EC1600 - ESS Earth Sciences
Contents
1. 4 Cl U 02lsample temperature 2507 Sensor description The 1600 sensor is a fully submersible device used for measuring water conductivity It is constructed from durable machined plastic components and epoxy resins For reliability there are no wetted metal components to corrode making this sensor suitable for high conductivity high dissolved solids application and even for water with high acidity The 1600 EC sensor is designed for very long term deployment at unattended monitoring stations The sensor head is fully epoxy encapsulated and has a hole through the middle to allow the flow of water through it It is here that the water provides magnetic coupling for the measurement to take place An 8mm diameter submersible rated cable is hardwired to the back of the sensor length specified during ordering Although care must be taken to secure the sensor at all times the sensor may be suspended from the cable for short periods such as during installation Once installed and powered the sensor will measure conductivity from O to 100 000 uS cm The dry end of the cable has fife wires for supply ground SDI 12 and current output signals Connectors can be fitted for direct connection to ESS Earth Sciences equipment such as the 3500 logger or custom connectors can be fitted upon request There are no moving parts on the 1600 EC sensor and no serviceable components This sensor is a dual output 3 wire current loop device2. plus SDI 12 as detailed in the Installation section Installation Site Selection Before installing a 1600 EC sensor it is recommended a suitable site be selected first The installation and maintenance complexity as well as the reliability of the instrument in critical applications depends on the site chosen and the length of cable required can then be determined Well chosen sites slow flowing water no stratification minimal or no accumulation of debris around sensor easy and safe access away from waterway traffic sensor head is always submerged in at least 200mm of water sensor head is at least 100mm from bottom and at least 50mm from any metal sensor cannot be dislodged during high flows Avoid sites with very low or stagnant water flows where debris can accumulate inside sensor head excessive air bubbles in water difficult or unsafe access high siltation rates where sensor will be exposed in air during low flows The following is also recommended for EC sensor installation Install the sensor out of direct sunlight especially when in shallow water Sunlight will heat the sensor head to produce a false temperature and compensated EC reading Algae will tend to grow within the sensor hole This can be minimized by covering the sensor with a shield to make the head as dark as possible No sunlight means no algae Silt can accumulate in the sensor hole Install the sensor so water can flow through the hol
3. EC1600 AUTO RANGING ELECTRICAL CONDUCTIVITY SENSOR 14 Palmer Street Richmond VIC olei Australia T 61 3 8420 9999 F 61 3 8420 8900 Table of Contents Quality Assurance Statement ce eoee eene nn annu n nnn 2 ISOS9S001 accreditato x 22 25 9R18s rRsE RE CU NIE REE REESE EU NUR SA REESE E FE LRNEARKEEREREREANU ARM DNE MESE 2 Terms OF Warranty rii iain ac evatEsusevesuas cesa E E E EKEUE MEE EE VENE 2 Conductivity An Introduction nece eee onn n nnne 3 What is electrical conductivity e iueeeeerriee nennen annu nnaa unns 3 How is conductance measured in practice ecce eaae neenon annes 3 How does the 1600 conductivity sensor work eee coeant 4 What is temperature compensation ererrrriue nennen annua u unn an 5 Sensor descrIDUODB uos pex uEHxVR V RR EI FRIEND V MERE a e Riu MEE EVA V V Ed eiEE 6 Installaatio N meer 7 SITE SGISCUION ete E 7 WEIS CNOSCIINSINGS asrni a a aa a a a a 7 ANMOICUSIEOS WIIN Siriana a E a a a aa a a aaa 7 Installation Orientation EN E ER S 8 Sensor Clearance unciis a aa a a a ORES 8 SILE PFE PaFatlOM eset 9 EC1600 Electrical Connection c nenne eene eere nnne 10 SDI 12 and 4 20mA connections c eonun uen nnnuuuuuuuuuuuuusuuuuusua uuu 10 420mA Interface 5i iiv novo ssrenciuacuau vasi a
