™
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 3.10), and RS-485 ID (section 3.5.5f and 3.12).
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
3.18 Software Flow Chart
Model FP-624C 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-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 f ield adjustable,
fully programmable alarms and provides relays for two alarms plus fault as standard.
The sensor comes with two different outputs: analog 4-20 mA, and serial RS-485.
These outputs allow for greater flexibility in system integration and installation. 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 window which allows for the display of sensor readings as well
as access to 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. The technique is referred to as
non-selective and may be used for the detection and monitoring of target combustible gases. Model FP-624C 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 bead of alumina. 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 module uses gold plated pins and mounts inside the stainless steel sensor head via mating gold plated sockets.
3.0.2 Microprocessor Control Circuit
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, alarm status LED indicators, magnetic programming switches, an RS-485 communication port, and a linear 4-20 mA DC output.
Model FP-624C Combustible Gas Sensor PG.3
3.0.3 Base Connector Board
NC
ALARM 1
WHT
BLK
YEL
BLU
MA
V
DC Power In
N
O
NC
N
O
NC
N
O
NO/NC
COM
NO/NC
COM
NO/NC
COM
FAULT ALM -2 ALM -1
Alarm Dry Contacts
ALARM 2
FAULT
R1
A
B
A
B
4
-20 mA Output
R
S-485 In
RS-485 Out
Optional Voltage
Developing Resistor
Use 250 ohm 1/4w
JUMPERS
UN-USED
J
umper Programmable Alarm Outputs
Normally Open or Normally Closed
Sensor
Place un-used alarm programming
jumper tabs here
d
etcon inc.
Program Switch #2
FLT
A
LM
1CAL
M
icroSafe™ LEL Gas Sensor
HOUS TON, TEX AS
P
GM 2
PGM 1
A
LM
2
MODEL FP-624C
C
ONTRAST
A
larm & Cal LEDs
P
rogram Switch #1
Menu Driven Display
Plug-in Microprocessor Control Circuit
Display Contrast Adjust
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, alarm relays, lugless terminals for all field wiring, and a terminal strip
for storing unused programming jumper tabs.
The alarm relays are contact rated 5 amps @
125 VAC, 5 amps @ 30 VDC and coil rated
at 24 VDC. Gold plated program jumpers are
used to select either the normally open or
normally closed relay contacts.
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. All calibration and alarm level adjustments can be accomplished without removing the cover
or declassifying the area. Electrical classification is Class I; Groups B, C, D; Div. 1.
3.1 PRINCIPLE OF OPERATION
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 assembly. The sensor response and clearing characteristics are quite rapid resulting in a method of continuous and accurate monitoring of ambient air conditions.
Model FP-624C Combustible Gas Sensor PG.4
3.1.2 Characteristics
% Methane in Air Concentration
0
20
40
60
80
100
020406080
Bridge Output %
0
4
8
12
16
20
20 40 60 80 100
% LEL (lower explosive limit)
mA DC Signal Output
Response Curve
Response Curve
Functional
Block
Diagram
Functional
Block
Diagram
Analog 4-20 mA Out
Power In
Relays Out
Pre-Amp Display
Tem per atu re
Compensation
Alarm & Fault
Relays
RS-485 & 4-20mA
Micro-
processor
Tran smit ter
Power Supply
Sensor
Element
I/O Circuit
Protection
Serial RS-485 Out
2.2V
Zero
S
et
O
utput
Detector/Active
Compensator/Reference
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.
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.
3.2 APPLICATION
Model FP-624C 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 2 - 4 feet above grade.
Model FP-624C Combustible Gas Sensor PG.5
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. Since these factors are theoretical, they will only give a guide to
the response expected in other gases. The Model FP-624C 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-624C 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
3 relays (alarm 1, alarm 2, and fault) contact rated 5 amps @ 125 VAC, 5 amps @ 30 VDC;
Linear 4-20 mA DC; RS-485 Modbus™
Input Voltage
22-28 VDC
Power Consumption
Normal operation = 84 mA (2 watts); Full alarm = 128 mA (3.1 watts)
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. 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 f low chart.)
01. Normal Operation
a) Current Status
02. Calibration Mode
a) Zero
b) Span
03. Program Menu
a) Program Status
b) Alarm 1 Level
Model FP-624C Combustible Gas Sensor PG.6
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”
3.4.2.1 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 adjustment of alarm set point levels, the selection of the target gas K factor, the selection of the calibration gas K factor and the selection of the calibration gas
level 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 V6.4”
* The alarm set point level of alarm 1. The menu item appears as: “ALM1 SET @ ##%”
* The alarm firing direction of alarm 1. The menu item appears as: “ALM1 ASCENDING” or descending.
* The alarm relay latch mode of alarm 1. The menu item appears as: “ALM1 NONLATCHING” or latching.
* The alarm relay energize state of alarm 1. The menu item appears as: “ALM1 DE-ENERGIZED” or energized.
