INSTRUCTION MANUAL Detcon Model DM-200 DM-200 Toxic Gas Sensors DM-200 O 2 Deficiency Sensors Covers all ranges of electrochemical and O 2 deficiency sensors offered in the Detcon Product Line DETCON, Inc. 3200 Research Forest Dr., The Woodlands, Texas 77387 Ph.281.367.4100 / Fax 281.298.2868 0Hwww.detcon.com September 04, 2009 Document #3454 Revision 2.0
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Table of Contents 1. Introduction... 1 1.1 Description... 1 1.2 Sensor Technology... 1 1.3 Universal Transmitter Module (UTM)... 2 1.4 Intelligent Sensor Module (ISM)... 3 2. Installation... 4 2.1 Sensor Placement/Mounting... 4 2.2 Interference Data... 5 2.3 Field Wiring Table (4-20 ma output)... 6 2.4 Sensor Location... 6 2.5 Local Electrical Codes... 7 2.6 Installation Procedure... 7 2.7 Remote Mounting Applications... 8 2.8 Start Up... 9 2.9 Initial Operational Tests... 9 3. Operation... 10 3.1 Normal Operation... 10 3.2 Calibration Mode... 10 3.3 Program Mode... 10 3.4 Calibration - Toxics... 13 3.4.1 Calibration Procedure - Zero... 13 3.4.2 Calibration Procedure - Span... 13 3.4.3 Calibration Frequency... 16 3.5 Calibration Oxygen... 16 3.5.1 O 2 Calibration Procedure - Span... 16 3.5.2 O 2 Calibration Procedure - Zero... 18 3.6 Status of Programming and ISM Parameters... 18 3.6.1 View Program Status... 19 3.6.2 Set Date... 19 3.7 Program Features... 20 4. Service and Maintenance... 21 4.1 Exchanging the ISM... 21 4.1.1 Physical Exchange... 21 4.1.2 Establishing Communication... 21 4.1.3 Maintaining "Biased" ISM s using the Battery Back-up Module (Optional)... 21 4.2 Exchanging Electrochemical Sensors... 22 4.3 Display Contrast Adjust... 23 5. Trouble Shooting Guide... 24 6. Customer Support and Service Policy... 26 7. Warranty... 26 8. Spare Parts... 27 9. Specifications... 29 Appendix A... 31 Interference Table... 31 Appendix B... 38 Revision Log... 38 Appendix C... 39 Drawings and Diagrams... 39 Model DM-200 iii
Table of Figures Figure 1 UniTox Sensor assembly... 1 Figure 2 Sensor Cell Diagram... 2 Figure 3 Function Block diagram... 2 Figure 4 Universal Transmitter Module... 3 Figure 5 4-20 ma Field Wiring... 3 Figure 6 Intelligent Sensor Module... 4 Figure 7 Recommended Electrical Installation Method... 5 Figure 8 Sensor assembly orientation... 7 Figure 9 Universal Transmitter Module (Bottom view)... 8 Figure 10 Remote Mount Configuration... 8 Figure 11 Magnetic Programming Tool... 11 Figure 12 Software Flow Chart... 12 Figure 13 Auto Span Sequence - Toxics... 15 Figure 14 Auto Span Sequence - Oxygen... 17 Figure 15 UTM-ISM breakaway...error! Bookmark not defined. Figure 16 ISM Battery Backup Module... 22 Figure 17 Sensor Cell Replacement... 23 Figure 18 Spare parts Breakaway...Error! Bookmark not defined. Model DM-200 Shipping Address: 3200 A-1 Research Forest Dr., The Woodlands Texas 77381 Mailing Address: P.O. Box 8067, The Woodlands Texas 77387-8067 Phone: 888.367.4286, 281.367.4100 Fax: 281.292.2860 1Hwww.detcon.com iv
1. Introduction Model DM-200 1.1 Description Detcon UniTox Model 200 Series universal toxic sensors are non-intrusive Smart sensors designed to detect and monitor for toxic gases in the ppm range. The UniTox sensor family also includes ambient O 2 detection in the 0-25% range. UniTox sensors are designed to operate as standard two-wire 4-20 ma looppowered devices. Their intrinsically safe electronics design, when used with specified intrinsically safe field wire barriers, conforms to a Class 1, Division 1, Group A, B, C, D area classification. The Sensor Assembly includes a metal Nema 7 junction box and electropolished 316SS ISM assembly The UniTox gas sensor consists of two major components: 1) the Universal Transmitter Module (UTM) and 2) the gas/range specific Intelligent Sensor Module (ISM). The universality of the design allows any ISM type to be plugged into any UTM with seamless operation. The ISM consists of an electrochemical toxic gas sensor and associated PCB providing pre-amplifier, microprocessor, and memory storage functions. A 2-line 16-character alpha/numeric LCD is used to display sensor readings and provides the user interface with the sensor s menu driven features via a hand-held programming magnet. Typical ranges of detection are 0-1ppm, 0-10ppm, 0-25ppm, 0-50 ppm, and 0-100ppm. Other ranges are available and all ranges are covered by this manual. To determine model number, gas type, and range of detection, reference the labeling on the ISM or refer to the instructions found in Section 10 (View Program Status). Figure 1 UniTox Sensor assembly 1.2 Sensor Technology The sensors are electrolytic chemical cells. Each cell consists of three electrodes embedded in an electrolyte solution, housed beneath a diffusion membrane. Sensitivity to specific target gases is achieved by varying composition of any combination of the sensor components. Good specificity is achieved in each sensor type. The cells are diffusion limited via small capillary barriers resulting in long service life of up to 3 or more years. The oxygen cell is of the two-electrode, galvanic metal air battery type that functions as a direct current generator proportional to the amount of oxygen adsorption. DM-200 Instruction Manual Rev. 2.0 Page 1 of 40
Air Supply Difusion Barrier Difusion Barrier Electrolyte Solution Cathode Anode Sensing Electrode Reference Electrod Counter Electrode Electrolyte Reserv Construction of Galvanic O2 Cell Construction of Electrochemical Sensor Figure 2 Sensor Cell Diagram The Method of detection is by an electrochemical reaction at the surface of an electrode called the sensing electrode. Air and gas diffuse through the capillary diffusion barrier. The controlling circuit maintains a small external operating voltage between the sensing and counter electrodes of the proper bias and magnitude so that no current flows to or from the reference electrode while its potential is maintained at the correct fixed voltage usually ground. The electrochemical reaction creates a change in current flow from the counter electrode to the sensing electrode. This change in current is proportional to the gas concentration and is reversible. The quick response of the sensor results in continuous monitoring of ambient air conditions. Figure 3 Function Block diagram 1.3 Universal Transmitter Module (UTM) The UTM is microprocessor based, and is packaged as a field replaceable module mounted in an explosion proof enclosure. This facilitates easy replacement and minimum down time. Circuit functions include a PIC microprocessor, 2-line alphanumeric display, magnetic programming switches, and a linear 4-20 ma DC output. Field wiring is terminated on the bottom side of the UTM. The UTM also provides an easily accessible LCD contrast adjust pot and a protective input fuse (refer Figure 5 below). Calibration can be accomplished without removing the cover. The low power intrinsically safe electronics design provides for an area classification, which is Class 1; Division 1: Groups B, C, D. DM-200 Instruction Manual Rev. 2.0 Page 2 of 40
