_ pressure transducers. User Manual

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1 _ pressure transducers User Manual

2 summary introduction DescriPTION preliminary checks Installation taking measurements data management Troubleshooting maintenance Appendix 1 Page 4 Page 5 Page 6 Page 6 Page 7 Page 8 Page 9 Page 9 Page10 Page 2 of 10

3 Notes on the use of product For a safe and efficient use of the product, please read carefully the following instructions before starting any operation. Any use of the product other than the one described in this manual shall be considered at user s full responsibility. The same applies for any unauthorized modifications. In addition to the hereby listed standards, the user must comply with the provisions of the current legislation on the matter of personal safety and health of persons in the workplace. SISGEO is not responsible for any trouble, breakdowns, accidents etc.. due to the lack of knowledge and/or confidence (or non-compliance with) with the requirements contained in this manual. Check that the product has not been damaged during the transport. Verify that the package includes all items as well as any requested optional accessories; if anything is missing, please promptly contact the manufacturer. The user must strictly follow all the operations described in this manual. Maintenance or repair of the device is allowed only to authorized operators. These operators must be physically and intellectually suitable. For information about instrument or order spare parts request, please always specify data written on the identification label. When replacing parts, always use ORIGINAL SPARE PARTS. The manufacturer reserves the right to make changes without prior notice for any technical or commercial requests. We ll try anyway to keep the manuals updated in order to reflect product s revisions/ updates. Symbols Below are the symbols used to catch reader s attention on the manual: Pay particular attention to the following instruction. Identification Instruments can be identified From a production lot number (written on the Compliance Certificate) From a serial number (s/n) engraved indelibly on the instrument From a label on the instrument From a label on the cable Page 3 of 10

4 Introduction Readout Pressure transducers provides accurate measurements of groundwater level in open standpipes and Casagrande standpipes, wells, boreholes and artesian wells. SISGEO uses two types of sensors: Vibrating wire (VW) Resistive Suspension head Cable In the vibrating wire piezometers, the diaphragm deflection causes a change in the tension of the steel wire stretched between the diaphragm and the instrument body. The vibration frequency is detected from a readout. A thermistor for temperature monitoring is included. VW piezometers assure an high reliability for long term measures. Pressure Transducer The resistive piezometers have a ceramic diaphragm with printed strain gauges that changes their resistance and electric signal according to diaphragm deflections due to water pressure. They allow high insulation (useful for example in industrial plants) and the possibility to take dynamic measures. Case Ø1.5 Pressure transducers can be relative or absolute. Relative pressure transducer (only resistive models) is used to measure groundwater level. It has a little tube, within the electric cable, to compensate the barometric pressure. In this way the measure is not affected from water level variations due to atmospheric pressure. Filter cell Page 4 of 10

DESCRIPTION Pressure transducer consists of: 1. Stainless steel cylindrical body; 2. hydraulic chamber; 3. filter housing (relative models); 4. measuring sensor; 5.

5 DESCRIPTION Pressure transducer consists of: 1. Stainless steel cylindrical body; 2. hydraulic chamber; 3. filter housing (relative models); 4. measuring sensor; 5. thermistor for temperature monitoring (only VW model); 6. electric cable for the connection with readout. 1 2 Diaphragm position Filters saturation The purpose of filters saturation is to remove the air in filters pores and replace it with water in order to have a faster answer to pressure variations and more accurate measures. Pressure transducers used as level meter use a filter with 40μm. We recommend to perform the saturation on site just before the installation. Usually the filter must be left in a container of de-aired water for at least 24h. Screw the filter housing with the saturated filter on the pressure transducer immersed in a container of clean water. In case of instruments with low full scale (100/200kPa), is necessary to connect the pressure transducer to a readout to check the induced pressure, and to screw slowly the filter housing in order to avoid overpressures that could damage the transducer. Page 5 of 10

PRELIMINARY CHECKS Before the installation we recommend to check the instrument connecting it to a readout (see Taking measurements ): the read value has to be similar to the zero value written on

6 PRELIMINARY CHECKS Before the installation we recommend to check the instrument connecting it to a readout (see Taking measurements ): the read value has to be similar to the zero value written on the Calibration Report. The possible differences could be due to height, barometric pressure (for absolute models) and, for the VW type, temperature. Please remember that the Calibration Report shows the conditions during the test issued at 115 m.a.s.l. The atmospheric pressure lowers approximately 0.1kPa every 10 m. height. We recommend to leave the VW model temperature to stabilize for at least 20 minutes before taking any measure. Acceptable differences are: Resistive model: ±1% of full scale =0.16 ma VW model: ±100digits For low full scale values, is necessary to consider the barometric pressure value. Indeed, on a transducer of 0,2MPa a barometric pressure variation of 50mbar (0,005MPa) is like 2,5% of full scale (1 millibar is 1 cm of water level). INSTALLATION Installation of pressure transducer for level measures Once the filter and the tube are installed, you can proceed easily with the transducer installation: lay down instrument cable and mark the length according to installation depth, taking as a reference the transducer diaphragm position that is carved on the steel body; drop the the transducer to the fixed depth holding it with the cable; once reached the fixed quota, hold the instrument through the suspension head (if available). For installation in wells or transducers with a small diameter ( 5cm) is important to remember that both cable and submerged instrument volume, cause an increase in the water level. Wait a few hours, depending on soil porosity, to stabilize the ground-water level, before to take zero measure. To clean the filter (if needed) proceed as follows: Unscrew the filter housing. Remove Seeger ring with a gripper, remove the filter pushing lightly the central hole. Clean the filter with hot water and use air compressed to clean the pores. Reassemble. Page 6 of 10

