detcon inc.
™
Detcon MicroSafe
TP-624C Hydrogen Sulfide Sensor
his manual covers the following ranges: 0-20 PPM, 0-50 PPM, and 0-100 PPM
T
Operator’s Installation & Instruction Manual
February 01, 2010 • Document #2017 • Version 8.2
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 Calibration
3.8 Status of Programming: Software Version, Alarms, Calibration Level, RS-485 ID,
Heater Voltage, Range, and Sensor Life
3.9 Programming Alarms
3.10 Program Features
3.11 RS-485 Protocol
3.12 Display Contrast Adjust
3.13 Trouble Shooting Guide
3.14 Spare Parts List
3.15 Warranty
3.16 Service Policy
3.17 Software Flow Chart
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.2
3.0 DESCRIPTION
Construction of
Semiconductor Sensor
Sensor
Film
Heater
Film
Silicon
Microchip
Detcon MicroSafe™ Model TP-624C, hydrogen sulfide sensors are non-intrusive “Smart” sensors designed to detect
and monitor H2S in air. Ranges of detection are user-settable between 0-20 ppm, 0-50 ppm, and 0-100 ppm. One of
the primary features of the sensor is its method of automatic calibration which guides the user through each step
via instructions displayed on the backlit LCD. The sensor features field adjustable, fully programmable alarms,
relays for two gas level alarms, and one for any fault condition. The sensor is equipped with both an analog 4-20
mA, and serial RS-485 output. 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.
3.0.1 Sensor Technology
The sensor technology is a patented solid state metal oxide semiconductor. The sensor consists of two thin films; a
temperature sensitive heater film, and an hydrogen sulfide sensitive sensor film. Both films are deposited on a silicon microchip by vacuum deposition. The heater film elevates the operating temperature of the sensor film to a
level where a good sensitivity and response to hydrogen sulfide is achieved. The sensor film is a proprietary metal
oxide that shows a dynamic response to hydrogen sulfide gas. Range of sensitivity is from part per billion to % by
volume. The rugged sensor is capable of maintaining its operating characteristics for periods of up to 7-10 years in
most industrial environments and as such, is supported by a 10-year conditional warranty.
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.3
3.0.2 Microprocessor Control Circuit
detcon inc.
Program Switch #2
FLT
ALM
1
CAL
MicroSafe™ H2S Gas Sensor
HOUS TON, TEX AS
PGM 2
PGM 1
ALM
2
MODEL TP-624C
CONTRAST
Alarm & Cal LEDs
Program Switch #1
Menu Driven Display
Display Contrast Adjust
Plug-in Microprocessor Control Circuit
NC
ALARM 1
WHT
BLK
YEL
BLU
MA
VDC Power In
NO
NC
NO
NC
NO
NO/NC
COM
NO/NC
COM
NO/NC
COM
F
AULT ALM-2 ALM-1
Alarm Dry Contacts
ALARM 2
FAULT
R1
A
B
A
B
4-20 mA Output
RS-485 In
RS-485 Out
Optional Voltage
Developing Resistor
Use 250 ohm 1/4w
JUMPERS
UN-USED
Jumper Programmable Alarm Outputs
Normally Open or Normally Closed
Sensor
Place un-used alarm programming
jumper tabs here
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, 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.
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, 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; Division 1; Groups B, C, D (explosion proof).
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.4
3.1 PRINCIPLE OF OPERATION
Functional
Block
Diagram
Functional
Block
Diagram
Analog 4-20 mA Out
P
ower In
Relays Out
Pre-Amp Display
Tem per atu re
C
ompensation
Alarm & Fault
R
elays
RS-485 & 4-20mA
Micro-
p
rocessor
T
ransmitter
Power Supply
S
ensor
E
lement
I
/O Circuit
P
rotection
Serial RS-485 Out
Method of detection is by diffusion/adsorption. Air and gas diffuse through a sintered stainless steel filter and contact
the heated surface of the metal oxide sensor film. As hydrogen sulfide gas molecules react with oxygen ions on the
film, there is a decrease in electrical resistance proportional to the gas concentration. The heater film elevates the temperature of the sensor film creating convection and promoting a quick response to changing gas concentrations.
Electronically, the heater film is used to maintain a constant temperature of the sensor film enhancing stability and
repeatability. The sensor response is reversible and results in continuous monitoring of ambient air conditions.
3.2 APPLICATION
Model TP-624C MicroSafe™ sensors are designed to detect and monitor hydrogen sulfide gas in ambient air in the
range of 0-100 parts per million. The sensor can also be programmed to operate in the range 0-20 ppm or 0-50 ppm.
Minimum sensitivity and scale resolution is 1 ppm. 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. Hydrogen sulfide gas is slightly heavier
than air (approximately 1.18); therefore, the sensors are generally located 2 - 4 feet above grade.
