Before operating the Model FP-524C sensor, read this manual thoroughly and verify that the
configuration of default factory settings are appropriate and correct for your application.
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, Calibration Level, Bridge Voltage, and Sensor Life
3.10 Program Features
3.11 Display Contrast Adjust
3.12 Trouble Shooting Guide
3.13 Spare Parts List
3.14 Warranty
3.15 Service Policy
3.16 Software Flow Chart
Model FP-524C Combustible Gas Sensor PG.2
3.0 DESCRIPTION
Alumina Bead
Platinum Wire
Catalyst
Construction of
Detector Bead
Sintered Stainless Steel Can
Header
Gold Plated Pins
Beads
Detcon MicroSafe™ Model FP-524C, 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 output is a standard 4-20 mA signal. The microprocessor supervised electronics are packaged as a plug-in module that mates to a standard connector board. Both are housed in an explosion proof condulet that includes a glass lens. A 16 character alpha/numeric indicator is used to display sensor readings as well as the sensor’s menu driven features via a hand-held programming magnet.
The sensor technology is of the catalytic pellistor type. Catalytic pellistors show a good response to a long list
of combustible gases. Refer to section 3.7.1 for a partial list of detectable gases. The technique is referred to as nonselective and may be used for the detection and monitoring of target combustible gases. Model FP-524C sensors are
specifically designed to be resistive to poisons such as sulfides, chlorides and silicone. The sensors are characteristically stable and capable of providing reliable performance for periods exceeding 5 years in most industrial environments.
3.0.1 Catalytic Detector
The catalytic detector is supplied as a matched pair of elements mounted in a plug-in replaceable housing. One element is an active catalytic detector and the other is a non-active compensating element. Each element consists of a
fine platinum wire embedded in a porous bead. A catalytic mixture is applied to the detecting element while the compensating element is treated so that catalytic oxidation of gas does not occur. The beads are mounted in a plug-in
module that is enclosed by a sintered porous stainless steel flame arrestor. The plug-in sensor features gold plated
pins and mounts inside a stainless steel sensor housing via a mating gold plated socket.
Model FP-524C Combustible Gas Sensor PG.3
3.0.2 Microprocessor Control Circuit
WHT
BLK
YEL
BLU
mA
VDC Power In
4-20 mA Output
Sensor
Base Connector Board
detcon inc.
Program Switch #2
FLTCAL
MicroSafe™ LEL Gas Sensor
H
OUST ON, T EXA S
P
GM 2
PGM 1
MODELFP-524C
CONTRAST
Fault & Cal LEDs
Program Switch #1
Menu Driven Display
Plug-in Microprocessor Control Circuit
Display Contrast Adjust
The control circuit is microprocessor based and is packaged as a plug-in field replaceable module, facilitating easy
replacement and minimum down time. Circuit functions include a basic sensor pre-amplifier, sensor temperature
control, on-board power supplies, microprocessor, back lit alpha numeric display, magnetic programming switches,
and a linear 4-20 mA DC output.
3.0.3 Base Connector Board
The base connector board is mounted in the explosion proof enclosure and includes: the mating connector for the
control circuit, reverse input and secondary transient suppression, input filter, and lugless terminals for field wiring.
3.0.4 Explosion Proof Enclosure
The sensors are packaged in a cast metal explosion proof enclosure. The enclosure is fitted with a threaded cover
that has a glass lens window. Magnetic program switches located behind the transmitter module face plate are activated through the lens window via a hand-held magnetic programming tool allowing non-intrusive operator interface with the sensor. Calibration can be accomplished without removing the cover or declassifying the area.
Electrical classification is Class I; Groups B, C, D; Division 1.
Model FP-524C Combustible Gas Sensor PG.4
3.1 PRINCIPLE OF OPERATION
% Methane in Air Concentration
0
20
40
60
80
100
020406080
Bridge Output %
0
4
8
12
16
20
20406080100
% LEL (lower explosive limit)
mA DC Signal Output
Response Curve
2.7V
Z
ero
Set
Output
Detector/Active
Compensator/Reference
Functional
Block
Diagram
4-20 mA Out
Power In
Pre-AmpDisplay
4-20mA
Micro-
processor
Tran smit ter
Power Supply
Sensor
Element
I/O Circuit
Protection
Method of detection is by a controlled rate of diffusion/adsorption. Air and gas diffuse through a sintered stainless
steel filter and contact both the active and reference detector beads. The surface of the active detector promotes
oxidation of the combustible gas molecule while the reference detector has been treated not to support this oxidation. The reference detectors serve as a means to maintain zero stability over a wide operating temperature range.
When combustible gas molecules oxidize on the surface of the active detector, heat is generated, effectively changing the electrical conductance of the active detector. Electronically, the detectors form part of a balanced bridge circuit. As the active detector changes in electrical conductance, the bridge circuit unbalances. This change in output is
conditioned by amplifier circuits that are an integral part of the sensor transmitter. The sensor response and clearing
characteristics are quite rapid resulting in a method of continuous and accurate monitoring of ambient air conditions.
