Rice Lake Weighing Systems RL9000TWM Operating Manual

RL9000 TWM

Load Cell Mount

Installation

Guide

To be the best by every measure

89284

Contents

1. Introduction............................................................................. 1

2. Mechanical Installation .......................................................... 2

2.1 General Installation Guidelines for Tank Mounts ....................... 2

2.2 Installing the RL9000TWM ........................................................... 3

3. Load Cell Wiring ..................................................................... 5

4. Junction Box Connections, Adjustments & Calibration ....... 6

5. Troubleshooting ...................................................................... 6

6. Dimensional Drawings ............................................................ 7

7. RL9000 TWM Limited Warranty ............................................. 9

© 2011 Rice Lake Weighing Systems. All rights reserved.

Printed in the United States of America.

Specifi cations subject to change without notice.

1. Introduction

The RL9000 TWM Load Cell Mount provides an extremely accurate method for weighing
medium and large capacity tanks and hoppers that are subject to large thermal expan­sion/contraction or vibration forces. The design uses a low profi le shear web load cell
(350Ω bridge) and transmits the load via a spherical washer on the load-bearing hub
of the cell. This design is very effective in providing for thermal expansion/contraction
with little friction.

In most applications, the assemblies are self­checking and held captive with no need for check or
stay rods, making this mount a good choice for most
vessel weighing applications. The shear web design
eases load cell installation and replacement without
the need to raise the weighed vessel a large amount,
which could disturb piping and other connections.

The RL9000 TWM is available in stainless steel, in capacity sizes from 1,000-450,000
lb. The RL9000 TWM utilizes a welded-seal stainless steel load cell.

The installation should be planned by a qualifi ed structural engineer. Each installation
is unique, and this manual is meant to serve only as a general guideline for installation.

The RL9000 TWM is capable of weighing accurately with as much as a 3˚ non-parallel
loading. The RL9000 TWM module offers 100% sideload, 100% uplift and 300%
overload protection.

Thermal

Expansion

Authorized distributors and their employees can
view or download this manual from the Rice Lake

Weighing Systems distributor site at www.rlws.com.

2. Mechanical Installation

2.1 General Installation Guidelines for Tank Mounts

1. The mounting surface for base and top plate must be level. After installation, the
top and bottom plates must be level within ±0.5°. If the mounting surfaces are not
level, then shims and or grout may be used to level the mount.

If possible, check that the mount is level when the vessel is fully loaded because

excessive defl ections in legs and supporting structures may cause additional side
forces which greatly affect accuracy. Defl ection of the mount’s top or base plate
due to loading should not exceed ±0.5°. Reinforcement of legs or other support
structures may be necessary to correct this. Vessels with long legs should have
cross bracing applied between adjacent legs to keep them from spreading under
load.

2. Compression mounting systems use three, four, or more mounts. More than eight­mount systems should be avoided as even weight distribution becomes extremely
diffi cult to achieve. The load on each mount assembly should vary by no more
than 20%. Add shims where necessary to achieve correct load distribution.

3. Take extreme care to prevent overload damage. A tank or hopper can exert huge
forces when dropped only a fraction of an inch.

4. It is crucial that all piping or conduit be
horizontal and fl exible. If fl exible piping
is not used, make sure distance from
vessel to the fi rst pipe support is 20-30
times pipe diameter. In smaller, lower
capacity tanks and hoppers, isolating
resultant forces becomes extremely
critical. For details, see our Weigh
Modules & Vessel Weighing Systems
manual, P/N 43918.

LEVEL ±0.5

FLEXIBLE PIPING

J-BOX

5. The weighing assemblies should not be
installed until all welding is completed.
The heat generated from welding current passing through a load cell can damage
the adhesive holding the strain gauge to the body. If possible, use a dummy mount
when welding to maintain fi nished height. If welding is unavoidable after load
cell installation, connect the ground in such a way that the current does not fl ow
through the load cell. For example, if welding on the mount top plate, the ground
must be connected to the vessel, not to the mount base or support structure. Also,
protect the load cell and cable from weld splatter.

6. Use only “hermetically sealed” load cells in washdown applications. “Environ­mentally protected” load cells are not suitable for such applications and will be
damaged. If tanks and surrounding equipment are frequently steam cleaned or if
the load cell is subjected to direct washdown, a protective shroud for the weighing
assembly is recommended. Proper drainage is necessary so the weighing assembly
is not standing in water.

7. All support points should be equally stiff so that they defl ect by the same amount
as the vessel is loaded.

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2.2 Installing the RL9000 TWM

1. The type of installation and strength of the mounting surface governs the method of
locating, attaching, and installing the RL9000 TWM assembly. Carefully consider
three areas which commonly cause accuracy problems:

• Are the supporting legs adequately braced so they will not spread when the system
is fully loaded?

• Does the supporting structure have the necessary strength to prevent excessive
defl ection when the system is fully loaded?