* The alarm set point level of alarm 2. The menu item appears as: “ALM2 SET @ ##%”
* The alarm firing direction of alarm 2. The menu item appears as: “ALM2 ASCENDING” or descending.
* The alarm relay latch mode of alarm 2. The menu item appears as: “ALM2 LATCHING” or nonlatching.
* The alarm relay energize state of alarm 2. The menu item appears as: “ALM2 DE-ENERGIZED” or energized.
* The alarm relay latch mode of the fault alarm. The menu item appears as: “FLT NONLATCHING” or latching.
* The alarm relay energize state of the fault alarm. The menu item appears as: “FLT ENERGIZED” or deenergized.
* 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%”
* Identification of the RS-485 ID number setting. The menu item appears as: “485 ID SET @ ##”
* The estimated remaining sensor life. The menu item appears as: “SENSOR LIFE 100%”
3.4.3.2 Alarm 1 Level Adjustment
The alarm 1 level is adjustable over the range 10 to 90%. For combustible gas sensors, the level is factory set at
20%. The menu item appears as: “SET ALM1 @ 20%”
3.4.3.3 Alarm 2 Level Adjustment
The alarm 2 level is also adjustable over the range 10 to 90%. For combustible gas sensors, the level is factory set at
40%. The menu item appears as: “SET ALM2 @ 40%”
3.4.3.4 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”
3.4.3.5 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”
Model FP-624C Combustible Gas Sensor PG.7
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”
3.5 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-624C 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.
AWG Meters Feet
20 240 800
18 360 1200
16 600 2000
14 900 3000
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
22 3A 16 10A
20 5A 14 20A
18 7A 12 25A
The RS-485 (if applicable) requires 24 gauge, two conductor, shielded, twisted pair cable between sensor and host
PC. Use Belden part number 9841. Two sets of terminals are located on the connector board to facilitate serial loop
wiring from sensor to sensor. Wiring designators are
This wiring table is based on stranded tinned copper wire and is designed to serve as a reference only.
Over-current Protection AWG Over-current Protection
(4-20 mA output)
A& B
+
(DC), –(DC) , and mA(sensor signal). Maximum
(IN) and A& B(OUT).
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:
(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) Accessibility for routine maintenance
Density
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
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.
- 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 f langes, valves, and tubing connec-
Model FP-624C Combustible Gas Sensor PG.8
Ventilation
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
Seal
Fitting
Drain
“T”
Plug any unused ports.
anner where the migration of gas clouds is quickly detected.
m
- Normal ventilation or prevailing wind conditions can dictate efficient location of gas sensors in a
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.
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 permanent sensor damage.
Figure #1
3.5.3 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.
3.5.4 Accessibility
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:
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.
3.5.5 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, RS-485 wiring, and applicable alarm wiring to the
sensor base connector board in accordance with the detail shown in Figure 3. Normally open and normally closed
Form C dry contacts (rated 5 amp @ 120VAC; 5 amp @ 30VDC) are provided for Fault, Alarm 1, and Alarm 2.
Figure #2
Note 1
volt power source to the next sensor in the serial loop (never mix VAC and VDC in the same conduit run).
Note 2:
voltages.
: The second electrical port should be used for wiring to relay contacts or to connect RS-485 and/or 24
Per U.L. approval, these relays may only be used in connecting to devices that are powered by the
same
Model FP-624C Combustible Gas Sensor PG.9
d)Position gold plated jumper tabs located on the connector board in accordance with desired Form C dry
FAULT
ALARM 1
Latch
Energize
Latch
Ascending
Energize
AL
ARM 2
L
a
tc
h
A
s
c
e
n
d
in
g
E
n
e
rg
iz
e
CPU Board - Top View
Alarm Programming Jumpers
Control Circuit - Side View
CPU Board
N
C
A
LARM 1
WHT
BLK
YEL
BLU
M
A
V
DC Power In
N
O
N
C
N
O
N
C
N
O
NO/NC
COM
NO/NC
COM
NO/NC
COM
F
AULT ALM-2 ALM-1
A
larm Dry Contacts
A
LARM 2
F
AULT
R
1
A
B
A
B
4
-20 mA Output
R
S-485 In
R
S-485 Out
Optional Voltage
Developing Resistor
Use 250 ohm 1/4w
JUMPERS
UN-USED
J
umper Programmable Alarm Outputs
N
ormally Open or Normally Closed
Sensor
Place un-used alarm programming
j
umper tabs here
contact outputs: NO = Normally Open; NC = Normally closed (see figure 3).
