Detcon H2S RoughNECK
™
H2S Gas Detection & Alarm System
Operator's Instruction Manual
November 1, 1997 Document #1915 Ver. 1.0
1.0 Description
2.0 Principle of Operation
3.0 Interference Data
4.0 Specifications
5.0 Installation
6.0 Power-up
7.0 Calibration
8.0 Heater Voltage Adjustment
9.0 Setting Alarms
10.0 Spare Parts List
11.0 Warranty
12.0 Wiring Diagram
detcon inc.
1.0 DESCRIPTION
The Detcon RoughNECK™ is a ruggedly constructed, single or dual channel H2S detector and alarm system designed specifically for use on workover and pulling unit rigs in the oil and gas well service industry.
The electronic controls consist of calibration and alarm adjustments housed in a NEMA 4 non-hazardous
enclosure that is raintight and suitable for outdoor location. An amber strobe is mounted on top of the
enclosure and a horn is mounted on the enclosure door. The system requires an external 12 VDC power
source. The system may be ordered with one or two remote mount H2S sensor assemblies. All wiring is
accomplished via plug-in type connectors that simplify installation and service maintenance.
2.0 PRINCIPLE OF OPERATION
In operation, the Detcon RoughNECK™ H2S detector is mounted on or near the rig so that the audible and
visual alarms are within sight and hearing of personnel in the area. The sensor(s) is placed on the rig in a
location that is suitable for the early detection of an H2S gas leak. The sensor consists of a solid state semiconductor that is specifically reactive to H2S gas. The sensor is located in a stainless steel housing that is
mounted in a metallic condulet. The condulet includes a connector for cable wiring to the detector. As the
sensor encounters H2S gas, its electrical resistance changes. This change in resistance is fed to the detector
motherboard and conditioned by the control circuitry. Once the H2S gas condition exceeds a predetermined set point, the circuitry will activate the alarm strobe light (factory set at 10 ppm). A further increase
in H2S gas concentration will activate the alarm horn (factory set at 15 ppm). When the H2S gas condition
has cleared, the alarm horn and strobe will turn off.
Detcon RoughNECK™ H2S Gas Detection & Alarm System PG.2
Remote
Mount
Sensor
™
detcon inc.
HOUSTON, TEXAS
H2S
RoughNECK
Slash Guard
3.0 INTERFERENCE DATA
Detcon RoughNECK™ H2S sensors are designed to detect and monitor hydrogen sulfide gas in ambient
air in the range of 0-100 parts per million. Minimum sensitivity and scale resolution is 1 ppm. Sensor specifications reflect an operating temperature range of -40° F. to +175° F. While the sensor is capable of operating outside these temperatures, performance specifications are verified within the limit.
Interference Data
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
Methonol 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
4.0 SPECIFICATIONS
Method of Detection
Solid state metal oxide. Diffusion/adsorption
Electrical Classification
NEMA 4 Non-Hazardous controller; NEMA 7 sensor
Response Time
80% < 2 minutes
Clearing Time
Detcon RoughNECK™ H2S Gas Detection & Alarm System PG.3
RoughNECK™ Block Diagram
Low
Alarm
Strobe
MOS
Sensor
RTD
Heater
Pre-amp
(span)
Constant
Temperature
Control
Alarm &
Signal
Conditioning
High
Alarm
Horn
Power In
80% < 2 minutes
Repeatability
± 5% FS
Range of Sensitivity
PPB to % by volume
Operating Temperature
-40° to +175° F
Accuracy
± 5% FS
Sensor Life
10 year conditional warranty
Field Wiring
4 conductor; max 10 ohms single conductor resistance
Input Power
12 VDC
Strobe Lamp
60 to 80 flashes per minute
1.75 Joules per flash
Intensity: 40 candela eff.
Audible Horn
HI/LO: 95 dBA @ 10 feet
Power Consumption
2 watts normal conditions
8 watts full alarm condition
5.0 INSTALLATION
Optimum performance of ambient air/gas sensor devices is directly relative to proper application, installation and adherence to recommended maintenance schedules including periodic recalibration.
Installation Procedure
a) Securely mount the H2S RoughNECK™ enclosure in accordance with recommended practice (See Fig.
1 and paragraph at section 2.0).
b) Securely mount the sensor condulet in accordance with recommended practice (See Fig. 2). Be sure sen-
sor orientation is pointing down to grade (see figure 2 and paragraph at section 2.0).
Detcon RoughNECK™ H2S Gas Detection & Alarm System PG.4
Figure 1
5 3/4"
Mounting Hole
Dia. 5/16"
7 3/8"
6 7/16"
4"
7 3/8"
5 1/8"
6 1/2"
c) Observing correct polarity, terminate 12 VDC power input. Use 2 conductor cable and the 2 pin
Amphenol plug-in connector (included) as shown in figure 3.
d) Terminate the sensor(s) as indicated in figure 4. Use 4 conductor cable and the 4 pin Amphenol plug-in
connector (included). The colors of four conductor cables may differ so be sure to wire sensor(s) according to the color code shown in figure 4.
