Instruction Manual PN 51-3081pH/rev.
ESSENTIAL INSTRUCTIONS READ THIS PAGE BEFORE PROCEEDING! Rosemount Analytical designs, manufactures, and tests its products to meet many national and international standards. Because these instruments are sophisticated technical products, you must properly install, use, and maintain them to ensure they continue to operate within their normal specifications.
WHAT YOU NEED TO KNOW BEFORE INSTALLING AND WIRING A ROSEMOUNT ANALYTICAL SENSOR TO THE MODEL 3081 pH/ORP TRANSMITTER 1. THE MODEL NUMBER OF THE SENSOR • Look on the label. • Also note the model option string. • If the label is missing or unreadable, see the flowcharts on pages 28 through 30. Write the sensor model number here 2. THE TYPE OF TEMPERATURE ELEMENT • Look on the label. • If the label is missing or unreadable, measure the resistance between the RTD leads.
• If the sensor is wired directly to the transmitter, the preamplifier can be in either the sensor or the transmitter. • Look at the wires in the sensor cable. A GREEN wire means the preamplifier is in the sensor. An coaxial cable means the preamplifier is in the transmitter. A coaxial cable is an insulated wire surrounded by a braided metal shield. The wire terminates in either a BNC connector or an ORANGE wire with a CLEAR shield.
QUICK START GUIDE FOR MODEL 3081pH/ORP Before using this Quick Start Guide, please read “WHAT YOU NEED TO KNOW BEFORE INSTALLING AND WIRING A ROSEMOUNT ANALYTICAL SENSOR TO THE MODEL 3081 pH/ORP TRANSMITTER” on the preceding page. Section 1.1 Setup for the Models 381+-52, 385+-04, 396P-02-54, 396P-02-55 and 396R-54 without a junction box A. The factory setting of the preamplifier switch is in the appropriate location, so no adjustment is necessary. B. Mount the transmitter in the desired location.
Section 2 Wiring A. Wire sensor Model 381+-55, 385+-03, or 396P-01-55 directly to the transmitter as shown in Figure 3. B. Wire sensor Model 381+-52, 385+-04, 396P-02-55, 396P-02-55, or 396R-54 as shown in Figure 4. C. Wire the 12 - 42.4 Vdc power supply to TB-15 (- 4 - 20 mA) and TB-16 (+ 4 - 20 mA). FIGURE 3 FIGURE 4 NOTES: 1. INSTRUMENT JUMPER SUPPLIED BY CUSTOMER. 2. DO NOT CONNECT BLUE WIRE INSIDE TRANSMITTER. INSULATE STRIPPED END OF BLUE WIRE. Section 3 Power up and Calibration A.
QUICK REFERENCE GUIDE MODEL 3081PH/ORP Automatic Buffer Calibration Note: A pH measurement is only as good as the calibration, and the calibration is only as good as the buffers used. For best results, calibrate with buffers having the same temperature as the process. Allow time for the sensor and buffers to reach the same temperature. If the process temperature is more than 10°C different from the buffer, allow at least 20 minutes. Be careful using buffers at high temperatures.
HART Communicator Fast Key Sequences Buffer Calibration 2 3 1 1 Toggle Hold Mode 2 5 View pH value 1 1 1 Standardize 2 3 2 1 pH Upper Range Value 3 2 2 View Analog Output 1 2 Trim Analog Output 2 4 pH Lower Range Value 3 2 1 View Transmitter Status 1 3 PROGRAM CALIBRATE CALIbrAtE Std tEMP AdJ CAL bF1 Std 7.00 tEMP 25.0 bF 1 SLOPE 59.01 DIAGNOSE InPut 58.9 GIMP 1000 rIMP 10 V Er 81PH.21 tEMP 25 C ShoW FLt nonE bF1 4.
MODEL 3081 pH/ORP TABLE OF CONTENTS MODEL 3081 PH/ORP MICROPROCESSOR TRANSMITTER TABLE OF CONTENTS Section 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Title DESCRIPTION AND SPECIFICATIONS ................................................................ Features................................................................................................................... Accessories..............................................................................................................
MODEL 3081 pH/ORP TABLE OF CONTENTS TABLE OF CONTENTS CONT’D 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 PROGRAMMING FOR pH MEASUREMENTS....................................................... General .................................................................................................................... Entering and Leaving the Program Menu ................................................................ Output Ranging...............................................................................
MODEL 3081 pH/ORP TABLE OF CONTENTS TABLE OF CONTENTS CONT’D 13.0 13.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 13.9 13.10 13.11 pH MEASUREMENTS............................................................................................. General .................................................................................................................... Measuring Electrode ................................................................................................ Reference Electrode ...............
MODEL 3081 pH/ORP TABLE OF CONTENTS TABLE OF CONTENTS CONT’D LIST OF FIGURES Number 2-1 2-2 2-3 2-4 2-5 2-6 2-7 3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 3-10 3-11 3-12 3-13 3-14 3-15 3-16 3-17 3-18 3-19 3-20 3-21 3-22 Title Page Model 3081 pH/ORP Transmitter - Exploded Drawing of Circuit Board Stack ......... 8 Model 3081 pH/ORP Transmitter - Analog Board .................................................... 9 Model 3081 pH/ORP Transmitter - CPU Board ....................................................
MODEL 3081 pH/ORP TABLE OF CONTENTS TABLE OF CONTENTS - CONT’D LIST OF FIGURES - CONT’D Number Title 3-23 Procedure for Removing BNC Connector and Preparing Coaxial Cable for ............ Connection to the Model 3081 pH/ORP Transmitter ................................................ 3-24 Preparation of Raw Connecting Cable (PN 9200273).............................................. 4-1 Intrinsically Safe BASEEFA Model 3081 pH/ORP Label ..........................................
MODEL 3081 pH/ORP TABLE OF CONTENTS TABLE OF CONTENTS CONT’D LIST OF TABLES Number Title 3-1 3-2 3-3 3-4 3-5 3-6 3-7 3-8 3-9 3-10 3-11 8-1 8-2 8-3 8-4 10-1 11-1 12-1 Page Wiring Diagrams for Model 399 Sensors.................................................................. Wiring Diagrams for Model 397 Sensors.................................................................. Wiring Diagrams for Model 396R Sensors ...............................................................
MODEL 3081 pH/ORP SECTION 1.0 DESCRIPTION AND SPECIFICATIONS SECTION 1.0 DESCRIPTION AND SPECIFICATIONS 1.1 1.2 1.3 1.4 1.5 1.6 Features Accessories Specifications - General for Model 3081 pH/ORP Specifications - pH Specifications - ORP Ordering Information • CHANGING FROM pH TO ORP operation takes only seconds. • REMOTE COMMUNICATION IS SIMPLE; use the hand-held infrared remote controller or any HART® compatible device. • LARGE TWO LINE DISPLAY shows pH or ORP, temperature, and output signal.
MODEL 3081 pH/ORP CALIBRATION: Two-point, temperature-corrected buffer calibration is standard. To reduce errors caused by impatient operators, the Model 3081 pH/ORP transmitter does not accept calibration data until programmed stability limits have been met. If data are not acceptable, the transmitter displays an error message and does not update the calibration. The transmitter recognizes every buffer scale in common use in the world. Manual twopoint and one-point calibration are also available.
MODEL 3081 pH/ORP 1.3 SECTION 1.0 DESCRIPTION AND SPECIFICATIONS SPECIFICATIONS -GENERAL FOR MODEL 3081 pH/ORP Case: Cast aluminum containing less than 8% magnesium. NEMA 4X (IP65), NEMA 7 (explosion-proof) Epoxy-polyester paint, Neoprene O-ring seals Dimensions: 6.3 in. x 6.9 in. x 6.4 in. (160 mm x 175 mm x 161 mm); diameter 6.1 in (155 mm) Conduit Openings: 3/4 in. FNPT Reference Impedance: Transmitter accepts high impedance (i.e. glass) reference electrodes as well as low impedance (i.e.