3.2.2 Interference Data
Gas PPM
Methane 25,000 = 0
Ethane 5,000 = 0
Hexane 5,000 = 0
Propane 5,000 = 0
Butane 5,000 = 0
Carbon Monoxide 800 = 0
Carbon Dioxide 5,000 = 0
Carbon Disulfide 14 = 0
Methanol 200 = 0
Isopropanol 200 = 0
Ammonia 500 = 0
Diesel Fuel = 0
Demethyl Sulfide 4.4 = 0
Ethylene 200 = 0
Freon 12 1000 = 0
Hydrogen 1000 = 8
Methyl Mercaptan 5 = 8
Sulfur Dioxide 300 = 0
Toluene 32 = 0
Ethanol 200 = 0
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.5
3.3 SPECIFICATIONS
Method of Detection
Solid state metal oxide diffusion/adsorption
Electrical Classification
CSA-NRTL approved Class I; Groups B, C, D; Div. 1.
Response Time
T50 < 45 seconds, T80 < 90 seconds
Clearing Time
T80 < 90 seconds
Repeatability
± 5% FS
Range
0-20 ppm, 0-50 ppm, or 0-100 ppm
Operating Temperature
-40° to +175° F
Accuracy
± 5% FS
Sensor Warranty
10 year conditional
Power Consumption
Normal operation = 83 mA (<2 watt); Full alarm = 118 mA (<3 watts)
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
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 flow chart.)
01. Normal Operation
a) Current Status
02. Calibration Mode
a) Span
03. Program Menu
a) View Program Status
b) Set Alarm 1 Level
c) Set Alarm 2 Level
d) Set Calibration Level
e) Set Heater Level
f) Set Range
g) Linearize Sensor
3.4.1 Normal Operation
In normal operation, the display reflects the current status of the sensor and gas concentration and appears as:
“0 PPM H2S”. The mA current output corresponds to the monitoring level and range of 0-100 ppm = 4-20 mA.
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.6
3.4.2 Calibration Mode
Calibration mode allows for sensor span adjustments. Unless otherwise specified, span adjustment is performed at
10 ppm H2S in air for the range 0-20 ppm, and 25 ppm H2S in air for the ranges 0-50 ppm and 0-100 ppm.
“AUTO SPAN”
3.4.3 Program Mode
The program mode provides a program status menu (View Program Status) to check operational parameters. It also
allows for the adjustment of alarm set point levels, the calibration gas level setting, the heater voltage level, range, and
linearity correction.
3.4.3.1 View 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: “H2S 0-100 V6.1”
* The alarm set point level of alarm 1. The menu item appears as: “ALM1 SET @ ##PPM”
* 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 @ ##PPM”
* 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.
* The calibration gas level setting. The menu item appears as: “CalLevel @ xxPPM”
* The sensor heater voltage setting. The menu item appears as: “HEATER @ #.##VDC”
* The range of detection setting. The menu item appears as: “RANGE @ 0-###PPM”
* 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% FS. For hydrogen sulfide gas sensors, the level is factory set
at 10 ppm. The menu item appears as: “SET ALM1 @ 10PPM”
3.4.3.3 Alarm 2 Level Adjustment
The alarm 2 level is also adjustable over the range 10 to 90% FS. For hydrogen sulfide gas sensors, the level is factory set at 20 ppm. The menu item appears as: “SET ALM2 @ 20PPM”
3.4.3.4 Calibration Level Adjustment
The Calibration level is adjustable from 10% to 50% of full scale range. The menu item appears as: “CalLevel @ ##PPM”
3.4.3.5 Set Heater Level Adjustment
The Heater Level is adjustable from 4.40 to 5.40 vdc (normally 5.25). The menu item appears as: “Heater @ #.## vdc”
3.4.3.6 Set Range
The full-scale range is adjustable between 0-20 ppm, 0-50 ppm and 0-100 ppm The item appears as: “Range @ 0-### ppm”
3.4.3.7 Sensor Linearization
The sensor linearization feature is a two point calibration reference used to characterize each sensor for linearity. Two calibration points are required: The menu item appears as: “Apply XX PPM Gas” & “Apply ## PPM Gas” depending on the
full-scale range selected.
3.5 INSTALLATION
Optimum performance of ambient air/gas sensor devices is directly relative to proper location and installation practice.
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.7
3.5.1 Field Wiring Table
(4-20 mA output)
Detcon Model TP-624C solid state H2S sensor assemblies require three conductor connection between power sup-
+
plies and host electronic controllers. Wiring designators are
(DC), –(DC) , and mA(sensor signal). Maximum
single conductor resistance between sensor and controller is 10 ohms. Maximum wire size for termination in the
sensor assembly terminal board is 14 gauge.
AWG Meters Feet
20 240 800
18 360 1200
16 600 2000
14 900 3000
Note 1:
This wiring table is based on stranded tinned copper wire and is designed to serve as a reference only.
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
Over-current Protection AWG Over-current Protection
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
A& B
(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) Maintenance access
Density
- Placement of sensors relative to the density of the target gas is such that sensors for the detection of
heavier than air gases should be located within 4 feet of grade as these heavy gases will tend to settle in low lying
areas. For gases lighter than air, sensor placement should be 4-8 feet above grade in open areas or in pitched areas
of enclosed spaces.
