Geosense HLC 6000 Series User manual

V1.0 July 2020
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HLC 6000 SERIES
HYDRAULIC ANCHOR LOAD CELLS

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CONTENTS
PAGE
1.0 INTRODUCTION
1.1 General description 3
1.2 Theory of operation 4
2.0 CONFORMITY 5
3.0 MARKINGS 6
4.0 DELIVERY 7
4.1 Packaging 7
4.2 Handling 7
4.3 Inspection/functionality 7
4.3.1 VW transducer 7
4.3.2 Pressure gauge/manometer 7
4.4 Storage 7
5.0 INSTALLATION
5.1 General issues 8
5.2 General considerations 8
5.3 Mounting surfaces 8
5.4 Installation 10
6.0 DATA HANDLING 13
6.1 Monitoring the load cell readings 13
6.2 Portable readouts 13
6.3 Data reduction 14
6.3.1 Overview 16
6.4 Load calculation 16
6.5 Calibration 17
6.6 Temperature considerations 19
7.0 MAINTENANCE 20
8.0 TROUBLESHOOTING 20
9.0 SPECIFICATION 23
10.0 SPARE PARTS 23
11.0 RETURN OF GOODS 24
12.0 LIMITED WARRANTY 25

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It is VITAL that personnel responsible for the installation and
use of the Geosense® Hydraulic Load Cells READS and
UNDERSTANDS the manual, prior to working with the
equipment.
1.1 General Description
The primary uses for the Geosense® HLC-6000 Series Hydraulic Anchor Load
Cells are used for measuring loads acting on:-
• Ground Anchors
• Rock bolts
• Tie backs
Particular features of the Geosense® HLC-6000 Series Hydraulic Anchor Load
Cells are:-
• Robust stainless steel construction
• Accommodates some eccentric loading
• Reliable long term performance
• Rugged, suitable for demanding environments
• High accuracy
• Data logger compatible
They consist of a sensitive pressure pad formed by joining two stiff steel discs at their
periphery. The void inside the cell is filled with de-aired fluid. When load is applied to the
cell the pressure of the inside liquid changes. The changes in pressure correspond
directly to the load applied.
Manufactured with a centre hole to accommodate anchors, rock bolts and tendons.
The pressure in the loads cell is measured either by a manometer or a vibrating wire
transducer (VWDT-5000) which are available in the following models:
HLC-6000 - Manometer (scale in bar for pressure indication)
HLC-6500 - Vibrating wire transducer
1.2 Theory of operation
HLC-6000 Series Hydraulic Anchor Load Cells consist of a sensitive pressure pad.
The void inside the cell is filled with de-aired fluid. When load is applied to the cell the
pressure of the inside liquid changes. The changes in pressure correspond directly to the
load applied.
The pressure inside the loads cell is measured either by a vibrating wire transducer or a
1.0 INTRODUCTION
This manual is intended for all users of Geosense® HLC-6000 series load cells
manufactured by Geosense and provides information on their installation, operation and
maintenance.

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2.0 CONFORMITY
Geosense Ltd
Nova House
Rougham Industrial Estate
Rougham, Bury St Edmunds
Suffolk , IP30 9ND
United Kingdom
Tel: [phone]
www.geosense.co.uk
Declaration of Conformity
We Geosense Ltd at the above address declare that the equipment detailed below complies with the
requirements of the following EU Directive:-
The Electromagnetic Compatibility Directive 2014/30/EU
Restriction on the use of certain Hazardous Substances RoHS2 2017/2102/EU
Waste electrical & electronic equipment WEEE 2012/19/EU
Equipment description: Hydraulic load cells
Make/brand: Geosense
Model numbers: HLC-6000, HLC-6500
Compliance has been assessed with reference to the following harmonised standard:-
EN 61326-1:2006 Electrical equipment for measurement, control and laboratory use.
EMC requirements. General requirements.
EN 61010-2-032:2002
Safety requirements for electrical equipment for measurement, control, and laboratory use.
A technical file for this equipment is retained at the above address
Martin Clegg
Director
Rougham, July 2020

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3.0 MARKINGS
Geosense HLC-6000 Series Hydraulic Anchor Load Cells are labelled with the following information:-
Manufacturers name & address
Product
Type/Model
Range
Serial number
CE mark
WEEE mark
HLC-6000 with Manometer
HLC-6500 with VW Transducer

