LF Conductivity Measuring Probe

Transcription

1 LF Conductivity Measuring Probe Contents 1 General 1.1 Introduction 1.2 Application range 2 Safety 2.1 Warnings and symbols 3 Transport and storage 4 Application 5 Measuring principle 6 Assembly 7 Construction 8 Technical data 8.1 Explosion protection 9 Calibration 10 Startup 10.1 Electrical connection 11 Spare parts 12 Related documents 13 Glass Testing 14 Avoiding damages to peripheral devices Annex 1 EC-Type-Examination-Certificate Annex 2 Declaration of conformity Operating Instructions e

2 LF Conductivity Measuring Probe 1 General 1.1 Introduction The probe may only be installed, started up and serviced by authorized personnel with special skills in measuring technology and in strict compliance with the present instructions as well as the valid provisions. Non-compliance with these provisions no matter whether by intention or by negligence shall release the manufacturer from all responsibility and reliability. The present operating instructions are designed to familiarize users with the equipment of the probe and its use. The operating instructions should be available to the operating and maintenance personnel and should be studied before performing any installation and/or maintenance work. By knowing these operating instructions, you can avoid damages to the measuring equipment and ensure trouble-free operation. The representations and data given in these Operating Instructions are subject to modification and further improvement. The latest edition hereof will always supersede all previous ones. 1.2 Application range LF probes are used to measure the conductivity of changes in conductivity. Never operate this measuring device outside its permissible operating conditions. 2 Safety The safety instructions refer exclusively to the scope of delivery. Please also note the valid safety regulations concerning electrical installations and facilities. 2.1 Warnings and symbols In the operating instructions, the danger symbol is used to draw your attention to especially important information. m Compliance with these mandatory instructions helps to avoid personal injury and damage to property. m Please note the following instructions: Do not practice any working methods which may endanger safety! 3 Transport and storage The probe should only be transported and stored in its closed original packaging. In order to guarantee an as-new condition of the probe, maintain the following storage conditions: dry and dust-free, steady temperature and ventilation When used probes are sent to the manufacturer or third parties for repair or other purposes, all parts must be cleaned and decontaminated. Appropriate safety instructions for further handling must be attached to the outside of the packaging. The probes do not need any preservatives, they are resistant to normal environmental influences. Figure 1 LF measuring probes 4 Application The fully glasslined LF measuring probe is used to measure the electrolytic conductivity and can be installed directly inside reactors or pipes. For the resistance of the glass lining used, please refer to our publication no The LF probe is preferably used for measurement in concentrated acids at high temperatures and high pressures up to 40 bar (special option up to 100 bar). 2 Pfaudler GmbH

3 LF Conductivity Measuring Probe 5 Measuring principle The 4-electrode method is used. A constant AC current flows through the external electrodes. The measuring-circuit voltage is picked up in the form of a resistancedependent voltage drop across the internal electrodes without current load. The voltage value is then supplied to a transmitter with a high-resistance input. This measuring method is largely insensitive to contamination of the electrodes. Polarization errors are impossible because polarization only occurs at the current electrodes. A built-in Pt 100 resistance thermometer compensates for the temperature dependence of the conductivity. By combining steel, glass and rhodium (for the electrodes) as materials for the probe, the LF probe was given a number of outstanding characteristics: high resistance to corrosion large temperature application range between C resistance to pressure: bar (option 100 bar) resistance to thermal shock Figure 2 LF measuring probe in pipes Rhodium electrodes equipotential bonding conductor, if necessary U R i = i Due to these properties, it is even suitable for extreme applications. 6 Assembly When measuring in pipes made of plastic materials or steel with an insulating lining, the use of conductive gaskets offers advantages. These gaskets are connected to the equipotential bonding system of the probe. DN50 part number DN80 part number Glass l k U Pt 100 Metal body Process conductometer ms/cm % by weight ma LF When installing the probe in steel pipes, only normal, non-conductive gaskets may be used due to the possible formation of electrolytic element couples between components. DN50 part number DN80 part number Figure 3 Structure of the LF measuring probes For the tightening torques of the split flange connection, please refer to Service Instructions 318. After the first temperature cycle (but by no means later than after 24 hours) the screws must be retightened with the prescribed torque. Pfaudler GmbH 3

