Analyze Single and Dual Input Analyzers for pH/Redox (ORP)

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Single and Dual Input Analyzers for pH/Redox (ORP)Models AX460, AX466 & AX416SS/AX4PH_4Reduced MaintenanceThrough In-line CleaningMany installed pH sensors benefit from regular cleaning. Whencarried out manually, this can be laborious and costly – so isoften ignored. Advanced AX400 pH analyzers make it possibleto automate sensor cleaning by using a programmable washtimercontact to activate a cleaning agent valve or pump.Pulsed water-wash and jet-wash chemical clean actions arestandard, user-selectable functions. The frequency and durationof the wash can be tuned to meet the requirements of theapplication.For chemical cleaning a 60 liter (13 gallon) sensor cleaningstation can be supplied (model no. AA0010), complete withdelivery pump and low level alarm. Chemical cleaning hasproved particularly successful on potable drinking water plantswhere manganese and iron in the sample can createunacceptably high levels of maintenance. Effective cleaningreduces cost of ownership.PowerSupplyContactAX46x Analyzer/WashControllerSensorCablesCleaningAgent TubesAA010 SensorCleaning Station1 or 2 SensorSystemsEfficient Auto-cleaning Control for One or Two Sensor SystemsCombined Conductivity and pHThe AX416 version measures conductivity and pH with the sameanalyzer. The option board provides the capability to retransmitpH, conductivity and both sample temperatures. Fiveprogrammable alarms can be assigned to suit the needs of theapplication, enabling even the most demanding requirements tobe met.AX460 Integral P, PI and PID ControlThe single input AX460 analyzers incorporate three-term PIDControl, offering three modes of sophisticated control: analog,pulse length (time proportional) and pulse frequency. These aresupplied as standard and can be operated in direct- or reverseactingmode, dependent upon the application.Auto/Manual and Bumpless TransferAn auto/manual feature is incorporated for rapid manual accessto the control functions. The controller facilitates bumplesstransfer between manual and auto modes, providing themeasured variable is within the proportional band and someintegral action time has been programmed.PumpControlSignalReagent PumpStroke PositionAdjustedAutomaticallyby ControllerSampleReagent TankAX460 pH AnalyzerSampleStirrerAX460 – Integral P, PI, and PID ControlPower SupplyElectrodeSystemCurrentOutputSampleCurrent Output Proportional ControlIn this case, the control signal is provided by the 4 to 20mAoutput of the AX460 analyzers rather than using the alarm/control contacts. The magnitude of the current output changesin proportion to the deviation from set point. This method is usedgenerally with motorized valves or when controlling the speed ofdosing pumps with a 4 to 20mA proportional input.Current Output (mA)204TimeSimultaneous Conductivity and pH MeasurementCurrent Acting Control4
Single and Dual Input Analyzers for pH/Redox (ORP)Models AX460, AX466 & AX416SS/AX4PH_4Time Proportioning Control (Pulse Length)With time proportioning control, the AX460 analyzer’s controlsignal output is in pulses, the duration of which changes inproportion to the system error. The pulses are delivered byvarying the length of time that the alarm/control contact isactivated.Time Proportioning Control is used generally to control dosingby low-cost solenoid valves or metering pumps and is alsoknown as pulse-length proportional or Mark Space control.EnergizedDe-energizedEnergizedDe-energizedEnergizedDe-energized2.5secondsPermanently De-energized5 seconds7.5 seconds7.5 seconds5 secondsCycle time = 10 seconds2.5secondsOutput= 0%Output= 25%Output= 50%Output= 75%Pulse-frequency Proportional ControlImpulse pumps dosing chemical reagents are controlled easilyby the AX460 analyzer’s pulse-frequency proportional controloutput. In this case, the pulse length of the alarm/control contactis fixed and the frequency of the delivered pulses increases inproportion to the system error, as set by the proportional band.Diaphragm metering pumps must have a remote pulse inputcapability in order to utilize this function.Pulse-frequency control in the AX460 analyzer operates bypulsing a relay on for 300ms and off for a period of timedetermined by the pulse frequency. The pulse frequency (PFr) isadjustable between 1 and 120 pulses per minute. The greaterthe difference between the measured variable and the set pointthe greater the pulse frequency.ExampleIf the pulse frequency is set at 120 pulses per minute and thepercentage output is 100% then the pulse rate is 2 pulses persecond. If the percentage output is reduced to 50%, the pulserate falls to one pulse per second.Time Proportioning ControlOutput = 0%Permanently De-energizedBi-directional ControlAs well as single set point control for both acid and baseaddition, the AX460 analyzer can be configured withindependent controllers.To avoid control overlap, a minimum of 0.5pH difference (ordeadband) between the set points is essential. The differencebetween the set points varies depending upon the application.Control of each set point can be configured independently aseither P or PI control in this mode. The setting of proportionalband or integral action can also be different for each set point.EnergizedOutput = 50%De-energized0.3s 0.7msEnergizedOutput = 100%0.3s 0.2s 0.3s 0.2sDe-energizedPulse Frequency = 120 pulses per minutePulse-frequency Proportional Control100%ControlOutputLowSet PointHighSet PointPower Failure RecoveryIn the event of a power failure the user can configure the controlmode to be Auto, Manual or Last. This optimizes controlconditions on power-up to ensure rapid recovery of processcontrol.0%0pH14Bi-directional Control5
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Analyze Single and Dual Input Analyzers for pH/Redox (ORP)

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