Figure #3
Note
: If a voltage signal output is desired in place of the 4-20mA output, a 1/4 watt resistor must be installed
in position R1 of the terminal board. A 250Ω resistor will provide a 1-5V output (– to mA). A 100Ω resistor will
provide a .4-2V output, etc. This linear signal corresponds to 0-100% of scale (see figure 3).
e) Program the alarms via the gold plated jumper tab positions located on the CPU board (see figure 4). Alarm 1
and Alarm 2 have three jumper programmable functions: latching/non-latching relays, normally energized/normally de-energized relays, and ascending/descending alarm set points. The fault alarm has two jumper programmable functions: latching/non-latching relay, and normally energized/normally de-energized relay. The default
settings of the alarms (jumpers removed) are normally de-energized relays, non-latching relays, and alarm points
that activate during descending gas conditions.
If a jumper tab is installed in the latch position, that alarm relay will be in the latching mode. The latching
mode will latch the alarm after alarm conditions have cleared until the alarm reset function is activated. The nonlatching mode (jumper removed) will allow alarms to de-activate automatically once alarm conditions have cleared.
If a jumper tab is installed in the energize position, that alarm relay will be in the energized mode. The energized mode will energize or activate the alarm relay when there is no alarm condition and de-energize or de-activate the alarm relay when there is an alarm condition. The de-energized mode (jumper removed) will energize or
activate the alarm relay during an alarm condition and de-energize or de-activate the alarm relay when there is
no alarm condition.
If a jumper tab is installed in the ascending position, that alarm relay will be in the ascending mode. The
ascending mode will cause an alarm to fire when the gas concentration detected is greater than or equal to the
alarm set point. The descending mode (jumper removed) will cause an alarm to fire when the gas concentration
detected is lesser than or equal to the alarm set point. Except in special applications, combustible gas monitoring will require alarms to fire in
Any unused jumper tabs should be stored on the connector board on the terminal strip labeled “Unused
Jumpers” (see figure 3).
“ASCENDING”
gas conditions.
Model FP-624C Combustible Gas Sensor PG.10
Figure #4
Preamp Board - Side View
RS-485 ID Set Dip Switches
Control Circuit - Side View
Preamp Board
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
SW2SW1
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. Use a jewelers screwdriver to
set the rotary dip switches according to the hexidecimal table listed below. If RS-485 communications are not
used, leave the dip switches in the default position which is zero/zero (0)-(0).
Hexidecimal Table
ID# SW1 SW2
none 00
101
202
303
404
505
606
707
808
909
10 0A
11 0B
12 0C
13 0D
14 0E
15 0F
16 10
17 11
18 12
19 13
20 14
21 15
22 16
23 17
24 18
25 19
26 1A
27 1B
28 1C
29 1D
30 1E
31 1F
32 20
33 21
34 22
35 23
36 24
37 25
38 26
39 27
40 28
41 29
42 2A
g) Replace the plug-in control circuit and replace the junction box cover.
ID# SW1 SW2
43 2B
44 2C
45 2D
46 2E
47 2F
48 30
49 31
50 32
51 33
52 34
53 35
54 36
55 37
56 38
57 39
58 3A
59 3B
60 3C
61 3D
62 3E
63 3F
64 40
65 41
66 42
67 43
68 44
69 45
70 46
71 47
72 48
73 49
74 4A
75 4B
76 4C
77 4D
78 4E
79 4F
80 50
81 51
82 52
83 53
84 54
85 55
ID# SW1 SW2
86 56
87 57
88 58
89 59
90 5A
91 5B
92 5C
93 5D
94 5E
95 5F
96 60
97 61
98 62
99 63
100 64
101 65
102 66
103 67
104 68
105 69
106 6A
107 6B
108 6C
109 6D
110 6E
111 6F
112 70
113 71
114 72
115 73
116 74
117 75
118 76
119 77
120 78
121 79
122 7A
123 7B
124 7C
125 7D
126 7E
127 7F
128 80
ID# SW1 SW2
129 81
130 82
131 83
132 84
133 85
134 86
135 87
136 88
137 89
138 8A
139 8B
140 8C
141 8D
142 8E
143 8F
144 90
145 91
146 92
147 93
148 94
149 95
150 96
151 97
152 98
153 99
154 9A
155 9B
156 9C
157 9D
158 9E
159 9F
160 A0
161 A1
162 A2
163 A3
164 A4
165 A5
166 A6
167 A7
168 A8
169 A9
170 AA
171 AB
ID# SW1 SW2
172 AC
173 AD
174 AE
175 AF
176 B0
177 B1
178 B2
179 B3
180 B4
181 B5
182 B6
183 B7
184 B8
185 B9
186 BA
187 BB
188 BC
189 BD
190 BE
191 BF
192 C0
193 C1
194 C2
195 C3
196 C4
197 C5
198 C6
199 C7
200 C8
201 C9
202 CA
203 CB
204 CC
205 CD
206 CE
207 CF
208 D0
209 D1
210 D2
211 D3
212 D4
213 D5
214 D6
ID# SW1 SW2
215 D7
216 D8
217 D9
218 DA
219 DB
220 DC
221 DD
222 DE
223 EF
224 E0
225 E1
226 E2
227 E3
228 E4
229 E5
230 E6
231 E7
232 E8
233 E9
234 EA
235 EB
236 EC
237 ED
238 EE
239 FF
240 F0
241 F1
242 F2
243 F3
244 F4
245 F5
246 F6
247 F7
248 F8
249 F9
250 FA
251 FB
252 FC
253 FD
254 FE
255 FF
Model FP-624C Combustible Gas Sensor PG.11
3.5.6 Remote Mounting Applications
1234
WHT
BLK
YEL
BLU
Install
Jumper
Remote Transmitter
FP-624-RT
Remote Sensor
FP-624-RS
Measure Bridge Voltage
From White (1) to Blue (4)
Target voltage is 2.7v
WHT
BLK
YEL
BLU
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 FP624C sensor in a remote-mount configuration in which the sensor (Model FP-624C-RS) and the transmitter (Model
FP-624C-RT) are provided in their own condulet housing and are interfaced together with a three conductor cable.