MODEL 3081 pH/ORP SECTION 1.0 DESCRIPTION AND SPECIFICATIONS 1.4 SPECIFICATIONS - pH 1.5 SPECIFICATIONS - ORP pH Input Range: 0 to 14 pH ORP Input Range: -1400 to 1400 mV Temperature Input Range: 5°F to 248°F (-15°C to 120°C) Temperature Input Range: 5°F to 248°F (-15°C to 120°C) Output Scale Expansion: Continuously expandable between pH 0 and 14 Output Scale Expansion: Continuously expandable between -1400 and 1400 mV Accuracy at 25°C: ±0.01 pH Accuracy at 25°C: ±1 mV Repeatability at 25°C: ±0.
MODEL 3081 pH/ORP SECTION 1.
MODEL 3081 pH/ORP SECTION 1.0 DESCRIPTION AND SPECIFICATIONS ACCESSORIES MODEL/PN 515 230A 275 23572-00 23555-00 23557-00 23550-00 23646-01 9200273 2002577 9241178-00 9120531 9210012 9210013 9210014 R508-16OZ 5103081P DESCRIPTION DC loop power supply, see Section 1.2.1 for details Two alarm module, see Section 1.2.2 for details HART communicator, order from Rosemount Measurement - (800) 999-9307 Infrared remote controller, includes two 1.
MODEL 3081 pH/ORP SECTION 2.0 INSTALLATION SECTION 2.0 INSTALLATION 2.1 2.2 2.3 2.4 2.5 Unpacking and Inspection Pre-Installation Set Up Orienting the Display Board Mechanical Installation Power Supply/Current Loop 2.1 UNPACKING AND INSPECTION Inspect the shipping container. If it is damaged, contact the shipper immediately for instructions. Save the box. If there is no apparent damage, remove the transmitter. Be sure all items shown on the packing list are present.
MODEL 3081 pH/ORP SECTION 2.0 INSTALLATION 2.2.4 Preamplifier Location pH sensors produce a high impedance voltage signal that must be preamplified before use. The signal can be preamplified before it reaches the transmitter or it can be preamplified in the transmitter. To work properly, the transmitter must know where preamplification occurs. Although ORP sensors produce a low impedance signal, the voltage from an ORP sensor is amplified the same way as a pH signal.
MODEL 3081 pH/ORP SECTION 2.0 INSTALLATION 5. Set the jumpers and the slide switch on the analog board. Refer to Figure 2-2. a. Temperature element jumper. Jumper position Temperature element JP-1 Pt 1000 RTD JP-2 Pt 100 RTD JP-3 3K Balco RTD The transmitter must also be programmed to recognize the RTD. If pH is being measured, see Section 8.5. If ORP is being measured, see Section 10.5. b. Reference impedance jumper. c.
MODEL 3081 pH/ORP SECTION 2.0 INSTALLATION 6. There are more jumpers on the CPU board. Refer to Figure 2-3. These jumpers are factory set and should NOT need to be moved. This step is for troubleshooting purposes only. Verify that jumpers JP-1, JP-3, and JP-4 on the CPU board are in the positions shown in Figure 2-3. For installations where 50 Hz ac power is present, closing JP-3 may improve immunity of the transmitter to noise. 7. To reassemble the stack, place the display board on the CPU board.
MODEL 3081 pH/ORP SECTION 2.0 INSTALLATION 4. Use weathertight cable glands to keep moisture out of the transmitter. 5. If conduit is used, plug and seal the connections at the transmitter housing to prevent moisture from getting inside the transmitter. NOTE Moisture accumulating in the transmitter housing can affect the performance of the transmitter and may void the warranty. 6.
MODEL 3081 pH/ORP SECTION 2.0 INSTALLATION 2.4.3 Pipe Mounting. See Figure 2-5. The pipe mounting kit (PN 2002577) accommodates 1-1/2 to 2 in. pipe. MILLIMETER INCH DWG. NO. 40308104 REV. G DWG. NO. 40308103 FIGURE 2-5. Using the Pipe Mounting Kit to Attach the Model 3081 pH/ORP Transmitter to a Pipe 12 REV.
MODEL 3081 pH/ORP SECTION 2.0 INSTALLATION 2.5 POWER SUPPLY/CURRENT LOOP 2.5.1 Power Supply and Load Requirements. Refer to Figure 2-6. The minimum power supply voltage is 12.5 Vdc and the maximum is 42.4 Vdc. The top line on the graph gives the voltage required to maintain at least 12.5 Vdc at the transmitter terminals when the output signal is 22 mA. The lower line is the supply voltage required to maintain a 30 Vdc terminal voltage when the output signal is 22 mA.
MODEL 3081 pH/ORP SECTION 3.0 WIRING SECTION 3.0 WIRING 3.1 3.2 General Information Wiring Diagrams 3.1 GENERAL INFORMATION pH and ORP sensors manufactured by Rosemount Analytical can be wired to the Model 3081 pH/ORP transmitter in three ways: 1. directly to the transmitter, 2. to a sensor-mounted junction box and then to the transmitter, 3. to a remote junction box and then from the remote junction box to the transmitter. The pH (or ORP) signal can also be preamplified in one of four places. 1.
MODEL 3081 pH/ORP SECTION 3.0 WIRING 3.2 WIRING DIAGRAMS FOR pH and ORP SENSORS Refer to Tables 3-1 through 3-12 to locate the appropriate wire function and wiring diagram. There is a separate table for each model. The sensor models having the highest number appear first. If you do not know the model number of the sensor, refer to the flow charts on pages 28 through 30. Only the model option numbers needed to select the correct wiring diagram are shown. Other numbers are not shown.
MODEL 3081 pH/ORP SECTION 3.
MODEL 3081 pH/ORP SECTION 3.
MODEL 3081 pH/ORP SECTION 3.0 WIRING REMOVE BNC AND TERMINATE COAXIAL CABLE BEFORE WIRING SENSOR TO TRANSMITTER. SEE FIGURE 3-23. ALTERNATIVELY, USE A BNC ADAPTER (PN 9120531) OR ORDER MODEL OPTION -62 (SENSOR WITH BNC REMOVED AND TERMINATIONS COMPATIBLE WITH 3081 pH/ORP). IF USING A BNC ADAPTER, THE RED WIRE IS MV OR pH IN AND THE BLACK WIRE IS REFERENCE IN. TO PREVENT SHORT CIRCUITS TO THE TRANSMITTER HOUSING, INSULATE THE BNC WITH BY WRAPPING IT WITH ELECTRICAL TAPE. FIGURE 3-2.
MODEL 3081 pH/ORP SECTION 3.0 WIRING REMOVE BNC AND TERMINATE COAXIAL CABLE BEFORE WIRING SENSOR TO TRANSMITTER. SEE FIGURE 3-23. ALTERNATIVELY, USE A BNC ADAPTER (PN 9120531) OR ORDER MODEL OPTION -62 (SENSOR WITH BNC REMOVED AND TERMINATIONS COMPATIBLE WITH 3081 pH/ORP). IF USING A BNC ADAPTER, THE RED WIRE IS MV OR pH IN AND THE BLACK WIRE IS REFERENCE IN. TO PREVENT SHORT CIRCUITS TO THE TRANSMITTER HOUSING, INSULATE THE BNC WITH BY WRAPPING IT WITH ELECTRICAL TAPE. FIGURE 3-6.
MODEL 3081 pH/ORP SECTION 3.0 WIRING FIGURE 3-10. Wire functions for Models 396R-50, 396R-54, 396R-54-61, 396P-02-50, 396P-02-54, 396P-02-55, 385+ -04, and 385+ -41-52. 3 4 5 3 NOTES: 1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "TRANSMITTER" POSITION (SEE SECTION 2.2). 2. IF SENSOR HAS 3K BALCO RTD, SET JUMPER (SECTION 2.2) AND PROGRAM TRANSMITTER TO RECOGNIZE RTD (SECTION 8.5-pH OR 10.5-ORP) 3. JUMPER SUPPLIED BY CUSTOMER. 4. DO NOT CONNECT BLUE WIRE.