Detcon RoughNECK™ H2S Gas Detection & Alarm System PG.5
Figure 2
Figure 3
2 5/8"
2 1/2"
4 1/2"
2.125"
Spalsh
Guard
2"
Power In
BOTTOM VIEW
A
B
Sensor 1
A
D
BC BC
Sensor 2
A
D
DC POWER IN
A = +12 VDC
B = DC COMMON
5.1 Field Wiring Table
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. Note the wiring table below.
AWG Max Meters Max Feet
20 240 800
18 360 1200
16 600 2000
14 900 3000
Note:
This wiring table is based on stranded tinned copper wire and is designed to serve as a reference only.
6.0 POWER UP
Upon completion of all mechanical mounting and termination of all field wiring, apply 12 VDC system
power, turn on the power switch, and observe the following normal conditions:
a) The door mounted power lamp is on.
b) A temporary upscale reading will occur as the sensor heats up. This upscale reading will clear to "0"
ppm within 5-10 minutes of turn-on, assuming there is no gas in the area of the sensor. The upscale
reading may, momentarily, surpass alarm set points and fire the alarm horn and strobe.
Detcon RoughNECK™ H2S Gas Detection & Alarm System PG.6
Figure 4
BOTTOM VIEW
Power In
A
B
Sensor 1
A
D
BC BC
YEL
BLK
BLU
WHT
Sensor 2
A
D
SENSORS
A = Blue
B = Yellow
C = Black
D = White
6.1 Heater Voltage Check
After a warm up period of approximately 15 minutes, the sensor heater voltage should be checked. Because
different installations will require differing lengths of cable, a significant voltage drop can occur in the conductors that carry the sensor heater voltage. This voltage change can affect calibration and should be
checked and adjusted if necessary after installation.
Note: If a RoughNECK™ system has been calibrated using the same cable lengths as those in the installation then the heater voltage should not be affected and adjustment will typically not be necessary.
Use the following procedure to check and adjust the sensor heater voltage:
Required Materials
Digital volt/ohm meter
Jeweler’s type screwdriver
Note: The goal of this procedure is to have a heater voltage reading of 5.2 V, ± .25V at the sensor.
a) Remove the sensor junction box cover of sensor #1.
b) At the sensor junction box connector, measure the voltage between the white (+) and black (–) wires
(see fig. 4). If the voltage is between 4.95 and 5.45 volts no adjustment is necessary. If it is outside these
limits make note of the voltage and proceed to item “c” below.
c) Measure the voltage of sensor #1 at the RoughNECK™ motherboard between test points TP4 (+) and
TP5 (–) (see fig. 5). Subtract the reading at the sensor from the reading at the motherboard (this will
give you the amount of the voltage drop across the cable.)
d) Add the voltage drop to 5.2 and then set the heater voltage, as measured between test points TP4 (+)
and TP5 (–), to that number. Adjust the voltage via the sensor heater potentiometer “P5”. This procedure will give you 5.2 V at the sensor.
Detcon RoughNECK™ H2S Gas Detection & Alarm System PG.7
Figure 6
HORNPWR
ON
OFF
RoughNECK™ Motherboard
STROBE
SW1
TP1
SIGNAL
SPAN 1 SPAN 2
12VDC
IN
BLU
SENSOR 1 SENSOR 2
P3
LOW
STROBE
P4
HIGH
HORN
P5 HEATER 1 P6 HEATER 2
TP2 TP3
CURRENT 1
TP4 TP5
HEATER 1
TP6 TP7
SIGNAL 1
YEL
BLK
WHT
TP8
LOW
TP9 TP10
HIGH
TP11 TP12
TP13 TP14
TP15 TP16
YEL
BLK
BLU
WHT
COM
CURRENT 2
HEATER 2
SIGNAL 2
Example: You measure 4.9 V at the sensor and 5.2 V at the motherboard. The difference is .3 V. Add
that to 5.2 V to arrive at 5.5 V. Set the heater voltage at the motherboard to 5.5 V.
e) If applicable repeat the procedure for sensor #2.
6.2 Initial Operational Tests
After the sensor heater voltage has been checked and a warm up period of approximately 30 minutes has
been allowed for, the sensor(s) should be checked to verify proper operation and sensitivity to H2S gas.
Required Materials
Digital volt/ohm meter
Jeweler’s type screwdriver
Test gas: H2S in air in the range 20 to 80 ppm. H2S and nitrogen mixes are not acceptable.