Figure 4 Universal Transmitter Module Figure 5 4-20 ma Field Wiring 1.4 Intelligent Sensor Module (ISM) The ISM is microprocessor-based and is packaged as a plug-in replaceable module that facilitates easy replacement and minimum downtime. The module is composed of sensor cell and ISM circuitry, permanently potted in epoxy, and retained within a plug-in stainless steel mechanical assembly. Circuit functions include an electrochemical sensor pre-amplifier, PIC microprocessor, and memory data storage. The ISM plugs into the UTM via 5 rigid gold plated pins and is then secured via a threaded machined collar that screws on and provides mechanical stability and a water-tight seal. DM-200 Instruction Manual Rev. 2.0 Page 3 of 40
Figure 6 Intelligent Sensor Module NOTE: The splashguard adapter is threaded and then secured to ISM housing using a setscrew. To replace sensor cell, remove setscrew from splashguard adapter, unscrew splashguard adapter from housing, replace sensor then re-secure splashguard adapter using setscrew. 2. Installation 2.1 Sensor Placement/Mounting Sensor location should be reviewed by facility engineering and safety personnel. Area leak sources and perimeter mounting are typically used to determine number and location of sensors. The sensors are generally located 2-4 feet above grade. Optimum performance of ambient air/gas sensor devices is directly related to proper location and installation practices. Refer Figure 7 for recommended electrical installation method NOTE: For Intrinsically Safe installation, reference drawing #2633 in Section Error! Reference source not found. Error! Reference source not found. NOTE: Intrinsically Safe barriers recommended for use include: MTL P/N 7706, P&F P/N Z706, and R.Stahl P/N 9001/51-280-091-14 DM-200 Instruction Manual Rev. 2.0 Page 4 of 40
Conduit "T" EYS Seal Fitting 3 4 " NPT Fitting Drain Recommended Electrical Installation Method 2.2 Interference Data Figure 7 Recommended Electrical Installation Method UniTox Model 200 series electrochemical sensors are subject to interference from other gases. This interaction is shown in the in the table in Table 4 Appendix A Interference Table as the relation between the amount of the interfering gas applied to the sensor, and the corresponding reading that will occur. All measurements are in ppm unless otherwise noted. The table is laid out with the Gas type of each UniTox sensor in a column on the left side of the page. The interfering gases are listed in a row across the top of the page. Each page lists all Model Numbers but 5 pages are necessary to list all interfering gases, thus each page is a repeat of the full line of Detcon UniTox sensors. Be sure to reference each page to ascertain the full listing of interfering gases for a particular UniTox sensor. In example: The first listing shows that the C2H30 Acetyldehyde sensor will have an interference reading of 340 ppm if 40 ppm of C2H2 (Acetylene) is applied. NOTE: Interference factors may differ from sensor to sensor and with lifetime. It is not DM-200 Instruction Manual Rev. 2.0 Page 5 of 40
advisable to calibrate with interference gases. They should be used only as a guide. 2.3 Field Wiring Table (4-20 ma output) Detcon UniTox toxic gas sensor assemblies require two-conductor connections between power supplies and host electronic controllers. Wiring designators are + (DC), and (DC). Maximum single conductor resistance between sensor and controller is 10 ohms. Maximum wire size for termination in the sensor assembly terminal board is 14 gauge. Table 1 Wire Gauge vs. Distance AWG Wire Dia. Meters Feet Over-Current Protection 22 0.723mm 700 2080 3A 20 0.812mm 1120 3350 5A 18 1.024mm 1750 5250 7A 16 1.291mm 2800 8400 10A 14 1.628mm 4480 13,440 20A NOTE: This wiring table is based on stranded tinned copper wire and is designed to serve as a reference only. NOTE: Shielded cable may be required in installations where cable trays or conduit runs include high voltage lines or other sources of induced interference. 2.4 Sensor Location Selection of sensor location is critical to the overall safe performance of the product. Five factors play an important role in selection of sensor locations: (1) Density of the gas to be detected (2) Most probable leak sources within the industrial process (3) Ventilation or prevailing wind conditions (4) Personnel exposure (5) Maintenance access Density - Placement of sensors relative to the density of the target gas is such that sensors for the detection of heavier than air gases should be located within 2-4 feet of grade as these heavy gases will tend to settle in low lying areas. For gases lighter than air, sensor placement should be 4-8 feet above grade in open areas or in pitched areas of enclosed spaces. Leak Sources - Most probable leak sources within an industrial process include flanges, valves, and tubing connections of the sealed type where seals may either fail or wear. Other leak sources are best determined by facility engineers with experience in similar processes. Ventilation - Normal ventilation or prevailing wind conditions can dictate efficient location of gas sensors in a manner where the migration of gas clouds is quickly detected. Personnel Exposure - The undetected migration of gas clouds should not be allowed to approach concentrated personnel areas such as control rooms, maintenance or warehouse buildings. A more general and applicable thought toward selecting sensor location is combining leak source and perimeter protection in the best possible configuration. DM-200 Instruction Manual Rev. 2.0 Page 6 of 40
