Geosense VWPHT-3600 Series User manual

V1.0 July 2020
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HIGH TEMPERATURE
VW PIEZOMETERS
VWPHT-3600

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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
4.2 Handling 7
4.3 Inspection 7
4.4 Storage 8
5.0 INSTALLATION 9
5.1 Zero Pressure Reading 9
5.2 Preparation for installation 11
6.0 DATA HANDLING 13
6.1 Monitoring the piezometer readings 13
6.1.1 Portable readouts 13
6.1.2 Data loggers 14
6.2 Data reduction 14
7.0 MAINTENANCE 18
8.0 TROUBLESHOOTING 18
9.0 SPECIFICATION 28
10.0 CALIBRATION 29
11.0 SPARE PARTS 30
12.0 RETURN OF GOODS 31
13.0 LIMITED WARRANTY 32

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It is VITAL that personnel responsible for the
installation and use of the piezometers READ and
UNDERSTAND the manual, prior to working with the
equipment.
1.1 General Description
Geosense® VWPHT-3600 Series High Temperature Piezometers are suitable for the
extreme environments of temperature and pressure found within applications such as
geothermal heat and enhanced oil recovery systems including steam assisted gravity
drainage (SAGD) and cyclic steam stimulation (CSS).
They are capable of monitoring high temperatures up to 250°C and pressures up to 34.5
MPa. They are available in two models VWPHT-3600 for temperatures up to 200°C and
VWPHT-3610 for temperatures up to 250°C
Manufactured from high temperature and corrosion-resistant materials throughout,
together with a comprehensive temperature calibration, they provide high accuracy stable
long-term data with no zero drift.
The specially-designed Tubular Encapsulated Cable (TEC) is both high temperature
resistant and highly flexible for easy installation within boreholes or above ground.
Each VW piezometer is fitted with a length of high temperature connecting cable, and an
internal high temperature thermistor.
A filter is used to protect and separate the sensing diaphragm from the surrounding
materials. It is a sintered Stainless Steel 50 micron (µm) filter, sometimes referred to as
Low (resistance to) Air Entry (LAE). The filter is mounted within a Stainless Steel housing
that is fitted onto the end of the sensor body.
Operating / calibration range
During calibration, the Geosense® range of VWPHT-3600 Series High Temperature
Piezometers / Transducers are calibrated over a series of different temperatures to
prove their function over a wide temperature range and provide the input data for any
temperature compensation that may be required.
Piezometers and Transducers are all tested to 1.5 times (150%) their standard,
calibrated, working range to prove their function at overpressure.
The calibration values will not be valid when the upper calibration value is exceeded.
However, the validity of the calibration will not be affected, providing the overpressure %
does not exceed 50 % (applied pressure is 150% working range).
1.2 Theory of Operation
(Continued on page 4)
1.0 INTRODUCTION
This manual is intended for all users of High Temperature Vibrating Wire Piezometers
VWPHT-3600 Series manufactured by Geosense® and provides information on their
principle, installation, operation and maintenance.

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The Vibrating Wire Piezometer consists of a tensioned steel wire, anchored at one
end to a flexible diaphragm (the sensing element) and at the other end to the inner
body, all sealed into a stainless steel shell. The internal parts of all Geosense®
piezometers and transducers are identical. Only the thickness of the diaphragm, the
geometry of the shell and the filter arrangements change.
Two opposing coils are located within the inner body, close to the axis of the sensing
wire. When a brief voltage excitation, or swept frequency excitation is applied to the
coils, a magnetic field is generated causing the wire to oscillate at its resonant
frequency. The wire continues to oscillate for a short period through the ‘field’ of the
permanent magnets in the coils, thus generating an alternating current (sinusoidal)
output.
The frequency of the generated current output is detected and processed by a
vibrating wire readout unit, or by a data logger equipped with a vibrating wire
interface, where it can be converted into ‘Engineering’ units of pressure.
As pressure is applied to the exposed side of the flexible diaphragm (gas or liquid),
the diaphragm deflects, causing a change in the tension of the sensing wire behind it.
The change in tension of the wire results in a change in the resonant frequency at
which the wire oscillates. The change in the square of the frequency of oscillation is
directly proportional to the pressure applied.
(Continued from page 3)

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2.0 CONFORMITY
Geosense Ltd
Nova House
Rougham Industrial Estate
Rougham, Bury St Edmunds
IP30 9ND
Email: [email protected].uk, Web: www.geosense.co.uk.
Declaration of Conformity
We Geosense® Ltd at above address declare under our sole responsibility that the Geosense® products
detailed below to which this declaration relates complies with protection requirements of the following
harmonized EU Directives:-
• The Electromagnetic Compatibility Directive 2014/30/EU
• Restriction on the use of certain Hazardous Substances RoHS2 2017/2102/EU
Equipment description Vibrating Wire Piezometers
Make/Brand Geosense
Model Numbers VWPHT-3600, VWPHT-3610
Compliance has been assessed with reference to the following harmonised standard:
EN 61326-1:2013 Electrical equipment for measurement, control and laboratory use.
EMC requirements. General requirements.
A technical file for this equipment is retained at the above address.
Martin Clegg
Director
July 2020