7 PRESSURE TRANSDUCER Installation of pressure transducer on pressure piezometer tubes The supplied pressure transducer is already assembled on a measure head (see picture), that must be screwed on the threaded head of the installed piezometer tube. Proceed as follows: Screw the measure head on piezometer tube, adjusting the component before blocking. It Is possible to use teflon; open the dump valve keeping the shut-off valve closed. Connect the pressure transducer to the readout (see Taking measurements); collect the value at atmospheric pressure. Open the shut-off valve leaving some water flow from the dump valve to remove any bubble; close the dump valve and detect, on the readout, the value that will be the zero reading. Compare the pressure-gauge value with the transducer one: please remember that the last one is more precise. The shut-off valve can be kept open or close depending on needings. No-vacuum valve Pressure-gauge Pressure transducer Dump valve Shut-off valve TAKING MEASUREMENTS Manual readings are taken connecting the conductors to a readout according the following scheme: Resistive Transducers (4-20 ma current loop signal) Red Black + Loop - Loop Vibrating wire (VW) Transducers Red Black White Green VW VW Thermistor Thermistor To obtain reliable measures, with ma instruments, we recommend a warm up time not less than 10 seconds. For automatic measures, connect the instrument to a datalogger. Page 7 of 10

8 DATA MANAGEMENT The following formulas allow to convert the electrical measures into engineering values: Linear factor L eng = L ele /S [kpa] Polynomial factors L eng = (L ele 2 x A) + (L ele x B) + C [kpa] L eng = engineering reading L elec = electric reading S = sensitivity factor A, B, C = polynomial conversion factors S, A, B, C factors are stated on Calibration Report The exercise readings refer to the initial reading (zero reading). P kpa = L i - L 0 L 0 = Zero reading [kpa] L i = Exercise reading [kpa] Zero reading shall be taken carefully once the installation is performed and the instrument is in operating conditions. For many applications is necessary to wait a few days to obtain a reliable zero value. Example Pressure Transducer full scale 700kP S = digit/kPa A = e-07; B =-1.955e-01; C =1.886e+03 L0 = 7357digit ; L1 = 6667digit Using: Linear factor (L 1 -L 0 )/S : ( )/ = Polynomial factor[(l 1 x A)+(L 1 x B)+C] [(L 0 x A)+(L 0 x B)+C]= = kPa Temperature measure Using a SISGEO readout, the temperature is read directly in C. If measured, the thermistor resistance value must be converted using the formula or the table shown in appendix 1. If the transducer is installed in an environment with uneven temperature, is necessary to correct pressure value already processed using the follow equation: P T = (T - T 0 ) K where: P T = correct pressure T = exercise temperature; T 0 = zero temperature; K = temperature factor (can be found on the transducer Calibration Report) Add the obtained correction to the pressure value found with the previous formula. Page 8 of 10

9 TROUBLESHOOTING VW Pressure Transducer Problem Cause Solution Unstable measure Wire not detected Cable shield not connected Electromagnetic fields generated by engines, generator, antennas, welder or high voltage lines nearby Grounding not well done Cable cut or damaged. Wiring not correct. Connect the shield Identify and remove the cause. Shield the signal cable Make proper wiring Measure the resistance between conductors red and black (150Ω±10%). Consider cable length. The resistance of the single conductors, for the model 0WE104VWS0, ic ca. 58Ω/km). Repair the cable. Cable splicing kit available at SISGEO. Make proper wiring Resistive Pressure Transducer Problem Cause Solution Unstable measure 0mA measure Overrange measure Wiring not correct. Cable cut or damaged Make proper wiring Repair the cable. Cable splicing kit available at SISGEO. Maintenance After-sales assistance for calibrations, maintenance and repairs, is performed by SISGEO s service department. The authorization of shipment shall be activated by RMA Return Manufacturer Authorization. Fill in the RMA module clicking on: Send back the instrument/equipment with the complete accessories, using suitable packaging, or, even better, the original ones. The shipping costs shall be covered by the sender. Please return to the following address with suitable delivery document: SISGEO S.r.l. Via F.Serpero, 4/F MASATE (MI) On the delivery document is mandatory to indicate the RMA code received. Technical assistance assistance@sisgeo.com Page 9 of 10

10 APPENDIX 1 THERMISTOR TEMPERATURE CONVERSION Resistance to temperature equation: T= 1 =273.2 A + B ( LnR ) + C ( LnR ) 3 Where: T= temperature in C LnR= natural Log of the thermistor resistance A= x10-3 (coefficents calculated over the -50 to +70 C span) B= 2.369x10-4 C=1.019x10-7 Ohms Temp Ohms Temp Ohms Temp Ohms Temp 16.60K K K K K K K K K K Page 10 of 10

Instruction Manual Model 4580

Instruction Manual Model 4580 VW Pressure Transducer No part of this instruction manual may be reproduced, by any means, without the written consent of Geokon, Inc. The information contained herein is