4 LF Conductivity Measuring Probe 7 Construction The four metal electrodes with a diameter of 2 mm have been fused into the glass layer of a measuring probe carrier so as to ensure insulation between them. Measuring probe carriers may include baffles, thermometer wells or spacing rings. The supply conductors for the electrodes are also fused into glass and lead to a terminal box at the flange of the probe carrier. The Pt 100 has been integrated into the steel body of the probe carrier. Baffles and thermometer wells are available in any desired size, spacing rings may be manufactured from DN ms/cm 1 g/l 0,1 1 10,05 100,6 0,1 0,01 0, % by weight Figure 4 Concentration table H 2 SO 4 20 C 8 Technical data Conductivity range: Temperature range: Pressure: Electrode material: Cell constant: 1 to ms/cm depends on the temperature compensation of the transmitter used glass limits between 25 and 200 C 40 bar as a standard; up to 100 bar in special design Rhodium 2 mm in diameter Glass lining: Glass WWG Explosion protection When using the measuring probe type LF (type of protection: intrinsic safety Ex ia IIC) in potentially explosive areas of zone 0, it is approved for connection to intrinsically safe circuits category ia with electrical isolation and the maximum electrical values specified in the certificate of conformity PTB No. Ex-88.B.2127X. approx. 0.2 cm 1, depending on design 9 Calibration The glasslined conductivity measuring probe is an open measuring cell, therefore, it has to be calibrated in the reactor/in the pipe in order to allow the stray field to be fully generated. For this reason, a transmitter is to be used which can be calibrated for the conductivity data of the product and which automatically calculates the cell constant after calibration. For calibration, the measuring probe is installed inside the reactor or the pipe and filled with product. Measure the conductivity of a product sample using an external conductivity meter. Then enter the measured conductivity manually into the transmitter. Please note that the product temperature must be identical to the sample temperature. 4 Pfaudler GmbH

5 LF Conductivity Measuring Probe # Conductor color Assignment 1 white voltage electrode coaxial cable 2 brown voltage electrode coaxial cable 3 brown current electrode + Pt green Pt blue current electrode 6 black Pt 100 Cable shield (total shield on connector to frame) 8 violet coaxial cable shield 1 (insulated at connector) 9 orange coaxial cable shield 2 (insulated at connector) Startup Connect the measuring probe and the transmitter according to the applicable wiring diagram. Startup comprises the parameterization and calibration of the transmitter. The wiring diagrams of suitable conductivity meters are available on request. During parameterization, enter a cell constant of approx. 0.2 cm 1. Measuring range of 1 ms and higher, for a conductivity 1 ms transmitter messages may be output (sensor not stable), depending on the design and place of installation of the transmitter. m Caution! When the probe has been installed in another measuring location, it has to be re-calibrated. Once a cell constant has been determined, it can always be used if the probe and place of installation are identical Electrical connection Figure 5 Connection cable assignment Figure 6 Terminal box Pfaudler GmbH 5

6 LF Conductivity Measuring Probe Figure 7 Wiring diagram female connector male connector female connector protective cap screwed connection conductivity processor (conductive) mains current output 14 Avoiding damages to peripheral devices When performing a spark test, please note the following information; otherwise, the components and/or the electronic transmitter may get damaged. The measuring transducers for temperature, glass monitoring, capacitive sensors and other electronic/ electric components that have been attached to the valve or the baffle must be disconnected prior to the spark test. Suitable equipment must be employed for the test (impulse voltage). We recommend using the GlaSparker, our high-voltage tester For glass lined measuring probes, the max. test voltage must not exceed 7 kv. The contact window around the measuring probe site (e.g. P) must not be tested. 11 Spare parts Designation Part no. 12 Related documents Service Instruction 318 Tightening Torques 400 mm O-ring made of Viton for protective cap, 25 x 1.5 mm D Connection cable, blue, 2 m with connector Connection cable, blue, 5 m with connector Connection cable, blue, 10 m with connector Glass testing During a spark test, inflammable sparks may occur at the pores in the form of an electric arc. Therefore, spark testing may only be carried out outside of potentially explosive atmospheres mm Figure 8 Contacs Measuring Points In general, however, we recommend calling our technical service for performing the test. 6 Pfaudler GmbH

7 Annex 1 PTB 03 ATEX 2132 X Pfaudler GmbH 7

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14 Annex 2 Declaration of conformity 14 Pfaudler GmbH

15 Notes Pfaudler GmbH 15

16 The information provided in this documentation corresponds to the state of the art at the time of printing. It is published in good faith. However, we will accept no warranty claims based on the information provided in this documentation. We reserve the right to include improvements, amendments and new findings in this documentation without prior notice. The actual design of products may deviate from the information contained in the calatoge if technical alterations and product improvements so require. The proposal made by Pfaudler for a concrete application will be binding in such cases. The present documentation is made available free of charge to our customers and other interested parties. The right to print or copy this documentation, or any parts there of, or to convert the same into electronic form shall be subject to our written permission. All rights reserved by us. Pfaudler Werke GmbH P.O. Box 1780 D Schwetzingen Pfaudlerstraße D Schwetzingen Phone Telefax info@pfaudler-instrumentation.com