MODEL 3081 pH/ORP SECTION 3.0 WIRING FIGURE 3-13. Wire functions for Models 396P-01-55, 385+ -03, 381+ -40-55, and 381+ -43-55. NOTES: 1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "SENSOR/JUNCTION BOX" POSITION (SEE SECTION 2.2). 2. TO EXTEND CABLE LENGTH, USE JUNCTION BOX PN 2355000 WITH EXTENSION CABLE PN 23646-01 (FINISHED) OR PN 9200273 (UNFINISHED). WIRE THROUGH TERMINALS POINT TO POINT. SEE FIGURE 3-24 FOR TERMINATION OF RAW CABLE PN 9200273. FIGURE 3-14.
MODEL 3081 pH/ORP SECTION 3.0 WIRING FIGURE 3-15. Wire functions for Model 385+ -02. NOTES: 1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "SENSOR/JUNCTION BOX" POSITION (SEE SECTION 2.2). 2. SEE FIGURE 3-24 FOR TERMINATION OF RAW INTERCONNECTING CABLE (PN 9200273). 3. JUMPER SUPPLIED BY CUSTOMER. 4. DO NOT CONNECT BLUE WIRE. INSULATE STRIPPED END OF WIRE TO AVOID ACCIDENTAL CONNECTIONS. FIGURE 3-16. Wiring diagram for Model 385+ -02.
MODEL 3081 pH/ORP SECTION 3.0 WIRING NOTE: MODEL 328A-08 HAS UNDRESSED COAXIAL CABLE. SEE SENSOR INSTRUCTION SHEET FOR CABLE PREPARATION PROCEDURE. FIGURE 3-17. Wire functions for Model 328A-07. NOTES: 1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "TRANSMITTER" POSITION (SEE SECTION 2.2). 2. JUMPERS SUPPLIED BY CUSTOMER. 3. MODEL 328A-08 HAS UNDRESSED COAXIAL CABLE. CABLE MUST BE TERMINATED BEFORE WIRING SENSOR TO TRANSMITTER. CENTRAL CONDUCTOR IS pH SIGNAL (TB-10) AND SHIELD IS REFERENCE SIGNAL (TB-7).
MODEL 3081 pH/ORP NOTES: 1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "TRANSMITTER" POSITION (SEE SECTION 2.2). 2. TERMINALS IN JUNCTION BOX ARE NOT NUMBERED. COUNT POSITION FROM LEFT TO RIGHT AS SHOWN IN DRAWING. 3. JUMPERS SUPPLIED BY CUSTOMER. 4. CUSTOMER MUST INSTALL AND WIRE pH ELECTRODE AND TEMPERATURE SENSOR. 5. SEE SENSOR MANUAL FOR PREPARATION OF EXTENSION CABLE (PN 661-646983). 6. DISCONNECT WHITE GUARD WIRE FROM TB-7 AND INSULATE STRIPPED END. FIGURE 3-19. Wiring diagram for Model 320HP-10-55.
MODEL 3081 pH/ORP SECTION 3.0 WIRING FIGURE 3-21. Wire Functions for Model 399-33 FIGURE 3-22.
MODEL 3081 pH/ORP FIGURE 3-23. Procedure for Removing BNC Connector and Preparing Coaxial Cable 26 SECTION 3.
MODEL 3081 pH/ORP SECTION 3.0 WIRING FIGURE 3-24. Preparation of Raw Connecting Cable (PN 9200273).
SENSOR FLOW CHART (continued on page 29) MODEL 3081 pH/ORP 28 SECTION 3.
SENSOR FLOW CHART (continued on page 30) MODEL 3081 pH/ORP SECTION 3.
SECTION 3.
MODEL 3081 pH/ORP SECTION 4.0 INTRINSICALLY SAFE & EXPLOSION PROOF SECTION 4.0 INTRINSICALLY SAFE & EXPLOSION PROOF 4.1 4.2 4.1 Intrinsically Safe Installations Explosion Proof Installations INTRINSICALLY SAFE INSTALLATIONS The installation wiring, operating parameters, or agency tags for intrinsically safe operation are given in Figures 4-1, 4-2, and 4-3. 4.2 EXPLOSION PROOF INSTALLATIONS The installation wiring and operating parameters for explosion proof operation are given in Figure 4-4.
32 FIGURE 4-2.
33
34 FIGURE 4-3.
35
36 FIGURE 4-4.
MODEL 3081 pH/ORP SECTION 5.0 OPERATION WITH REMOTE CONTROLLER SECTION 5.0 OPERATION WITH REMOTE CONTROLLER 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Displays Infrared Remote Controller (IRC) - Key Functions Menu Tree - pH Diagnostic Messages - pH Menu Tree - ORP Diagnostic Messages - ORP Security 5.1 DISPLAYS Figure 5-1 shows the process display screen, and Figure 5-2 shows the program display screen. pH or ORP (ORP in mV) Transmitter output signal in mA or % of full scale Temperature in °C or °F FIGURE 5-1.
MODEL 3081 pH/ORP SECTION 5.0 OPERATION WITH REMOTE CONTROLLER 5.2 INFRARED REMOTE CONTROLLER (IRC) - KEY FUNCTIONS The infrared remote controller is used to calibrate and program the transmitter and to read diagnostic messages. See Figure 5-3 for a description of the function of the keys. RESET - Press to end the current operation and return to the process display. Changes will NOT be saved. RESET does not return the transmitter to factory default settings.
MODEL 3081 pH/ORP SECTION 5.0 OPERATION WITH REMOTE CONTROLLER 5.3 MENU TREE - pH The Model 3081 pH transmitter has three menus: CALIBRATE, PROGRAM, and DIAGNOSE. Under the Calibrate and Program menus are several sub-menus. For example, under CALIBRATE, the sub-menus are CALIbrAtE, Std (standard), and tEMP AdJ (temperature adjust). Under each sub-menu are prompts. For example, under Std, the prompts are Std xx.xx and slope xx.xx. The DIAGNOSE menu lets the user view diagnostic messages.
MODEL 3081 pH/ORP SECTION 5.0 OPERATION WITH REMOTE CONTROLLER 5.5 MENU TREE - ORP The Model 3081 ORP transmitter has three menus: CALIBRATE, PROGRAM, and DIAGNOSE. Under the Calibrate and Program menus are several sub-menus. For example, under CALIBRATE, the sub-menus are Std (standard) and tEMP AdJ (temperature adjust). Under each sub-menu are prompts. For example, the Std sub-menu contains the single prompt Std. Other sub-menus may contain more than one prompt. Figure 5-5 shows the complete menu tree.
MODEL 3081 pH/ORP SECTION 5.0 OPERATION WITH REMOTE CONTROLLER 5.7 SECURITY 5.7.1 General. Use the programmable security code to protect program and calibration settings from accidentally being changed. The transmitter is shipped with the security feature disabled. To program a security code, refer to Section 8.6, Display Units. 5.7.2 Entering the Security Code. PROGRAM Id EXIT 000 ENTER 1.
MODEL 3081 pH/ORP SECTION 6.0 OPERATION WITH MODEL 275 SECTION 6.0 OPERATION WITH MODEL 275 6.1 6.2 6.3 6.1 Note on Model 275 HART Communicator Connecting the HART Communicator Operation Note on Model 275 HART Communicator The Model 275 HART Communicator is a product of Rosemount Measurement. This section contains selected information on using the Model 275 with the Rosemount Analytical Model 3081 pH/ORP Transmitter.
MODEL 3081 pH/ORP 6.3 Operation 6.3.1 Off-line and On-line Operation SECTION 6.0 OPERATION WITH MODEL 275 The Model 275 Communicator features off-line and on-line communications. On-line means the communicator is connected to the transmitter in the usual fashion. While the communicator is on line, the operator can view measurement data, change program settings, and read diagnostic messages. Off-line means the communicator is not connected to the transmitter.
MODEL 3081 pH/ORP SECTION 6.0 OPERATION WITH MODEL 275 (Figure 6-2 is continued on page 41) FIGURE 6-2a.
MODEL 3081 pH/ORP SECTION 6.0 OPERATION WITH MODEL 275 FIGURE 6-2b.
MODEL 3081 pH/ORP SECTION 6.0 OPERATION WITH MODEL 275 (Figure 6-3 is continued on page 43) FIGURE 6-3a.