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4.0 DELIVERY
This section should be read by all users of the HLC-6000 Series Hydraulic Anchor
Load Cells manufactured by Geosense.
4.2 Handling
Whilst they are a robust devices, HLC-6000 Series Hydraulic Anchor Load Cells are
precision measuring devices. They and their associated equipment should always be
handled with care during transportation, storage and installation.
Once the shipment has been checked it is recommended that Geosense® Vibrating wire
load cells remain in their original packaging for storage or transportation.
Cable should be handled with care. Do not allow it to be damaged by sharp edges, rocks
for example, and do not exert force on the cable as this my damage the interim
conductors and render the installation useless.
4.1 Packaging
HLC-6000 Series Hydraulic Anchor Load Cells are packed for transportation to site.
Packaging is suitably robust to allow normal handling by transportation companies.
Inappropriate handling techniques may cause damage to the packaging and the enclosed
equipment. The packaging should be carefully inspected upon delivery and any damage
MUST be reported to both the transportation company and Geosense®
4.3 Inspection/functionality
It is vital to check all the equipment in the shipment as soon as possible after taking
delivery and well before installation is to be carried out. Check that all the components
detailed on the documents are included in the shipment. Check that the equipment has
not been physically damaged.
ALL HLC-6000 Series Hydraulic Anchor Load Cells carry a unique identification serial
number which is located on the cable connection block.
All HLC-6000 Series Hydraulic Anchor Load Cells are supplied with individual
calibration sheets that include their serial numbers and these will shipped with them.
Calibration Sheets contain VITAL information about the Geosense®
Vibrating wire load cells. They MUST be stored in a safe place.
Only copies should be taken to site.

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4.3 Inspection/functionality contd...
4.3.1 Vibrating wire transducer
CHECK the VW transducer readings against the factory ‘Zero Readings’ on arrival to
ensure they have not changed significantly due to damage during transportation. This is a
basic ‘out of the box’ functional check.
Prior to carrying out a reading check, ensure that the load cells have been stored in a
reasonably stable temperature for at least 30 – 60 minutes.
To carry out the check, connect a Vibrating Wire readout to the bare cable ends (Red
connector to Red wire and Black connector to Black wire) – The Green and White
connectors / wires are for the temperature sensor and are not
required for this checking exercise - see the readout manual
for connection guidance.
Record the values (and units) displayed on the readout together
with the load cell serial numbers.
The “CHECK” readings should coincide with the factory zero on
the calibration sheet (see the example calibration sheet in
Section 9) within +/- 50 digits after barometric and temperature
corrections are made.
The elevation of the Geosense® factory is +60 metres above sea level and barometric
pressures change with altitude by approximately 1.2kPa per 100 metres.
4.3.2 Pressure gauge/manometer
Check the gauge offset is at zero
4.4 Storage
All HLC-6000 Series Hydraulic Anchor Load Cells and associated equipment should be
stored in an environment that is protected from direct sunlight.
It is also recommended that cables be stored in a dry environment to prevent moisture
migrating along inside them in the unlikely event of prolonged submersion of exposed
conductors. The cables should also be protected from rodents and traffic.
The ‘CHECK Readings WILL be affected by changes in
atmospheric pressure and temperature changes.
Calibration Sheets contain VITAL information.
They MUST be stored in a safe place.
Only COPIES of calibration certificates should be taken to site
The original certificates should be stored safely.

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It is VITAL that personnel responsible for the installation and use of the
Geosense® HLC-6000 Series Hydraulic Anchor Load Cells READS and
UNDERSTANDS the manual, prior to working with the equipment.
**********
As stated before, it is vital to check all the equipment in the shipment soon
after taking delivery and well before installation is to be carried out. Check
that all components that are detailed on the shipping documents are
included.
5.0 INSTALLATION
This section of the manual is intended for all users of HLC-6000 Series Hydraulic Anchor
Load Cells manufactured by Geosense® and is intended to provide guidance with
respect to their installation.
5.1 General Issues
• Note serial number against location
• Mark cables for future identification. Use an appropriate coding system and mark
cables at frequent intervals, not just at the ends.
• Protect the ends of the signal cable. Cables should be terminated at a waterproof
box or with waterproof connectors.
5.2 General considerations
Ensure that the internal diameter of the cell is correct for the anchor strands or bolt
head.
Ensure that the capacity of the cell is sufficient for the anchor including the
tensioning.
Provide support brackets where necessary to ensure the load cell is kept centralised
during installation.
5.3 Mounting surfaces
Mounting surfaces should be flat and parallel for optimum performance the
mounting surface MUST be flat and perpendicular toi the direction of loading
(anchor or rod). Very stiff abutment plates and load distribution plates is
recommended.
The abutment plate (provided locally) is normally made to suit specific site
requirements and the load distribution plate (supplied by Geosense) should be I
inserted between the load cell and the anchor head (see next page)