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.
The performance of the detector elements may be temporarily impaired by operation in the presence of substances
described as inhibitors. These are usually volatile substances containing halogens and the detectors may recover
after short periods of operation in clean air. When the inhibiting substance produces a permanent effect on the catalyst with a catastrophic reduction in sensitivity, the detector is said to be poisoned. Examples of poisons are; silicone oils and greases, anti-knock petrol additives and phosphate esters. Activated carbon filters will provide adequate protection from poisoning in the majority of cases.
Model FP-524C Combustible Gas Sensor PG.5
3.2 APPLICATION
Model FP-524C MicroSafe™ sensors are designed to detect and monitor combustible gas in ambient air in the range of
0-100% LEL. Minimum sensitivity and scale resolution is 1%. Operating temperature range is -40° F. to +175° F. While
the sensor is capable of operating outside these temperatures, performance specifications are verified within the limit.
3.2.1 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 4-6 feet above grade.
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
virtually any combustible gas. 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. Since these factors are theoretical, they will only
give a guide to the response expected from other gases. The Model FP-524C sensor can be configured to detect any
of the listed gases. The gas selected for detection is referred to as the target gas. The sensor can also be configured
to allow the user to calibrate with a listed gas other than the target gas. This selection is referred to as the calibration gas. Unless otherwise specified, Model FP-524C sensors are configured to detect methane and are calibrated
with methane to a scale of 0-100% LEL. Refer to section 3.7 for details.
3.3 SPECIFICATIONS
Method of Detection
Catalytic detector diffusion/adsorption
Measurment Range
0-100% (lower explosive limit) LEL
Accuracy/Repeatability
± 3% LEL in 0-50% LEL Range
± 5% LEL in 51-100% LEL Range
Response/Clearing Time
T50 <10 seconds; T90 <30 seconds
Zero Drift
< 5% per year
Operating Temperature Range
-40° to +175° F; -40° to +75°C
Operating Humidity Range
0-99% non-condensing
Output
Linear 4-20 mA DC
Input Voltage
12-28 VDC
Power Consumption
1.9 watts @ 24V
Electrical Classification
Explosion Proof; Class I; Div. 1; Groups B, C, D
Safety Approvals
CSA/NRTL (US OSHA Certified)
Sensor Warranty
2 year conditional
3.4 OPERATING SOFTWARE
Operating software is menu listed with operator interface via the two magnetic program switches located under the
face plate (reference figure 6). 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 the last page of this manual for a complete software
flow chart.)
01. Normal Operation
Model FP-524C Combustible Gas Sensor PG.6
a) Current Status
02. Calibration Mode
a) Zero
b) Span
03. Program Menu
a) Program Status
b) Target gas selection (gas K factor)
c) Calibration gas selection (cal K factor)
d) Calibration Level
e) 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”
3.4.2.1 Zero Adjustment
Zero is set in ambient air with no combustible gas present or with zero gas applied to the sensor. “AUTO ZERO”
3.4.2.2 Span Adjustment
Unless otherwise specified, span adjustment is performed at 50% LEL methane in air. “AUTO SPAN”
3.4.3 Program Mode
The program mode provides a program status menu, allows for the selection of the target gas K factor, the selection
of the calibration gas K factor, the selection of the calibration gas level setting, and the selection of the bridge voltage setting.
3.4.3.1 Program Status
The program status scrolls through a menu that displays:
* The gas type, range of detection and software version number. The menu item appears as: “LEL 0-100 V#.#”
* Identification of the target gas K factor. The menu item appears as: “GAS FACTOR #.##”
* Identification of the calibration gas K factor. The menu item appears as: “CAL FACTOR #.##”
* The calibration gas level setting. The menu item appears as: “CalLevel @ xx%”
* Sensor bridge voltage. The menu item appears as: “BRIDGE @ #.## VDC”
* The estimated remaining sensor life. The menu item appears as: “SENSOR LIFE 100%”
3.4.3.2 Target Gas Selection
The target gas K factor is adjustable over the range 0.79 to 5.65. For combustible gas sensors configured for the
detection of methane, the level is factory set at 1.00. The menu item appears as: “GAS FACTOR 1.00”
3.4.3.3 Calibration Gas Selection
The calibration gas K factor is adjustable over the range 0.79 to 5.65. For combustible gas sensors that are calibrated
using methane, the level is factory set at 1.00. The menu item appears as: “CAL FACTOR 1.00”
3.4.3.4 Calibration Level Adjustment
The Calibration level is adjustable from 10% to 90% LEL. The menu item appears as: “CalLevel @ ##%”
Factory default setting is 50%.
3.4.3.5 Set Bridge Volts
The bridge voltage is adjustable from 1.80 to 3.10 VDC. The menu item appears as: “BRIDGE @ #.## VDC”
The factory default setting is 2.70 VDC.