4. I 12 in out common 0V Conductor Conductor Designation Requirement Connector Colour 5 pin 4 20mA output EC Source max 120 Ohm load 4 20mA output Temp Source max 120 Ohm load 10 4 20mA Interface To obtain a measurement from the 1600 sensor e Install the sensor according to recommendations in Section Installation e Apply power to the sensor e 2x4 20mA current output will be produced at the respective outputs e Conductivity and temperature data is available on the SDI 12 bus A current output signal will be available for measurement after 1 second For power conserving applications the sensor can be switched off immediately after the reading is attained The sensor can also be left on continuously if required The 4 20mA current output will be available for reading 1 second after switched power is applied With proper care and routine maintenance the sensor can be left operating unattended for several months Of course as each application will be different it is recommended that the total time between services is determined experimentally SDI 12 Interface The SDI 12 interface of the EC1600 handles all of the communication and power down features of the SDI 12 protocol All standard SDI 12 commands are supported In addition extended commands can be used to calibrate sensor outputs Each of the measurements can be scaled and offset with user supplied calibration coefficients The factory sets these para
5. S cm EC linearity lt 2 over the range 0 to 30 C Temperature lt 0 2 C over the range O to 30 C 10 to 60 C storage in dry environment operating 0 to 50 C 2 seconds to full accuracy Magnetic inductive coupling EC in uS cm standard Scaled to maximum range EC 4mA OuS cm user adjustable 20mA 100 000uS cm user adjustable Temperature 4mA 0 C user adjustable 20mA 50 C user adjustable 12VDC current capability 500mA 0 3mAh per reading on average typical Secondary surge protection Can absorb 0 6J of energy 262 long 56 dia mm 16 Product Return Form As part of our Quality Assurance initiative and to improve response time we request that the forms below are completed in as much detail as possible for product returns SITE Describe site Is unit in protective hut or enclosure List any other sensors which are used at the site Estimate cable length to sensors tomm wem 0 em EARTHING Describe any special earthing arrangements in place 17 DESCRIPTION OF PROBLEM How did the problem manifest itself Weather conditions while fault occurred especially temperature What commands were being used SDI12 or serial If possible list the exact commands used and the sequence List the commands sent through the logger What action was taken to get the unit going again Have you noticed anything in common with the last time there was a fault Was the
6. an be measured from first principles by using a conductivity cell This is a box containing a liquid with two plates each of area A separated by a distance L The first step to determining conductivity is to measure the conductance of the material which is simply the ratio of the current to the voltage across the cell The basic unit of conductance is the Siemen S We then compensate for the size of the cell to derive the specific conductivity C in S cm This is simply the product of measured conductance G and the electrode cell constant C G x L A How is conductance measured in practice For field use it is not practical to use two plates separated in a cell A common method of field conductivity measurement uses a miniaturized version of the conductivity cell Two electrodes are separated by a short distance typically 1 cm and a voltage is connected across them and the current is measured In practice a sinusoidal voltage is used to reduce DC effects and four electrodes rather than two are used The dimensions are compensated for and the conductivity is derived a similar manner to the conductivity cell The above method is very common it is simple to implement and its operation is intuitively obvious However it has a serious drawback To work correctly the electrodes must be in direct contact with the liquid This leads to corrosion of the electrodes resulting in unstable results long term drift and overall low reliabi
7. d algae lodged in the hole can cause inaccurate readings It is recommended the sensor is checked during every visit or at least every 3 6 months You may find the sensor will not require any maintenance for even longer periods however warmer climates or high silt laded rivers and streams can accelerate these effects General e Ensure the sensor is not affected by debris silt or algae or marine growth The sensor should be removed from its installed location for a thorough inspection Using the recommended installation method outlined in the section Installation removal should be easy and maintenance staff do not need to enter the waterway e Ensure the installation is sound and the sensor is still secure from moving and there are no obvious signs of erosion or damage Calibration check The sensor output can be checked against a reference instrument if it is available Ideally the measurement should be taken in the same solution as the sensor while the sensor is installed If there is a large difference an installation problem may be highlighted All sensor measurements should be within the specified accuracy e Compare the sensor measurement to that of the reference instrument e Ensure the reference instrument calibration error is also known 15 Specifications Range Accuracy Temperature range Response Time Type SDI 12 Output 4 20mA Output Power Supply Surge Dimensions 8 mm 200 to 100 000 U