MODEL 3081 pH/ORP SECTION 6.0 OPERATION WITH MODEL 275 FIGURE 6-3b.
MODEL 3081 pH/ORP SECTION 7.0 CALIBRATION OF pH MEASUREMENTS SECTION 7.0 CALIBRATION OF pH MEASUREMENTS 7.1 7.2 7.3 7.4 7.5 7.6 7.7 General Entering and Leaving the Calibrate Menu Using the Hold Function Temperature Calibration Auto Calibration Manual Calibration Making the Transmitter Reading Match a Second pH Meter (Standardization) 7.1 GENERAL The Calibrate menu allows the user to calibrate the pH and temperature response of the sensor. The transmitter does a two-point pH calibration.
MODEL 3081 pH/ORP SECTION 7.0 CALIBRATION OF pH MEASUREMENTS 7.4 TEMPERATURE CALIBRATION 7.4.1 Purpose 1. As discussed in Section 13.6, Glass Electrode Slope, measuring temperature is an important part of measuring pH. The accuracy of a new sensor and transmitter loop is about ±1°C, which is adequate for most applications. A new sensor seldom requires temperature calibration. 2. Calibrate the sensor/transmitter loop if . . . a. ±1°C accuracy is NOT acceptable, or b.
MODEL 3081 pH/ORP SECTION 7.0 CALIBRATION OF pH MEASUREMENTS 7.5 AUTO CALIBRATION 7.5.1 Purpose 1. 2. 3. New sensors must be calibrated before use. Regular recalibration is also necessary. The use of auto calibration instead of manual calibration is strongly recommended. Auto calibration avoids common pitfalls and reduces errors. For more information about calibration in pH measurements and the use of buffers, refer to Section 13.7, Buffers and Calibration. 7.5.2 What Happens During Auto Calibration? 1.
MODEL 3081 pH/ORP SECTION 7.0 CALIBRATION OF pH MEASUREMENTS NOTE A transmitter adjacent to the one being calibrated may pick up signals from the IRC. To avoid accidentally changing settings, use a different security code for each nearby transmitter. See Section 5.7, Security. NOTE During calibration, the sensor may be exposed to solutions having pH outside the normal range of the process.
MODEL 3081 pH/ORP SECTION 7.0 CALIBRATION OF pH MEASUREMENTS 7.6 MANUAL CALIBRATION 7.6.1 Purpose 1. 2. 3. 4. 5. New sensors must be calibrated before use. Regular recalibration is also necessary. Manual calibration is an alternative to auto calibration. Because auto calibration eliminates many common calibration errors, it is strongly recommended. In auto calibration, the transmitter recognizes the buffer and uses the temperature-corrected pH value in the calibration.
MODEL 3081 pH/ORP SECTION 7.0 CALIBRATION OF pH MEASUREMENTS NOTE A transmitter adjacent to the one being calibrated may pick up signals from the IRC. To avoid accidentally changing settings, use a different security code for each nearby transmitter. See Section 5.7, Security. NOTE During calibration, the sensor may be exposed to solutions having pH outside the normal range of the process.
MODEL 3081 pH/ORP SECTION 7.0 CALIBRATION OF pH MEASUREMENTS 7.7 MAKING THE TRANSMITTER READING MATCH A SECOND pH METER (STANDARDIZATION). 7.7.1 Purpose 1. This section describes how to make the transmitter reading match the reading from a second pH meter. The measurement made with the second meter is called the standard pH (pHstd). The process of making the two readings agree is called standardization. 2. This section also describes how to enter an independently determined slope into the transmitter. 7.
MODEL 3081 pH/ORP SECTION 7.0 CALIBRATION OF pH MEASUREMENTS NOTE A transmitter adjacent to the one being calibrated may pick up signals from the IRC. To avoid accidentally changing settings, use a different security code for each nearby transmitter. See Section 5.7, Security. 7.7.3 Procedure CALIBRATE 1. Enter the CALIBRATE menu by pressing CAL on the IRC. The CALibrAtE sub-menu appears (pictured above left). Std EXIT NEXT ENTER 3. With the Std sub-menu displayed, press ENTER .
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 General Entering and Leaving the Program Menu Output Ranging Diagnostic Parameters Temperature Related Settings Display Units Buffer Calibration Parameters Isopotential Parameters Generating a Test Current 8.1 GENERAL This section describes how to do the following: 1. assign pH values to the 4 and 20 mA outputs, 2.
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS TABLE 8-1. pH Settings List ITEM MNEMONIC DISPLAY LIMITS FACTORY SETTINGS USER SETTINGS PROGRAM LEVEL (Sections 8.0 - 8.9). A. Output Range (Section 8.3) 1. 4 mA Output 2. 20 mA Output: 3. Hold 4. Dampening 5. Fault Current Output Setting OutPut HOLd dPn FAULt 0 - 14 pH 0 - 14 pH 3.80 to 22.00 mA 0 to 255 seconds 3.80 to 22.00 mA B. Diagnostic (Section 8.4) 1.
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS 8.3 OUTPUT RANGING 8.3.1 Purpose This section describes how to do the following: 1. assign pH values to the 4 and 20 mA outputs, 2. set the output current generated by the transmitter during hold, 3. set the output current generated by the transmitter when a fault is detected, 4. control the amount of dampening on the output signal. 8.3.2 Definitions 1. CURRENT OUTPUTS.
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS PROGRAM 8.3.3 Procedure OutPut EXIT NEXT ENTER PROGRAM 4MA 00.00 EXIT ENTER PROGRAM 20MA 1 4.00 EXIT ENTER PROGRAM HoLd 21 . 0 0 EXIT FAULt 22.00 ENTER PROGRAM dPn EXIT 2. Press ENTER . The screen displays the 4 MA prompt. Use the editing keys to change the displayed number to the desired pH. The allowed range is 0.00 to 14.00. Press ENTER to save. 3. The screen displays the 20 MA prompt.
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS 8.4 DIAGNOSTIC PARAMETERS 8.4.1 Purpose This section describes how to do the following: 1. change the standardization or reference offset, 2. enable and disable sensor diagnostics, 3. enable and disable glass impedance temperature compensation, 4. set the high and low warning and failure limits for the glass electrode. 5. set the high and low warning and failure limits for the reference electrode. 8.4.2 Definitions 1.
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS 4. REFERENCE IMPEDANCE. The majority of reference electrodes used in industry are low impedance silver-silver chloride electrodes. Every pH and ORP sensor manufactured by Rosemount Analytical has a low impedance reference. However, there are applications that call for either a high impedance sodium or pH glass reference electrode. Both high impedance and low impedance reference electrodes can be used with the Model 3081 pH/ORP transmitter. 5.
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS 8.4.3 Procedure PROGRAM 1. Press PROG on the infrared remote controller (IRC). dIAGnOSTIC EXIT NEXT ENTER PROGRAM rOFFSt 060 EXIT ENTER PROGRAM dIAG OFF EXIT 2. Press NEXT until the diAGnOStIC sub-menu appear. Press ENTER . 3. The screen displays the rOFFSt prompt. Use the editing keys to change the flashing display to the desired standardization (reference) offset (in millivolts). The range is 0 to 1000 mV. Press ENTER to save.
MODEL 3081 pH/ORP PROGRAM rFH EXIT 1 400 NEXT SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS 12. The rFH prompt appears. Use the editing keys to change the display to the desired reference electrode high impedance fault value. The allowed ranges are ENTER Type of reference electrode Allowed range Low impedance (LO in step 11) 0 - 2000 kilohms High impedance (HI in step 11) 0 - 2000 megohms Entering 0000 disables the feature.
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS 8.5 TEMPERATURE RELATED SETTINGS 8.5.1 Purpose This section describes how to do the following: 1. activate and deactivate automatic temperature compensation, 2. set a manual temperature compensation value, 3. match the transmitter to the type of temperature element in the pH sensor. 8.5.2 Definitions 1. AUTOMATIC TEMPERATURE COMPENSATION. The transmitter uses a temperaturedependent factor to convert measured cell voltage to pH.