Detcon calibration adapter, PN6038
a) On sensor #1, apply a test gas in the range 20-80 ppm H2S in air. After a brief period observe that the
alarm strobe and horn fire (this is assumming alarm set points of 10 ppm and 15 ppm).
b) Remove the test gas and observe that the alarm strobe and horn go off.
c) If applicable, repeat steps “a” and “b” with sensor #2.
Note: If the strobe and/or horn failed to fire proceed to section 7.0, “Calibration”.
Initial operational tests are complete. Detcon RoughNECK™ H2S detectors are pre-calibrated prior to shipment and will, in most cases, not require significant adjustment on start up. However, Detcon recommends
that a complete calibration test and adjustment be performed within 24 hours of installation. Refer to calibration instructions in later text.
7.0 CALIBRATION
Note: Detcon solid state MOS hydrogen sulfide sensors give erroneous readings in oxygen depleted environments. Calibration gas mixtures of H2S and air are required. Do not use span gas cylinders with nitrogen and H2S mixtures.
Material Requirements
Digital volt/ohm meter
Jeweler’s type screwdriver
Detcon PN 6038 Threaded Calibration Adapter
Span Gas: 20 ppm H2S in air at a controlled flow rate between 100 and 1,000 ml/min.
NOTE: Span gas mixtures in the range 20 to 80 ppm are acceptable but 20 to 40 ppm is recommended
to provide the best signal linearity. Span gas mixtures less than 20 ppm are not recommended as these
will reduce the accuracy of signal linearity.
a) Check and adjust the sensor heater voltage as instructed in section 6.1.
b) Measure the signal voltage of sensor #1 between signal test points TP6 (+) and TP7 (–). A zero gas read-
ing of equal to or less than 1V is expected.
c) Remove the rain shield from sensor #1 and attach the threaded calibration adapter.
d) At a flow rate of between 100 ml/min to 1000 ml/min, apply a gas standard of 20 ppm. Wait 3-5 min-
utes for signal stability.
e) Using the Span 1 potentiometer, adjust the signal to a reading equal to the level as reflected in the cali-
bration table below.
f) Remove the gas standard and calibration adapter. Observe that the signal decreases to ≤1 V within 3-5
minutes.
Detcon RoughNECK™ H2S Gas Detection & Alarm System PG.8
Calibration Table
Each 1 ppm increase in H2S gas will increase the signal by 40 millivolts from a baseline of 1 volt. Below is a
sample of gas concentrations and the correct signal output they will provide.
PPM V DC
0 ≤1
10 1.4
20 1.8
30 2.2
40 2.6
50 3
60 3.4
70 3.8
80 4.2
90 4.6
100 5
g) If applicable, repeat the procedure for sensor #2. Use signal test points TP15 (+), TP16 (–), and Span pot
#2 for adjustment.
7.1 CALIBRATION FREQUENCY
In most applications, monthly intervals will assure reliable detection. However, to insure optimum reliability, it is recommended that the sensors be calibrated each time the job location is changed.
8.0 HEATER VOLTAGE ADJUSTMENT
Each sensor is pre-calibrated and tested prior to shipment. The heater voltage is set to 5.2 volts. This temperature is referenced to 72° F ambient. Slight variations in heater voltage will occur in higher or lower
ambient temperatures. Maximum deviation is + or – 5% of original value. For a sensor rated for 5.2 VDC @
72 degrees, the temperature offset at 100 degrees should not exceed –.25 VDC; @ 32 degrees, + .25 VDC.
The nature of the heater function is such that a lower voltage will cause a slower, but more stable response
to gas, while a higher voltage will cause a slightly quicker response. If it should become necessary to elevate heater voltage to maintain response and clearing characteristics, do not exceed 5.5 volts in any temperature range. Note that any adjustment to the heater voltage will require that the sensor be recalibrated with
H2S gas.
The heater voltage is adjusted via the “HEATER” potentiometer and is measured at the two test points
labeled “HEATER”.
Optional Heater Power Adjustment Instructions
A new feature included with the latest revision of Detcon’s proprietary solid state H2S sensor allows for a
more accurate adjustment to be made to the sensor heater circuit. This feature is based on power rather
than voltage. Setting the sensor heater voltage, as measured at the “HEATER” test points, is an acceptable
method. However, the new power feature is an option that allows the user to calculate and implement a
more precise method of temperature control to the sensor over longer periods of service. After several
months and even years, of service the sensor heater film may degrade and require more precise power
level adjustment.
The main objective of the sensor heater circuit is to elevate the temperature of the solid state sensor element to between 500 and 527°F. This temperature provides the best combination of speed and stability for
detecting H2S gas. Because the sensor heater resistance increases with age, the power being applied to the
sensor changes even if the heater voltage remains constant. This change in power also changes the sensor
temperature. Thus, a constant power being applied to the sensor will render better performance than a constant voltage.
The desired power setting which is measured in milliwatts, will vary depending on ambient temperatures.