There is a limit 0.5 ohm maximum resistance drop per wire over the seperation distance.
AWG
Maximum Seperation (feet)
20 50
18 75
16 125
14 175
Reference figure 5A 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.
Figure #5A
Remote Mounting Configuration - Bridge Voltage Adjustment
When a sensor is remotely mounted away from the transmitter, 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 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 3.6.1 for instructions.
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:
a) FP-624C “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:
All alarms will be disabled for 1 minute after power up. In the event of power failure, the alarm disable peri-
od will begin again once power has been restored.
Note 2: If the display contrast needs adjustment, refer to section 3.11.
Note 3: 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).
Model FP-624C Combustible Gas Sensor PG.12
3.6.1 Remote Mount Bridge Voltage Setup
Magnetic Programming Tool
detcon inc.
Program Switch #2
FLT
ALM
1
CAL
MicroSafe™ LEL Gas Sensor
HOUS TON , TEX AS
PGM 2
PGM 1
ALM
2
MODEL FP-624C
CONTRAST
Alarm & Cal LEDs
Program Switch #1
Menu Driven Display
Plug-in Microprocessor Control Circuit
Display Contrast Adjust
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.
3.6.2 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
labeled “PGM 1” and “PGM 2” allow for complete calibration and alarm level programming without removing the
enclosure cover, thereby eliminating the need for area de-classification or the use of hot permits.
A magnetic programming tool (see figure 6) 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 7.
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.
Figure #7
3.6.1 Continued - Set Sensor Bridge Voltage Procedure
a) Declassify the area around the sensor.
b) Remove the junction box cover from the remote sensor enclosure (see figure 5A).
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 5A. Target voltage is 2.7 ±0.2 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 VOLTS U/D”.
f) Use the programming magnet to make an adjustment to “PGM 1” to increase or “PGM 2” to decrease the
bridge voltage.
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.
Model FP-624C Combustible Gas Sensor PG.13
h) 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.
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.
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 f low 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”
c) If alarms are activated during the test, and have been programmed for latching operation, reset them according to
the instructions in section 3.10.2.
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.
.
3.7 TARGET GAS AND CALIBRATION GAS SELECTION
Because of the catalytic detector elements almost universal response to lower explosive limits of combustible gas,
the FP-624C 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-624C 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 f igure 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 in other gases.
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.
Verification of specific target gas and calibration gas settings is required before commissioning.
Material Requirements:
Detcon PN 3270 MicroSafe™ Programming Magnet
Model FP-624C Combustible Gas Sensor PG.14
Methylethylketone
Cyclohexane
Benzene
Hydrogen Sulphide
Methyl n-propylketone
Toluene
2,3-Dimethylpentane
Triethylamine
2,2-Dimethylpropane
Ethylcyclopentane
Aniline
m-Xylene
p-Xylene
n-Heptane
n-Butyric Acid
n-Octane
n-Hexane
o-Xylene
Ethyl Benzene
n-Butyl Alcohol
Naphthalene
Naptha
Decane
n-Amyl Alcohol
iso-Butyl Benzene
n-Butyl Benzene
n-Nonane
Biphenyl
Carbon Disulphide
2.42
2.43
2.45
2.45
2.46
2.47
2.51
2.51
2.52
2.52
2.54
2.55
2.55
2.59
2.63
2.67
2.71
2.79
2.80
2.91
2.94
3.03
3.05
3.06
3.12
3.18
3.18
4.00
5.65
Ethyleneoxide
Ethyl Acetate
Methylpropionate
Propylene
Alkyl Alcohol
trans-Butene-2
Methyl Acetate
Diethylamine
cis-Butene-2
Trimethylamine
n-Propylamine
Hydrogencyanide
n-Propyl Alcohol
