in the Calibration section of the integrator manual.

SPAN

The test load used in the calibration procedure is the two sets of test weights ( 1 to 12 ) supplied, one for each
MSI suspension.

Place each set of the test weights onto the calibration weight bar of the respective MSI as shown.
Perform the span calibration as described in the Calibration section of the integrator instruction manual.

After the span calibration has been completed, remove the test load and store it.

( )

OR

( )

MSI

PL-327 8

test weight(s)

MATERIAL TEST

The MSI is guaranteed to be accurate to ±0.25% when installed on a conveyor in accordance with this manual
and meeting the qualifications outlined in Manual PL-328 "MMI Applications Guidlines". This guarantee is
based on calibrations performed using the test weights furnished with the scale and as previously referenced.

When the existing conditions are such that the installation of the scale cannot meet the above mentioned
requirements for an approved installation it is recommended that material tests be performed. This will enable
the user to compare the present scale results to the results of the material tests. The scale is then adjusted or
factored so that subsequent scale calibrations with test weights will agree with actual run of material.

At least 3 samples of a minimum of 10 minutes duration at normal capacity should be taken to insure
repeatability. Refer to "Material Test" and subsequent "Factoring" sections of the integrator manual.

RE-RATING

Any significant change in rate, speed and /or idler spacing from original design specifications should be
referred to your local Milltronics office to insure that proper design parameters are maintained.

MAINTENANCE AND SPARE PARTS

Each weighbridge should be kept clean. Accumulations of material between the weighing assembly and
static assembly as well as around each load cell can be detrimental to the weighing accuracy.

Periodically check the mechanical integrity of the scale and alignment of the stringers and idlers within the
weighing area.

The integrity of the load cells can be seen when zero and span calibrations are performed. If the zero and
span deviations display a continuous unidirectional drift or the system becomes uncalibratable for no apparent
mechanical reason, the load cells may be suspect.

Replacement of load cell(s) will require a re-balancing of the load cells. Refer to the load cell balancing
procedure for four load cells in the integrator manual.

The only spare part recommended for the MSI is the load cell. Refer to the load cell nameplate for the proper
size and model number.

Precautions :

» when arc welding near the scale do not allow current to pass through the belt scale.
» reset the shipping stops to reduce physical shock to the load cells during maintenance.
» recalibrate after maintenance and prior to use.

PL-327 9

IDLER MOUNTING

The MSI is usually installed in conveyors employing conventional rigid structure idlers. Within this type of
idler, construction will vary depending on the manufacture and the application. The idler depicted in the
Installation Procedure uses an angle iron spine. The following depicts alternate idler construction and tips on
how they should be modified and installed.

TROUGHED IDLER WITH CHANNEL SPINE

gusset reinforcement
if required, see
Installation Procedure

customer’s idler

12.7 mm
(0.5")

foot pads welded
to idler spine

before after

100 mm
(4")

idler modification

idler clip

idler installation

PL-327 10

customer bolts
(4 places)

TROUGHED IDLER WITH PIPE SPINE

customer’s idler

12.7 mm
(0.5")

foot pads welded
to idler spine

before after

100 mm
(4")

idler modification

idler clip

idler installation

PL-327 11

customer bolts
(4 places)

FLAT IDLER

customer’s idler

before after

in most applications standard
conveyor manufacturers’
brackets cannot be used,
replacement brackets
(as shown) are needed

12.7mm
(0.5")

idler modification

customer bolts
(4 places)

idler installation

PL-327 12

idler clip

MMI-2 WIRING

load cell ‘A’ (‘C’)

see detail ‘A’

load cell ‘A’

MSI #2

belt travel

MSI #1

load cell ‘B’ (‘D’)

load cell ‘B’

DETAIL ‘A’

conduit and connector

load cell

‘A’

+

E
X
E

–

E
X
E

MSI #1

–

+

S

S

I

I

G

G

A

A

to integrator

belt travel

load cell

‘B’

load cell

‘A’

MSI #2

load cell

‘B’

customer

junction

box

–

+

–

S

S

S

I

G

B

H

I

I

G

E
L

B

D

–

+

E

E

X

X

E

E

+

S

S

I

I

G

G

A

A

+

–

S

I

G
B

S

S

H

I

I

G

E
L

B

D

to integrator

PL-327 13

OUTLINE DIMENSIONS - CEMA

‘C’

178 mm
(7")

‘D’

‘A’

‘B’

conveyor mounting scale minimum drop-in ‘C’ ‘D’ weight
belt width width ‘A’ width ‘B’

18 " 27 " 24.5 " 9.5 " 5.5 " 82 lb
20 " 29 " 26.5 " 9.5 " 5.5 " 85 lb
24 " 33 " 30.5 " 9.5 " 5.5 " 90 lb
30 " 39 " 36.5 " 9.5 " 5.5 " 99 lb
36 " 45 " 42.5 " 9.5 " 5.5 " 107 lb
42 " 51 " 48.5 " 9.5 " 5.5 " 116 lb
48 " 57 " 54.5 " 12 " 8" 162 lb
54 " 63 " 60.5 " 12 " 8" 174 lb
60 " 69 " 66.5 " 12 " 8" 185 lb
72 " 81 " 78.75 " 12 " 8" 235 lb
84 " 93 " 90.75 " 12 " 8" 261 lb
96 " 105 " 102.75 " 12 " 8" 288 lb

PL-327 14

LINE DIMENSIONS - METRIC

‘C’

178 mm
(7")

‘D’

‘A’

‘B’

conveyor mounting scale minimum drop-in ‘C’ ‘D’ weight

belt width width ‘A’ width ‘B’

500
650
800

800
1000
1000
1200
1200
1400
1600
1800
2000

mm
mm
mm
mm

mm
mm
mm
mm
mm
mm
mm
mm

740

mm

890

mm

1040

mm

1090

mm

1240

mm

1290

mm

1450

mm

1540

mm

1650 / 1740
1900 / 1940
2100 / 2140
2300 / 2340

mm
mm
mm
mm

677

mm

827

mm

977

mm

1027

mm

1177

mm

1227

mm

1387

mm

1477

mm

1587 / 1677
1837 / 1877
2037 / 2077
2237 / 2277

mm
mm
mm
mm

241
241
241
241
241
305
305
305
305
305
305
305

mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm

140
140
140
140
140
203
203
203
203
203
203
203

mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm

37 kg
40 kg
44 kg
48 kg
52 kg
73 kg
78 kg
83 kg
88 kg
93 kg
98 kg

103 kg

PL-327 15

Siemens Milltronics Process Instruments Inc.
1954Technology Drive, P.O. Box 4225
Peterborough, ON.Canada K9J 7B1
Tel: [phone] Fax: [phone]
www.milltronics.com

c

Siemens Milltronics Process Instruments Inc. 2001

Subject to change without prior notice

*7ML19981dr01*

Printed in Canada