Maintenance Access Consideration should be given to easy access by maintenance personnel as well as the consequences of close proximity to contaminants that may foul the sensor prematurely. NOTE: In all installations, the sensor element in SS housing points down relative to grade Figure 8. Improper sensor orientation may result in false reading and permanent sensor damage. Figure 8 Sensor assembly orientation 2.5 Local Electrical Codes Sensor and transmitter assemblies should be installed in accordance with all local electrical codes. Use appropriate conduit seals. Drains & breathers are recommended. 2.6 Installation Procedure a) Securely mount the sensor junction box in accordance with recommended practice. See dimensional drawing in Section Error! Reference source not found.. b) Unscrew the enclosure cover. Release the UTM assembly by removing and retaining two mounting screws and washers on the transmitter. Observing correct polarity, connect the loop power field wiring to the terminals labeled + and 4-20 ma (reference Figure 9). Reinstall transmitter and secure using screws and washers. Reinstall enclosure cover. DM-200 Instruction Manual Rev. 2.0 Page 7 of 40
Figure 9 Universal Transmitter Module (Bottom view) 2.7 Remote Mounting Applications Some sensor mounting applications require that the gas sensor head be remotely mounted away from the sensor transmitter. This is usually true in instances where the gas sensor head must be mounted in a location that is difficult to access. Such a location creates problems for maintenance and calibration activities. Detcon provides the UniTox Model Series 200 in a remote-mount configuration in which the sensor and the transmitter are provided in their own condulet housing and are interfaced together with a four conductor cable. The separation distance can be up to 75 feet. Refer Figure 10 for wiring diagram Figure 10 Remote Mount Configuration DM-200 Instruction Manual Rev. 2.0 Page 8 of 40
2.8 Start Up Model DM-200 Upon completion of all mechanical mounting and termination of all field wiring, apply system power and observe the following normal condition: A temporary upscale reading will occur as the sensor powers up. This upscale reading should clear to 0ppm within approximately 30 minutes of turn-on, assuming there is no gas in the area of the sensor. NOTE: If the display contrast needs adjustment, refer to Section 4.3 Display Contrast Adjust Zero Clearing with Biased Cells Some electrochemical sensors are biased with an excitation voltage. When power to the sensor is lost, this bias voltage slowly decays. When power is restored after long periods of time (multiple hours), a surge in sensor output takes place and a long and slow re-establishing of the sensor s zero baseline takes place. This re-stabilization time may range from 1 hour to 24 hours depending on the type of sensor and range of operation. The sensor types that this applies to are the following: HCl, NO, NH3 (DM-202-NH3), plus all the VOC sensors, C2H30, C2H2, C3H3N, C4H6, CS2, COS, C2H6S, C3H5OCL, C2H5OH, C2H4, C2H4O, CH2O, CH3OH, C4H4S, C4H6O2, C6H5CH3 and C2H3CL. If this characteristic is problematic for your specific application, a battery backup or uninterruptible power supply is recommended. 2.9 Initial Operational Tests After a warm up period has been allowed for, the sensor should be checked to verify sensitivity to its target gas. Material Requirements * Span gas containing the target gas in air or nitrogen. It is recommended that the target gas concentration be 50% of scale at a controlled flow rate of 500 ml/min. For example, a Model DM- 200-H2S UniTox sensor in the range 0-100ppm would require a test gas of 50ppm H2S. For a sensor with a range of 0-10ppm a test gas of 5ppm is recommended, etc. For oxygen, use test gas containing 100% nitrogen. a) Attach tubing to the center port connection of Splashguard. Apply the test gas at a controlled flow rate of 500ml/m. Observe that the LCD display increases to a level of 20% of range or higher. For oxygen, observe that the display decreases to a level of 3% or less. b) Remove the test gas and observe that the LCD display decreases to 0 PPM. For oxygen, observe that the LCD display increases back close to 20.9%. Initial operational tests are complete. Detcon toxic gas sensors are pre-calibrated prior to shipment and in most cases will not require significant adjustment on start up. However, it is recommended that a complete calibration test and adjustment be performed within 24 hours of installation. Refer to calibration instructions in later text. DM-200 Instruction Manual Rev. 2.0 Page 9 of 40
3. Operation Model DM-200 Operating software is menu listed with operator interface via the two magnetic program switches located under the enclosure cover. The two switches are referred to as PGM 1 and PGM 2. The menu list consists of 3 items which include sub-menus as indicated below. (Note: see section 8 for a complete software flow chart.) 01. Normal Operation a) Current Status 02. Calibration Mode a) Zero Cal b) Span Cal 03. Program Mode a) View Program Status b) Set Span Level c) Set Date 3.1 Normal Operation In normal operation, the display tracks the current status of the sensor and gas concentration and appears as: 0 PPM xxx (the xxx is the abbreviated gas type, i.e., 0 PPM H2S ) or for oxygen 20.9 % O2. The ma current output corresponds to the monitoring level of 0-100% of range = 4-20 ma. If applicable, the second line of the display will show current Fault conditions. 3.2 Calibration Mode Calibration mode allows for sensor zero and span adjustments. 1-Zero Cal, 2-Span Cal Zero Adjustment Zero is set in ambient air with no target gas present or with zero gas applied to the sensor. Auto Zero For oxygen, zero is performed with 100% nitrogen test gas applied. Span Adjustment Span adjustment is performed with a target gas concentration of 50% of range in balance of air or nitrogen. Span gas concentrations other than 50% of range may be used. Refer to section 3.3 for details. Auto Span For oxygen, span is set in normal ambient air or with test gas containing 20.9% O2 applied to the sensor. 3.3 Program Mode The program mode provides a program status menu (View Program Status) to check all operational parameters. It also allows for the adjustment of the auto span gas level setting and the current calendar date. View Program Status The view program status scrolls through a menu that displays the following information (the slash means the data shown is on line two of the display). The information shown is an example of a typical status display. 1. The sensor type. The menu item appears as: Sensor Type / CO 2. The sensor range of detection. The menu item appears as: Sensor Range / 0-100 PPM DM-200 Instruction Manual Rev. 2.0 Page 10 of 40
