Description
INTRODUCTION
The conductivity of the water solution containing electrolytic substance changesdepending on the concentration of the component and temperature of the solution, and ifthe temperature is constant, the conductivity of the solution and concentration indicate arelationship peculiar to the solution.In particular, when a very small amount of electrolytic substance is dissolved in purewater, conductivity increases in proportion to the concentration of the solution ; therefore,the purity of water can be known by measuring the conductivity. Thus, a conductivity
meter is an indispensable gauge for water quality control.Additionally, the conductivity meter plays an important role in the quality control ofmanufacturing process solutions for chemical, foods and pharmaceutical industries as wellas water quality control.The EXAsC series, SC200 intelligent two wire conductivity transmitter system is asolution conductivity meter for processing, whose measuring function has been heightenedand maintenance simplified with the introduction of a micro-processor.The SC200 system consists of a SC200口intelligent conductivity transmitter, SC21口Gconductivity detector and distributor. Transmitters are largely classified as“nonexplosion-proof”types which are used under ordinary environmental conditions and“intrinsicallysafe explosion-proof” types which can be utilized even under environments where explosive
gas may be generated.
The detector basically has three types of electrodes which are selected and used dependingon the conductivity of the. measuring solution. They are classifled as either types whichare connected directly to a process pipe, etc. or types which introduce the measuringsolution through a connected sampling pipe.Thus, the SC200 system provides the best choice of devices to fit the conditions of themeasuring solution and installation environment, so that an optimum measuring systemfor individual applications can be established to ensure highly reliable conductivity
measurement.
Contents of This M anualThis instruction manual describes the whole range of handling including installation,operation, inspection and maintenance of the SC200C ] intelligent conductivity transmitterand SC21口G conductivity detector, of which the intelligent two-wire conductivitytransmitter system consists.For handling of the distributor and safety barrier, refer to the instruction manualsmentioned below.
1.2 System Components1.2.1 Conductivity DetectorThe conductivity detector can be classified into the following three types in terms ofapplication and cell constant.SC210G – A conductivity detector for low range(cell constant : 0.05 cm – 1 )SC210G – B conductivity detector for medium range(cell constant:5 cm- 1)SC211G- C conductivity detector for high range(cell constant: 10 cm-1 )These conductivity detectors are structured (flow-through strueture) to introduce a
measuring solution to themselves through a connected sampling pipe (nominal diameter:15A).The SC210G-A and SC210G- B have a type which is connected directly to a process pipe(direct insertion type).(1) SC210G- A conductivity detector for low range (cell constant: 0.05 cm-1)This detector’s electrode is a stainless steel (SUS316) 2-electrode coaxial type and is
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used to measure a solution whose conductivity is 0 to 200 puS/cm.(2) SC210G – B conductivity detector for medium range (cell constant:5 cm-1)This detector’s electrode is a 2-electrode type having three ringed platinumelectrodes arranged at an equal distance in its glass tube bore (ofthe three platinumelectrodes, two on the sides are short- circuited internally and serve as a pair with themiddle electrode). It is used to measure a solution whose conductivity is 200 μS/cm to20 mS/cm.(3) SC211G- C conductivity detector for high range (cell constant: 10 cm-1)This detector is used to measure a solution whose conductivity is 1 mS/cm to 1 S/cm.The electrode is a 4-electrode type with four platinum electrodes inside its cylindricalbody.One of the characteristics of the 4-electrode type is that it is difficult for ameasured value to be affected by contamination, if any.1.2.2 Intelligent Conductivity TransmitterWith square wave AC voltage with a specified frequency and voltage applied to theelectrode of the conductivity detector, the SC200G (or SC200S) intelligent conductivitytransmitter receives a current signal proportional to the conductivity of the measuringsolution and temperature signal for temperature compensation.Then, it converts thesesignals to a“conductivity”value and displays them in digitally on the display unit. 4 to20 mA DC analog signals corresponding to the measuring range are transmitted to thedistributor.
Additionally, the signals for ABNORMAL and HOLD contact outputsaresuperimposed on the analogsignal .The SC200G (or SC200S) conductivity transmitter incorporates a variety of functions tooperate the system under the optimum conditions and simplifymaintenance.1.2.3 Distributor / Safety BarrierThe distributor supplies operating power to the conductivity transmitter and receives 4to 20 mA DC analog transmission signals in return. Transmission and reception areperformed directly by the distributor and conductivity transmitter in case of thenonexplosion- proof system; however, they are performed via. the safety barrier in case ofthe explosion proof system.The distributor converts 4 to 20 mA DC analog signals from the conductivity transmitter to1 to 5V DC output signals and outputs them to a receiving device such as a recorder.When the conductivity transmitter detects an“abnormality”with a FAIL indication orholds a transmission signal, signals superimposed on transmission signals are also
transmitted from the conductivity transmitter to the distributor. (can be stopped).However, this signal cannot be used except with the PH201G distributor.
When the PH201G distributor receives such a signal, the appropriator ABNORMAL orH0LD contact signal is output separately.
The safety barrier is the device used to build a intrinsically safe explosion-proof
system. The SC200 intelligent two-wire conductivity transmitter system utilizes theBARD400 safety barrier.2.3 Handling of the Intrinsically safe
Explosion-proof Conductivity TransmitterThe SC200S intelligent conductivity transmitter is an instrument whose explosion-proof
characteristics have been verified by examination based on the Labor Safety and Hygiene
Law.Thus this instrument can be installed in a places where explosive gas may be generated.However, because the environmental conditions and handling are restricted, be sure tofollow the precautions mentioned on the product and in the instruction manual.2.3.1 Explosion-proof Specifications for SC200S IntelligentConductivity TransmitterThe SC200S intelligent conductivity transmitter has a intrinsically safe explosion-proofconstruction.2.3.2 Explosion-proof SpecificationsLook at the conductivity transmitter you are going to use. The intrinsically safeexplosion- proof type conductivity transmitter indicates its name, examination pass No.,explosion-proof structure and object gas, and ambient temperature. Additionallyprecautions on use are also mentioned.2.3.3 Restriction on Installation PlaceThe intrinsically safe explosion-proof type conductivity transmitter can be installed in aplace where the explosive characteristics of an object gas was verified for this instrumentmay be generated. However, avoid installation in a class 0 plocation.2.3.4 Environmental Conditions of Installation SiteAs the environmental conditions for this instrument, the humidity and altitude are asfollows. If a temperature is indicated, use it under that condition.Humidity : 45 to 85 % RH
AltitudeUp to 1000 m2.3.5 Outside Wiring Work
The wiring cable to be connected to the intrinsically safe explosion proof structure(safety barrier / conductivity transmitter) must not be so long as to exceed the specifiedinductance and electrostatic capacity, and the terminal connection must be terminated in aspecified manner. Duringwiring, take care in prevent contact between the intrinsicallysafe circuit and nonintrinsically safe circuit as well as damage to cables.2.3.6 Maintenance
Upon replacing a part or repairing the intrinsically safe explosion-proof construction,the instrument must be restored to its original condition electrically and mechanically as arule. Thus, never change the specifcations or make modification.Further, repair is limited to the extent which requires no use of a soldering iron. Also,before repair work, be sure to move the instrument. to a safe place.
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