Leak Sources
- Most probable leak sources within an industrial process include flanges, valves, and tubing connections of the sealed type where seals may either fail or wear. Other leak sources are best determined by facility engineers with experience in similar processes.
Ventilation
- Normal ventilation or prevailing wind conditions can dictate efficient location of gas sensors in a
manner where the migration of gas clouds is quickly detected.
Personnel Exposure
- The undetected migration of gas clouds should not be allowed to approach concentrated personnel areas such as control rooms, maintenance or warehouse buildings. A more general and applicable thought
toward selecting sensor location is combining leak source and perimeter protection in the best possible configuration.
Maintenance Access
Consideration should be given to easy access by maintenance personnel as well as the consequences of close proximity to contaminants that may foul the sensor prematurely.
Note:
In all installations, the sensor element in SS housing points down relative to grade (Fig. 1). Improper sensor
orientation may result in false reading and permanent sensor damage.
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.8
EYS
Seal
Fitting
Drain
“T”
Plug any unused ports.
Figure #1
4 3/4"
3/4" NPT
1/4" Dia.
Mounting Holes
7"
6 1/8"
5 1/2"
3/4" NPT
Rainshield/
Splashguard
2"
2 1/8"
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 & breathers are recommended. The sensor assemblies are CSA-NRTL approved for Class I;
Groups B, C, D; Div. 1 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.
Securely mount the sensor junction box in accordance with recommended practice and proper orientation (see fig. 1 & 2).
b)
Figure #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 @ 125VAC; 5 amp @ 30VDC) are provided for Fault, Alarm 1, and Alarm 2.
Note:
Per U.L. approval, these relays may only be used in connecting to devices that are powered by the
voltages.
d) Position gold plated jumper tabs located on the connector board in accordance with desired Form C dry con-
tact outputs: NO = Normally Open; NC = Normally closed (see 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).
same
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.9
NC
ALARM 1
WHT
BLK
YEL
BLU
MA
VDC Power In
NO
NC
NO
NC
NO
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
RS-485 In
RS-485 Out
Optional Voltage
Developing Resistor
Use 250 ohm 1/4w
JUMPERS
U
N-USED
Jumper Programmable Alarm Outputs
Normally Open or Normally Closed
S
ensor
P
lace un-used alarm programming
j
umper tabs here
Figure #3
FAULT
ALARM 1
Latch
Energize
Latch
Ascending
Energize
ALARM 2
Latch
Ascending
Energize
CPU Board - Top View
Alarm Programming Jumpers
Control Circuit - Side View
CPU Board
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.
Figure #4
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, H2S 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
“ASCENDING”
Jumpers” (see figure 3).
gas conditions.
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.10
f) If applicable, set the RS-485 ID number via the two rotary dip switches located on the preamp board (see figure
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
5). There are 256 different ID numbers available which are based on the hexadecimal 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 hexadecimal table listed below. If RS-485 communications are not
used, leave the dip switches in the default position which is zero/zero (0)-(0).
Figure #5
Hexadecimal 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
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
g) Replace the plug-in control circuit and replace the junction box cover.
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.11
3.5.6 Remote Mounting Applications
1234
WHT
BLK
YEL
BLU
Remote Transmitter
TP-624C-RT
Remote Sensor
FP-624C-RS
WHT
BLK
YEL
BLU
Measure Heater V oltage
From White (1) to Black (2)
Target voltage is 5.25v
±.05 v
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 TP624C sensor in a remote-mount configuration in which the sensor (Model TP-624C-RS) and the transmitter (Model
TP-624C-RT) are provided in their own condulet housing and are interfaced together with a four conductor cable.
Reference figure 5A below for wiring diagram.
Figure #5A
Remote Mounting Configuration - Heater Voltage Adjustment
When a sensor is remote mounted, consideration must be given to the length and gauge of cable used and how it
affects the sensor heater voltage. Fourteen to sixteen gauge wire is recommended. Differing lengths of cables will
have varying amounts of resistance which will shift the sensor heater voltage. Because of this, the heater voltage will
need to be adjusted after initial power up. Replacement of the sensor will also require readjusting the heater voltage.
See section 3.6.2 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) TP-624C “Fault” LED is off.
b) A temporary upscale reading may occur as the sensor heats up. This upscale reading will clear to “0”
ppm within 1-2 minutes of turn-on, assuming there is no gas in the area of the sensor.
Important Note:
A desiccant cap is attached to the sensor housing during storage and shipping. This prevents H20 from contacting
the sensor film while it is off power, and thus helps to retain the stability of the factory span calibration. Remove
the desiccant cap 5~10 minutes after applying power to the sensor, then install the weatherproof splashguard accessory supplied with your sensor.
Store the desiccant caps in a sealed container (i.e., zip-lock bag) for future use. It is advised (but not mandatory) to
use the desiccant caps during long periods without power.
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.12
Note 1: All alarms will be disabled for 1 minute after power up. In the event of power failure, the alarm disable
period will begin again once power has been restored.