3. The ISM software version number. The menu item appears as: ISM Code Ver. / 1.10 Apr 2001 4. The UTM software version number. The menu item appears as: UTM Code Ver. / 1.10 Apr 2001 5. The time weighted average and peak data (last 8 hours). The menu item appears as: TWA: xx PPM / PK: xx PPM@ xx Min 6. The estimated remaining sensor life. The menu item appears as: Sensor Life / 100% 7. The calibration span gas level setting. The menu item appears as: Auto Span Level / 50 PPM 8. The date. The menu item appears as: Present Date/ 5/1/01 9. The last successful span date. The menu item appears as: Last Span Date / 5/1/01 10. The temperature. The menu item appears as: Present Temp / 23 C Set Span Level Adjustment The Span level is adjustable from 10% to 90% of range. The menu item appears as: Span Gas Value / xx PPM Set Date Adjustment Set the present date. The menu item appears as: Date / 05/01/01 Programming Magnet Operating Instructions Operator interface to UniTox gas detection products is via magnetic switches located behind the UTM enclosure cover. DO NOT remove the cover to calibrate or change programming parameters. Two switches labeled PGM 1 and PGM 2 allow for complete calibration and programming without removing the enclosure cover, thereby eliminating the need for area de-classification or the use of hot permits. Figure 11 Magnetic Programming Tool A magnetic programming tool (see figure 5) is used to operate the switches. Switch action is defined as momentary contact, 3 second hold, and 15 second hold. In momentary contact use, the programming magnet is waved over a switch location. In 3 second hold, the programming magnet is held in place over a switch location for 3 or more seconds. In 15 second hold, the programming magnet is held in place over a switch location for 15 seconds. Three (3) and fifteen (15) second holds are used to enter or exit calibration and program menus while momentary contact is used to make set-point adjustments. The location of PGM 1 and PGM 2 is shown in Figure 4 NOTE: If, after entering the calibration or program menus, there is no interaction with the menu items for more than 30 seconds, the sensor will return to its normal operating condition. DM-200 Instruction Manual Rev. 2.0 Page 11 of 40
Figure 12 Software Flow Chart DM-200 Instruction Manual Rev. 2.0 Page 12 of 40
3.4 Calibration - Toxics 3.4.1 Calibration Procedure - Zero NOTE: Before performing a zero calibration, be sure there is no background gas present or apply a zero gas standard for 1-2 minutes prior to performing zero calibration. a) Enter the calibration menu by holding the programming magnet stationary over PGM 1 (see Figure 4) for 3 seconds until the display reads 1-Zero Cal 2-Span Cal, and then withdraw the magnet. b) Next, enter the Zero Cal menu by holding the magnet stationary over PGM 1 for 3 seconds until the display reads: Auto Zero, then withdraw the magnet. The sensor has now entered the Auto Zero mode which lasts for 7 seconds. When it is complete the display will read Zero Complete for 2 seconds and then report the date of the last span as a reminder. Following that the display will read Return to Normal Operation for 3 seconds and then Auto Zero is complete. If applicable, remove gas. NOTE: If the circuitry is unable to adjust the zero to the proper setting, the sensor will enter a calibration fault mode which will cause the display to alternate between the sensor s current status reading and the calibration fault screen which appears as: Zero Cal Fault. NOTE: Upon entering the calibration menu, the 4-20 ma signal drops to 3.5 ma until the unit returns to normal operation. NOTE: When a Zero Cal Fault occurs, the sensor microprocessor retains its previous zero calibration reference. 3.4.2 Calibration Procedure - Span NOTE: It is best practice to do a Zero Cal just prior to a Span Cal. Material Requirements Detcon PN 327-000000-000 Programming Magnet Span gas containing the target gas in air or nitrogen. The target gas concentration is recommended at 50% of range (which is the factory default) at a controlled flow rate of 500 ml/min. Example: for a Model DM-200-H2S sensor with a range of 0-100 ppm, a test gas of 50 ppm is recommended. For a sensor with a range of 0-10ppm a test gas of 5 ppm is recommended, etc. Other concentrations can be used as long as they fall within 10% to 90% of range. See below for details. See section 3.6.1 if you do not know the sensor target gas or range of detection. CAUTION: Verification of the correct calibration gas level setting and calibration span gas concentration is required before span calibration. These two numbers must be equal before proceeding. Calibration consists of entering the calibration function and following the menu-displayed instructions. The display will ask for the application of span gas in a specific concentration. This concentration is equal to the span gas level setting. The factory setting for span gas concentration is typically 50% of range, but may be different depending on gas availability. For normal calibration, a span gas containing a concentration equal to 50% of range is required. If a span gas containing 50% of range is not available, other concentrations may be used as long as they fall within 10% to 90% of range. However, any alternate span gas concentration value must be programmed via the calibration gas level menu before proceeding with span calibration. Follow the instructions below for span calibration. DM-200 Instruction Manual Rev. 2.0 Page 13 of 40