Model FP-524C Combustible Gas Sensor PG.7
3.5 INSTALLATION
Optimum performance of ambient air/gas sensor devices is directly relative to proper location and installation practice.
3.5.1 Field Wiring Table
Detcon Model FP-524C combustible gas sensor assemblies require three conductor connection between power supplies and host electronic controllers. Wiring designators are
single conductor resistance between sensor and controller is 10 ohms. Maximum wire size for termination in the
sensor assembly terminal board is 14 gauge.
AWGMetersFeet
20240800
183601200
166002000
149003000
Note 1:
Note 2: Shielded cable may be required in installations where cable trays or conduit runs include high voltage
lines or other sources of induced interference.
Note 3: The supply of power must be from an isolating source with over-current protection as follows:
AWG
223A1610A
205A1420A
187A1225A
3.5.2 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:
This wiring table is based on stranded tinned copper wire and is designed to serve as a reference only.
Over-current ProtectionAWGOver-current Protection
(4-20 mA output)
+
(DC), –(DC) , and mA(sensor signal). Maximum
(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
heavier than air gases should be located within 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
tions 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
manner where the migration of gas clouds is quickly detected.
Personnel Exposure
sonnel 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.
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.
- Placement of sensors relative to the density of the target gas is such that sensors for the detection of
- Most probable leak sources within an industrial process include flanges, valves, and tubing connec-
- Normal ventilation or prevailing wind conditions can dictate efficient location of gas sensors in a
- The undetected migration of gas clouds should not be allowed to approach concentrated per-
Model FP-524C Combustible Gas Sensor PG.8
4 3/4"
3/4" NPT
1/4" Dia.
Mounting Holes
7 1/4"
6 1/8"
5 1/2"
3/4" NPT
Rainshield/
Splashguard
2"
2 1/8"
EYS
S
eal
Fitting
Drain
“T”
Plug any unused ports.
Figure #1
Note:
In all installations, the sensor element in SS housing points down relative to grade (Fig. 1). Improper sensor
orientation may result in false reading and premature sensor damage.
3.5.4 Local Electrical Codes
Sensor and transmitter assemblies should be installed in accordance with all local electrical codes. Use appropriate
conduit seals. Drains are required at the bottom of vertical conduit runs. The sensor assemblies are designed to
meet NEC and CSA requirements for Class I; Div. 1; Groups B, C, D, environments.
Note:
An appropriate conduit seal must be located within 18" of the sensor assembly. Crouse Hinds type EYS2,
EYD2 or equivalent are suitable for this purpose.
Figure #2
3.5.4 Installation Procedure
a) Remove the junction box cover and un-plug the control circuit by grasping the two thumb screws and pulling outward.
b) Securely mount the sensor junction box in accordance with recommended practice. See dimensional drawing (Fig. 2).
c) Observing correct polarity, terminate 3 conductor field wiring to the sensor base connector board in accordance
with the detail shown in Figure 3.
d) Use a 3/4 NPT plug to block the unused port.
e) Replace the plug-in transmitter circuit and replace the junction box cover.
3.5.5 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 FP524C sensor in a remote-mount configuration in which the sensor (Model FP-524C-RS) and the transmitter (Model
FP-524C-RT) are provided in their own condulet housing and are interfaced together with a three conductor cable.
Model FP-524C Combustible Gas Sensor PG.9
There is a limit 0.5 ohm maximum resistance drop per wire over the seperation distance.
WHT
BLK
YEL
BLU
mA
VDC Power In
4-20 mA Output
S
ensor
Base Connector Board
1234
WHT
BLK
YEL
BLU
Install
Jumper
Remote Transmitter
FP-524C-RT
Remote Sensor
FP-524C-RS
Measure Bridge Voltage
From White (1) to Blue (4)
Target voltage is 2.7v
WHT
BLK
YEL
BLU
Plug unused port
with 3/4 NPT plug.
AWGMaximum Seperation (feet)
2050
1875
16125
4175
1
Figure #3
Reference figure 4 for wiring diagram. Also note the jumper that is required on the remote sensor connector board.
Failure to install this jumper will cause a sensor fault condition.
Remote Mounting Configuration - Bridge Voltage Adjustment
When a sensor is remote mounted, consideration must be given to the lengths of cable used and how it affects the
sensor bridge voltage. Differing lengths of cables will have varying amounts of resistance which will shift the sensor
bridge voltage. Because of this, the bridge voltage will need to be adjusted after initial power up. This adjustment is
only required after initial installation and will not be necessary thereafter, even in the event of replacement of the
plug-in sensor. See section 3.6.2 for instructions.
Figure #4
3.6 START UP
Upon completion of all mechanical mounting and termination of all field wiring, apply system power and observe
the following normal conditions:
Model FP-524C Combustible Gas Sensor PG.10
a) FP-524C “Fault” LED is off.
b) A temporary upscale reading may occur as the sensor heats up. This upscale reading will clear to “0”
% within 1-2 minutes of turn-on, assuming there is no gas in the area of the sensor.