MODEL 3081 pH/ORP 8.5.3 Procedure PROGRAM tEMP EXIT SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS 1. Press PROG on the infrared remote controller (IRC). NEXT ENTER 2. Press NEXT until the tEMP sub-menu appears in the display. Press ENTER . PROGRAM tAUtO EXIT 3. The screen displays the tAUTO prompt. Press Ï or Ð to enable (On) or disable (OFF) automatic temperature compensation. Press ENTER to save. ON ENTER PROGRAM tMAn EXIT 025.0 ENTER PROGRAM tC EXIT 1 00-33 4. The tMAN prompt appears.
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS 8.6 DISPLAY UNITS 8.6.1 Purpose This section describes how to do the following: 1. switch the process display units between pH and ORP (millivolts), 2. select °C or °F for the temperature display, 3. select percent of full scale or milliamps for the output display, 4. program a security code. 8.6.2 Definitions 1. DISPLAY UNITS. Select pH if the transmitter is being used to measure pH. Select ORP if the transmitter is being used to measure ORP.
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS 8.7 BUFFER CALIBRATION PARAMETERS 8.7.1 Purpose This section describes how to do the following: 1. activate or deactivate auto calibration, 2. identify which buffers will be used during auto calibration, 3. set the stability criteria for auto calibration. 8.7.2 Definitions 1. AUTO CALIBRATION. In auto calibration, screen prompts direct the user through a two point buffer calibration.
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS TABLE 8-3. pH values of commercial (technical) buffers and the temperature range over which pH values are defined pH Merck temp (°C) 2.00 0 - 95 pH 2.00 4.01 7.00 9.00 0 - 95 0 - 95 12.00 0 - 95 Ingold temp (°C) DIN 19267 pH temp (°C) 1.09 0 - 90 0 - 95 3.06 0 - 90 4.65 6.79 0 - 90 0 - 90 9.23 0 - 90 12.75 0 - 90 0 - 95 7.00 0 - 95 9.21 0 - 95 3. STABILITY CRITERIA.
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS 8.8 ISOPOTENTIAL PARAMETERS 8.8.1 Purpose This section describes how to do the following: 1. convert the pH at the measurement temperature to the pH at a reference temperature by entering a solution temperature coefficient, 2. change the transmitter isopotential pH.
MODEL 3081 pH/ORP 8.8.3 Procedure PROGRAM 1. Press PROG on the infrared remote controller (IRC). ISOPOtntAL EXIT NEXT ENTER PROGRAM tCOEFF EXIT 0.000 NEXT ENTER PROGRAM ISO 07.00 EXIT NEXT ENTER PROGRAM Snr 07.00 EXIT NEXT SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS ENTER 2. Press NEXT until the ISOPOtntAL sub-menu appears. Press ENTER . 3. The screen displays the tCOEFF prompt. Use the editing keys to change the display to the desired solution temperature coefficient.
MODEL 3081 pH/ORP SECTION 8.0 PROGRAMMING FOR pH MEASUREMENTS 8.9 GENERATING A TEST CURRENT 8.9.1 Purpose This section describes how to generate output currents for testing recorders and data handling systems. 8.9.2 What happens while the transmitter is generating a test current? 1. The output current goes to the programmed test value and remains there until the TEST function is disabled. 2. The main display continues to show the pH of the process stream. The word HOLD appears in the display. 3.
MODEL 3081 pH/ORP SECTION 9.0 CALIBRATION OF ORP MEASUREMENTS SECTION 9.0 CALIBRATION OF ORP MEASUREMENTS 9.1 9.2 9.3 9.4 9.5 General Entering and Leaving the Calibrate Menu Using the Hold Function Temperature Calibration Standardization 9.1 GENERAL The Calibrate menu allows the user to calibrate the ORP and temperature response of the sensor. The ORP calibration is a one-point standardization against an ORP standard.
MODEL 3081 pH/ORP SECTION 9.0 CALIBRATION OF ORP MEASUREMENTS 9.4 TEMPERATURE CALIBRATION 9.4.1 Purpose 1. As discussed in Section 14.6 (ORP, Concentration, and pH), ORP is a function of temperature. The accuracy of a new sensor/transmitter loop is about ±1°C, which is adequate for most applications. A new sensor seldom requires temperature calibration. 2. Calibrate the sensor/transmitter loop if . . . a. ±1°C accuracy is NOT acceptable, or b. the temperature measurement is suspected of being in error.
MODEL 3081 pH/ORP SECTION 9.0 CALIBRATION OF ORP MEASUREMENTS 9.5 Standardization 9.5.1 Purpose This section describes how to prepare ORP standard solutions and how to make the transmitter reading match the ORP of the standard. Procedures for making ORP standards are taken from ASTM Method D1498-93. 9.5.2 Preparation of ORP Standard Solutions ASTM D 1498-93 gives procedures for making iron (II) - iron (III) and quinhydrone ORP standards. The iron (II) - iron (III) standard is recommended.
MODEL 3081 pH/ORP SECTION 10.0 PROGRAMMING FOR ORP MEASUREMENTS SECTION 10.0 PROGRAMMING FOR ORP MEASUREMENTS 10.1 10.2 10.3 10.4 10.5 10.6 10.7 General Entering and Leaving the Program Menu Output Ranging Diagnostic Parameters Temperature Element Display Units Generating a Test Current 10.1 GENERAL This section describes how to do the following: 1. assign ORP values to the 4 and 20 mA outputs, 2. set the current generated by the transmitter during hold, 3.
MODEL 3081 pH/ORP SECTION 10.0 PROGRAMMING FOR ORP MEASUREMENTS TABLE 10-1. ORP Settings LIst ITEM MNEMONIC DISPLAY LIMITS FACTORY SETTINGS USER SETTINGS -1400 to 1400 mV -1400 to 1400 mV 3.80 to 22.00 mA 0 to 255 seconds 3.80 to 22.00 mA -1400 mV 1400 mV 21.00mA 0 seconds 22.00mA _______ _______ _______ _______ _______ PROGRAM LEVEL A. Output Range (Section 10.3) 1. 4 mA Output 2. 20 mA Output: 3. Hold 4. Dampening 5. Fault Current Output Setting B. Diagnostic (Section 10.4) 1.
MODEL 3081 pH/ORP SECTION 10.0 PROGRAMMING FOR ORP MEASUREMENTS 10.3 OUTPUT RANGING 10.3.1 Purpose This section describes how to do the following: 1. assign ORP values to the 4 and 20 mA outputs, 2. set the output current generated by the transmitter during hold, 3. set the output current generated by the transmitter when a fault is detected, 4. control the amount of dampening on the output signal. 10.3.2 Definitions 1. CURRENT OUTPUTS.
MODEL 3081 pH/ORP PROGRAM 10.3.3 Procedure OutPut EXIT NEXT SECTION 10.0 PROGRAMMING FOR ORP MEASUREMENTS ENTER 1. Enter the Program menu by pressing PROG on the IRC. The OutPut sub-menu appears. PROGRAM 4MA -1 4 0 0 EXIT NEXT ENTER PROGRAM 1 400 20MA EXIT NEXT ENTER 2. Press ENTER. The screen displays the 4 MA prompt. Use the editing keys to change the displayed number to the desired ORP. The allowed range is -1400 to 1400.
MODEL 3081 pH/ORP SECTION 10.0 PROGRAMMING FOR ORP MEASUREMENTS 10.4 DIAGNOSTIC PARAMETERS 10.4.1 Purpose This section describes how to do the following: 1. change the standardization (reference) offset, 2. enable and disable sensor diagnostics, 3. enable and disable glass impedance temperature compensation for a glass reference electrode, 4. set the high and low warning and failure limits for a glass reference electrode. 10.4.2 Definitions 1. STANDARDIZATION OFFSET (REFERENCE OFFSET).