a) Verify the current calibration gas level setting as indicated by the programming status menu. To do this, follow the instructions in Section 10 and make note of the setting found in listing number 7. The item appears as Auto Span Level / xx PPM. b) If the calibration gas level setting is equal to your calibration span gas concentration, proceed to item f. If not, adjust the calibration gas level setting so that it is equal to your calibration span gas concentration, as instructed in items c through e. c) Enter the programming menu by holding the programming magnet stationary over PGM 2 for 15 seconds until the display reads View Program Status, and then withdraw the magnet. At this point you can scroll through the programming menu by momentarily waving the programming magnet over PGM 1 or PGM 2. The menu options are: View Program Status, Set Span Level, and Set Date. d) From the programming menu scroll to the calibration level listing. The menu item appears as: Set Span Level. Enter the menu by holding the programming magnet stationary over PGM 1 for 3 seconds until the display reads Auto Span Level / ##PPM, then withdraw the magnet. Use the programming magnet to make an adjustment using PGM 1 to increase or PGM 2 to decrease the display reading until the reading is equal to the desired calibration span gas concentration. To accept/retain the newly entered value, hold the programming magnet over PGM1 for 3 seconds. NOTE: The newly entered span gas value is not saved to permanent memory until a span calibration is successfully executed with it. New span gas values that are not saved to permanent memory will be lost when power is lost. e) Exit back to normal operation by holding the programming magnet over PGM 2 for 3 seconds, or automatically return to normal operation in 30 seconds. f) From the calibration menu 1-Zero Cal 2-Span Cal (section 3.4.1) proceed into the span adjust function by holding the programming magnet stationary over PGM 2 for 3 seconds then withdraw the programming magnet. At this point the display will ask for the application of the target gas and concentration. The display reads Apply xxppm Span Gas. The xx here will indicate the concentration requested. DM-200 Instruction Manual Rev. 2.0 Page 14 of 40
Figure 13 Auto Span Sequence - Toxics g) Apply the calibration test gas at a flow rate of 500 milliliters per minute. When the sensor response exceeds 10% of the applied test gas, the display will change to Auto Span Test for a period of 2 minutes. If sensor response does not exceed 10% of applied gas after 1 minute, the menu 1-Abort Span / 2-Continue Span appears. This gives the user an opportunity to verify proper span gas delivery and concentration before continuing forward. If it is desirable to Abort Span and try again, then that choice may be exercised. At two minutes the message will change to Auto Span Adjust for an additional 30 seconds. During this period the sensor will analyze the signal for stability. The criterion for stability is signal drift within ±2% of full scale in 30 seconds. If met, the message changes to Auto Span Complete. If not met, up to 4 additional 30 second stability check periods are administered. If all 5 stability checks fail, then the unit returns to Normal Operations with the original Auto Span parameter intact. An alternating message of Span Calibration Fault is displayed to remind the user that a re-calibration is still necessary. With Auto Span Complete achieved, the display now reports the remaining Sensor Life xx%, then the New Span Date, and then Remove Span Gas / xx PPM which prompts the user to remove the span gas from the sensor. During Remove Span Gas / xx PPM, the sensor recovers toward zero, and when the signal level falls below 10% of full scale the display changes to Return to Normal Operation. Additional Notes 1. Upon entering the calibration menu, the 4-20 ma signal drops to 3.5 ma and is held at this level until the unit returns to normal operation. DM-200 Instruction Manual Rev. 2.0 Page 15 of 40
2. If during calibration the sensor circuitry is unable to attain the proper adjustment for span, the sensor will enter into the Span Calibration Fault mode which will cause the display to alternate between the sensor s current status reading and the calibration fault screen which appears as: Span Cal Fault. If this occurs you may attempt to recalibrate by entering the calibration menu as described in section 3.4.1. If the sensor fails again, defer to technical trouble shooting. NOTE: The newly entered span gas value is not saved to permanent memory until a span calibration is successfully executed with it. New span gas values that are not saved to permanent memory will be lost when power is lost. 3.4.3 Calibration Frequency In most applications, monthly to quarterly calibration intervals will assure reliable detection. However, industrial environments differ. Upon initial installation and commissioning, close frequency tests should be performed, weekly to monthly. Test results should be recorded and reviewed to determine a suitable calibration interval. 3.5 Calibration Oxygen 3.5.1 O 2 Calibration Procedure - Span Material Requirements: Detcon PN 327-000000-000 Programming Magnet 0-25% O2 Range: Span gas containing 20.9% O2 in nitrogen at a controlled flow rate of 500 ml/min. Ambient air (no calibration adapter) may be used directly as long as it is absolutely known that 20.9% O2 level exists at the time of calibration. Other Ranges: Span gas at 50% of range. CAUTION: Verification of the correct calibration gas level setting and calibration span gas concentration is required before span calibration. These two numbers must be equal before proceeding. Calibration consists of entering the calibration function and following the menu-displayed instructions. The display will ask for the application of span gas in a specific concentration. This concentration is equal to the span gas level setting. The factory default setting for span gas concentration is typically 50% of range but for the 0-25% O2 range it is set to 20.9%. If a span gas containing 50% of range is not available, other concentrations may be used as long as they fall within 10% to 90% of range. However, any alternate span gas concentration value must be programmed via the calibration gas level menu before proceeding with span calibration. Follow the instructions below for span calibration. a) Verify the current calibration gas level setting as indicated by the programming status menu. Refer Section 3.6.1 and make note of the setting found in item number 7. The item appears as Auto Span Level / xx PPM/%. b) If the calibration gas level setting is equal to your calibration span gas concentration, proceed to item f. If not, adjust the calibration gas level setting so that it is equal to your calibration span gas concentration, as instructed in items c through e. c) Enter the programming menu by holding the programming magnet stationary over PGM 2 for 15 seconds until the display reads View Program Status, and then withdraw the magnet. At this point you can scroll through the programming menu by momentarily waving the programming magnet over PGM 1 or PGM 2. The menu options are: View Program Status, Set Span Level, and Set Date. DM-200 Instruction Manual Rev. 2.0 Page 16 of 40