Note 1: If the display contrast needs adjustment, refer to section 3.11.
Note 2: If the sensor has been installed using the remote mounting configuration as described in section 3.5.5, the
sensor bridge voltage must be adjusted after initial power up. If this is the case, first adjust the bridge voltage as
described in section 3.6.2, then proceed with the initial operation tests below (section 3.6.1).
3.6.1 Initial Operational Tests
After a warm up period of approximately 15 minutes, the sensor should be checked to verify sensitivity to combustible gas.
Material Requirements
*Detcon PN 6132 Threaded Calibration Adapter
*Span Gas 50% LEL methane in air at a controlled flow rate of 200 ml/min.
NOTE: If the sensor has been configured for calibration with a gas other than methane you will need to use
that gas. See section 3.7 for further information on calibration gas.
a) Attach the calibration adapter to the threaded sensor housing. Apply the test gas at a controlled flow rate of
200 ml/m. Observe that the LCD display increases to a level of 20% or higher.
b) Remove the test gas and observe that the LCD display decreases to “0 % LEL”
.
Initial operational tests are complete. Detcon combustible gas sensors are pre-calibrated prior to shipment and will,
in most cases, 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.
3.6.2 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. Follow the steps below to set the sensor bridge voltage.
Note: Refer to section 3.6.3 for programming magnet operating instructions.
a) Declassify the area around the sensor.
b) Remove the junction box cover from the remote sensor enclosure (see figure 4).
c) Using the digital volt/ohm meter, measure the bridge voltage at the remote sensor connector board from the
“White” terminal to the “Blue” terminal as shown in figure 4. Target voltage is 2.7 volts.
d) At the transmitter, 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.
e) Next, scroll to the “SET BRIDGE VOLTS” listing and then hold the programming magnet over “PGM 1”
for 3 seconds. The menu item appears as “BRIDGE @ #.## VDC”.
f)Use the programming magnet to make an adjustment to “PGM 1” to increase or “PGM 2” to decrease the
bridge voltage. Set the voltage to 2.7 VDC.
g) Exit to the programming menu by holding the programming magnet over “PGM1” for 3 seconds, or automati-
cally return to the programming menu in 30 seconds.
h) Exit back to normal operation by holding the programming magnet over “PGM 2” for 3 seconds, or automati-
cally return to normal operation in 30 seconds.
i)Replace the junction box cover on the remote sensor enclosure.
Bridge voltage adjustment is complete.
3.6.3 Programming Magnet Operating Instructions
Operator interface to MicroSafe™ gas detection products is via magnetic switches located behind the transmitter
face plate. DO NOT remove the glass lens cover to calibrate or change programming parameters. Two switches
Model FP-524C Combustible Gas Sensor PG.11
labeled “PGM 1” and “PGM 2” allow for complete calibration and programming without removing the enclosure
Magnetic Programming Tool
detcon inc.
Program Switch #2
FLTCAL
MicroSafe™ LEL Gas Sensor
HOUS TON , TEX AS
PGM 2
PGM 1
MODELFP-524C
C
ONTRAST
Fault & Cal LEDs
Program Switch #1
Menu Driven Display
Plug-in Microprocessor Control Circuit
Display Contrast Adjust
cover, thereby eliminating the need for area de-classification or the use of hot permits.
Figure #5
A magnetic programming tool (see figure 5) is used to operate the switches. Switch action is defined as momentary
contact, 3 second hold, and 30 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 30 second hold, the programming magnet is held in place over a switch location for 30 or more seconds. Three and thirty second hold is used to enter or exit calibration and program menus while momentary contact is used to make adjustments. The location of “PGM 1” and “PGM 2” are shown in figure 6.
Figure #6
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.
3.7 TARGET GAS AND CALIBRATION GAS SELECTION
Because of the catalytic detector elements almost universal response to lower explosive limits of combustible gas,
the FP-524C sensor can be configured to specifically detect any of the combustible gases listed in table 1. This specific gas is referred to as the “target gas”. In addition, the sensor can be configured so that it can be calibrated with
any of the listed gases, regardless of which target gas is selected. This gas is referred to as the “calibration gas”. These
two features allow a significant degree of flexibility in the detection and calibration process.
Unless otherwise specified at time of order, Model FP-524C combustible gas sensors are configured to detect
methane gas in the range 0-100% LEL and are calibrated with 50% LEL methane in air. In this configuration,
methane is chosen as both the target gas and the calibration gas.
CAUTION:
To verify target gas and calibration gas settings, or to reconfigure the target gas or calibration gas, follow the
instructions below.
