User ’s Model PH18 Manual Differential pH sensor

1 IM 12B6J4-E-A1st edition(Rev. 4th edition H)User sManualModel PH18 Differential pH sensorIM 12B6J4-E-ATABLE OF Model PH18 Differential pH Model WU18 cable for PH18 Dimensions of the TYPE 18 PH information for the glass lined pH and Installation PH202 OR PH402 pH .. Temperature CIP cleaning OF THE DATA SHEET PH Differential PH 12B6J4-E-ACaution - Inappropriate handling cancause or scratching the sensor againsthard surfaces such as steel, stone, glass orceramic, may cause damage to theenamel.

2 Such damage may not affect thesensor performance immediately, but afterprolonged exposure to the process, flakingof the enamel may - Enable impedance checks in thePH202 or PH402 The sensor impedance checking can giveearly warning of damage to the enamellayers. If the transmitter signals animpedance failure of the PH18, the sensorshould be removed from the process, assoon as possible (within 24 hours). Theloss of significant amounts of enamel maythus be 12B6J4-E-APREFACEThe PH18 should only be used withequipment that meets the relevant IEC,American or Canadian accepts no responsibility for themisuse of this PH18 is packed carefully with shockabsorbing materials, nevertheless, it maybe damaged or broken if subjected tostrong shock, such as if the package isdropped.

3 Handle with care. Although thePH18 has a weatherproof construction, theconnections can be harmed if it becomessubmerged in water or becomesexcessively wet. Do not use an abrasive in cleaning of this Manual are subject tochange without notice. Yokogawa is notresponsible for damage to the sensor , poorperformance, or losses resulting from such,if the problems are caused operation by this of the sensor in the of the sensor in an adverseenvironment or incorrect utility or modification of the sensor byan engineer not authorized and serviceYokogawa products and parts areguaranteed free from defects inworkmanship and material under normaluse and service for a period of (typically) 12months from the date of shipment from themanufacturer.

4 Individual sales organisationscan deviate from the typical warrantyperiod, and the conditions of sale relatingto the original purchase order should beconsulted. Damage caused by wear andtear, inadequate maintenance, corrosion,or by the effects of chemical processes areexcluded from this warranty coverage. In the event of warranty claim, the defectivegoods should be sent ( freight paid) to theservice department of the relative salesorganisation for repair or replacement (atYokogawa discretion).The following information must be includedin the letter accompanying the number, Model code and purchase order and of time in service and adescription of the of the fault, and thecircumstances of conditions thatmay be related to the installation failureof the statement whether warranty or non-warranty service is shipping and billinginstructions for return of material.

5 Plusthe name and phone number of acontact person who can be reachedfor further goods that have been in contactwith process fluids must be decontamina-ted/disinfected before shipment. Goodsshould carry a certificate to this effect, forthe health and safety of our safety data sheets should beincluded for all components of theprocesses to which the equipment hasbeen and checkingUpon receipt of the goods, carefullyinspect the shipping package for anyevidence of damage. If the carton isdamaged, notify the shipping agent andthe sales organisation immediately.

6 If the shipping package is not damaged,remove the products and parts. Confirmthat all items shown on the packing list areavailable and that the package does notcontain any parts or accessories the sales organisation if items sensorThe box of the PH18 sensor contains thefollowing items: sensor complete, possible options (checkpart number for possible options),instruction Manual , material certificate andquality inspection certificate. The WU18cable is packed 12B6J4-E-A1. INTRODUCTIONThe PH18 is not a conventional electrode.

7 Itrelies on two dissimilar ion sensitive enamelmembranes to generate the signal. Themeasuring element is like a pH electrode,and the reference like a Sodium the PH18 can only be used incombination with pH meters that feature:1 Dual high impedance inputs2 Adjustable setting for IsothermalPoint3 Adjustable temperature coefficientThe Yokogawa models PH202 andPH402 satisfy these both cases the membrane enamels arebonded directly to the metal substrate withno filling response curves Fig. 1 (pH), Fig. 2(reference) and Fig.

8 3 (application range)show the way in which the potential isgenerated at each element and combinedin the output of the 1 Above pH11 the effect of sodium onthe pH membrane starts to causenon-linearity (Sodium error)Fig. 2 Below pH3 the high Hydrogen ioncontent causes a change in thereference responseFig. 3A linear response to pH is obtainedbetween 3 and 11 pHFig. 4A plot of reference voltage againstSodium revolutionary measuring principle hassome big advantages. The absence of fillingsolutions and reference junctions virtuallyeliminates the problems caused by agingand pollution of the reference cleaning of the sensor virtuallyeliminates drift, and the sensor benefitsfrom a very long working life.

9 It is vital,however, to fit the sensor to the applicationcorrectly. The special nature of thereference element dictates that there mustbe a certain Sodium level in the 4 shows a plot of reference voltageagainst Sodium of the exponential nature of theresponse, it is plain that above about NNa+ (30 g NaCl/l) in the solution, thereference output remains virtually course when the Sodium concentrationremains constant in a process the referencevoltage will also be constant at much lowerlevels of is because of the need to evaluate thechemistry of the process, that it isnecessary to have an Application DataSheet (page 16) completed beforeapproval for this sensor can be mechanical construction of the sensoralso means that it may be used inprocesses involving both high temperaturesand pressures.

10 By eliminating the fillingsolutions, the sensor is truly robust and caneven withstand severe thermal shocks thatwould ruin most stainless steel mounting adapter formsthe liquid earth (solution ground) connectionneeded to ensure best stability ofmeasurement. EXA also uses thisconnection in the diagnostic PH18 is a Differential pH sensor . Itdoes not measure absolute pH except inlimited applications. It does, however,measure a single control pointaccurately, repeatably and with minimummaintenance3IM 12B6J4-E-A4 Fig.