d) From the programming menu scroll to the calibration level listing. The menu item appears as: Set Span Level. Enter the menu by holding the programming magnet stationary over PGM 1 for 3 seconds until the display reads Auto Span Level / ##PPM/%, then withdraw the magnet. Use the programming magnet to make an adjustment using PGM 1 to increase or PGM 2 to decrease the display reading until the reading is equal to the desired calibration span gas concentration. To accept/retain the newly entered value, hold the programming magnet over PGM1 for 3 seconds. e) Exit back to normal operation by holding the programming magnet over PGM 2 for 3 seconds, or automatically return to normal operation in 30 seconds. Figure 14 Auto Span Sequence - Oxygen f) From the calibration menu 1-Zero Cal 2-Span Cal (section 3.4.1) proceed into the span adjust function by holding the programming magnet stationary over PGM 2 for 3 seconds then withdraw the programming magnet. At this point the display will ask for the application of the target gas and concentration. The display reads Apply xxppm/% Span Gas. The xx here will indicate the concentration requested. g) Apply the calibration test gas at a flow rate of 200 milliliters per minute. When the sensor response exceeds 10% of the applied test gas, the display will change to Auto Span Test for a period of 2 minutes. If sensor response does not exceed 10% of applied gas after 1 minute, the menu 1-Abort Span / 2-Continue Span appears. This gives the user an opportunity to verify proper span gas delivery and concentration before continuing forward. If it is desirable to Abort Span and try again, then that choice may be exercised. DM-200 Instruction Manual Rev. 2.0 Page 17 of 40
At two minutes the message will change to Auto Span Adjust for an additional 30 seconds. During this period the sensor will analyze the signal for stability. The criteria for stability is signal drift within ±2% of full scale in 30 seconds. If met, the message changes to Auto Span Complete. If not met, up to 4 additional 30 second stability check periods are administered. If all 5 stability checks fail, then the unit returns to Normal Operations with the original Auto Span parameter intact. An alternating message of Span Calibration Fault is displayed to remind the user that a re-calibration is still necessary. With Auto Span Complete achieved, the display now reports the remaining Sensor Life xx%, then the New Span Date, and then Remove Span Gas / xx PPM/% which prompts the user to remove the span gas from the sensor. This is not necessary for the 0-25% O2 range if spanning at 20.9% level. During Remove Span Gas / xx PPM/%, the sensor recovers toward zero, and when the signal level falls below 10% of full scale the display changes to Return to Normal Operation. 3.5.2 O 2 Calibration Procedure - Zero Material Requirements Detcon PN 327-000000-000 Programming Magnet Oxygen free gas standard such as 100% N 2 Detcon PN 943-000000-000 Wind Guard for Splashguard a) Apply an oxygen free gas standard for 2 minutes using the splashguard calibration port with wind guard in place. b) Enter the calibration menu by holding the programming magnet stationary over PGM 1 (refer Figure 4 ) for 3 seconds until the display reads 1-Zero Cal 2-Span Cal, and then withdraw the magnet. c) Enter the Zero Cal menu by holding the magnet stationary over PGM 1 for 3 seconds until the display reads: Auto Zero, then withdraw the magnet. The sensor has now entered the Auto Zero mode which lasts for 7 seconds. When it is complete the display will read Zero Complete for 2 seconds and then report the date of the last span as a reminder. Following that the display will read Return to Normal Operation for 3 seconds and then Auto Zero is complete. Remove the test gas. NOTE 1: If the circuitry is unable to adjust the zero to the proper setting, the sensor will enter a calibration fault mode which will cause the display to alternate between the sensor s current status reading and the calibration fault screen which appears as: Zero Cal Fault. NOTE 2: Upon entering the calibration menu, the 4-20 ma signal drops to 3.5 ma until the unit returns to normal operation NOTE 3: When a Zero Cal Fault occurs, the sensor microprocessor retains its previous zero calibration reference. 3.6 Status of Programming and ISM Parameters The programming menu has a View Program Status listing that allows the operator to view the sensor type, range, software version numbers, time weighted average (TWA) and peak reading in last 8 hours, remaining sensor life, auto span level, present date, last span date, and present temperature. The programming menu also allows the changing of the span gas level setting (see section 9.2), and calendar date. DM-200 Instruction Manual Rev. 2.0 Page 18 of 40
3.6.1 View Program Status The following procedure is used to view the programming status of the sensor: b) Enter the programming menu by holding the programming magnet stationary over PGM 2 for 15 seconds until the display reads VIEW PROG STATUS, and then withdraw the magnet. At this point you can scroll through the programming menu by momentarily waving the programming magnet over PGM 1 or PGM 2. The menu options are: View Program Status, Set Span Level, and Set Date. c) Scroll to the VIEW PROG STATUS listing and then hold the programming magnet over PGM 1 for 3 seconds. The menu will then automatically scroll, at 3 second intervals, through the following information before returning back to the VIEW PROG STATUS listing. 1. The sensor type. The menu item appears as: Sensor Type / CO 2. The sensor range of detection. The menu item appears as: Sensor Range / 0-100 PPM 3. The ISM software version number. The menu item appears as: ISM Code Ver. / 1.10 Apr 2001 4. The UTM software version number. The menu item appears as: UTM Code Ver. / 1.10 Apr 2001 5. The time weighted average and peak. The menu item appears as: TWA: xx PPM / PK: xx PPM@ xx Min 6. The estimated remaining sensor life. The menu item appears as: Sensor Life / 100% 7. The calibration span gas level setting. The menu item appears as: Auto Span Level / 50 PPM 8. The date. The menu item appears as: Present Date/ 5/1/01 9. The last successful span date. The menu item appears as: Last Span Date / 5/1/01 10. The temperature. The menu item appears as: Present Temp / 23 C d) Exit back to normal operations by holding the programming magnet over PGM 2 for 3 seconds, or automatically return to normal operation in 30 seconds. 