3.7.1 The “K” Factor
Most detectable gases, as listed in table 1, produce a similar output, however the signal amplitudes will differ. This
difference in amplitude is reflected by a numeric figure known as a “K factor”. The K factors are referenced to
methane which has a K factor of 1.00. It should be noted that these factors are theoretical and should only be used
as a guide to the response expected from other gases.
Verification of specific target gas and calibration gas settings is required before commissioning.
3.7.2 Verification of Target Gas and Calibration Gas Configuration
Verification of target gas and calibration gas configuration is obtained via interaction with the menu driven display
which requires the use of a programming magnet.
Material Requirements:
Detcon PN 3270 MicroSafe™ Programming Magnet
a) First, enter the programming menu by holding the programming magnet stationary over “PGM 2” for 30 sec-
onds 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 Gas Factor (target gas), Set Cal Factor (calibration
gas), Set Cal Level, and Set Bridge Voltage.
b) Next, 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 five second intervals, through the following information before returning back to the “VIEW PROG STATUS” listing. Note that the “K factor” for the target gas
is displayed in item #2 and the “K factor” for the calibration gas is displayed in item #3. Compare the K factors
to the listing in Table 1 to determine the target/calibration gas configuration.
The gas type, range of detection and software version number. The menu item appears as:
1 -
“LEL 0-100 V6.0”
2 - The target gas K factor. The menu item appears as: “GAS FACTOR #.##”
3 - The calibration gas K factor. The menu item appears as: “CAL FACTOR #.##”
4 - The calibration gas level setting. The menu item appears as: “CalLevel @ xx%”
5 - Sensor bridge voltage. The menu item appears as: “BRIDGE @ #.## VDC”
6 - The estimated remaining sensor life. The menu item appears as: “SENSOR LIFE 100%”
c) Exit back to normal operations by holding the programming magnet over “PGM 2” for 3 seconds, or automati-
cally return to normal operation in 30 seconds.
3.7.2 Changing the Target Gas
To change the target gas setting, select the applicable K factor from Table 1 and follow the instructions below.
a) First, enter the programming menu by holding the programming magnet stationary over “PGM 2” for 30 sec-
onds until the display reads “VIEW PROG STATUS”, then withdraw the magnet.
b) Next, scroll to the “SET GAS FACTOR” listing and then hold the programming magnet over “PGM 1” for
3 seconds. The menu item appears as “GAS 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. Save value by holding the programming magnet over “PGM1” for 3 seconds.
c) Exit back to normal operations by holding the programming magnet over “PGM 2” for 3 seconds, or automati-
cally return to normal operation in 30 seconds.
3.7.3 Changing the Calibration Gas
Optimum calibration of the FP-524C sensor requires that the calibration gas be the same as the target gas. However, if
the applicable calibration gas is not available, any other gas listed in Table 1 can be used to calibrate the sensor. Note
that the K factors are theoretical and calibration with a gas other than the target gas may be subject to error. A calibration gas of 50% LEL in air is required. To change the calibration gas setting, select the applicable K factor from Table 1
and follow the instructions below.
a) First, enter the programming menu by holding the programming magnet stationary over “PGM 2” for 30 sec-
onds until the display reads “VIEW PROG STATUS”, then withdraw the magnet.
Model FP-524C Combustible Gas Sensor PG.14
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 adjust-
ment to “PGM 1” to increase or “PGM 2” to decrease the display reading until the reading is equal to the
desired K factor. Save value by holding the programming magnet over “PGM1” for 3 seconds.
c) Exit back to normal operations by holding the programming magnet over “PGM 2” for 3 seconds, or automati-
cally return to normal operation in 30 seconds.
3.8 CALIBRATION
Material Requirements
*Detcon PN 3270 MicroSafe™ Programming Magnet
*Detcon PN 6132 Threaded Calibration Adapter
*Span Gas containing the applicable calibration gas in air (see section 3.7). Span gas concentration is recom-
mended at 50% of range (which is the factory default) at a controlled flow rate of 200 ml/min. Other concentrations can be used as long as they fall within 10% to 90% of range. See section 3.8.2 for details.
3.8.1 Calibration Procedure - Zero
NOTE: Before performing a zero calibration, be sure there is no background combustible gas present or be pre-
pared to apply a zero gas standard.
a) Enter the calibration menu by holding the programming magnet stationary over “PGM 1” (see figure 7) for 3 sec-
onds until the display reads “1-ZERO 2-SPAN”, then withdraw the magnet. Note that the “CAL” LED is on.
b) Next, enter the zero menu by holding the magnet stationary over “PGM 1” for 3 seconds until the display
reads: “ZERO 0%”, then withdraw the magnet. The sensor has now entered the auto zero mode. When it is
complete the display will read “ZERO COMPLETE” for 5 seconds and then return to the normal operations
menu, “0 % LEL”.
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: “CAL FAULT” (see section 3.8.3).
NOTE 2: When a “cal fault” occurs, the sensor microprocessor retains its previous calibration references but
the 4-20 mA signal drops to 0 mA until the Fault is corrected.