MODEL 3081 pH/ORP SECTION 10.0 PROGRAMMING FOR ORP MEASUREMENTS PROGRAM 10.4.3 Procedure dIAGnOSTIC 1. Press PROG on the infrared remote controller (IRC). EXIT NEXT ENTER 2. Press NEXT until the diAGnOStIC sub-menu appears. Press ENTER . PROGRAM rOFFSt 060 EXIT ENTER PROGRAM dIAG OFF EXIT 3. The screen displays the rOFFSt prompt. Use the editing keys to change the flashing display to the desired standardization (reference) offset (in millivolts). The range is 0 to 1000 mV.
MODEL 3081 pH/ORP PROGRAM rWJH EXIT 0040 ENTER SECTION 10.0 PROGRAMMING FOR ORP MEASUREMENTS 8. The rWH prompt appears. In the display, W appears as w j. Use the editing keys to change the display to the desired reference electrode high impedance warning value. The allowed ranges are Type of reference electrode Allowed range Low impedance (LO in step 6) 0 - 2000 kilohms High impedance (HI in step 6) 0 - 2000 megohms Entering 0000 disables the feature.
MODEL 3081 pH/ORP SECTION 10.0 PROGRAMMING FOR ORP MEASUREMENTS 10.5 TEMPERATURE ELEMENT 10.5.1 Purpose This section describes how to match the transmitter to the type of temperature element in the ORP sensor. 10.5.2 Definition TEMPERATURE ELEMENT: ORP sensors use a variety of temperature elements. The Model 3081 ORP transmitter recognizes the following temperature elements and configurations: a. three and four wire 100 ohm platinum RTDs b. three and four wire 1000 ohm platinum RTDs c.
MODEL 3081 pH/ORP SECTION 10.0 PROGRAMMING FOR ORP MEASUREMENTS 10.6 DISPLAY UNITS 10.6.1 Purpose This section describes how to do the following: 1. switch the process display units between pH and ORP (millivolts), 2. select °C or °F for the temperature display, 3. select percent of full scale or milliamps for the output display, 4. program a security code. 10.6.2 Definitions 1. DISPLAY UNITS. Select pH if the transmitter is being used to measure pH.
MODEL 3081 pH/ORP SECTION 10.0 PROGRAMMING FOR ORP MEASUREMENTS 10.7 GENERATING A TEST CURRENT 10.7.1 Purpose This section describes how to generate output currents for testing recorders and data handling systems. 10.7.2 What happens while the transmitter is generating a test current? 1. The output current goes to the programmed test value and remains there until the TEST function is disabled. 2. The main display continues to show the ORP of the process stream. The word HOLD appears in the display. 3.
MODEL 3081 pH/ORP SECTION 11.0 MAINTENANCE SECTION 11.0 MAINTENANCE 11.1 11.2 11.3 11.4 11.5 Overview Transmitter Maintenance pH Sensor Maintenance ORP Sensor Maintenance Calibration 11.1 OVERVIEW This section gives general procedures for routine maintenance of the 3081 pH/ORP transmitter and pH and ORP sensors. The transmitter needs almost no routine maintenance. Sensors require periodic inspection and cleaning.
MODEL 3081 pH/ORP SECTION 11.0 MAINTENANCE TABLE 11-1. Replacement Parts for Model 3081 pH/ORP Transmitter Location in Figure 11-1 PN 1 23574-02 PCB stack consisting of the CPU (part 3) and analog (part 4) boards, display board is not included, CPU and analog boards are factorycalibrated as a unit and cannot be ordered separately 1 lb/0.5 kg 2 23652-01 LCD display PCB 1 lb/0.5 kg 5 33337-02 Terminal block 1 lb/0.5 kg 6 23593-01 Enclosure cover, front with glass window 3 lb/1.
MODEL 3081 pH/ORP SECTION 11.0 MAINTENANCE When using acid or alkaline solvents, be careful to keep the solvent away from the liquid junction. If the cleaning solvent contacts the junction, hydrogen ions (acid solvent) or hydroxide ions (alkaline solvent) will diffuse into the junction. Because hydrogen and hydroxide ions have much greater mobility than other ions, they produce a large junction potential.
MODEL 3081 pH/ORP SECTION 11.0 MAINTENANCE 11.4 ORP SENSOR MAINTENANCE 11.4.1 Frequency of Cleaning The frequency at which an ORP sensor should be inspected and cleaned can be determined only by experience. If the process liquid coats or fouls the sensor, frequent cleaning may be necessary. If the process does not contain a high level of suspended solids, the need for regular cleaning will be less. 11.4.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING SECTION 12.0 TROUBLESHOOTING 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 12.9 WARNING AND FAULT MESSAGES CALIBRATION ERRORS TROUBLESHOOTING - GENERAL TROUBLESHOOTING WHEN A DIAGNOSTIC MESSAGE IS SHOWING TROUBLESHOOTING WHEN NO DIAGNOSTIC MESSAGE IS SHOWING SYSTEMATIC TROUBLESHOOTING DISPLAYING DIAGNOSTIC VARIABLES TESTING THE TRANSMITTER BY SIMULATING pH FACTORY ASSISTANCE AND REPAIRS 12.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12.2 CALIBRATION ERRORS If an error occurs during calibration, an error message appears in the main display, and the transmitter does not update the calibration. The calibration errors are Std Err, SLOPE Err LO, and SLOPE Err HI. See Section 12.4 for an explanation of the error messages and suggested ways of correcting the problem. 12.3 TROUBLESHOOTING - GENERAL Troubleshooting is easy as 1, 2, 3 . . .
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12.4.1 GLASSFAIL GLASSFAIL is an electrode fault message. It means the glass impedance is outside the programmed Glass Fault High (GFH) or Glass Fault Low (GFL) limit. Glass Fault High suggests the electrode is aging or the electrode is not immersed in the process liquid. Glass Fault Low implies the pH sensitive glass is cracked. GLASSFAIL also appears if inappropriate limits have been entered into the transmitter.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING b. If the sensor was wired with the blue solution ground wire unattached and a jumper between terminals TB-8 and TB-7, remove the jumper and reattach the blue solution ground wire to TB-8. Keep the gray reference in wire attached to TB-7. c. For Rosemount Analytical PLUS (+) and TUpH sensors that do not have an integral preamplifier, attach the blue solution ground wire to TB-8 or, better, leave the blue wire unattached and jumper TB-7 to TB-8. d.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING SLOPE STATUS OF SENSOR 54-60 mV/unit pH Sensor is in good condition. 48-50 mV/unit pH Sensor is nearing the end of its life. Once the slope drops below 48 mV/unit pH, the sensor can no longer be calibrated. b. The Glass Fail High (GFH) limit is probably set too low for the sensor. Set the GFH limit to about 150 megohms greater than the measured glass impedance. c.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING Troubleshooting Flowchart - rEF FAIL A. Be sure the sensor is completely immersed in the process liquid. If the diagnostic message disappears, the sensor is in good condition. If the diagnostic message remains, go to step B. B. Check that the sensor is properly wired to the transmitter. See the appropriate wiring diagram in Section 3.0. Be sure the reference in wire is attached to TB-7 and the solution ground wire is attached to TB-8.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12.4.4 rEFWArn rEF WArn is an electrode fault message. It means the reference electrode impedance exceeds the programmed Reference Warning High (RWH) limit. Ideally, when the measurement system exceeds the warning limits, the user will have adequate time to diagnose and correct problems before a failure occurs. A high reference impedance implies that the liquid junction is plugged or the reference electrolyte is depleted.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING B. Check the sensor. Refer to the wiring diagrams in Section 3.0 to identify the RTD leads. Disconnect the RTD leads and measure the resistances shown in Figure 12-3. The measured resistance should agree with the value in Table 12-1 to within about 1%. If the measured resistance is appreciably different (between 1 and 5%) from the value shown, the discrepancy can be calibrated out. See Section 8.5. FIGURE 12-3.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING C. Check the transmitter. 1. Disconnect the RTD sensor leads and wire the circuit shown in Figure 12-4. Set the resistance to the value for 25°C shown in Table 12-1. The measured temperature should equal 25°C to within ±1°C. FIGURE 12-4. Temperature simulation into the Model 3081 pH/ORP transmitter. If the measured temperature is correct, the transmitter is working properly.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING B. The RTD sense or the RTD return wire inside the sensor cable may be broken. Keep the sensor wires attached and jumper TB-3 and TB-4. If the diagnostic message disappears, either the RTD return or RTD sense wire is broken. To verify a broken wire, disconnect the leads and measure the resistance between them. Installing the jumper completes the circuit, but bypasses the three-wire function.