Note 2: If the display contrast needs adjustment, refer to section 3.12.
Note 3: If the sensor has been installed using the remote mounting configuration as described in section 3.5.6, the
sensor heater voltage must be adjusted after initial power up. If this is the case, first adjust the heater voltage as
described in section 3.6.2, then proceed with the initial operation tests below (section 3.6.1).
Note 4: The 4~20mA signal will be held at 4mA for the first two minutes after power up.
3.6.1 Initial Operational Tests
After a warm up period has been allowed for, the sensor should be checked to verify sensitivity to H2S gas.
Material Requirements
* Detcon PN 6038 Threaded Calibration Adapter
* Span Gas 25 ppm H2S in air at a controlled flow rate between 200 and 500 ml/min (or 10 ppm for 0-20 ppm
range - see section 3.6.4 for more information on ranges). NOTE: Do not use H2S and nitrogen gas mixtures.
* Detcon PN 985-241100-321 In-Line Humidifying Tube
a) Attach the Perma-Pure tubing inline with the tubing between the Cal Gas Cylinder and the sensor. The humid-
ifying tube will introduce the ambient relative humidity into the Cal Gas as it passes through the tube.
b) Attach the calibration adapter to the threaded sensor housing. Apply a the test gas at a controlled flow rate of
200 to 500 ml/m (200cc/min is the recommended flow). Observe that the LCD display increases to a level of
10-25 ppm or higher (or 5-10 ppm for 0-20 ppm range).
c) Remove the test gas and observe that the LCD display decreases to “0 PPM H2S”
.
d) If alarms are activated during the test, and have been programmed for latching operation, reset them according to
the instructions in section 3.9.2.
Initial operational tests are complete. Detcon H2S 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 16 to 24 hours after power-up. Refer to calibration instructions in later text.
3.6.2 Remote Mount Heater Voltage Setup
If the sensor has been installed using the remote mounting configuration as described in section 3.5.6, the sensor
heater voltage must be adjusted after initial power up. Replacement of the sensor will also require readjusting the
heater voltage. Follow the steps below to set the sensor heater voltage.
Material Requirements
* Detcon PN 3270 MicroSafe™ Programming Magnet
* Digital volt/ohm meter.
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 5A).
c) Using the digital volt/ohm meter, measure the bridge voltage at the remote sensor connector board from the
“White” terminal to the “Black” terminal as shown in figure 5A. Target voltage is 5.25 volts.
d) At the transmitter, enter the programming menu by holding the programming magnet stationary over “PGM 2”
for 15 seconds until the display reads “VIEW PROG STATUS”, then withdraw the magnet.
e) Next, scroll to the “SET HEATER VOLTS” listing and then hold the programming magnet over “PGM 1”
for 3 seconds. The menu item appears as “HEATER @ #.## VDC”.
f) Use the programming magnet to make an adjustment to “PGM 1” to increase or “PGM 2” to decrease the volt-
age. Set this voltage so that the voltage measured at the remote sensor connector board is 5.25 VDC. This is the
correct voltage for an ambient temperature of 25°C at the remote sensor connector board. If ambient tempera-
ture is not 25°C reference the table in section 3.6.5 for the proper voltage setting.
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.
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.13
i) Replace the junction box cover on the remote sensor enclosure.
Magnetic Programming Tool
detcon inc.
Program Switch #2
FLT
ALM
1
CAL
MicroSafe™ H2S Gas Sensor
HOUS TON , TEX AS
PGM 2
P
GM 1
ALM
2
MODEL TP-624C
CONTRAST
Alarm & Cal LEDs
Program Switch #1
Menu Driven Display
Display Contrast Adjust
Plug-in Microprocessor Control Circuit
Heater 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
labeled “PGM 1” and “PGM 2” allow for complete calibration and programming without removing the enclosure
cover, thereby eliminating the need for area de-classification or the use of hot permits.
Figure #6
A magnetic programming tool (see figure 6) is used to operate the switches. Switch action is defined as momentary
contact, 3 second hold, and 15 second hold. In momentary contact use, the programming magnet is waved over a
switch location. In 3 second hold, the programming magnet is held in place over a switch location for 3 or more
seconds. In 15 second hold, the programming magnet is held in place over a switch location for 15 or more seconds. Three and fifteen 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 6B.
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 #6B
3.6.4 Setting Range
Detcon Model TP-624C can be programmed to operate in one of three ranges of detection: 0-20 ppm, 0-50 ppm, or
0-100 ppm. To determine the current range setting follow the instructions given in section 3.8.
To change the range of detection follow the instructions below:
a) First, enter the programming menu by holding the programming magnet stationary over “PGM 2” for 15 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, Set Alarm 2, Set Cal Level, Set Heater Volts,
Set Range, and Linearize Sensor.
b) Next, scroll to the “SET RANGE” listing and then hold the programming magnet over “PGM 1” for 3 sec-
onds. The menu appears as “Range @ 0-### ppm” listing.
c) Use the programming magnet to make an adjustment to “PGM 1” to increase or “PGM 2” to decrease the read-
ing to the desired range.
d) 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.