iso-Pentane
Diethyl Ether
Acetic Anhydride
n-Pentane
Propyleneoxide
Butene-1
Hydrazine
1,4-Dioxane
Ethyl Formate
Methylcyclohexane
Methylethylether
iso-Propylether
Dimethylsulphide
Vinyl Chloride
Vinylethylether
Propyne
1.93
1.95
1.95
1.95
1.96
1.97
2.01
2.05
2.06
2.06
2.07
2.09
2.12
2.15
2.16
2.17
2.18
2.18
2.20
2.22
2.24
2.26
2.26
2.27
2.29
2.30
2.32
2.38
2.40
Ammonia
Methane
Carbon Oxysulphide
Cyanogen
Methyl Alcohol
Methylamine
Hydrogen
Carbon Monoxide
tert-Buty-alcohol
Ethyl Alcohol
Ethylene
Ethane
Methyl Formate
Cyclopropane
Dimethyl Ether
Methylmercaptan
Acetaldehyde
Butane
Nitromethane
Dimethylamine
Acetylene
Ethylmercaptan
1,3-Butadiene
Propane
Acetic Acid
iso-Butyl Alcohol
Ethylamine
Acetone
iso-Butane
0.79
1.00
1.07
1.12
1.16
1.29
1.30
1.32
1.34
1.37
1.41
1.47
1.49
1.60
1.60
1.64
1.66
1.71
1.72
1.73
1.76
1.78
1.79
1.81
1.84
1.89
1.90
1.93
1.93
Gas KGas KGas K
TABLE 1b (numerical listing)
Dimethyl Ether
Methylethylether
Methylethylketone
Methyl Formate
Methylmercaptan
Methylpropionate
Methyl n-propylketone
Naptha
Naphthalene
Nitromethane
n-Nonane
n-Octane
n-Pentane
iso-Pentane
Propane
n-Propyl Alcohol
n-Propylamine
Propylene
Propyleneoxide
iso-Propylether
Propyne
Toluene
Triethylamine
Trimethylamine
Vinyl Chloride
Vinylethylether
o-Xylene
m-Xylene
p-Xylene
1.60
2.27
2.42
1.49
1.64
1.95
2.46
3.03
2.94
1.72
3.18
2.67
2.18
2.15
1.81
2.12
2.07
1.95
2.18
2.29
2.40
2.47
2.51
2.06
2.32
2.38
2.79
2.55
2.55
Decane
Diethylamine
Dimethylamine
2,3-Dimethylpentane
2,2-Dimethylpropane
Dimethylsulphide
1,4-Dioxane
Ethane
Ethyl Acetate
Ethyl Alcohol
Ethylamine
Ethyl Benzene
Ethylcyclopentane
Ethylene
Ethyleneoxide
Diethyl Ether
Ethyl Formate
Ethylmercaptan
n-Heptane
n-Hexane
Hydrazine
Hydrogencyanide
Hydrogen
Hydrogen Sulphide
Methane
Methyl Acetate
Methyl Alcohol
Methylamine
Methylcyclohexane
3.05
2.05
1.73
2.51
2.52
2.30
2.24
1.47
1.95
1.37
1.90
2.80
2.52
1.41
1.93
2.16
2
.26
1.78
2
.59
2.71
2.22
2.09
1.30
2.45
1.00
2.01
1.16
1.29
2.26
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
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
1.89
1.34
3.18
3.12
2.63
5.65
1.32
1.07
1.12
2.43
1.60
Gas KGas
K
Gas K
TABLE 1a (alphabetical listing)
Model FP-624C Combustible Gas Sensor PG.15
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 Alarm 1 Level, and Set Alarm 2 Level, Set Gas
Factor (target gas), Set Cal Factor (calibration gas).
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 #12 and the “K factor” for the calibration gas is displayed in item #13. Compare the K factors to the listing in Table 1 to determine the target/calibration gas conf iguration.
The gas type, range of detection and software version number. The menu item appears as:
1 -
“LEL 0-100 V6.0”
2 - The alarm set point level of alarm 1. The menu item appears as: “ALM1 SET @ 20%”
3 - The alarm firing direction of alarm 1. The menu item appears as: “ALM1 ASCENDING”
4 - The alarm relay latch mode of alarm 1. The menu item appears as: “ALM1 NONLATCHING”
5 - The alarm relay energize state of alarm 1. The menu item appears as: “ALM1 DE-ENERGIZED”
6 - The alarm set point level of alarm 2. The menu item appears as: “ALM2 SET @ 40%”
7 - The alarm firing direction of alarm 2. The menu item appears as: “ALM2 ASCENDING”
8 - The alarm relay latch mode of alarm 2. The menu item appears as: “ALM2 LATCHING”
9 - The alarm relay energize state of alarm 2. The menu item appears as: “ALM2 DE-ENERGIZED”
10 - The alarm relay latch mode of the fault alarm. The menu item appears as: “FLT NONLATCHING”
11 - The alarm relay energize state of the fault alarm. The menu item appears as: “FLT ENERGIZED”
12 - The target gas K factor. The menu item appears as: “GAS FACTOR #.##”
13 - The calibration gas K factor. The menu item appears as: “CAL FACTOR #.##”
14 - The calibration gas level setting. The menu item appears as: “CalLevel @ xx%”
15 - Identification of the RS-485 ID number setting. The menu item appears as: “485 ID SET @ 1”
16 - 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-624C 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.