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12.4.9 SLOPE Err LO SLOPE Err LO means that a two-point buffer calibration attempt has failed. The slope is too low (<40 mV/pH) for a good measurement. Troubleshooting Flowchart-SLOPE Err LO A. Repeat the calibration. 1. Inaccurate buffers can cause a low slope. Repeat the calibration using fresh buffers. Alkaline buffers, pH 10 or greater, are particularly susceptible to changing value in air or with age.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12.4.10 SLOPE Err HI SLOPE Err HI means that a two-point buffer calibration attempt has failed. The slope is too high (>62 mV/pH) for a good measurement. Troubleshooting Flowchart-SLOPE Err HI A. Repeat the calibration. 1. Inaccurate buffers can cause a low slope. Repeat the calibration using fresh buffers. Alkaline buffers, pH 10 or greater, are particularly susceptible to changing value in air or with age.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING If the sensor is not rebuildable... Try the reference electrode rejuvenation procedure described in Section 11.3.4. If the rejuvenated sensor can be calibrated, the problem has been corrected. If the sensor cannot be calibrated, replace the sensor. 12.4.12 rOM FAIL or CPU FAIL rOM FAIL or CPU FAIL means the transmitter electronics have failed. Replace the electronic board stack (PN 23574-02). 12.4.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12.4.15 FACt FAIL FACt FAIL appears if the transmitter factory calibration message has been triggered. A stray noise spike can cause this message to appear. If the pH reading seems acceptable, reset the calibration flag. 1. Enter the factory calibration menu by pressing Í on the IRC ten times. The display will not change. Immediately press Ï. FActorYCAL appears in the display. 2. Press NEXT. rEPAir appears in the display. 3. Press NEXT.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12.5.1 Id 000 in Display A security code has been programmed into the transmitter. The correct code must be entered before the transmitter can be programmed or calibrated. To retrieve a lost security code see Section 5.7. To change the security code, see Section 8.6. 12.5.2 Transmitter Does Not Respond to Infrared Remote Controller (IRC) A. Be sure the transmitter is receiving the signal. 1. Clean the window in front of the IR detector.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12.5.5 pH Reading in Buffer Drifts During Manual Calibration A. Allow adequate time for the temperature of the sensor to reach the temperature of the buffer. If the sensor was in a process substantially hotter or colder than the buffer, allow at least 20 minutes for readings in the buffer to stabilize. Alternatively, place the sensor in a container of water at ambient temperature for 20 minutes before starting the calibration. B.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12.5.8 Buffer Calibration Is Acceptable; Process pH is Grossly Different from Expected Value. The symptoms suggest a ground loop (measurement system connected to earth ground at more than one point), a floating system (no earth ground), or noise being induced into the transmitter by sensor cabling. The problem arises from the process or installation. It is not a fault of the transmitter. The problem should disappear once the sensor is taken out of the system.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 4. Occasionally, noise can travel into the transmitter housing from the metal it is mounted on. The noise is then radiated into the transmitter electronics. If isolating the transmitter from its metal mounting eliminates the symptoms, move the transmitter to a different location or mount it with isolating materials. 5. If ground loop problems persist, consult the factory.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12. 5.13 Transmitter Locks Up A. Turn the dc power off, then turn it back on. B. If the problem persists, replace the electronic board stack (PN 23574-02). 12. 5.14 Transmitter Periodically Restarts Itself A. The problem is usually related to improperly wired RTD input terminals. 1. The RTD return wire must be connected to TB-3. The RTD sense wire must be connected to TB-4, and the RTD in wire must be connected to TB-5. See the wiring diagrams in Section 3.0.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING Process pH measurement problem Perform buffer calibration (outside of the process) Refer to Section 7.5 Buffer calibration OK? YES 1. Measure pH of a grab sample in a beaker. If pH is correct, then the process is OK. NO 2. Resolve the ground loop; insulate shield wires from grounded metal. See Section 12.5.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING pH measurement problem Perform buffer calibration (outside of the process) Refer to Section 7.5 YES Buffer calibration OK? 1. Measure pH of a grab sample in a beaker. If pH is correct, then the process is OK. NO NO Place transmitter internal preamplifier switch in proper position. Likely Process Problem or Ground Loop: 2. Resolve the ground loop; insulate shield wires from grounded metal. See Section 12.5.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12.7 DISPLAYING DIAGNOSTIC VARIABLES 12.7.1 Purpose This section describes how to display the diagnostic variables listed below: DIAGNOSTIC MEASUREMENTS 1. Sensor voltage in mV (InPut) 2. Glass impedance in megohms (GIMP) 3. Reference impedance in kilohms* (rIMP) 4. Temperature in °C (tEMP) DIAGNOSTIC MESSAGES 1. Software version (VEr) 2.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12.8.2 pH Simulation When the Preamplifier Is Located in the Transmitter. 1. Verify that switch S-1 is set to "transmitter". See Section 2.2. 2. Turn off sensor diagnostics. See Section 8.4. 3. Turn off automatic temperature compensation. Set manual temperature compensation to 25°C. See Section 8.5. 4. Disconnect the sensor and wire the transmitter as shown in Figure 12-7. 5. Attach a jumper between TB-7 (REF IN) and TB-10 (pH IN). 6. Measure the voltage.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 12.8.4 pH Simulation with the Model 381+ Sensor 1. Verify that switch S-1 is set to "sensor or junction box". See Section 2.2. 2. Turn off sensor diagnostics. See Section 8.4. 3. Turn off automatic temperature compensation. Set manual temperature compensation to 25°C. See Section 8.5. 4. Refer to Figure 12-9 for connections to the sensor. 5. Remove the cover from the sensor. Leave the sensor cable connector attached. 6.
MODEL 3081 pH/ORP SECTION 12.0 TROUBLESHOOTING 10. Touch the other end of the second jumper to the center pin of the BNC connector on the preamplifier. DO NOT LET THE WIRE TOUCH THE OUTSIDE OF THE BNC CONNECTOR. 11. Measure the voltage. The measured voltage should be 0 mV, and the pH should be approximately 7. Because the calibration data in the transmitter may be offsetting the input voltage, the displayed pH may not be exactly 7.0.
MODEL 3081 pH/ORP SECTION 13.0 pH MEASUREMENTS SECTION 13.0 pH MEASUREMENTS 13.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 13.9 13.10 13.11 General Measuring Electrode Reference Electrode Liquid Junction Potential Converting Voltage to pH Glass Electrode Slope Buffers and Calibration Isopotential pH Junction Potential Mismatch Sensor Diagnostics Shields, Insulation, and Preamplifiers 13.
MODEL 3081 pH/ORP designed, the liquid junction potential is usually small and relatively constant. All three potentials depend on temperature. As discussed in Sections 13.5 and 13.6, the factor relating the cell voltage to pH is also a function of temperature. The construction of each electrode and the electrical potentials associated with it are discussed in Sections 13.2, 13.3, and 13.4. 13.2 MEASURING ELECTRODE SECTION 13.
MODEL 3081 pH/ORP 13.4 LIQUID JUNCTION POTENTIAL The salt bridge (see Figure 13-4) is an integral part of the reference electrode. It provides the electrical connection between the reference electrode and the liquid being measured. Salt bridges take a variety of forms, anything from a glass frit to a wooden plug. Salt bridges are highly porous, and the pores are filled with ions. The ions come from the filling solution and the sample. Some bridges permit only diffusion of ions through the junction.
MODEL 3081 pH/ORP 4. the liquid junction potential. The second term, 0.1984 T pH, is the potential (in mV) at the outside surface of the pH glass. This potential depends on temperature and on the pH of the sample. Assuming temperature remains constant, any change in cell voltage is caused solely by a change in the pH of the sample. Therefore, the cell voltage is a measure of the sample pH.
