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1 INTRODUCTION 1.1 Description Sample inlet and drain connections are at the base of the The Model 8237 Carbon Dioxide Monitor is a microprocessor instrument. A peristaltic pump, mounted centrally, proportions based analyser using a gas sensing membrane probe to monitor sample and reagent through a mixing and reaction coil to a flow- the level of CO in cooling water samples in AGR Nuclear Power...
2 INSTALLATION 2.1 Accessories 2.4 Sampling Requirement 1 x reagent bottle In addition to being as close as possible to the monitor, the 4 x calibration bottles sampling point must provide a thoroughly mixed representative 1 x 8237 probe kit sample.
…2 INSTALLATION 2.6 Connections, General Warnings. • A disconnecting device such as a switch or circuit breaker conforming to local safety standards must be fitted to the final installation. It must be fitted in close proximity to the instrument within easy reach of the operator and must be marked clearly as the disconnection device for the instrument.
2 INSTALLATION… 2.7 External Electrical Connections – Fig. 2.3 The connections are as follows: The external electrical connections are to be found in the User Junction Box with the exception of the optional serial interface a) Mains input 115V (110 to 120V) or 230V (220 to 240V). The which is connected directly into the Microprocessor Unit.
…2 INSTALLATION 2.8 Relay Contact Protection and Interference as shown in Fig. 2.5A. If the instrument malfunctions the value of Suppression – Fig. 2.5 the RC network is too low for suppression and an alternative If the relays are used to switch loads on or off the relay contacts value must be used.
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2 INSTALLATION NC C NO Relay Contacts 0 to 1mA 0 to 10mA 0 to 20mA 4 to 20mA Load External AC Supply A – AC Applications Link for the Current Output required NC C NO Relay Contacts Diode Captive Screws Load External...
3 SETTING UP 4 LIQUID HANDLING SECTION 4.1 Principle of Operation Note. Before proceeding any further, ensure that all switches Neither bicarbonate ion content nor total carbon dioxide can are set to OFF on the right hand side of the electronics unit – be measured directly in an untreated sample, since the probe see Fig.
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4 LIQUID HANDLING SECTION f) The sample then flows to waste via the contaminated drain connection. g) During a calibration, the monitor introduces two calibration solutions sequentially in place of the sample by means of the solenoid valves SV1 and SV2. To provide remote indication of a calibration in progress, the calibration relay is activated.
5 ELECTRONICS SECTION 5.1 Electronic Layout – Fig. 5.1 5.4 Front Panel Controls – Fig. 5.2 The electronic section comprises two separate sections: The programme controls comprise eight tactile membrane switches. These switches are situated behind a hinged door • The User Junction Box at the top right hand side.
5 ELECTRONICS SECTION Note. If the 'Hold' facility is inadvertently left 20-character Alarm and Status 5-digit Display switched-in, it is automatically cancelled after a Dot-Matrix Display L.E.D.s (Concentration) period of approximately 3 hours has elapsed. Used for storing the programmed function parameters Enter and values in the instrument's nonvolatile memory.
6 PROGRAMMING… 6.1 Normal Operation 6.2 Programming Pages In normal operation (Operating Page 1) the lower, dot matrix, Operation of the switch enables a series of 'programming' display gives indication of the units of measurement, millivolt pages to be displayed. Unauthorised entries to this page are value, sensor slope and time.
…6 PROGRAMMING 6.2.1 Operating Page 1 The values displayed in Operating Page 1 are for viewing only and cannot be altered in this page. Measurement Units Carbon Dioxide <Unit> The measurement units are displayed, e.g. Carbon dioxide mg l Advance to next parameter. Mode Sensor Output •...
6 PROGRAMMING… 6.2.2 Operating Page 2 To gain access to the Calibration Page (Operating Page 2), operate the switch. Enable Automatic Calibrations Enable Auto Cals Yes Select 'Yes' to enable or 'No' to disable the automatic calibrations. Store. Enter Advance to next parameter. Page header.