8. d dashes ceed cM I NIMM PMID ETE UN ME ERN U IE 11 SDI 12 TNC AGCC pete 11 ODeratiOn ness bU AAA ECU SUE IVA ERII EEUU S 12 Standard SDI 12 Commands siisii eususu M EEREERRI DAR SARESREREERA RI RE AR ES KEEN AUR NR ESAE 12 EC1600 specific SDI 12 Commands ere eeea enne nnn nnn nhan 13 Example program to read SDI 12 eeeeo inen eee na anna nnns 14 Maintenarnce 35 EXE HE IER IMERIUROE upUU URS ORO ER IDE DMDQVEM E Di E CE RGR EUR 15 GENCE Ali eec n mem n 15 SI DFAatlon CHECK ee ec 15 SDECIFICAUONS sieur OR ain ROCK GRECIA ER CROCI ROC ORC RR TER VER RR ERG 16 Prod ct Return FOEFIdW asisiisessuesevsssesssUaE Eua ERES EREREREEE ERRARE EEEFEEEE EE PII TMER 17 Quality Assurance Statement ISO9001 accreditation ESS Earth Sciences is currently an AS NZS ISO9001 2008 certified organisation This certification is evidence that sound practices are used to get high quality instrumentation to your organization within a reasonable time interval Standard practices are used for all areas of manufacture beginning with the efficient procurement of incoming orders right through to shipment Stringent quality assurance procedures are applied to all aspects of manufacturing including the calibration of scientific instruments against NATA traceable references Every sensor is accompanied by a test and calibration certificate that can be used as reference information as well as
9. e Typically most sites that are already equipped with hydrographic instrumentation can be used for installation of the 1600 EC sensor Installation Orientation For correct installation the following recommendations apply With the exception of the sensor head the part with the hole through it the rest of the sensor can be completely covered by an installation tube If 50mm ID poly tube is used for installation a suitable compression gland is available from irrigation hardware suppliers The sensor outside diameter is smaller than the compression gland internal diameter and can be clamped easily and securely using this method When this system is used the sensor head must protrude from the gland by at least 60mm Sensor Clearance Correct orientation of the sensor will help to reduce the buildup of silt and debris within the hole in the center of the EC head Where algal blooms are likely it is recommended the sensor is covered with a sun shield keeping the sensor in the shade thereby reducing algae buildup When installing a shield ensure the shield clears the sensor head by at least 50mm The shield should ideally be installed 100mm from the sensor and cover the sensor sufficiently from direct sunlight A shield will also prevent excessive temperature variations Site preparation Before the sensor can be installed the site must be prepared to ensure the sensor will be secured protected and serviceable The follow
10. ec_adc ec ec25 status Vcc range Example result 0432 5 76 02359 2281 4 0 0 OK 11 46 rO 13 Example program to read SDI 12 The following program can be used with the Campbell Scientific CR1000 logger Program name CR1000 sample display reading CR1 Date written 3 06 2009 using the CRBasic programming tool from Campbell Scientific LoggerNet 3 4 1 This program is used to test the SDI 12 Interface using a Campbell s CR1000 logger Sensor powered from 12V terminal and a G terminal and with SDI 12 onm C1 terminal Logger ClseeNgISSIS Oeec Sensor SDI 12 12V red Sensor Power ve G black Sensor Ground The program below will collect data each second from the five SDI 12 Interface channels Use one of the Data Displays from the LoggerNet Connect Screen Set the table cells to sdidata 1 to sdidata 5 The information from each of the four channels of the SDI 12 Sensor Engine will be displayed and updated every second Publrcoc sdidave 5 sdidata 1 ec25 Sdidata 2 ec Sdidata 3 temperature edidata 4 adc conductivity edrdatato ade temperature BeginProg Socamtloecs S 0 SDITZROecCOFXTOSITCSODPOdLbg e Lg UV NEU ID wu Nextscan EndProg 14 Maintenance The 1600 sensor will require little periodic maintenance to ensure that measurements remain accurate While all wetted components are no metallic and cannot corrode in high salt or acidity liquids Debris silt an