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5.3 Mounting surfaces contd…
Details shown below are for a typical installation but conditions may vary from site to site.
Before installing the following conditions should apply
The applied load must be perpendicular, centered, and uniform over the
Load Cell surface.
Avoid load concentrations.
Make sure loading surfaces are accurately levelled and parallel.
If necessary fabricate an anchor load bearing/abutment plate
anchor
load distribution
plates
cables /
strands
bearing plate
wedge plate
wedges
anchor load bearing / abutment plate
anchor load cell
centralising
supports

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STEP 1
Place the Bearing Plate (optional) over the tensioning member(s) and onto the loading surface
abutment plate
STEP 2
Lower the Load Cell over the tensioning member(s) and
onto the loading surface (abutment plate)
TAKE A ZERO LOAD READING (SEE DATA HANDLING FOR VW)
STEP 3
Lower the Distribution Plate over the tensioning member(s)
and onto the VW Hydraulic Load Cell
5.4 Installation
MAKE SURE THE LOAD CELL IS SUPPORTED & CENTRALISED

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STEP 4
Place the Wedge Plate over the tensioning member(s)
and onto the load distribution plate and additional top load
plate (optional)
STEP 5
Slowly lower the tensioning jack over the tensioning
member(s)
.
5.4 Installation contd...

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STEP 6
Carefully lower the tensioning Jack onto the load
distribution plate or top load plate where applicable
STEP 7
Tension the strands as required and take readings from
the VW transducer or manometer as necessary
TAKE CARE NOT TO OVER RANGE THE LOAD CELL
If required protect the installation with a suitable cap
5.4 Installation contd...

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6.0 DATA HANDLING
The function of the instrument is to provide useful and reliable data.
Accurate recording and handling of the data is essential if it is to be
of any value.
6.1 Monitoring the Load Cell Readings
Geosense® HLC-6000 Series Hydraulic Anchor Load Cells contain a temperature
sensor within the VW transducer. Where a load cell is installed in a zone where its
temperature is likely to fluctuate significantly, records of both load and temperature
data should be used to assess any affects that temperature have on the data (see
section 6.6).
6.2 Portable Readouts
Geosense offer a range of readout and data logging options. Specific operation
manuals are supplied with each readout device.
Below is a brief, step-by-step procedure for use with the Geosense® VWR-1 portable
readout.
1. Connect signal cable from the sensor to the readout following the wiring colour
code. Conductor colours may vary depending upon the extension cable used.
Commonly these are:
RED =VW +
BLACK =VW -
GREEN =Temp
WHITE =Temp
2. Press the ‘On/Off’ button to switch the unit on.
Press it again to acquire a reading from the
connected instrument.
3. The readout displays the Vibrating Wire readings in both
‘Frequency’ (in Hz) and Linear ‘B’ Digits (in Hz2/1000).
Temperature reading in both resistance (Ohms) and
degrees C.
For more details see the readout manual.
4. Press and hold down the On/Off’ button to switch the
unit off.
Whilst it is not critical that the polarity be observed for most
Vibrating Wire instruments, a better signal may be obtained if
the correct polarity is adopted. Since the temperature sensor
is a Thermistor, its connection polarity is not important.

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.
6.3 Data Reduction
6.3.1 Overview
Readings from a Vibrating Wire Transducer are in a form that is a function of frequency, ra-
ther than in units of pressure. Commonly the units would be either Frequency - Hz, Linear
B Digits - Hz2/1000 or Hz2/1000000 Linear B Digits are required for all calculations.
To convert the readings to units of pressure some calculation is required. Calibration factors
must be applied to the recorded values. For most Vibrating Wire sensors, these factors are
unique and are detailed on the individual sensor calibration sheets. A unique calibration
sheet is supplied with every Geosense® Vibrating Wire Transducer.
If the readout displays ‘Frequency’ values, (e.g. 2768.5 Hz) only a simple calculation is re-
quired to convert the readings to Linear Digits.
Linear Digits (Hz2/1000) = ( 2768.5 ) 2 / 1000
=7664.6
Certain data loggers store their Vibrating Wire data in Linear Digits but further divided by
1000. In this case the data would have to be multiplied by a further 1000 to maintain the
standard Linear Digits (Hz2/1000) format for standard calculations.
The first step to producing an engineering value is to convert the reading to Linear Digits
(Hz2/1000). An example of this calculation can be seen on the next page.
(1) Readout Display =0.03612
Linear Digits (Hz2/1000) = ( 1 / 0.03612 x 10–2 ) 2 / 1000
=7664.8
(2) Readout Display = 3612
Linear Digits (Hz2/1000) = ( 1 / 3612 x 10 –7 ) 2 / 1000
=7664.8