…6 PROGRAMMING …6.2.2 Operating Page 2 Calibrating Standard 2 Calibrating Std 2 The upper display shows the CO concentration value. The display remains until a stable output is obtained from the sensor. Toggle between the two displays. Electrode Millivolts – – –...
6 PROGRAMMING… 6.2.4 Set Up Input Page Page header. SET UP INPUT Advance to next parameter. – C Control Temperature Control Temp – – • Set the required block control temperature within the range 30 to 45C in 0.1C increments Store.
…6 PROGRAMMING 6.2.5 Current Output Page The current output is assigned to the CO concentration but is only operative if the relevant output modules are fitted – see Fig. 2.4. Page header. CURRENT OUTPUT Advance to next parameter. OP1 Cal Hold Output 1 Calibration Hold Current Output 1 can be held during calibration, if required.
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6 PROGRAMMING… 6.2.5 Current Output Page Continued from previous page. Output 2 Calibration Hold OP2 Cal Hold Current Output 2 can be held during calibration, if required. Select 'YES' or 'NO'. Store. Enter Advance to next parameter. Output 2 Law OP2 Law Current Output 2 can be either logarithmic or linear.
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…6 PROGRAMMING …6.2.5 Current Output Page Test Output Zeros Test Current Output Zeros The instrument automatically transmits a current output zero test signal on both outputs. Example – For a 4 to 20mA current output range, 4mA is transmitted. Advance to next parameter. Test Current Output Full Scale Test Output FSD The instrument automatically transmits a current output full scale test signal on...
6 PROGRAMMING… 6.2.6 Set Up Alarms Page Alarm l.e.d. indication and relay output can be assigned either to the CO concentration or switched off. Page header. SET UP ALARMS Advance to next parameter. A1 Enabled Alarm A1 Enable Select 'YES' to enable or 'NO' to disable. Store.
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…6 PROGRAMMING …6.2.6 Set Up Alarms Page – – – – A1 Setpoint A1 Setpoint • Set the required setpoint value. Enter Store. Advance to next parameter. A2 Enabled A2 Enabled Repeat the programming procedures as for Alarm Relay 1. A2 Setpoint –...
6 PROGRAMMING… 6.2.7 Set Up Clock Page Page header. SET UP CLOCK Advance to next parameter. Set Up Real Time Clock Set Clock? Select 'Yes' to set up the clock, otherwise select 'No'. Store. Enter Advance to next parameter. – – Set Year Set Year Set the appropriate year.
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…6 PROGRAMMING …6.2.7 Set Up Clock Page – – Set Minutes Set Minutes Set the appropriate minutes. Store. Enter Advance to next parameter. – – Set Seconds Set Seconds Set the appropriate seconds. Enter Store. Advance to next parameter. Flashing Calibration Date (day of the month) Cal Date DD :MM:YY...
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6 PROGRAMMING… 6.2.7 Set Up Clock Page Continued from previous page. Flashing Calibration Time (hour – 24 hour clock) Cal Time Set the hour of the day when the first automatic calibration is to be carried out. Store and advance to next parameter. Enter Flashing Calibration Time (minutes)
…6 PROGRAMMING 6.2.8 Calibration User Code Page The calibration user code is required to gain access to the Set Up Temperature Control and Calibration Pages. The access code can be altered in the Calibration Page, if required – see Section 6.2.11. ----- Calibration User Code CAL USER CODE...
6 PROGRAMMING… 6.2.9 Set Up Temperature Control Page The parameters within this page are factory preset and should not require any adjustment. SET UP TEMP. CONTROL Page header. Advance to next parameter. Cycle Time Cycle Time The cycle time is adjustable between 5 and 60 seconds in 1 second increments. Advance to next parameter.
…6 PROGRAMMING 6.2.11 Electrical Calibration Page Page header. CALIBRATION Advance to next parameter. mV Zero Millivolt Input Zero – – – – Set the millivolt source to –400mV. Set the display to '–400'mV. Store. New value is accepted only when input is stable. Enter Advance to next parameter.