Zero calibration is complete.
3.8.2 Calibration Procedure - Span
CAUTION:
required before “span” calibration. These two numbers must be equal.
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 calibration gas
level setting. The factory default setting for span gas concentration is 50% LEL. In this instance, a span gas containing a concentration equal to 50% LEL is required. If a span gas containing 50% LEL 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. To do this, follow
the instructions in section 3.9 and make note of the setting found in listing number 4. The item appears as
“CalLevel @ xx%”.
Verification of the correct calibration gas level setting and calibration span gas concentration is
Model FP-524C Combustible Gas Sensor PG.15
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 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, Set Alarm 2 Level, Set Gas Factor, Set Cal
Factor, Set Cal Level, and Set Bridge Voltage.
d) From the programming menu scroll to the calibration level listing. The menu item appears as: “SET CAL
LEVEL”. Enter the menu by holding the programming magnet stationary over “PGM 1” for 3 seconds until
the display reads “CalLevel @ ##%”, then withdraw the magnet. 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 calibration span gas concentration. Save value by holding 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 automati-
cally return to normal operation in 30 seconds.
f)From the calibration menu “1-ZERO 2-SPAN” (section 3.8.1-a) proceed into the span adjust function by
holding the programming magnet stationary over “PGM 2” for 3 seconds until the display reads “APPLYxx% LEL” then withdraw the programming magnet. The x’s here indicate the gas concentration requested.
g) Apply the calibration gas at a flow rate of 200 milliliters per minute. As the sensor signal changes, the display
will change to “SPAN XX%”. The “XX” part of the reading indicates the actual gas reading which will increase
until the sensor stabilizes. When the sensor signal is stable it will auto span to the request concentration and
the display will change to “SPAN COMPLETE” for two seconds and then “REMOVE GAS”. Remove the
gas. When the signal level has fallen below 10% of full scale, the display will return to the normal operation
menu, “0 % LEL”.
NOTE 1: If the circuitry is unable to adjust the span to the proper setting the sensor will enter into the 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: “CAL FAULT” (see section 3.8.3).
NOTE 2: If, after entering the span function, more than one minute elapses before calibration gas is applied,
the sensor will enter the 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: “CAL FAULT” (see section 3.8.3).
Span calibration is complete.
3.8.3
Additional Notes
1. Upon entering the calibration menu, the 4-20 mA signal drops to 2 mA and is held at this level until you
return to normal operation.
2. If during calibration the sensor circuitry is unable to attain the proper adjustment for zero or span, the sensor will
enter into the calibration fault mode causing the display to alternate between the sensor’s current status reading
and the calibration fault screen which appears as: “CAL FAULT”. During “Cal Fault” the Fault LED will light
and the 4-20 mA signal is taken to 0 mA until the Fault is corrected by re-calibration. If this occurs you may
attempt to recalibrate by entering the calibration menu as described in section 3.8.1-a. If the sensor fails again,
defer to technical trouble shooting.
3.8.4 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.
Model FP-524C Combustible Gas Sensor PG.16
3.9 STATUS OF PROGRAMMING, TARGET GAS, CALIBRATION GAS, CALIBRATION LEVEL, SENSOR LIFE, AND BRIDGE VOLTAGE
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 target and calibration gas settings, calibration gas level setting,
bridge voltage, and estimated remaining sensor life. The programming menu also allows the changing of target gas
and calibration gas settings (see section 3.7), the calibration gas level setting (see section 3.8.2), and bridge voltage
setting (see section 3.6.2).
The following procedure is used to view the programming status of the sensor:
First, enter the programming menu by holding the programming magnet stationary over “PGM 2” for 30 seconds
a)
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 Gas Factor, Set Cal Factor, Set Cal Level, and Set Bridge Voltage.
b) Next, 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 five second intervals, through the following information before returning back to the “VIEW PROG STATUS” listing.
The gas type, range of detection and software version number. The menu item appears as:
1 2 - The target gas K factor. The menu item appears as: “GAS FACTOR #.##”
3 - The calibration gas K factor. The menu item appears as: “CAL FACTOR #.##”
4 - The calibration gas level setting. The menu item appears as: “CalLevel @ xx%”
5 - Sensor bridge voltage. The menu item appears as: “BRIDGE @ #.## VDC”
6 - The estimated remaining sensor life. The menu item appears as: “SENSOR LIFE 100%”
c) Exit back to normal operations by holding the programming magnet over “PGM 2” for 3 seconds, or automati-
cally return to normal operation in 30 seconds.
“LEL 0-100 V6.0”
3.10 PROGRAM FEATURES
Model FP-524C MicroSafe™ 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.
Over-Range
When the sensor detects gas greater than 100% LEL, it will cause the display to flash “100 % LEL” on and off.
Under-Range Fault
If the sensor zero base line should drift to below a –10% LEL, the display will indicate a fault: “SIGNAL FAULT”.