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.
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.14
NOTE: When switching between ranges, remember to readjust your Cal Level setting if necessary (see section 3.7.2).
Also remember to adjust your alarm setpoints if necessary (see section 3.9.1)
3.6.5 Setting Heater Voltage
The Detcon TP-624C H2S sensor is factory set for the correct heater voltage and should be ready to install without
further adjustment being required. The correct heater voltage for the sensor is 5.25 VDC when set at 25°C room
temperature. It is not normally necessary to adjust this heater voltage unless 1) the sensor is going to be used in
the remote mount format or 2) the sensor is being swapped out with a new replacement sensor.
If the user needs to adjust the heater voltage due to the above-mentioned conditions, it is necessary to make the
adjustment based on the current ambient temperature condition. Refer to the table below for guidance on proper
heater voltage set-point:
Ambient Temp Heater Voltage Set-point
25°C 5.25 VDC
35°C 5.18 VDC
45°C 5.10 VDC
55°C 5.00 VDC
15°C 5.32 VDC
5°C 5.39 VDC
-5°C 5.45 VDC
-15°C 5.50 VDC
-25°C 5.55 VDC
-40°C 5.60 VDC
3.7 CALIBRATION
NOTE: Before calibration, verify the range setting as described in section 3.6.4.
3.7.1 Material Requirements
* Detcon PN 3270 MicroSafe™ Programming Magnet
* Detcon PN 6038 Threaded Calibration Adapter
* Span gas containing the H2S gas in air. Nitrogen mixtures are not acceptable. H2S gas concentration is recom-
mended at 25 ppm (which is the factory default for ranges 0-50 ppm and 0-100 ppm) or 10 ppm (which is the
factory default for the range 0-20 ppm) at a controlled flow rate of 200 to 500 ml/min. Other concentrations
can be used as long as they fall within allowable levels. See section 3.7.2 for details.
* Detcon PN 985-241100-321 In-Line Humidifying Tube.
NOTE: Span gas bottles contain 0% humidity and this ultra-low humidity condition will cause inaccurate readings
when used to calibrate a sensor. To prevent this error, Detcon prescribes the use of a 24” flexible In-Line
Humidifying Tube, which adds the relative humidify to the span gas. The humidifying tube is not necessary when
using a gas generating calibration device that consists of pumped ambient air and an H2S generating source.
3.7.2 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 10 ppm for the range 0-20 ppm and 25 ppm
for the ranges 0-50 ppm and 0-100 ppm. If a span gas containing the prescribed default concentration is not available, other concentrations may be used as long as they fall within 10% and 50% of full-scale 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
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.15
a) Verify the current calibration gas level setting as indicated by the programming status menu. To do this, follow
the instructions in section 3.8 and make note of the setting found in listing number 12. The item appears as
“CalLevel @ xxPPM”.
b) If the calibration gas level setting is equal to your calibration span gas concentration, proceed to item “f”. If
not, adjust the calibration gas level setting so that it is equal to your calibration span gas concentration, as
instructed in items “c” through “e”.
c) Enter the programming menu by holding the programming magnet stationary over “PGM 2” for 15 seconds
until the display reads “VIEW 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 Heater Level, Set Range,
and Linearize Sensor.
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 @ ##PPM”, 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. Exit to the programming menu 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) Enter the calibration span menu by holding the programming magnet stationary over “PGM 1” for 3 seconds
The display will read “1-SPAN 2-EXIT” Hold PGM 1 for 3 seconds to proceed with a span or hold PGM 2
for 3 seconds to exit back to normal operation mode. After choosing span you may, within 1 minute, abort the
span procedure by a 3 second hold on PGM 2.
g) Apply the calibration test gas with the humidifying tube installed at a flow rate of 200 to 500 milliliters per
minute (200cc/min is the recommended flow). The display will read “AUTO SPAN xxPPM”. The “xx” part
of the reading will change in single-digit increments as the sensor responds to the test gas. During the first 2
minutes of gas application, the sensor must satisfy a minimum resistance change which represents an “in range”
sensor response (see NOTE 2 below). “Auto Span” cycle is programmed for 3 full minutes of exposure at which
point an auto-adjustment is triggered. If, for example, automatic calibration is set for 25 ppm and the sensor
response after 3 minutes is 17 ppm, the auto span function adjusts the reading to 25 ppm. After this adjust-
ment, stability is verified for a period of 30 seconds. If less than 3 ppm of change occurs within the 30 second
time, then auto span is completed and the display reads “REMOVE GAS”. Remove the gas sample and
observe that the display clears to a reading of 0 ppm in less than 2 to 3 minutes.
If instability is greater than or equal to 3 ppm, auto span makes another adjustment and an additional 30
second period is allowed for final stabilization.
NOTE 1: If the sensor does not clear to <10% of range in <5 minutes after completing a span calibration, the
sensor will enter into a calibration fault mode which will cause the display to alternate between “ZERO
FAULT” and the sensor’s current reading.