3.6.2 Set Date The following procedure is used to set the present calendar date: a) Enter the programming menu by holding the programming magnet stationary over PGM 2 for 15 seconds until the display reads View Program Status, and then withdraw the magnet. At this point you can scroll through the programming menu by momentarily waving the programming magnet over PGM 1 or PGM 2. The menu options are: View Program Status, Set Span Level, and Set Date. b) From the programming menu scroll to the Set Date listing. Enter the menu by holding the programming magnet stationary over PGM 1 for 3 seconds until the display reads Set Date / xx/xx/xx, and then withdraw the magnet. The first set of numbers (month) will flash on and off indicating they are ready for adjustment. Use the programming magnet to make an adjustment to PGM 1 to increase or PGM 2 to decrease the display reading until the reading is equal to the desired month. c) Next, advance to the second set of numbers (the day) by holding the programming magnet stationary over PGM 1 for 3 seconds until the month set flashes on and off indicating they are ready for adjustment. Use the programming magnet to make an adjustment to PGM 1 to increase or PGM 2 to decrease the display reading until the reading is equal to the desired day. d) Next, advance to the third set of numbers (the year) by holding the programming magnet stationary over PGM 1 for 3 seconds until the year set flashes on and off indicating they are ready for DM-200 Instruction Manual Rev. 2.0 Page 19 of 40
adjustment. Use the programming magnet to make an adjustment to PGM 1 to increase or PGM 2 to decrease the display reading until the reading is equal to the desired year. To retain the newly entered value, hold the programming magnet over PGM1 for 3 seconds. e) Exit back to normal operation by holding the programming magnet over PGM 2 for 3 seconds, or automatically return to normal operation in 30 seconds. 3.7 Program Features Detcon UniTox toxic gas sensors incorporate a comprehensive program to accommodate easy operator interface and fail-safe operation. Program features are detailed in this section. Each sensor is factory tested, programmed, and calibrated prior to shipment. Sensor Life The sensor life feature is a reference based on signal output from the sensor cell. When a sensor life of 25% or less remains the sensor cell should be replaced within a reasonable maintenance schedule. Data Logging The data logging feature records the most recent 8 hours of data: time-weighted average (TWA) and peak (PK) reading. The menu item appears as TWA: xx PPM / PK: xx PPM@ xx Min. TWA is a rolling 8 hour average updated at 30 minute intervals. The peak (PK) reading is the instantaneous peak reading recorded in the last 8 hours and the @ xx Min represents the number of minutes ago that the peak reading took place. For example: PK: 33 PPM@ 360 Min explains that a peak reading of 33 ppm took place 6 hours (360 minutes) ago. NOTE: For oxygen sensing, the Peak (PK) reading is the lowest reading recorded in the last 8 hours Over Range When the sensor detects gas greater than 100% of range, it will display the highest reading of its range and an output of 20 ma. Under Range Fault If the sensor should drift below a zero baseline of 10% of range, the display will indicate a fault: Sensor Fault and report an output of 3.5 ma. This is typically fixed by performing another zero cal. Span Calibration Fault If during calibration the sensor circuitry is unable to attain the proper adjustment for span, the sensor will enter into the span calibration fault mode and cause the display to alternate between the sensor s normal operation reading and the calibration fault screen which appears as: Span Cal Fault. The previous calibration settings will remain saved in memory. Zero Calibration Fault If during calibration the sensor circuitry is unable to attain the proper adjustment for zero, the sensor will enter into zero calibration mode and cause the display to alternate between the sensor s normal operation reading and the calibration fault screen which appears as: Zero Cal Fault. The previous calibration settings will remain saved in memory. DM-200 Instruction Manual Rev. 2.0 Page 20 of 40
Missing Sensor If the ISM is missing or not connected properly, the UTM will report Missing Sensor and an output of 1.0 ma will be set. Memory Fault If new data points cannot successfully be retrieved from memory the display will indicate: Memory Fault. Comm Error If the ISM and UTM are not communicating properly, then the UTM will report Comm Error. 4. Service and Maintenance 4.1 Exchanging the ISM A key feature of the UniTox product is its complete universality (exchangeability) between any combination of ISM and UTM. The ISM carries all necessary identification and parameter data stored in permanent memory, which allows for any ISM to instantly begin seamless operation with any UTM. 4.1.1 Physical Exchange In order to remove an ISM, the user should twist the retaining collar in a counter clockwise direction. When the threads are cleared, the ISM should be pulled straight out. To reinstall the ISM, first view the mating gold pin pattern until proper alignment is achieved. Then press in the ISM until mechanical surfaces touch. Finally, move the retaining collar up and thread clockwise until snug. NOTE: Remember to twist the retaining collar tight after successful ISM/UTM communication is established. The collar should tighten snugly up to the mating surface in order to create a water tight seal. Never grab the ISM main housing and attempt to twist. This may damage the gold pin connections. 4.1.2 Establishing Communication The UTM will display "Missing Sensor" during time when the ISM is not connected. When an ISM is disconnected from a UTM, the end-user must wait approximately 7 seconds before another ISM can be plugged into the UTM. This 7 second period is the time required by the UTM to reach the "ready-to-receive" state. After plugging an ISM into the UTM, within 1-3 seconds the ISM identification/parameter information will be displayed and at the conclusion of the data string a "Returning to Normal Operation" message will be shown. If for some reason the ISM identification/parameter information does not come up after 10 seconds, then unplug the ISM and repeat the process again after 10 seconds. 4.1.3 Maintaining "Biased" ISM s using the Battery Back-up Module (Optional) When and How to Use Some electrochemical sensors are biased with an excitation voltage. When power to the ISM is lost, this bias voltage slowly decays. When power is restored after long periods (multiple hours) of being un-powered, a surge in sensor output takes place and a long and slow re-establishing of the sensor s zero baseline takes place. This re-stabilization time may range from 1 hour to 24 hours depending on the type of sensor and range of operation. The sensor types that this applies to are the following: HCl, NO, plus all the VOC sensors, C2H30, DM-200 Instruction Manual Rev. 2.0 Page 21 of 40