Open Sensor Bridge Fault
If either the active or reference side of the catalytic sensor bead should fail and become electrically open, the display will indicate a fault: “SENSOR FAULT”.
Sensor Heater Voltage Functions/Fault
The heater voltage is continuously monitored. Normal heater voltage is 2.7 VDC. If the voltage has drifted from
the programmed heater voltage value by more than ±.1V, the display will indicate a fault: “HEATER FAULT”.
Calibration Fault
If during calibration the sensor circuitry is unable to attain the proper adjustment for zero or span, the sensor will
enter into the calibration fault mode and cause the display to alternate between the sensor’s current status reading and
the calibration fault screen which appears as: “CAL FAULT”. The Fault LED will light and the 4-20 mA signal is
dropped to 0 mA until the Fault is corrected.
Model FP-524C Combustible Gas Sensor PG.17
Fail-Safe/Fault Supervision
Model FP-524C MicroSafe™ sensors are programmed for fail-safe operation. Any of the following fault condition
will illuminate the fault LED, and cause the display to read its corresponding fault condition: “SENSORFAULT”, “SIGNAL FAULT”, “HEATER FAULT”, or “CAL FAULT”. A “Sensor Fault”, “Signal Fault”, “Cal
Fault”, and “Heater Fault”, will also cause the mA output to drop to zero (0) mA.
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.
3.11 DISPLAY CONTRAST ADJUST
Model FP-524C MicroSafe™ sensors feature a 16 character backlit liquid crystal display. Like most LCDs, character
contrast can be affected by viewing angle and temperature. Temperature compensation circuitry included in the
MicroSafe™ design will compensate for this characteristic, however temperature extremes may still cause a shift in
the contrast. Display contrast can be adjusted by the user if necessary. However, changing the contrast requires that
the sensor housing be opened, thus declassification of the area is required.
To adjust the display contrast, remove the enclosure cover and use a jewelers screwdriver to turn the contrast
adjust screw located beneath the metallic face plate. The adjustment location is marked “CONTRAST”. See figure 6
for location.
3.12 TROUBLE SHOOTING GUIDE
Sensor Fault
1. Open Sensor – broken wire or contact in sensor.
2. Remove replaceable sensor element and check adjacent pin pairs with ohm-meter. Normal reading is 1-4 ohms
and failed reading is an open circuit.
3. Replace sensor if verified as Open Sensor.
Heater Fault
1. Open sensor or drifted heater voltage setting.
2. Check heater voltage setting and re-adjust to target reading. Unplug/replug transmitter to see if Fault clears.
3. Remove replaceable sensor element and check adjacent pin pairs with ohm-meter. Normal reading is 1-4 ohms
and failed reading is an open circuit.
1. Check that correct Heater Voltage is applied to your Sensor.
NOTE:
The C-Style sensor measures 0.9”across the exposed stainless steel sinter face and has a serial number format C??###. The C-Style sensor requires 2.7 VDC.
The J-Style sensor measures 0.4”across exposed the stainless steel sinter face and has a serial number format J??-###.
The J-Style sensor requires 2.2 VDC.
2. If heater voltage is incorrect, adjust accordingly for the correct sensor type.
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.
Detcon has two version sensors: C-Style and the J-Style. Each uses a different heater voltage setting.
Model FP-524C Combustible Gas Sensor PG.18
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. Check area for presence of sensor poisoning gases such as silicon grease vapors, HMDS, high H2S, chlorine or
chlorinated compounds if sensor failures persist.
Drifting Zero
1. It may be the correct reading if there are real gas leaks or the sensor was zero calibrated when actual gas was
around and subsequently cleared.
2. Check Heater voltage is set correctly for sensor type (check voltage at the sensor if remote mounted).
3. Replace plug-in sensor if Sensor Life is < 50%.
4. If sensor drift is gradual and continuously positive then contact Detcon for sensor replacement.
Unstable Output/ Sudden Spiking/Nuisance Alarms
1. Check condulet for accumulated water.
2. Check transmitter and Terminal PCB for abnormal corrosion.
3. Determine if problem correlates with condensation cycles.
7. If correlates with radio communications then use Detcon RFI filter accessory.
8. Contact Detcon for assistance in optimizing shielding, grounding, and RFI protection.
Span Calibration Fault – (Sensitivity, Stability, Clearing)
To remove any calibration fault repeat calibration process successfully or unplug/replug transmitter.
Sensitivity - Check Heater Voltage Setting (should be 2.7V C-Style and 2.2V J-Style), Check for obstructions through
stainless steel sinter element (including being wet), check validity and flow rate of cal gas.
Stability - Check Heater Voltage Setting (should be 2.7V C-Style and 2.2V J--Style), check validity and flow rate of
cal gas, Check for obstructions through stainless steel sinter element (including being wet).
Clearing - Must recover to < 10% of range before calibration cycle is complete and returns to normal operation.
Use bottled or fresh air if necessary.
