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I

NSTRUCTION 

M

ANUAL 

FIBER-OPTIC PRESSURE TRANSDUCER 

 FOP Series 

 

 

 

 

 

 

 

 

 

 

 

 Roctest Limited, 2020. All rights reserved. 

 

This product should be installed and operated only by qualified personnel.  Its misuse is potentially dangerous.  The 

Company makes no warranty as to the information furnished in this manual and assumes no liability for damages resulting 

from the installation or use of this product.  The information herein is subject to change without notification.  

 

 

Tel. 

: 1.450.465.1113 • 1.877.ROCTEST (Canada, USA) • 33 (1) 64.06.40.80 (Europe) • www.roctest.com • www.telemac.com

 

 
 

 

E10160-200722 

 

Summary of Contents for FOP

Page 1: ...misuse is potentially dangerous The Company makes no warranty as to the information furnished in this manual and assumes no liability for damages resulting from the installation or use of this produc...

Page 2: ...ETERS USING UNIQUE GAUGE FACTOR 8 2 6 POLYNOMIAL PRESSURE EQUATIONS FOR FOP MICROPZ AND FOP PZ PIEZOMETERS 9 Equation with temperature compensation 10 2 7 LINEAR PRESSURE EQUATION FOR PIEZOMETERS WITH...

Page 3: ...CTOR 21 5 TROUBLESHOOTING 22 5 1 FIBER OPTIC READOUT UNIT 22 Battery charge and discharge cycles for portable readout unit 22 Cleaning the connectors 22 5 2 FIBER OPTIC PIEZOMETERS TROUBLESHOOTING 23...

Page 4: ...the gauge is under pressure there is a variation of the Fabry Perot cavity length made by the inner surfaces of the stainless steel diaphragm on one side and the tip of an optical fiber on the other s...

Page 5: ...Both high and low air entry filters are available Model FOP F The model FOP F piezometer is a thick wall version of the FOP piezometer with an outside diameter of 25 4mm Model FOP MicroPZ and FOP PZ T...

Page 6: ...h each gauge lists the following Serial number Gauge factor and or calibration factors Working pressure in bar or psi Temperature at time of factory calibration Barometric pressure at time of factory...

Page 7: ...eter 50 m Ceramic filter high air pressure entry pore diameter 1 m Filter generally used Filter usually installed for use in unsaturated fine grain material Does not allow suction measurements If wate...

Page 8: ...3 mm outside diameter Filter Stainless steel 316 porosity 40 m 1 5FOP PZ SPECIFICATIONS Range 100 200 350 standard range 500 750 1000 kPa Accuracy1 0 5 F S Resolution 0 065 F S Overload 1 5x F S Outer...

Page 9: ...ppropriate gauge factor pre selected the reading will indicate 0 or a very small value Obviously the transducer should not be submitted to pressure for a true zero reading and should be stabilized in...

Page 10: ...readings to ensure a stable value is recorded This is the initial reading Record ambient and water temperature barometric pressure and the initial reading and diagnostic value of the sensor See secti...

Page 11: ...present at time of factory calibration are eliminated The function check can be made relative to barometric pressure or to a difference of piezometric head in the pipe In both cases barometric pressu...

Page 12: ...0 1 002 1 013 Pcorr 4 500 0 007 0 011 4 504 bar 2 6POLYNOMIAL PRESSURE EQUATIONS for FOP MicroPZ and FOP PZ Piezometers For piezometers FOP MicroPZ and FOP PZ with polynomial equation you should assig...

Page 13: ...apply barometric corrections Pcorr Prec B1 B0 Where Pcorr Corrected pressure in kPa Prec Pressure previously calculated in kPa see above Bo B1 Initial at installation and current barometric pressure...

Page 14: ...Prec0 99 56 kPa Note that the calibration in factory is done compared to the zero absolute that explains the initial value of 14 44 psi although there is no pressure applied to the sensor This value s...

Page 15: ...ord always the reading in raw units in nanometers nm The calibration factor CF is obtained using a linear regression Then to convert changes in readings internal unit in nm to changes in pressure use...

Page 16: ...ted soils Low air entry sintered stainless steel filters The filter on the FOP piezometer body is removed by holding the piezometer in one hand and pulling and twisting the filter housing with the oth...

Page 17: ...ded With the water temperature ambient temperature and piezometer temperature in equilibrium raise the piezometer by the cable until it is out of the water about two centimetres We recommend to take t...

Page 18: ...cult to obtain 3 3INSTALLATION IN FILL Compacted clay Excavate a trench or recess about 30 cm deep by about 0 8 m2 Form a cylindrical hole in the side wall of the trench The hole diameter should be sl...

Page 19: ...the cable taut to prevent the bentonite from hooking up in the casing Pour the bentonite slowly in the hole to avoid bridging A brush or a thirty centimetre layer road salt can be used to unplug a bl...

Page 20: ...nate way to install piezometers in boreholes is to fill the entire borehole with grout after having lowered the instruments This method known as the Fully Grouted Borehole Installation is peculiar in...

Page 21: ...ct zones are generally installed in shallow boreholes to protect them against concentrated loads or movements Run cables emerging from these holes through the dam core and locate the vertical to horiz...

Page 22: ...ioning 4 Relation between gauge factor and calibration factor The Gauge Factor GF is specific for each pressure sensor and is written on the fiber optic cable near the connector It gives the relations...

Page 23: ...seful to have the Fabry Perot cavity distance in nanometers To do so the gauge factor 0001000 known as the Default Gauge Factor must be enter in the readout unit instead of the sensor gauge factor gen...

Page 24: ...nm Pressure calculation psi psi nm nm 0 200 192 5 5 1038 4 3Determination of the Gauge Factor Finally it can be shown that the Gauge Factor can be determined from the Calibration Factor by the followi...

Page 25: ...TANT WARNING Waiting for a complete discharge is not recommended Completely discharging the battery strongly reduces its lifespan Make sure to fully recharge the battery before storing the FTI 10 for...

Page 26: ...you take a reading with a fiber optic piezometers and a readout unit we recommend to complete also a diagnostic of the sensor using the diagnostic function With the diagnostic function DIAG the user c...

Page 27: ...connector Cable is damaged Verify if the cable is not damaged or cut Check if the same troubles No signal occur with other instruments connected If so the readout unit may be suspected and the factory...

Page 28: ...ated with recorded temperature and barometric pressure Check if corrections to raw pressure are applied correctly Try to perform a calibration on site and contact Roctest with reading for evaluation 6...

Page 29: ...methods of recording and the protection of piezometers A 6 Clements D J and A C Durney 1982 Instrumentation Developments proceedings of the Autumn Conference on the British National Committee on Large...

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