detcon inc. Detcon MicroSafe™ FP-624C Combustible Gas Sensor (0-100% LEL) Operator’s Installation & Instruction Manual May 18, 2010 • Document #2246 • Revision 7.1 CAUTION: Before operating the Model FP-624C sensor, read this manual thoroughly and verify that the configuration of default factory settings are appropriate and correct for your application. The settings include: Target gas and calibration gas (section 3.7), relay contact outputs (section 3.5.5d), alarm settings (section 3.5.5e and 3.
Table of Contents 3.0 Description 3.1 Principle of Operation 3.2 Application 3.3 Specifications 3.4 Operating Software 3.5 Installation 3.6 Start-up 3.7 Target Gas and Calibration Gas Selection 3.8 Calibration 3.9 Status of Programming, Alarms, Calibration Level, RS-485 ID, and Sensor Life 3.10 Programming Alarms 3.11 Program Features 3.12 RS-485 Protocol 3.13 Display Contrast Adjust 3.14 Trouble Shooting Guide 3.15 Spare Parts List 3.16 Warranty 3.17 Service Policy 3.
.0 DESCRIPTION Detcon MicroSafe™ Model FP-624C, combustible gas sensors are non-intrusive “Smart” sensors designed to detect and monitor combustible gas in air over the range of 0-100% lower explosive limit (LEL). One of the primary features of the sensor is its method of automatic calibration which guides the user through each step via instructions displayed on the backlit LCD. The sensor features field adjustable, fully programmable alarms and provides relays for two alarms plus fault as standard.
Program Switch #1 Plug-in Microprocessor Control Circuit CONTRAST PGM Display Contrast Adjust MODEL 1 detcon inc.
Compensator/Reference Zero Set 2.2V Detector/Active Output 3.1.2 Characteristics The detector elements maintain good sensitivity to combustible gases in air in the lower explosive limit range, as shown in the response curve illustration below. However, for gas concentrations above the LEL range, the bridge output decreases. Ambiguous readings above LEL range conditions dictate that alarm circuitry be of the latching type wherein alarms are held in the “on” position until reset by operations personnel.
3.2.2 Response to Different Gases An attractive feature of the catalytic detector elements is their almost universal response to lower explosive limits of hydrocarbons. Most detectable gases produce a similar output, however the signal amplitudes differ. The table in section 3.7 lists theoretical factors (K factors) for different gases which are a measure of their signal amplitude as compared to methane which has a K factor of 1.00.
c) Alarm 2 Level d) Target gas selection (gas K factor) e) Calibration gas selection (cal K factor) f) Calibration Level g) Set Bridge Volts 3.4.1 Normal Operation In normal operation, the display tracks the current status of the sensor and gas concentration and appears as: “0 % LEL”. The mA current output corresponds to the monitoring level and range of 0-100% = 4-20 mA. 3.4.2 Calibration Mode Calibration mode allows for sensor zero and span adjustments. “1-ZERO 2-SPAN” 3.4.2.
3.4.3.6 Calibration Level Adjustment The Calibration level is adjustable from 10% to 90% LEL. The menu item appears as: “CalLevel @ ##%” 3.4.3.7 Set Bridge Volts For applications where the sensor is remotely mounted away from the sensor transmitter, the detector bridge voltage is adjustable to compensate for differing wire resistances. The menu item appears as: “SET BRIDGE VOLTS” 3.
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.
d)Position gold plated jumper tabs located on the connector board in accordance with desired Form C dry contact outputs: NO = Normally Open; NC = Normally closed (see figure 3).
Control Circuit - Side View Preamp Board - Side View RS-485 ID Set Dip Switches 3456 SW2 7 8 9A 7 8 9A Preamp Board BCDE F012 3456 BCDE F012 SW1 Figure #5 f) If applicable, set the RS-485 ID number via the two rotary dip switches located on the preamp board (see figure 5). There are 256 different ID numbers available which are based on the hexidecimal numbering system. If RS485 communications are used, each sensor must have its own unique ID number.
3.5.6 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.
3.6.1 Remote Mount Bridge Voltage Setup If the sensor has been installed using the remote mounting configuration as described in section 3.5.6, the sensor bridge voltage must be adjusted after initial power up. If this is not the case skip this section and proceed to Initial Operational Tests. Otherwise follow the steps below to set the sensor bridge voltage. Material Requirements * Detcon PN 3270 MicroSafe™ Programming Magnet * Digital volt/ohm meter. 3.6.
h) 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. i) Replace the junction box cover on the remote sensor enclosure. Bridge voltage set is complete. This procedure need only be done once after initial power up. 3.6.3 Initial Operational Tests After a warm up period has been allowed for, the sensor should be checked to verify sensitivity to combustible gas.