Memory or Error Reports
1. Reinitialize Sensor - Unplug transmitter and replug transmitter then swipe magnet over PGM 1 in the first 3 seconds. This will clear the processor and recover from error state. Remember to put in all customer settings for range,
alarm and cal gas level after re-initialization.
Non-readable Display
1. If display has blue background when hot, install sunshade to reduce temperature.
2. If poor contrast, adjust contrast pot accordingly.
Nothing Displayed – Transmitter not Responding
1. Verify condulet has no accumulated water or abnormal corrosion.
2. Verify required DC power is applied to correct terminals.
3. Swap with a known-good transmitter to determine if transmitter is faulty.
Bad 4-20 mA Output
1. Check that wiring is connected to correct terminal outputs.
2. Swap with a known-good transmitter to determine if transmitter is faulty.
Model FP-524C Combustible Gas Sensor PG.19
3.13 SPARE PARTS LIST
Spash Guard
Rain Shield
Enclosure less cover
Connector Board
Calibrati on Ad apte r
Enclosure glass lens cover
Plug-in control circuit
Sensor: field replaceable plug-in detector
LEL Main Sensor Housing Assembly
Programming Magnet
Condensation
Prevention Packet
(replace annually)
613-010000-000Sensor rain shield
613-120000-000Sensor splash guard
943-000006-132Threaded Calibration Adapter
399-602016-000LEL sensor housing assembly with plug-in detector included
612-820000-000LEL sensor housing assembly (plug-in detector, PN370-201600-000, not included)
370-201600-000Sensor: field replaceable plug in detector
925-525400-100FP-524C Plug-in control circuit
500-005065-007Connector board
327-000000-000Programming Magnet
897-850800-0003-port enclosure less cover
897-850700-000Enclosure glass lens cover
960-202200-000Condensation prevention packet (replace annually).
Figure #7
3.14 WARRANTY
Detcon, Inc., as manufacturer, warrants each LEL plug-in sensor element (part no. 370-201600-000), for a two year
period under the conditions described as follows: The warranty period begins on the date of shipment to the original purchaser and ends two years thereafter. The sensor element is warranted to be free from defects in material and
workmanship. Should any sensor fail to perform in accordance with published specifications within the warranty
period, return the defective part to Detcon, Inc., 3200 A-1 Research Forest Dr., The Woodlands, Texas 77381, for
necessary repairs or replacement.
3.15 SERVICE POLICY
Detcon, Inc., as manufacturer, warrants under intended normal use each new MicroSafe™ plug-in control circuit to
be free from defects in material and workmanship for a period of two years from the date of shipment to the original purchaser. Detcon, Inc., further provides for a five year fixed fee service policy wherein any failed transmitter
shall be repaired or replaced as is deemed necessary by Detcon, Inc., for a fixed fee of $55.00. The fixed fee service
policy shall affect any factory repair for the period following the two year warranty and shall end five years after
expiration of the warranty. All warranties and service policies are FOB the Detcon facility located in The
Woodlands, Texas.
Model FP-524C Combustible Gas Sensor PG.20
3.16 SOFTWARE FLOW
NORMAL
OPERATION
CALIBRATION
PGM1 (3) PGM2 (3)
PGM1 (M) PGM2 (M)
PGM1 (3)
INC
DEC
PGM1 (3) PGM2 (M)
1
-ZERO 2-SPAN
L
EGEND
PGM1 - program switch location #1
PGM2 - program switch location #2
(
M) - momentary pass of magnet
(3) - 3 second hold of magnet
(
30) - 30 second hold of magnet
I
NC - increase
DEC - decrease
# - numeric value
A
UTO ZERO
A
UTO SPAN
PGM1 (3) PGM2 (M)
VIEW PROG STATUS
PGM1 (M) PGM2 (M)
PGM1 (3)
CAL FACTOR #.##
INC
DEC
PGM1 (3) PGM2 (M)
SET CAL FACTOR
PGM2 (3)PGM2 (3)PGM2 (3)
P
GM1 (3)
PGM2 (30)
PGM1 (M) PGM2 (M)
PGM1 (3)
INC
DEC
PGM1 (3) PGM2 (M)
PGM1 (M) PGM2 (M)
PGM1 (3)
INC
DEC
PGM1 (3) PGM2 (M)
PGM2 (3)PGM2 (3)
BRIDGE @ #.## VDC
SET BRIDGE VOLTS
GAS FACTOR #.##
SET GAS FACTOR
CAL LEVEL @ ##%
SET CAL LEVEL
LEL 0-100 V#.#
GAS FACTOR #.##
CAL LEVEL @ ##%
BRIDGE @ #.## VDC
SENSOR LIFE ##%
CAL FACTOR #.##
Shipping Address: 3200 A-1 Research Forest Dr., The Woodlands, Texas 7381
Mailing Address: P.O. Box 8067, The Woodlands, Texas 77387-8067