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6.3.1 Data Reduction overview contd...
An instrument calibration sheet similar to the example in the Section 6.6 of this manual in-
cludes the following information:
Model This refers to the Geosense model number.
Serial Number This is a unique sensor identification number that can be found
on the load cell body and, for long cables, at the end of the cable.
Works ID Unique works batch and range code
Cal Date Date the calibration was performed
Baro Barometric Pressure at the time of calibration
Temp oCTemperature at which the load cell was calibrated
Applied Pressure Pressure applied to the transducer as part of the calibration
cycle
Readings [digit] Readings from the transducer as pressure is applied and as
pressure is reduced, in steps. The average is calculated.
Calculated Pressure Calculation of the applied pressure using the calculated
3rd order Polynomial for comparison with the actual Applied
Pressure.
Error % FSO Non Linearity expressed as a percentage of the transducers
Full Scale.
Calibration Factors ‘‘Polynomial’ factors are provided for conversion to kN
An example of the calculation from Linear Digits ( Hz2/1000) to kN using a polynomial equa-
tion is given below:-
Calibration Factors for kN
A= - 5.14962E-10
B= 1.1669E-5
C = - 0.333375086
D = 2599.399697
Current Reading in Linear Digits = 8475
Equation
Load in kN = [ A x ( Reading )3 ] + [ B x ( Reading )2 ] + [ C x Reading ] + D
= [- 5.14962E-10 x (8475)3] + [1.1669E-5 x (8475)2] + [- 0.333375086 x 8475] + 2599.399697
= -313.468787 + 838.133218 + -2825.353854 + 2599.399697
= 298.710 kN

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6.5 CALIBRATION
Vibrating Wire

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6.5 CALIBRATION contd...
Pressure gauge/Manometer

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6.6 Temperature Considerations
The environment which HLC-6000 Series Hydraulic Anchor Load Cells are often installed
in environments that are subjected to significant variations in temperature and these
changes will affect their readings.
Thermal influences are complex because it is not only the load cell that is affected but the
element to which it is attached and whole structure that is affected. The rate of temperature
change and the distribution of the thermal gradients also play a major part in influencing the
actual load at any point and its effect on the load cell and its readings.
Consequently, in order to apply any correction for temperature it is necessary to first
establish the effects of the temperature changes on the load cell and the medium in/on which
it is installed.
A useful exercise to carry out on site to establish the in-situ effects of temperature changes is
to observe the installed load cell readings, together with both ambient and cell
temperatures, when no other factors are changing. This should be carried out prior to any
loading or other structural changes / works are carried out.
An alternative, is to use a ‘No load”, load cell installed close to the monitoring cells. This will
enable an assessment of temperature affects on the cell itself in the working environment for
a particular location. For further discussion about ‘No load”, load cells please contact
Geosense®.
For HLC-6000 series load cells fitted with a manometer engineering judgement will be
required to understand any temperature effects.

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7.0 MAINTENANCE
Geosense® HLC-6000 Series Hydraulic Anchor Load Cells are basically maintenance free
device for most applications but the following should be considered during the service life:-
• Keep away from direct sunlight to avoid large thermal affects
• Keep the cable connection cap on when Readout not connected
• Avoid any impacts or significant vibration which can damage internal sensors
• Keep cables away from physical damage
• Keep cable ends waterproof
8.0 TROUBLESHOOTING
Unexpected readings
The following are common scenarios which lead to the readings and performance of load cells
being questioned.
The reading taken on the Jack is taken at a different time from that taken on the load cell
The strand is tensioned using the jack, the locking collets are then replaced and the anchor left
to take the load. It is at this point the load on the installed permanent cell is read and does not
equate the load in the Jack prior to release. This is because of the Young’s modulus of the
anchor and all the slight play in the fixtures and fittings of the system that cause elasticity in the
system, it is the release of the stored energy in the system whilst transferring load to the
anchor and so at the same time through the load cell that cause this indifference. It is not the
fault of the load cell installed but merely a part of the stressing process that is overlooked due
to a lack of knowledge that trusting the instruments will help provide. It is recommended to
carry out Lift Off Testing for cell reading versus jack reading to identify any loss of load
transfer.
The use of a jack which is much longer than the squat load cells
This is more prone to inaccurate measurement of the loading due to eccentric loading causing
the system more likely to contain bending moment in the system and so likely to cause friction
between the ram and the seal, otherwise known as binding of the seal of the Jack. This will
cause the loading to be over registered by the Jack. Unfortunately this is often understood as
under registering load by the load cell. It is worth noting that each cell has been individually
calibrated before despatch and not touched since while the ram has probably been used on
site to install hundreds of anchors since its last cal date and so its calibration data must also be
viewed as less valid.