Model FP-624C Combustible Gas Sensor PG.16
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 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 f low 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 target gas present.
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: In every instance where a sensor is re-zeroed, the zero error is directly proportional to resulting span
error. For example, if a sensor zero error is 2 %, upon completion of auto zero, the resulting span error is 2 %.
When this error exceeds 5% of full scale sensitivity, the sensor should be calibrated with span gas.
NOTE 3: When a “cal fault” occurs, the sensor microprocessor retains its previous calibration references.
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.
Verification of the correct calibration gas level setting and calibration span gas concentration is
Model FP-624C Combustible Gas Sensor PG.17
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”.
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, and Set Cal Level.
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 “APPLY
xx% LEL” then withdraw the programming magnet. The x’s here indication 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 which will activate fault alarm functions (see section 3.11) and cause the display to alternate between the sensor’s current status reading and the calibration fault screen which appears as:
“CAL FAULT”. 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-624C Combustible Gas Sensor PG.18
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. 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 3.82), and alarm levels (see section 3.10).
The following procedure is used to view the programming status of the sensor:
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 Alarm 1 Level, Set Alarm 2 Level, Set Gas Factor,
Set Cal Factor, and Set Cal Level.
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 alarm set point level of alarm 1. The menu item appears as: “ALM1 SET @ 20%”
3 - The alarm firing direction of alarm 1. The menu item appears as: “ALM1 ASCENDING”
4 - The alarm relay latch mode of alarm 1. The menu item appears as: “ALM1 NONLATCHING”
5 - The alarm relay energize state of alarm 1. The menu item appears as: “ALM1 DE-ENERGIZED”
6 - The alarm set point level of alarm 2. The menu item appears as: “ALM2 SET @ 40%”
7 - The alarm firing direction of alarm 2. The menu item appears as: “ALM2 ASCENDING”
8 - The alarm relay latch mode of alarm 2. The menu item appears as: “ALM2 LATCHING”
9 - The alarm relay energize state of alarm 2. The menu item appears as: “ALM2 DE-ENERGIZED”
10 - The alarm relay latch mode of the fault alarm. The menu item appears as: “FLT NONLATCHING”
11 - The alarm relay energize state of the fault alarm. The menu item appears as: “FLT ENERGIZED”
12 - The target gas K factor. The menu item appears as: “GAS FACTOR #.##”
13 - The calibration gas K factor. The menu item appears as: “CAL FACTOR #.##”
14 - The calibration gas level setting. The menu item appears as: “CalLevel @ xx%”
15 - Identification of the RS-485 ID number setting. The menu item appears as: “485 ID SET @ 1”
16 - 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 PROGRAMMING ALARMS
3.10.1 Alarm Levels
Both alarm 1 and alarm 2 levels are factory set prior to shipment. Alarm 1 is set at 20%; alarm 2 at 40%. Both
alarms can be set in 1% increments from 10 to 90%. The following procedure is used to change alarm set points:
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 Alarm 1 Level, Set Alarm 2 Level, Set Gas Factor,
Set Cal Factor, and Set Cal Level.
b) ALARM 1 LEVEL
“SET ALARM 1 LEVEL”. Enter the menu by holding the programming magnet stationary over “PGM 1”
for 3 seconds until the display reads “SET ALM1 @ 20%”, then withdraw the magnet. Use the programming
From the programming menu scroll to the alarm 1 level listing. The menu item appears as:
Model FP-624C Combustible Gas Sensor PG.19
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
“SET ALARM 2 LEVEL”. Enter the menu by holding the programming magnet stationary over “PGM 1”
for 3 seconds until the display reads “SET ALM2 @ 40%”, 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 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.
d) 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.
3.10.2 Alarm Reset
An alarm condition will cause the applicable alarm to activate its corresponding relay and LED. If alarm 1, alarm 2,
or fault alarms have been programmed for latching relays, an alarm reset function must be activated to reset the
alarms after an alarm condition has cleared. To reset the alarms, simply wave the programming magnet over either
“PGM 1” or “PGM 2”, momentarily, while in normal operations mode and note that the corresponding alarm
LED(s) turn off.
3.10.3 Other Alarm Functions
Alarms are factory programmed to be non-latching, de-energized; and to fire under ascending gas conditions. The
fault alarm relay is programmed as normally energized which is useful for detecting a 24VDC power source failure.
All alarm functions are programmable via jumper tabs. Changing alarm functions requires the sensor housing to be
opened, thus declassification of the area is required. See section 3.5.5-e for details.