MODEL 3081 pH/ORP SECTION 13.0 pH MEASUREMENTS pH 7.00 and pH 10.00. When the electrodes are placed in pH 7 buffer the cell voltage is V7, and when the electrodes are placed in pH 10 buffer, the cell voltage is V10. Note that V7 is not 0 mV as would be expected in an ideal sensor, but is slightly different. The microprocessor calculates the equation of the straight line connecting the points. The general form of the equation is: E = A + B (t + 273.15) (pH - 7) (2) The slope of the line is B (t + 273.
MODEL 3081 pH/ORP junction potentials in the buffers are assumed to be equal and are exaggerated for clarity. If the liquid junction potential in the sample differs from the buffers, a measurement error results. Figure 13-8 illustrates how the error comes about. Assume the true pH of the sample is pHs and the cell voltage is Es. The point (pHs, Es) is shown on the graph. If the liquid junction potential in the sample were equal to the value in the buffers, the point would lie on the line.
MODEL 3081 pH/ORP SECTION 14.0 ORP MEASUREMENTS SECTION 14.0 ORP MEASUREMENTS 14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8 General Measuring Electrode Reference Electrode Liquid Junction Potential Relating Cell Voltage to ORP ORP, Concentration, and pH Interpreting ORP Measurements Calibration 14.1 GENERAL Figure 14-1 shows a simplified diagram of an electrochemical cell that can be used to determine the oxidationreduction potential or ORP of a sample.
MODEL 3081 pH/ORP SECTION 14.0 ORP MEASUREMENTS 14.2 MEASURING ELECTRODE 14.4 LIQUID JUNCTION POTENTIAL Figure 14-2 shows a typical ORP measuring electrode. The electrode consists of a band or disc of platinum attached to the base of a sealed glass tube. A platinum wire welded to the band connects it to the lead wire. A salt bridge (see Figure 14-3) is an integral part of the reference electrode. It provides the electrical connection between the reference electrode and the liquid being measured.
MODEL 3081 pH/ORP SECTION 14.0 ORP MEASUREMENTS FIGURE 14-4. The Origin of Liquid Junction Potentials. The figure shows a thin section through a pore in the junction plug. The junction separates a solution of potassium chloride on the left from a solution of hydrochloric acid on the right. The solutions have equal molar concentration. Driven by concentration differences, hydrogen ions and potassium ions diffuse in the directions shown. The length of each arrow indicates relative rates.
MODEL 3081 pH/ORP SECTION 14.0 ORP MEASUREMENTS is described by the following equation, called the Nernst equation: In the Nernst equation, E is the electrode potential and E° is the standard electrode potential, both in millivolts, t is temperature in °C, n is the number of electrons transferred (n = 1 in the present case), and [Fe+2] and [Fe+3] are the concentrations of iron (II) and iron (III) respectively. There are several ways of defining the standard electrode potential, E°.
MODEL 3081 pH/ORP SECTION 14.0 ORP MEASUREMENTS The Nernst equation for reaction 3 is: 0.1987 (t + 273.15) log E = E°- 6 [Cr+3] 2 [Cr2O7-2] [H+]14 free chlorine. Although the details are beyond the scope of this discussion, the result is shown in equation 7: (4) Note that the hydrogen ion factor in the concentration ratio is raised to the fourteenth power. The table shows the expected effect of changing pH on the measured ORP at 25°C. pH changes ORP changes by from 2.0 to 2.2 7 mV from 2.0 to 2.
MODEL 3081 pH/ORP SECTION 14.0 ORP MEASUREMENTS The ORP of the iron (II) - iron (III) standard when measured with a platinum electrode against a saturated silver-silver chloride reference is 476 ± 20 mV at 25°C. The range of values is caused primarily by the high and variable liquid junction potential generated in solutions containing high acid concentrations. Quinhydrone - hydroquinone ORP standards are also used. They are prepared by dissolving excess quinhydrone in either pH 4.00 or pH 6.86 buffer.
MODEL 3081 pH/ORP SECTION 15.0 THEORY - REMOTE COMMUNICATIONS SECTION 15.0 THEORY - REMOTE COMMUNICATIONS 15.1 15.2 15.3 Overview of HART Communications HART Interface Devices AMS Communication 15.1 OVERVIEW OF HART COMMUNICATION HART (highway addressable remote transducer) is a digital communication system in which two frequencies are superimposed on the 4 to 20 mA output signal from the transmitter. A 1200 Hz sine wave represents the digit 1, and a 2400 Hz sine wave represents the digit 0.
MODEL 3081 pH/ORP SECTION 15.0 THEORY - REMOTE COMMUNICATIONS If your communicator does not recognize the Model 3081 pH/ORP transmitter, the device description library may need updating. Call the manufacturer of your HART communication device for updates. 15.3 ASSET MANAGEMENT SOLUTIONS Asset Management Solutions (AMS) is software that helps plant personnel better monitor the performance of analytical instruments, pressure and temperature transmitters, and control valves.
MODEL 3081 pH/ORP SECTION 16.0 GLOSSARY SECTION 16.0 GLOSSARY TERM DEFINITION Acid When dissolved in water acids increase the hydrogen ion concentration. Pure water at 25°C contains 1 x 10-7 moles per liter of hydrogen ions (H+) and an equal concentration of hydroxide ions (OH-). An acid increases the hydrogen ion concentration above the value found in pure water and decreases the hydroxide ion concentration. However, the product of the hydroxide and hydrogen concentrations remains constant.
MODEL 3081 pH/ORP SECTION 16.0 GLOSSARY Combination electrode In a combination electrode, the measuring electrode and reference electrode are combined in a single body. Often the temperature element is included in the body as well. Common A point in a circuit against which voltages are measured. Diagnostics Diagnostics, also called advanced sensor diagnostics, automatically and continuously monitor the condition of the sensor.
MODEL 3081 pH/ORP SECTION 16.0 GLOSSARY Fault A fault is a system disabling condition. Measurement data displayed during a fault condition are probably in error and should be regarded with great suspicion. The Model 3081 pH/ORP transmitter displays fault messages to aid in trouble-shooting. Filling solution The electrolyte solution inside an electrode is called the filling solution. The buffered electrolyte solution inside a glass electrode is usually called the internal filling solution.
MODEL 3081 pH/ORP SECTION 16.0 GLOSSARY Hold function During hold the Model 3081 pH/ORP transmitter generates a pre-programmed output current or remains at the last value. Placing the transmitter in hold avoids false alarms and unwanted operation of chemical dosing pumps while the sensor is being calibrated or cleaned.
MODEL 3081 pH/ORP SECTION 16.0 GLOSSARY pH Although pH is often defined as the negative common logarithm of the hydrogen ion activity, pH is best defined by describing how it is measured. The measurement requires three steps. Assemble an electrochemical cell consisting of a glass electrode, a reference electrode, and the solution. Calibrate the cell by measuring the voltage of two standard buffer solutions. Finally, measure the cell voltage with sample present.
MODEL 3081 pH/ORP SECTION 16.0 GLOSSARY Solution ground A solution ground is a metal post or ring incorporated into the sensor body and making contact with the process stream. Glass and reference impedances are measured by applying a voltage pulse between the electrode and the solution ground. Solution temperature compensation The pH of many solutions, particularly alkaline ones, is a function of temperature.
MODEL 3081 pH/ORP SECTION 17.0 RETURN OF MATERIAL SECTION 17.0 RETURN OF MATERIAL 17.1 GENERAL. 17.3 NON-WARRANTY REPAIR. To expedite the repair and return of instruments, proper communication between the customer and the factory is important. Call 1-949-757-8500 for a R e t u r n Materials Authorization (RMA) number. The following is the procedure for returning for repair instruments that are no longer under warranty: 1. Call Rosemount Analytical for authorization. 2.
WARRANTY Goods and part(s) (excluding consumables) manufactured by Seller are warranted to be free from defects in workmanship and material under normal use and service for a period of twelve (12) months from the date of shipment by Seller. Consumables, pH electrodes, membranes, liquid junctions, electrolyte, O-rings, etc. are warranted to be free from defects in workmanship and material under normal use and service for a period of ninety (90) days from date of shipment by Seller.
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