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6 PROGRAMMING… 6.2.11 Electrical Calibration Page Continued from previous page. Adjust Current Output 1 Zero Adjust Output 1 Zero The monitor transmits a zero signal, e.g. for a 4 to 20mA output range, 4mA is transmitted. Set the milliammeter reading to the current output 1 zero level, i.e. 0mA (zero-based ranges) or 4mA (4 to 20mA range).
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…6 PROGRAMMING …6.2.11 Electrical Calibration Page Continued from previous page. 25 m Cal Time 1 Calibration Time 1 The displayed value is preset at the factory and must not be altered. See Table 7.1. Advance to next parameter. Calibration Time 2 25 m Cal Time 2 The displayed value is preset at the factory and must not be altered.
7 CALIBRATION 7.1 Calibration Sequence Once a valve is energised, sufficient time (preset to suit the sensor response time) is allowed for the previous solution to be Calibration of the monitor is carried out by replacing the sample solution sequentially with two standard solutions of known displaced, and for the sensor to respond to the new solution, concentration.
8 MAINTENANCE 8.1 Chemical Solutions The two standard solutions are stored in plastic bottles (packed separately). Freshly made up solutions should be made up using The reagent and standard solutions described below are required to maintain the monitor in operation. Where possible, they should carbon dioxide-free water taken directly from the outlet of a be freshly made and stored in plastic (e.g.
8 MAINTENANCE… 8.2 Scheduled Servicing 8.2.2 Four Weekly a) Inspect all tubing and connections for leaks and deterioration. The following servicing schedule has been produced as a general guide only. Because the monitor has been designed for a very wide range of applications, where the nature of the sample can b) Examine all tubing for signs of accumulation of solid deposits.
…8 MAINTENANCE 8.2.4 Consumables Spares Kit d) Remove the flow-through cap and place the white washer in the bottom of the recess of the cap. The monitor is supplied with a consumable spares kit (see Section 10). This consumable spares kit includes all the components which are recommended for replacement annually e) Take one of the white plastic membranes from the spares kit (refer to the details in the spares kit).
8 MAINTENANCE… 8.2.6 Fitting the Probe – Fig. 8.2 When the 8237 probe has been prepared for use in accordance with Section 8.2.5 above, proceed as follows: a) Hinge down the flowcell block cover to gain access to the block. Fit the assembled probe into the recess in the temperature– controlled block, ensuring that the probe sits at the bottom of the recess.
…8 MAINTENANCE 8.2.7 Peristaltic Pump – Fig. 8.3 It is recommended that the pump tubing and pump capstans, supplied in the Consumable Spares Kit, are replaced after one year of operation. Carry out the following procedure 1 to 8: Remove the pump platen by turning the catch mechanism to the vertical position and pulling the catch forward.
8 MAINTENANCE… 8.3 Shutdown Procedure In general, any problems are likely to be due to the probe, which 8.3.1 Short Term may require refurbishment (see Section 8.4.3), but may be due to The monitor can be left with the power switched off for up to 24 other parts of the liquid handling section of the monitor.
…8 MAINTENANCE b) Disassemble probe and reassemble – see Section 8.2.5. Ageing of the glass electrode After the probe has been in use for some months, the c) Check glass electrode – see Section 8.4.3. performance of the glass electrode may eventually deteriorate due to its continued use in weakly buffered solutions at near d) Check reference element –...
8 MAINTENANCE 8.5 Microprocessor Unit Error Messages d) Constant current supply, 2mA d.c. The instrument incorporates an automatic self-diagnostic checking facility for detection of input and output errors. If such a e) Silver wire (counter electrode). fault occurs, one of the error messages detailed below is shown on the dot matrix display.
APPENDIX A – REPLACING SOFTWARE EPROM A.2 Access the PCB – Fig. A.2 Warning. Switch off the monitor and electrically isolate it before carrying out the following steps. Unlock and open cover plate and hinge out to expose captive A.1 Access the Transmitter Unit – Fig. A.1 screws.
…APPENDIX A A.3 Removing the PCB – Fig. A.3 Remove the four screws attaching the PCB to the assembly. Note that there are washers between the PCB cover and the PCB. Withdraw the PCB and turn it over to reveal the component side. Locate and change the EPROM IC1 –...
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