C2H2, C3H3N, C4H6, CS2, COS, C2H6S, C3H5OCL, C2H5OH, C2H4, C2H4O, CH2O, CH3OH, C4H4S, C4H6O2, C6H5CH3 and C2H3CL. The Battery Back-up Module (Optional) has been designed to eliminate re-stabilization down-time by keeping the ISM completely powered and in a 100% ready state. The Battery Back-up module has a service life of 1.5 years in continuous use. It is recommended that the "biased" ISM types remain connected to the Battery Back-up Module when not in use for long periods of time. While transporting a calibrated ISM from the office to the field, it is recommended to use the Battery Back-up Module to eliminate re-stabilization time. However, for short durations of 5-10 minutes or less in the un-powered state, it is not necessary to use the Battery Back-up Module. NOTE: The Battery Back-up Module can be used to warm-up a "biased" ISM that has been un-powered. Plugging the ISM into the Battery Back-up Module for 24 hours prior to calibration is recommended. The ISM plugs into the Battery Back-up Module in the same way it plugs into the UTM. The gold pin pattern is aligned, pressed together, and the retaining collar is tightened. Reverse instructions to remove. Figure 15 ISM Battery Backup Module 4.2 Exchanging Electrochemical Sensors If an electrochemical sensor exchange is necessary, due to poor sensor performance (See Trouble Shooting Guide for details). The following procedure should be used. Remove the ISM from UTM per Section 4.1 Loosen the locking setscrew in splashguard adapter. While firmly holding the center of the ISM main housing, twist the sensor splashguard adapter counter-clockwise to remove. It may be secured very tight, so some firm twisting will be required. Once removed the electrochemical sensor is exposed. To remove it, grab the electrochemical sensor body and pull straight out. Take your replacement electrochemical sensor and carefully verify that it is identical in gas type and part number. This information is listed on the label of the electrochemical sensor. You may refer to Table 3 to verify the correct part number of replacement electrochemical sensors. DM-200 Instruction Manual Rev. 2.0 Page 22 of 40
NOTE: This is critical because each ISM is pre-set to accept a specific electrochemical sensor. Take your replacement sensor and observe the gold pin mating pattern. Once aligned, press the sensor into the sockets and replace the sensor rain cover with a firm twist to create the water tight seal. NOTE: If the sensor splashguard adapter cannot be removed, it maybe locked down by the setscrew or may have been intentionally, permanently bonded in place. In this case, the entire ISM must be replaced. Intelligent Sensor Housing (With support Electronics) Intelligent Sensor Module (ISM) Electrochemical cell Grasp and pull down to remove Splashguard adapter Twist counter-clockwise to remove Figure 16 Sensor Cell Replacement 4.3 Display Contrast Adjust Detcon UniTox sensors feature a 2-line, 16-character liquid crystal display. Like most LCDs, character contrast can be affected by viewing angle and temperature. Temperature compensation circuitry included in the UniTox design will compensate for this characteristic; however temperature or operating voltage extremes may still cause a shift in the contrast. Display contrast can be adjusted by the user if necessary. To adjust the display contrast, remove the enclosure cover, remove transmitter, and use a small screwdriver to turn the blue contrast potentiometer adjust screw located on the side of the UTM circuit board (refer Figure 5). Adjust per preference. The adjustment location is marked CONTRAST. Secure transmitter in condulet. Replace enclosure cover. DM-200 Instruction Manual Rev. 2.0 Page 23 of 40
5. Trouble Shooting Guide Model DM-200 "Missing Sensor" Message Probable Cause: ISM not being registered by UTM. 1. Reinstall ISM after waiting 10 seconds. 2. Re-power UniTox sensor. Upscale reading (for > 30 minutes) after ISM connection Probable Cause: Biased ISM type re-stabilizing. 1. Wait 8 hours minimum. 2. Use Battery Back-up Module to prevent this condition. "Comm Error" Message Probable Causes: Faulty wiring/connection, UTM or ISM microprocessor failure. 1. Re-Install ISM. 2. Swap ISM and UTM with another functional pair to determine if ISM or UTM is the problem. No LCD or 4-20 ma signal activity with power applied Probable Causes: Blown input fuse, Insufficient Operating Voltage, Mis-wired connection. 1. Check/Replace Fuse. 2. Check for correct polarity and verify Operating voltage at the UTM input terminals. 3. Check status of external field wire I.S. Barrier. 4. Replace UTM with functional UTM. Noise Spikes or Oscillation on the 4~20mA signal 1. Contact Detcon to report incidence. 2. Install 150µF capacitor across the terminating load resistor at the controller (i.e. install between DC common and ma input). LCD not Easily Readable 1. Adjust contrast pot (see section 14). Erratic Sensor Behavior False/Fault Alarms Probable Causes: Wet/Intermittent terminals, RFI Interference, Bad Electrochemical Sensor, Target or Crossinterfering Gases being detected. 1. Check that ISM collar and splashguard adapter are firmly seated and terminals are not wet. 2. RFI- Use shielded cabling. 3. Re-calibrate sensor and make sure it calibrates successfully and Sensor Life is acceptable. 4. Make sure alarms are not being caused by real gas clouds or cross-interfering gases. "Span Cal Fault" Message DM-200 Instruction Manual Rev. 2.0 Page 24 of 40