11. en as a transfer of oscillating current in receiver Rx coil The degree of transfer is an indication of water conductivity What is temperature compensation Like resistance conductivity changes with temperature The lower the temperature the less the conductivity and this is because electrons find it harder to flow through dissociated salt molecules at lower temperature This makes measurement confusing when actually trying to determine the water conductivity over a temperature range To overcome this effect conductivity measurements at any temperature are output as if the temperature is 259C and is called temperature compensated output The relationship between compensated and non compensated raw output is linear and simply put a percentage is added or subtracted from the raw measurement to determine compensated output For the 1600 EC sensor the compensation is set at approximately 2 per C For temperatures below 25 C the proportion is subtracted and is added for temperatures above 25 C Of course the temperature needs to be measured for compensation and therefore the 1600 EC sensor has an internal temperature sensor As an additional feature the 1600 EC sensor also has a separate temperature output available to loggers and controllers as a 4 20mA signal Temperature compensation operates between 0 and 50 C the typical expected water temperature for most environmental conditions TA us Corrected EC at 256 in E Raw EC in
12. evidence of sensor accuracy Terms of Warranty The warranty covers part or complete replacement repair or substitution of new instrumentation that has failed in part or completely within the warranty period While every effort has been made to supply robust and user friendly instrumentation the warranty does not cover instruments incorrectly installed misused or operated in conditions outside those specified The warranty does not cover shipment costs for instrumentation installation or removal and under no circumstances whatsoever indirect or consequential losses caused by the failed instrumentation ESS Earth Sciences believes the warranty conditions to be fair and just and in accordance with standard business practices worldwide ESS Earth Sciences reserves the right to arbitrate any warranty issues and will ensure that warranty issues are treated with the highest standards of professional conduct At ESS Earth Sciences we believe your investment in our products and services is a good decision and we will therefore ensure all your requirements are met at all times both now and in the future Conductivity An Introduction What is electrical conductivity Electrical conductivity is a measure of how easily electrons flow through a material For all materials conductivity is proportional to the cross sectional area of the current path and inversely proportional to the distance the current has to flow Conductivity c
13. ing recommendation is based on typical installation methods practiced by today s hydrographers Several variations of this method are used to suit particular applications Please study the diagram below Site preparation involves the installation of a larger plastic tube along the waterway bank as shown The tube should ideally be continuous but may also be made from sections One end of the tube must be installed into the water ensuring the sensor optical path will not be obstructed according to the previous section Sensor Clearance The other end can be terminated in a junction pit that is large enough so that the sensor can be inserted from the pit Typically an underground electrical pit is used as this also allows a sensor carrier assembly to be inserted easily The pit must be installed on a stable part of the bank that cannot erode Site shelter Junction pit Sensor tube with sensor installed at end Detail view below waterway bank doi rnt Optional guide a Guide tube Sensor is made from plastic Cable tie or strapped to side of tube similar devices EC1600 Electrical Connection SDI 12 and 4 20mA connections Ed 12 volts dc red E o The EC1600 is an SDI 12 sensor SDI I O green plus two 3 wire current loop N Q devices EC out 4 20mA blue Common black o Temp out 4 20mA yellow switched 12Vdc 4 20mA EC out 4 20mA temperature out SD
14. lity in the field How does the 1600 conductivity sensor work The 1600 EC sensor employs a different measuring technique Instead of electrical contact probes it uses an inductive or magnetic method to determine conductivity By using this approach there is no direct contact with the liquid Although more difficult to implement this toroidal method is inherently more reliable and has very low drift compared with electrode type sensors and will operate for many years even in difficult environments Two coils are placed a known distance apart One coil has an oscillating current applied that forms a magnetic field inside the coil centre The other coil receives the magnetic flux produced inside the transmit coil Because of the coil arrangement the receiving coil will only receive signal when a conductive material is placed between the coils If water is allowed to flow through the coil centre impurities in the form of dissolved salts will provide the necessary magnetic coupling Note Conductivity should not be confused with conductance which is the inverse of the material s resistance Tx coil Magnetic flux is concentrated in the middle of coils Conductive water flowing through middle increases magnetic coupling between transmit and receive coils The above diagram shows how the sensor works Transmit TX coil forms a magnetic flux inside the coil pair Conductive water increases the magnetic coupling which is se