From the programming menu scroll to the alarm 2 level listing. The menu item appears as:
3.11 PROGRAM FEATURES
Model FP-624C 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 should drift below a zero baseline of approximately 10% of scale, 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. The 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”.
Model FP-624C Combustible Gas Sensor PG.20
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.
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.
3.12 RS-485 PROTOCOL
Detcon MicroSafe™ sensors feature Modbus™ compatible communications protocol and are addressable via rotary
dip switches for multi-point communications. Other protocols are available. Contact the Detcon factory for specific
protocol requirements. Communication is two wire, half duplex 485, 9600 baud, 8 data bits, 1 stop bit, no parity,
with the sensor set up as a slave device. A master controller up to 4000 feet away can theoretically poll up to 256
different sensors. This number may not be realistic in harsh environments where noise and/or wiring conditions
would make it impractical to place so many devices on the same pair of wires. If a multi-point system is being utilized, each sensor should be set for a different address. Typical address settings are: 01, 02, 03, 04, 05, 06, 07, 08, 09,
0A, 0B, 0C, 0D, 0E, 0F, 10, 11, etc.
In most instances, RS-485 ID numbers are factory set or set during installation before commissioning. If required,
the RS-485 ID number can be set via rotary dip switches located on the preamp circuit board. However, any change
to the RS-485 ID number would require the sensor housing to be opened, thus declassification of the area would
be required. See section 3.5.4-f for details on changing the RS-485 ID number.
The following section explains the details of the Modbus™ protocol that the MicroSafe™ sensor supports.
Code 03 - Read Holding Registers, is the only code supported by the transmitter. Each transmitter contains 6 holding registers which reflect its current status.
Register #
40000 Gas type Sensor Life
Gas type is one of the following:
01=CO, 02=H2S, 03=SO2, 04=H2, 05=HCN, 06=CL2, 07=NO2, 08=NO, 09=HCL, 10=NH3, 11=LEL, 12=O2
Sensor life is an estimated remaining use of the sensor head, between 0% and 100%
Example: 85=85% sensor life
Register #
40001 Detectable Range
i.e. 100 for 0-100 ppm, 50 for 0-50% LEL, etc.
Register #
40002 Current Gas Reading
The current gas reading as a whole number. If the reading is displayed as 23.5 on the display, this register would
contain the number 235.
High Byte Low Byte
High Byte Low Byte
High Byte Low Byte
Register #
40003 Alarm 1 Setpoint
High Byte Low Byte
Model FP-624C Combustible Gas Sensor PG.21
This is the trip point for the first alarm.
Register #
High Byte Low Byte
40004 Alarm 2 Setpoint
This is the trip point for the second alarm.
Register #
High Byte Low Byte
40005 Status Bits Status Bits
High Byte
Bit 7 Not used, always 0
Bit 6 Not used, always 0
Bit 5 Not used, always 0
Bit 4 Not used, always 0
Bit 3 1-Unit is in calibration 0-Normal operation
Bit 2 1-Alarm 2 is ascending 0-Alarm 2 is descending
Bit 1 1-Alarm 2 is normally energized 0-Alarm 2 is normally de-energized
Bit 0 1-Alarm 2 is latching 0-Alarm 2 is non-latching
Low Byte
Bit 7 1-Alarm 2 Relay is energized 0-Alarm 2 Relay is not energized
Bit 6 1-Alarm 1 is ascending 0-Alarm 1 is descending
Bit 5 1-Alarm 1 is normally energized 0-Alarm 1 is normally de-energized
Bit 4 1-Alarm 1 is latching 0-Alarm 1 is non-latching
Bit 3 1-Alarm 1 Relay is energized 0-Alarm 1 Relay is not energized
Bit 2 1-Fault is normally energized 0-Fault is normally de-energized
Bit 1 1-Fault is latching 0-Fault is non-latching
Bit 0 1-Fault Relay is energized 0-Fault Relay is not energized
The following is a typical Master Query for device # 8:
Field
Name HEX DEC RTU
Slave Address 08 8 0000 1000
Function 03 3 0000 0011
Start Address Hi 00 0 0000 0000
Start Address Lo 00 0 0000 0000
No. of Registers Hi 00 0 0000 0000
No. of Registers Lo 06 6 0000 0110
CRC ## #### ####
CRC ## #### ####
The following is a typical Slave Response from device # 8:
Name HEX DEC RTU
Field
Slave Address 08 8 0000 1000
Function 03 3 0000 0011
Byte Count 0C 12 0000 1100
Reg40000 Data Hi 02 2 0000 0010
Reg40000 Data Lo 64 100 0110 0100
Reg40001 Data Hi 00 0 0000 0000
Reg40001 Data Lo 64 100 0110 0100
Reg40002 Data Hi 00 0 0000 0000
Model FP-624C Combustible Gas Sensor PG.22
Reg40002 Data Lo 07 7 0000 0111
Reg40003 Data Hi 00 0 0000 0000
Reg40003 Data Lo 0A 10 0000 1010
Reg40004 Data Hi 00 0 0000 0000
Reg40004 Data Lo 14 20 0001 0100
Reg40005 Data Hi 05 5 0000 0101
Reg40005 Data Lo 50 80 0101 0000
CRC ## #### ####
CRC ## #### ####
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.