• Is there attached equipment such as skirting, venting, or piping which is likely to
cause binding or lack of fl exibility?

2. Determine where to position each mount. The RL9000 TWM is designed to allow
for lateral movement in any direction. Sample mounting orientations to accom­modate different vessel shapes are as follows:

Load Plate

Caulk supplied

Base Plate

by others

3. Make necessary preparations to the mounting surfaces. A 1" sub plate can be used
to ensure a good mounting surface.

4. Lift and block the vessel to the same height as the assembled mounts. Slide mount
into position.

5. If the mount is being fi tted under the leg of a vessel, verify that the leg’s center
line passes through the center of the top plate (through the center of the load cell).

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6. Lower the corner or side of the vessel carefully onto the top plate. The force of a
vessel weighing several tons can damage a load cell if dropped only a fraction of
an inch.

7. With the top plate positioned approximately level, mark holes for attaching the
top plate to the vessel’s mounting surface. Drill holes and attach top plate loosely
to vessel with suitable fasteners.

8. Repeat steps 4-10 for the mounting assemblies at the remaining corners or sides.

9. Verify that there is no initial misalignment between the base plate and top plate.

10. Attach the base plates to the foundation using suitable anchors for concrete or by
bolting or welding to a steel structure or subplate. Verify that the base plates are as
level as possible. They should be fully supported. Shimming is not recommended.

11. Check that the top plates are no more than ±.5° out or level. Shim if necessary and
fully tighten mounting bolts.

12. To achieve equal load distribution, fi nal height adjustments can be made with shims
between the top plate loading bracket and the weighing vessel. The variation in
load among the cells should be no more than 20%. The load distribution can be
checked accurately by exciting each load cell in turn and measuring the output
with a voltmeter.

13. Consider using a bead of fl exible caulk between the load cell and the base on lighter
capacity assemblies. This will prevent debris from lodging between the load cell
and the base and causing repeatability or accuracy problems.

14. The top plate must move freely. The RL9000 TWM come directly from the fac­tory correctly assembled and locktighted and should not require adjustment. If
the RL9000 TWM has been disassembled for any reason, perform the following:

a. Remove the large center screw

b. Align the convex load disc and the load cell with the center hole in the base

plate

c. Locktight and install the large screw and continue to turn until the rubber o-

ring just contacts the convex load disc

d. Back the screw off 1/4 turn. The screw provides lateral restraint and lift off

protection. Never remove it or back it off more than the suggested amount.

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3. Load Cell Wiring

1. Route the load cell cables so they will not be damaged or cut. Cable should not

be routed near heat sources greater than 150 °F. Do not shorten any load cell
cable. The load cell is temperature compensated with the supplied length of cable.

Cutting the cable will affect temperature compensation. Coil and protect excess
cable so it will not be mechanically damaged or be sitting in water.

2. Provide a drip loop in all cables so that water or other liquids will not run directly
down the cables onto either the load cells or the junction box. Attach load cell
cable to the dead structure, not the vessel.

3. If conduit protection is necessary against mechanical or rodent damage to the load
cell cables, use fl exible conduit and conduit adapters at the load cells.

4. Connect cables for load cells to the summing board in the junction box according
to the guide shown below and the labels on the terminal strips of the junction box.
To verify the wiring scheme, see the certifi cation shipped with each load cell.

5. For better performance, use positive and negative remote sense lines if the wiring
running from the junction box to the indicator is longer than 25 feet.

Drip Loop

Load Cell Wire Colors

Wire Color

Green

Black

Red

White

Gray or Bare

Function

Positive Reading

+EXC

-EXC

-SIG

+SIG

Shield

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4. Junction Box Connections, Adjustments & Calibration

1. Refer to junction box manual for trimming details.

2. Refer to indicator manual for system calibration details.

5. Troubleshooting

If the system powers up and gives some type of stable digital readout that varies with
the load on the system, any system problems are probably caused by factors other than
the load cells. The load cells are often blamed for a malfunctioning system, but 90% of
the time, the problem lies elsewhere. Look for mechanical causes for your problem fi rst.

If the system can be calibrated but doesn’t return to zero, loses calibration, or demon­strates non-linearity or non-repeatability, see the following chart for possible causes
and do the following checks.

Symptom

No return to zero

Non-Linearity

Non-Repeatability

Lost Calibration

Drifting Readout

Possible Cause

Mechanical binding of debris in seals or under load cells; may

have lost system calibration
Thermal expansion or deflection under load causing binding
or side load
Loose load cell mount; drifting caused by moisture, load cell
overload or shock damage; mechanical binding

Out of level or plumb; moisture problem; mechanical binding

Moisture in junction box, cables, or load cell; mechanical binding

1. Check load cell mount for debris restricting load cell movement or debris be­tween scale and structure.

2. Check that tank/vessel and mounts are plumb, level, and square at critical areas.

3. Check all piping and conduit for connections which restrict vessel movement.

4. If check rods are used, loosen all connections to fi nger tight only for testing.

5. Check load cell cables for physical or water damage.

6. Check all electrical connections, especially in the junction box.

If the problem still is not found:

7. Check possible indicator malfunction by using a load cell simulator to input a known
good signal into the indicator.

8. Disconnect each load cell’s signal leads at the junction box and check individual load
cell outputs with a multimeter. Then check input/output impedances for comparison
with load cell manufacturer’s specifi cations.