TABLE 1a (alphabetical listing) Gas Acetaldehyde Acetic Acid Acetic Anhydride Acetone Acetylene Alkyl Alcohol Ammonia n-Amyl Alcohol Aniline Benzene Biphenyl 1,3-Butadiene Butane iso-Butane Butene-1 cis-Butene-2 trans-Butene-2 n-Butyl Alcohol iso-Butyl Alcohol tert-Buty-alcohol n-Butyl Benzene iso-Butyl Benzene n-Butyric Acid Carbon Disulphide Carbon Monoxide Carbon Oxysulphide Cyanogen Cyclohexane Cyclopropane K 1.66 1.84 2.17 1.93 1.76 1.96 0.79 3.06 2.54 2.45 4.00 1.79 1.71 1.93 2.20 2.06 1.97 2.91 1.
a) First, enter the programming menu by holding the programming magnet stationary over “PGM 2” for 30 seconds until the display reads “VIEW PROG STATUS”, 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 Alarm 1 Level, and Set Alarm 2 Level, Set Gas Factor (target gas), Set Cal Factor (calibration gas).
a) First, enter the programming menu by holding the programming magnet stationary over “PGM 2” for 30 seconds until the display reads “VIEW PROG STATUS”, then withdraw the magnet. b) Next, scroll to the “SET CAL FACTOR” listing and then hold the programming magnet over “PGM 1” for 3 seconds. The menu item appears as “CAL FACTOR #.##”. 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 K factor.
a) Verify the current calibration gas level setting as indicated by the programming status menu. To do this, follow the instructions in section 3.9 and make note of the setting found in listing number 14. The item appears as “CalLevel @ xx%”. 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”.
3.9 STATUS OF PROGRAMMING, ALARMS, TARGET GAS, CALIBRATION GAS, CALIBRATION LEVEL, RS-485 ID, AND SENSOR LIFE The programming menu has a programming status listing that allows the operator to view the gas, range, and software version number of the program, as well as the current alarm settings, target and calibration gas settings, calibration gas level setting, RS-485 ID number, and estimated remaining sensor life.
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 alarm set point. Exit to the programming menu by holding the programming magnet over “PGM1” for 3 seconds, or automatically return to the programming menu in 30 seconds. c) ALARM 2 LEVEL From the programming menu scroll to the alarm 2 level listing. The menu item appears as: “SET ALARM 2 LEVEL”.
Fail-Safe/Fault Supervision Model FP-624C MicroSafe™ sensors are programmed for fail-safe operation. Any of the following fault condition will activate the fault relay, illuminate the fault LED, and cause the display to read its corresponding fault condition: “SENSOR FAULT”, “SIGNAL FAULT”, “HEATER FAULT”, or “CAL FAULT”. A “Sensor Fault”, “Signal Fault”, and “Heater Fault”, will also cause the mA output to drop to zero (0) mA.
This is the trip point for the first alarm. Register # 40004 High Byte Low Byte Alarm 2 Setpoint This is the trip point for the second alarm.
Reg40002 Data Lo Reg40003 Data Hi Reg40003 Data Lo Reg40004 Data Hi Reg40004 Data Lo Reg40005 Data Hi Reg40005 Data Lo CRC CRC 07 00 0A 00 14 05 50 ## ## 7 0 10 0 20 5 80 0000 0111 0000 0000 0000 1010 0000 0000 0001 0100 0000 0101 0101 0000 #### #### #### #### Additional Notes: The calibration LED will light when the transmitter is sending a response to a Master Query. Communications are 9600 baud, 8 data bits, 1 stop bit, No parity, half duplex 485. 3.
Excessive Span Drift or Slow Response 1. Check Heater Voltage Setting (should be 2.7V C-Style and 2.2V J-Style) and check heater voltage at the sensor if remote mounted. 2. Verify correct cal gas flow rate and proper use of the cal gas adapter. 3. Check validity of cal gas via the expiration date and use pull tube if necessary. 4. Check for obstructions through stainless steel sinter element (including being wet) 5. Replace plug-in sensor if Sensor Life is < 50%. 6.
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