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3.0 MARKINGS
Geosense® VWPHT-3600 Series High Temperature Piezometers / Transducers are labelled with the
following information:-
Product Name
Product Type
Calibrated Operating Range
Individual Serial Number
Manufacturers Name & Address
CE Mark
CABLE
The Tubular Encapsulated Cable (TEC) is supplied in a coil and can have bare conductors, a connector or
spliced onto a standard VW cable as shown below.
THE POSITION OF LABELS MAY VARY ACCORDING TO THE CABLE
REQUIREMENTS.
THE LABEL ON THE PIEZOMETER BODY SHOULD BE REMOVED PRIOR
TO INSTALLATION

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4.3 Inspection / functionality check readings
It is important 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. If any components are missing or
damaged, please contact Geosense®.
ALL Geosense® VWPHT-3600 High Temperature Piezometers carry a unique
identification serial number which is included on the label on the piezometer plus the
splice connector (where fitted) and at the free end of the cable. All VW piezometers
are supplied with individual calibration sheets that include their serial numbers and
these are shipped with the piezometers.
Cable marks also carry the model type and the length of cable fitted at the factory.
CHECK the piezometer 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 piezometers have been stored
in a reasonably stable temperature for at least 30 - 60 minutes.
(Continued on page 8)
4.0 DELIVERY
This section should be read by all users of VWPHT-3600 High Temperature
Piezometer Series manufactured by Geosense®
4.2 Handling
Whilst they are a robust devices, VWPHT-3600 High Temperature Piezometers are
precision measuring instruments. They, and their associated equipment, should
always be handled with care during transportation, storage and installation.
Once the shipment has been inspected (see below), it is recommended that
piezometers remain in their original packaging for storage or onward transportation.
Cable should also 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 may damage
the internal conductors and could render an installation useless.
4.1 Packaging
VWPHT-3600 High Temperature Piezometers 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®.

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4.3 Inspection/functionality contd…
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 piezometer
serial numbers.
The “CHECK” readings should coincide with the factory zero
on the calibration sheet within +/- 50 Digits (see the example
calibration sheet in Section 9) .
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.
*however, copies may be obtained from Geosense, in
case of loss
4.4 Storage
All equipment should be stored in an environment that is protected from direct
sunlight. It is recommended that cables be stored in a dry environment to prevent
moisture migrating along inside them in the event of prolonged submersion of
exposed conductors.
Storage areas should be free from rodents as they have been known to damage
connecting cables.
No other special requirements are needed for medium or long-term storage although
temperature limits should be considered when storing or transporting associated
components, such as readout equipment.
If a piezometer is supplied with a pre-saturated filter or has been saturated on site, it
must be kept at a temperature above zero degrees Celsius. If the water freezes,
damage could be caused to the diaphragm.
(Continued from page 7)
The ‘CHECK Readings WILL be affected by temperature
changes and slightly by changes in atmospheric pressure
Calibration Sheets contain VITAL information about the
piezometer. 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 piezometers READ and UNDERSTAND 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
Installation will be dependent on the actual application and therefore should be
installed in accordance with the project specification. Installation methods typically
include attachment to grout pipes or special installation rods together with other items
being installed simultaneously within the borehole.
5.1 ZERO PRESSURE Reading
Vibrating wire transducers differ from most other pressure sensors in that they
indicate a positive value at zero applied pressure. They will never read ZERO. Their
readings at ZERO PRESSURE can vary significantly between sensors.
As with most transducers, do not directly handle the Pressure Transducer when
recording the ZERO PRESSURE readings, as this will cause local temperature
gradients across the body that will distort the readings.
The Pressure Transducer is supplied with a filter inside its threaded bulkhead. The
bulkhead has a threaded socket (1/4” BSPF) that is used for connection to liquid (or
gas) pressure sources. The treaded bulkhead should be removed prior to
establishing ZERO PRESSURE values.
IT IS ESSENTIAL TO TAKE ZERO PRESSURE READINGS
BEFORE
INSTALLATION IS CARRIED OUT

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The ‘on-site’ ZERO PRESSURE readings for
Vibrating Wire Piezometers and Transducers are
obtained as follows:
1. Fill a large bucket with clean, potable water,
ideally at a temperature close to 20o C. Ensure
that the bucket is away from any heat sources
in an air temperature close to 20oC. ( +/- 3oC is
acceptable). Remove any fitted filters and
place the sensor(s) in the bucket.
Leave the sensor bodies covered with water for
a minimum of 4 hours - preferably over night.
2. At the free end of the cable, connect the leads
to a vibrating wire readout unit and occasionally
monitor the sensor output by turning on the
readout and observing the display (see the
readout user manual for assistance).
Be sure to turn off the readout between periods
of readings so as to avoid ‘heating’ the Vibrating
Wire element.
3. Turn on the readout and, holding only the
5.1 ZERO PRESSURE Reading contd...
cable, lift the sensor out of the bucket, allowing it to hang vertically downwards
and immediately record 2 or 3 readings. Replace the sensor in the water as
before.
After approximately two minutes of re-immersion, repeat and record another
set of readings. Repeat three times, checking that the readings displayed are
within +/- 1 digits of each other.
4. On the calibration sheet, note these readings together with the sensor
temperature, local barometric pressure, approximate elevation above sea level,
date and time.
5. Return the sensor to the water and ensure that no air is trapped inside the
body.
6. Still all underwater, refit the filter, taking care not to trap air inside the sensor.
Either leave the sensor in the bucket of water or transfer it to another water
filled container, for transport to site for installation. If, for any reason the water
escapes from the sensor body, repeat the water filling exercise, just prior to
installation. (the Site Zero need not be repeated)