NOTE 2: If the sensor fails the minimum signal change criteria, then a “RANGE FAULT” message will be dis-
played alternately with the sensor’s current reading.
NOTE 3: When a “zero fault”, or “range fault” occurs, the sensor microprocessor retains its previous calibration
references.
3.7.3
Additional Notes
1. Upon entering the calibration menu, the 4-20 mA signal drops to 2 mA and is held at this level until the pro-
gram returns to normal operation.
2.
If during calibration the sensor circuitry is unable to attain the proper span adjustment, the sensor will enter into
the calibration fault mode which will activate fault alarm functions (see section 3.10) and cause the display to alter-
nate between the sensor’s current status reading and the calibration fault screen which appears as either:
FAULT, or RANGE FAULT”.
If this occurs you may attempt to recalibrate by entering the calibration menu as
“ZERO
described in section 3.7.2-f. If the sensor fails again, defer to technical trouble shooting.
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.16
3.7.4 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.
3.7.5 Sensor Linearization
Sensor linearization is a function performed via a two point calibration process that optimizes the microprocessors
ability to interpret a sensors response curve.
service requirement once a sensor is in the field.
a “Linearize Sensor” procedure be performed on an annual basis or upon replacement of the sensor (PN 3998-B).
To perform a “Linearize Sensor” procedure, follow the instructions below.
The “Linearize Sensor” feature is performed at the factory and is not a
However, for optimum full scale accuracy, it is recommended that
Material Requirements
* Detcon PN 3270 MicroSafe™ Programming Magnet
* Detcon PN 6038 Threaded Calibration Adapter
* Span gas containing the 10 ppm H2S gas in air. Nitrogen mixtures are not acceptable.
* Span gas containing the 50 ppm H2S gas in air (for 0-100 ppm ppm & 0-50 ranges). Nitrogen mixtures are not
acceptable.
* Span gas containing the 20 ppm H2S gas in air (for 0-20 ppm range). Nitrogen mixtures are not acceptable.
* Detcon PN 985-241100-321 Perma-Pure humidify tubing.
a) Enter the programming menu by holding the programming magnet stationary over “PGM 2” for 15 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 Cal Level, Set Heater
Level, Set Range, and Linearize Sensor.
b) From the programming menu scroll to the Linearize Sensor listing. The menu item appears as: “LINEARIZE
SENSOR”. Enter the menu by holding the programming magnet stationary over “PGM 1” for 3 seconds
until the display reads “Apply 10 PPM H2S”, then withdraw the magnet.
c) Apply 10 ppm H2S at a controlled flow rate of 200-500 ml/m (200cc/min is the recommended flow). The dis-
play will report a value reading during the linearization check that reads “LinCheck ## PPM”. The actual
reading is unimportant. After waiting approximately 3 minutes for the 10 ppm sample to stabilize, the display
will then ask for either a 20 ppm gas sample (if programmed for 0-20 ppm range) or a 50 ppm gas sample (if
programmed for 0-50 ppm or 0-100 ppm range), “Apply ## PPM H2S”.
d) Apply the H2S gas sample at a controlled flow rate of 200-500 ml/m (200cc/min is the recommended flow).
The display will report a value reading during the linearization check that reads “LinCheck ## PPM”. The
actual reading is unimportant. After waiting approximately 3 minutes for the sample to stabilize, the display will
change to “Remove Gas ## PPM” and when the unit clears to < 5 ppm a “Linearization OK” message
will appear indicating a successful completion. Immediately following linearization, a normal span calibration is
required and prompted by the sensor. Apply your regular span gas as described in section 3.7.2g. Upon comple-
tion of the span calibration, the unit will return to the “LINEARIZE SENSOR” menu.
f) 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.
NOTE 1: If during this operation no gas is applied or the circuitry is unable to adjust the linearization 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 3.7.3).
3.8 STATUS OF PROGRAMMING, ALARMS, CALIBRATION LEVEL, RS-485 ID, HEATER LEVEL, RANGE, 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, calibration gas level setting, RS-485 ID
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.17
number, heater level, range of detection, and estimated remaining sensor life. The programming menu also allows
the changing of alarm levels (see section 3.9), the programming of the calibration gas level setting (see section
3.7.2), the sensor heater level (see section 3.6.2), the range of detection (see section 3.6.4), and the linearize sensor
(see section 3.7.5).
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 15 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 Cal Level, Set
Heater Level, Set Range, and Linearize Sensor.
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 informa-
tion 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 @ xxPPM”
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 @ xxPPM”
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 - Calibration gas level setting. The menu item appears as: “CalLevel @ xxPPM”
13 - The sensor heater voltage setting. The menu item appears as: “HEATER @ #.##VDC”
14 - The range of detection setting. The menu item appears as: “RANGE @ 0-###PPM”
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%”
17 - The raw resistance from the sensor. The menu item appears as: “RESISTANCE XXXXX”
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.