15. lmer Street Hichmond VIC CSS olcl Australia EARTH SCIENCES T1 6l 3 8420 8999 F 61 3 8420 S900 www essearth com
16. meters so the output is in uS cm Any changes to these parameters should take into account their factory calibration values as these have been established by measurement for each sensor The SDI 12 Interface also has an on board temperature sensor The interface has been fully tested with the NR Systems SDI 12 Verifier 11 Operation Standard SDI 12 Commands The commands assume that the sensor address is 0 but any address could be substituted into the commands below Arn is carriage return and line feed characters commana pess NM or remwemen reus same ares OO Begin a measurement Then use ODO To display result Get data use this after a OM Command 5 values are being returned EC25 EC Temperature Raw EC Raw Temperature Measure and display as above include a CRC OMCDO as defined in the SDI 12 standard Symbols and Units EC 25 Compensated conductivity at 25 C in uS cm EC Conductivity in uS cm Temperature Temperature in 9C Raw EC EC in ADC counts Raw Temperature Temperature in ADC counts The display command ODO produces 5 values in this sequence id EC25 ECc Temperature Raw EC c Raw Temperature Note The value for EC25 is always O0 at present Example command and response OM 00015 ODO 0 00000 007744 20 51 000977 00538 Ot O13ES amp S EC16000 8 160159 12 EC1600 specific SDI 12 Commands The following list shows EC1600 specific commands that have been impleme
17. nted in addition to the required commands of the SDI 12 standard Depending on the utility used the commands need to be completed by a preceding address character in the examples below we use O zero and terminated by an exclamation mark For example the command Xuptime needs to be send to the device with the address O OXuptime Command Description SDI 12 Command Example comment General Maintenance and Setup Commands Reset device OXreset YP Status information OXstatu Jooo O c Set SDI 12 address OXaddr 5 In this example it sets SDI 12 address from O to 5 This is an alternative to the standard SDI 12 nA command lower range upper range auto ranging temperature is 4mA from 0 0 to 50 0 Query 4 20mA Interface what OXcte 20 50 0 temperature is 20mA Set temperature at 20mA OXcte 20 float Can be any floating point value from 0 0 to 50 0 Query 4 20mA Interface what OXcec 4 EC value is at 4mA Set temperature at 4mA OXcec 4 lt float gt Can be any value from 0 0 to 100000 0 Query 4 20mA Interface what OXcec 20 100000 0 EC value is at 20mA Set temperature at 20mA OXcec 20 lt float gt Can be any value from 0 0 to 100000 0 Measurement commands Take a measurement OXm Takes a measurement and displays the result faster than the 2 step standard SDI 12 command The measurement command OXm produces 5 values in this sequence temp adc temperature
18. unit permanently disabled or is the fault intermittent Is this the first time the fault occurred Is there anything unusual about this site compared to other sites Is there any other equipment or facilities e g local power lines which could cause interference Please list any other issues relating to the site or the fault 18 DELIVERING WATER MONITORING SOLUTIONS 2600 Turbidity Sensor The 2600 Turbidity sensor is a miniature backscatter nephelometer that detects turbidity and suspended solids in water Applications include rivers streams irrigation runoff water quality sediment transportation aquaculture waste water quality EPA compliance monitoring LevelPro 6100 The LevelPro 6100 advanced liquid level sensor is used to measure water level determination 0 70 metres Applications include river irrigation water level tidal monitoring groundwater level amp landfill monitoring dam tank reservoir levels waste water monitoring food warning systems process industry liquid level PumpPro 6150 The PumpPro 6150 combines an integrated air compressor module and levelpro 6100 advanced liquid level sensor to form a fully self contained hydrostatic pressure sensor designed to measure water and liquid levels reliably and accurately Dipmeter The Water Level Indicators Dipmeters are typically used to measure the depth of water levels in boreholes standpipes or observation wells 141 Pa
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