3.13 DISPLAY CONTRAST ADJUST
Model FP-624C 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 7 for
location.
3.14 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.
4. Replace sensor if verified as Open Sensor.
Signal Fault
1. Zero has drifted too far negative.
2. Re-zero sensor in clean air.
Poor Sensor Performance (Slow Response, Drifting Sensor)
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.
Detcon has two version sensors: C-Style and the J-Style. Each uses a different heater voltage setting.
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.
Model FP-624C Combustible Gas Sensor PG.23
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. 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.
4. Add/change Detcon condensation prevention packet PN 960-202200-000 (replace annually).
5. Check for unstable power supply.
6. Check for inadequate grounding.
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 or RS485 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-624C Combustible Gas Sensor PG.24
3.15 SPARE PARTS LIST
Spash Guard
Rain Shield
Enclosure less cover
Connector Board
Calibrati on Ad ap te 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)
613-010000-000 Sensor rain shield
613-120000-000 Sensor splash guard
943-000006-132 Threaded Calibration Adapter
612-820000-000 LEL sensor housing assembly (plug-in detector, PN370-201600-000, not included)
370-201600-000 Sensor: field replaceable plug in detector
926-525500-100 FP-624C Plug-in control circuit
500-001794-004 Connector board
327-000000-000 Programming Magnet
897-850800-000 3 port enclosure less cover
897-850700-000 Enclosure glass lens cover
960-202200-000 Condensation prevention packet (replace annually).
Figure #8
3.16 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.
3.17 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 $65.00. The fixed fee service
policy shall affect any factory repair for the period following the two year warranty and shall end f ive years after
expiration of the warranty. All warranties and service policies are FOB the Detcon facility located in The
Woodlands, Texas.
Model FP-624C Combustible Gas Sensor PG.25
3.18 SOFTWARE FLOW CHAR
NORMAL
OPERATION
CALIBRATION
PGM1 (3) PGM2 (3)
PGM1 (M) PGM2 (M)
PGM1 (3)
SET ALM1 @ ##%
INC
DEC
PGM1 (3) PGM2 (M)
1-ZERO 2-SPAN
LEGEND
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
INC - increase
DEC - decrease
# - numeric value
A
UTO ZERO
A
UTO SPAN
S
ET ALARM 1 LEVEL
LEL 0-100 V#.#
PGM1 (3) PGM2 (M)
V
IEW PROG STATUS
ALM1 SET @ ##%
ALM2 SET @ ##%
GAS FACTOR #.##
PGM1 (M) PGM2 (M)
PGM1 (3)
SET ALM2 @ ##%
INC
DEC
PGM1 (3) PGM2 (M)
S
ET ALARM 2 LEVEL
P
GM2 (3)
P
GM2 (3)
P
GM2 (3)
CAL LEVEL @ ##%
ALM1 (Firing Direction)
ALM1 (Latch State)
ALM1 (Energize State)
ALM2 (Firing Direction)
ALM2 (Latch State)
ALM2 (Energize State)
FLT (Latch State)
FLT (Energize State)
PGM1 (3) PGM1 (M)
PGM2 (30) PGM2 (M)
ALARM RESET
ALARM RESET
485 ID SET @ #
SENSOR LIFE ##%
PGM1 (M) PGM2 (M)
PGM1 (3)
INC
DEC
PGM1 (3) PGM2 (M)
PGM1 (M) PGM2 (M)
PGM1 (3)
CAL FACTOR #.##
INC
DEC
PGM1 (3) PGM2 (M)
SET CAL FACTOR
PGM2 (3) PGM2 (3)
PGM1 (M) PGM2 (M)
PGM1 (3)
BRIDGE VOLTS U/D
INC
DEC
PGM1 (3) PGM2 (M)
SET BRIDGE VOLTS
PGM2 (3)
CAL FACTOR #.##
PGM1 (M) PGM2 (M)
PGM1 (3)
GAS FACTOR #.##
INC
DEC
PGM1 (3) PGM2 (M)
S
ET GAS FACTOR
P
GM2 (3)
CAL LEVEL @ ##%
SET CAL LEVEL
phone 888-367-4286, 281-367-4100 • fax 281-292-2860 • www.detcon.com • sales@detcon.com
Shipping Address: 3200 A-1 Research Forest Dr., The Woodlands, Texas 7381
Mailing Address: P.O. Box 8067, The Woodlands, Texas 77387-8067
Model FP-624C Combustible Gas Sensor PG.26
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