“H2S 0-100 V6.1”
3.9 PROGRAMMING ALARMS
3.9.1 Alarm Levels
Both alarm 1 and alarm 2 levels are factory set prior to shipment. For the ranges 0-50 ppm and 0-100 ppm, alarm 1
is set at 10ppm; alarm 2 at 15ppm. For the range 0-20 ppm, alarm 1 is set at 5ppm; alarm 2 at 10ppm. Both alarms
can be set in 1 ppm increments; the range 0-100 ppm from 10 to 90 ppm, the range 0-50 ppm from 5 to 45 ppm,
and the range 0-20 ppm from 2 to 18 ppm. 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 15 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, 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 @ ##PPM”, then withdraw the magnet. Use the program-
ming 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.
From the programming menu scroll to the alarm 1 level listing. The menu item appears as:
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.18
c) ALARM 2 LEVEL From the programming menu scroll to the alarm 2 level listing. The menu item appears as:
“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 @ ##PPM”, then withdraw the magnet. Use the program-
ming 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.
3.9.2 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.
3.9.3 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 3.5.4-e for details.
3.10 PROGRAM FEATURES
Detcon MicroSafe™ H2S gas sensors incorporate a comprehensive program to accommodate easy operator interface and fail-safe operation. Program features are detailed in this section. Each sensor is factory tested, programmed,
and calibrated prior to shipment.
Over Range
When the sensor detects gas greater than its selected full scale range (20, 50, or 100 ppm), it will cause the display to flash
“20/50/100 PPM H2S” on and off.
Zero Fault
If the sensor does not clear to <10% of range in <5 minutes after completing a span calibration, the sensor will
enter into a calibration fault mode which will cause the display to alternate between “ZERO FAULT” and the sen-
sors current reading.
Range Fault
If the sensor fails the minimum signal change criteria, then a “RANGE FAULT” message will be displayed.
Open Heater Fault
If the sensor heater should fail and become electrically open, the display will indicate a fault: “HEATER FAULT”.
System Fault
If the detector has an irrecoverable calculation error, the display will indicate: “SYSTEM FAULT”.
Sensor Heater Voltage Fault
Approximately one minute after start-up, the sensor will check the heater voltage. Normal heater voltage is 5.25
VDC. If the voltage drifts from this value by more than ±.3V, the display will indicate a fault: “HEATER
FAULT”.
Fail-Safe/Fault Supervision
Model TP-624C MicroSafe™ sensors are programmed for Fail-Safe operation. Any of the following fault conditions
will activate the fault relay, illuminate the fault LED, and cause the display to read its corresponding fault condition:
“RANGE FAULT”, “ZERO FAULT”, “HEATER FAULT”, or “SYSTEM FAULT”. A “Heater Fault”,
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.19
“System Fault”, “Zero Fault”, and “Range Fault” will also cause the mA output to drop to zero (0) mA until the
condition is corrected.
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 RS-485 PROTOCOL
Model TP-624C 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 TP-624C 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 # High Byte Low Byte
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 # High Byte Low Byte
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.
Register #
40003 Alarm 1 Setpoint
This is the trip point for the first alarm.
High Byte Low Byte
High Byte Low Byte
Register #
40004 Alarm 2 Setpoint
High Byte Low Byte
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.20
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:
Field
Name HEX DEC RTU
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
Reg40002 Data Lo 07 7 0000 0111
Reg40003 Data Hi 00 0 0000 0000
Reg40003 Data Lo 0A 10 0000 1010
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.21
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.
3.12 DISPLAY CONTRAST ADJUST
Model TP-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.
3.13 TROUBLE SHOOTING GUIDE
SENSOR FAULTS
Open Heater
Verify resistance between black and white wires using ohm-meter with the sensor unplugged and at room temperature. Heater Film’s normal reading range should be 65-95 ohms. Failure would be an open circuit.
Open Sensor
Verify resistance between blue and yellow wires using ohm-meter with the sensor unplugged and at room temperature. Sensor Film’s normal reading range should be 5-100 k-ohms. For sensors with an “X” in the serial number, the
normal reading range should be 75 k-ohms to 2 meg-ohms. Failure would be open circuit.
SPAN CALIBRATION FAULTS – (Range, Stability, Zero)
To remove the span calibration fault, you must repeat the calibration process successfully.
Range Fault
1. Check Heater Voltage Setting (should be 5.25 V).
2. Use humidifier with Distilled Water.
3. Check validity of cal gas using H2S pull tube or other means.
4. Check for obstructions through s/s sinter element (including being wet).
5. Check sensor lot # and report to Detcon .
Zero Fault
Must recover to <10% of range before calibration cycle is complete and returns to normal operation. Use bottled
air if necessary.
Poor calibration Repeatability
1. Check for adequate Sensor Life.
2. Check Heater Voltage Setting (should be 5.25 V).
3. Use humidifier filled with Distilled Water.
4. Check validity of cal gas.
5. Check for obstructions through s/s sinter element (including being wet).
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.22
6. Check sensor lot # and report to Detcon.
7. Check area for presence of reducing gases such as Cl2 and ozone which may cause low readings.
Unstable output/ Sudden spiking
Unstable power supply, Inadequate grounding, Inadequate RFI protection.