If after all these checks the problem still cannot be isolated, reconnect all but one load
cell. Replace load cell with a load cell simulator. Alternate so that each load cell is
individually disconnected and replaced with a simulator. If there is a problem with a
particular load cell, the symptom should disappear when that load cell is disconnected
and replaced with simulator.

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6. Dimensional Drawings

DIMENSIONS (INCHES)

Rated Capacity A B1 C D E F G H I Conduit Adapter

1K-10K 4.0 2.0 3.25 3.5 0.4 3/8-16 1.35 .375 .75 N/A
15K 4.0 2.0 3.25 3.5 0.4 3/8-16 1.60 .625 .75 N/A
20K-50K 7.0 3.75 5.50 6.0 .63 1/2-13 2.48 .75 1.3 1/2-14 NPT
60K-100K 8.0 4.25 6.50 7.0 .81 3/4-16 2.50 1.0 1.3 1/2-14 NPT

1K to 100K Assembly

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DIMENSIONS (INCHES)

Rated Capacity A B2 C D E F G H I Conduit Adapter

150K-200K 10.0 7.825 8.0 9.0 1.1 1-14 4.75 2.0 1.7 1/2-14 NPT

150K to 200K Assembly

DIMENSIONS (INCHES)

Rated Capacity A B2 C D E F G H I Conduit Adapter

250K-450K 11.0 7.75 9.0 9.0 1.3 7/8-14 6.42 3.0 2.25 1/2-14 NPT

250K to 450K Assembly

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7. RL9000 TWM Limited Warranty

Rice Lake Weighing Systems (RLWS) warrants that all RLWS brand load cells properly
installed by a Distributor or Original Equipment Manufacturer (OEM) will operate per
written specifi cations. All load cell products are warranted against defects in materials and
workmanship for two (2) years. Products marked as “waterproof” are warranted against
defects in materials and workmanship relating to moisture ingress.

RLWS warrants that the equipment sold hereunder will conform to the current written speci­fi cations authorized by RLWS. RLWS warrants the equipment against faulty workmanship
and defective materials. If any equipment fails to conform to these warranties, RLWS will,
at its option, repair or replace such goods returned within the warranty period subject to the
following conditions:

• Upon discovery by Buyer of such non-conformity, RLWS will be given prompt written

notice with a detailed explanation of the alleged defi ciencies.

• Examination of such equipment by RLWS confi rms that the non-conformity actually

exists, and was not caused by accident, misuse, neglect, alteration, improper installa­tion, improper repair or improper testing; RLWS shall be the sole judge of all alleged
non-conformities.

• Such equipment has not been modifi ed, altered, or changed by any person other than

RLWS or its duly authorized repair agents.

• RLWS will have a reasonable time to repair or replace the defective equipment. Buyer

is responsible for shipping charges both ways.

• In no event will RLWS be responsible for travel time or on-location repairs, including

assembly or disassembly of equipment, nor will RLWS be liable for the cost of any
repairs made by others.

THESE WARRANTIES EXCLUDE ALL OTHER WARRANTIES, EXPRESSED OR
IMPLIED, INCLUDING WITHOUT LIMITATION WARRANTIES OF MERCHANT­ABILITY OR FITNESS FOR A PARTICULAR PURPOSE. NEITHER RLWS NOR
DISTRIBUTOR WILL, IN ANY EVENT, BE LIABLE FOR INCIDENTAL OR CONSE­QUENTIAL DAMAGES.

RLWS AND BUYER AGREE THAT RLWS’S SOLE AND EXCLUSIVE LIABILITY
HEREUNDER IS LIMITED TO REPAIR OR REPLACEMENT OF SUCH GOODS.
IN ACCEPTING THIS WARRANTY, THE BUYER WAIVES ANY AND ALL OTHER
CLAIMS TO WARRANTY.

SHOULD THE SELLER BE OTHER THAN RLWS, THE BUYER AGREES TO LOOK
ONLY TO THE SELLER FOR WARRANTY CLAIMS.

No terms, conditions, understanding, or agreements purporting to modify the terms of this
warranty shall have any legal effect unless made in writing and signed by a corporate offi cer
of RLWS and the Buyer.

© 2011 Rice Lake Weighing Systems, Inc. Rice Lake, WI USA. All Rights Reserved.

RICE LAKE WEIGHING SYSTEMS • 230 WEST COLEMAN STREET

RICE LAKE, WISCONSIN 54868 • USA

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