1. Verify Power source.
2. Contact Detcon to optimize shielding and grounding.
3. Add RFI protection accessory.
Nuisance Alarms
1. Check condulet for accumulated water and abnormal corrosion.
If Nuisance alarms happening at night suspect condensation in condulet.
2. Add/Replace Detcon Condensation Prevention Packet P/N 960-202200-000
Memory or Error reports
1. Reinitialize Sensor - Unplug transmitter, 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 blue background, 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.
Swap with a known-good transmitter to determine if transmitter is faulty.
3.14 SPARE PARTS LIST
600-500000-000 Sensor rain shield
600-610000-000 Sensor splash guard
943-000006-038 Threaded Calibration Adapter
399-800000-000 H2S sensor in stainless steel housing
926-015500-100 TP-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).
985-241100-321 In-Line Humidifying Tube
943-020000-000 Span Gas Kit: Includes calibration adapter, In-Line Humidifying Tube, 200 ml/m span
gas regulator, and carrying case. Does not include span gas.
942-010112-010 Span gas bottle containing 58 liters 10ppm H2S in air (operating range dependent).
942-010112-020 Span gas bottle containing 58 liters 20ppm H2S in air (operating range dependent).
942-010112-025 Span gas bottle containing 58 liters 25ppm H2S in air (operating range dependent).
942-010112-050 Span gas bottle containing 58 liters 50ppm H2S in air (operating range dependent).
943-090005-502 200 ml/m regulator for span gas bottle
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.23
Spash Guard
Rain Shield
Enclosure less cover
Connector Board
Calibrati on Ad ap ter
E
nclosure glass lens cover
P
lug-in control circuit
H2S Sensor in Housing
Programming Magnet
C
ondensation
Prevention Packet
(replace annually)
Figure #8
3.15 WARRANTY
Detcon, Inc., as manufacturer, warrants each hydrogen sulfide sensor element (PN 399-800000-000), for a ten 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.
First year No Charge
2nd-5th years $25.00 handling charge
6th year $60.00 handling charge
7th year $96.00 handling charge
8th year $120.00 handling charge
9th year $150.00 handling charge
10th year $176.00 handling charge
Warranty voided $200.00 charge
Non-warranty $295.00 charge
Terms & Conditions
* The original serial number must be legible on each sensor element base.
* Shipping point is FOB the Detcon factory.
* Net payment is due within 30 days of invoice.
* Detcon, Inc. reserves the right to refund the original purchase price in lieu of sensor replacement.
3.16 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 five years
after expiration of the warranty. All warranties and service policies are FOB the Detcon facility located in The Woodlands, Texas.
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.24
3.17 SOFTWARE FLOW CHART
P
GM1 (3) PGM2 (3)
NORMAL
OPERATION
P
GM1 (M)PGM2 (M)
PGM1 (3)
SET ALM1 @ ##PPM
I
NC
D
EC
PGM1 (3) PGM2 (M)
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 SPAN
S
ET ALARM 1 LEVEL
GAS RANGE V#.#
PGM1 (3) PGM2 (M)
V
IEW PROG STATUS
A
LM1 SET @ ##PPM
ALM2 SET @ ##PPM
485 ID SET @ #
P
GM1 (M)PGM2 (M)
PGM1 (3)
CalLevel @ ##PPM
I
NC
D
EC
PGM1 (3) PGM2 (M)
S
ET CAL LEVEL
P
GM2 (3)
P
GM2 (3)
P
GM2 (3)
SENSOR LIFE ##%
A
LM1 (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)
P
GM2 (30) PGM2 (M)
ALARM RESET
A
LARM RESET
P
GM1 (M)
P
GM2 (M)
PGM1 (3)
SET ALM2 @ ##PPM
I
NC
D
EC
PGM1 (3) PGM2 (M)
S
ET ALARM 2 LEVEL
P
GM2 (3)
CAL LEVEL @ ##PPM
RANGE @ 0-###PPM
HEATER @ #.##VDC
PGM1 (3) PGM2 (M)
PGM2 (3)
APPLY 10 PPM H2S
LINEARIZE SENSOR
PGM1 (M)
PGM2 (M)
PGM1 (3)
INC
DEC
PGM1 (3) PGM2 (M)
PGM2 (3)
HEATER @ ##VDC
SET HEATER VOLTS
APPLY 50 PPM H2S
PGM1 (M) PGM2 (M)
PGM1 (3)
INC
DEC
PGM1 (3) PGM2 (M)
PGM2 (3)
RANGE @ 0-###PPM
SET RANGE
Shipping Address: 3200 A-1 Research Forest Dr., The Woodlands, Texas 7381
phone 888-367-4286, 713-559-9200 • fax 281-292-2860 • www.detcon.com • sales@detcon.com
Mailing Address: P.O. Box 8067, The Woodlands, Texas 77387-8067
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.25
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