Detcon RoughNECK™ H2S Gas Detection & Alarm System PG.9
If the ambient temperature is 72° F, the desired power setting should be 218 mW, ±3%. On hotter days
when the ambient temperature is 100°F, the optimal power setting should be 207mW, ±3%. A cold day
with an ambient temperature of 32°F, would call for a power setting of 238mW, ±3%.
To set the sensor heater for power rather than voltage, follow the instructions below.
Note 1: Power (P) is the result of multiplying the heater voltage “VOLT” (V) by the heater current “CURRENT” (I). P = V x I
Note 2: Because the heater current is routed through a 1 ohm resistor located between the test points labeled
“CURRENT”, it is not necessary to set your volt/ohm meter to measure current to obtain the proper reading. Your
meter should be set to measure millivolts and the reading is simply interpreted as heater current in milliamps.
1 - Measure the heater voltage at the test points labeled “HEATER”. (example - 5.2V @ 72°F)
2 - Next, measure the heater current at the test points labeled “CURRENT”. (example .043 A)
Thus, 5.2 (volts) x .043 (amps) = .223 (watts or 223 milliwatts). This falls within 3% of the target power setting of 218 mW and is acceptable. If the value was too low, you would increase the voltage by turning the
potentiometer labeled “HEATER” clockwise, and then recalculate with the new voltage and current readings. If the value was too high, you would decrease the voltage and repeat the process as necessary to reach
the desired power setting.
9.0 SETTING ALARMS
The alarm strobe and horn are factory set at 10 ppm for the low alarm (strobe) and 15 ppm for the high
alarm (horn). The strobe and horn specifications are listed in section 4.0. Each alarm can be set independently over the range of 10 to 90 ppm. To set the alarm strobe and horn follow the instructions below.
LOW ALARM - STROBE SET
a) Insert your volt meter probes into TP8 (+) and TP10 (–).
b) Use the low alarm - strobe potentiometer (P3) to adjust the reading to the desired alarm set point as
indicated in the table below
PPM V DC
10 1.4
15 1.6
20 1.8
25 2
30 2.2
35 2.4
40 2.6
45 2.8
50 3
55 3.2
60 3.4
65 3.6
70 3.8
75 4
80 4.2
85 4.4
90 4.6
HIGH ALARM - HORN SET
a) Insert your volt meter probes into TP9 (+) and TP10 (–).
b) Use the high alarm - strobe potentiometer (P4) to adjust the reading to the desired alarm set point as
indicated in the same table.
Detcon RoughNECK™ H2S Gas Detection & Alarm System PG.10
10.0 S
PARE PARTS LIST
Part # Description
3548 Amber strobe light
700-01914-0 Strobe guard
400-01916-0 H2S RoughNECK™ label
0322 Strobe seal O’ring
3533 Horn
2836 Power lamp body
2836-L12 Power lamp bulb
2836-G Power lamp - green dome cap
500-01909-0 Motherboard PCB Assembly
3077 Power input connector
3079 Sensor input connector
Detcon RoughNECK™ H2S Gas Detection & Alarm System PG.11
3548 Strobe Light
3533 Horn
013-24412-0 Horn Gasket
700-01914-0 Strobe Guard
400-01916-0 Label
2836 Lamp Body
2836-G Dome
2836-L12 Lamp
3077 2 Pin Socket Connector
3080 2 Pin Straight Connector
0322 Seal O-ring
500-01909-0
PCB Assembly
3079 4 Pin
Socket Connector
3082 4 Pin
Straight Connector
3084 Cable Clamp
10.2 Sensor Spare Parts
Part # Description
969-13998 Complete sensor assembly
301-40254 4 pin terminal block
8534-275 Sensor condulet
3998-B H2S sensor in stainless steel housing
6006 Splash guard
11.0 WARRANTY
Detcon, Inc., as manufacturer, warrants under intended normal use each new RoughNECK™ gas detection
and alarm system to be free from defects in material and workmanship for a period of one year from the
date of shipment to the original purchaser. All warranties and service policies are FOB the Detcon, Inc.
facility located in The Woodlands, Texas.
Detcon, Inc., as manufacturer, further warrants each solid state hydrogen sulfide sensor element (part no.
3998B), 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 ten years thereafter. The sensor element is warranted
to be free from defects in material and workmanship. Should any sensor element fail to perform in accordance with published specifications within the warranty period, return the defective part to Detcon, Inc.,
for necessary repairs or replacement in accordance with the conditions noted below.
First 5 years $10.00 handling charge
6th year $44.00 handling charge
7th year $76.00 handling charge
8th year $110.00 handling charge
9th year $144.00 handling charge
10th year $176.00 handling charge
Non-warranty $200.00 charge
Detcon RoughNECK™ H2S Gas Detection & Alarm System PG.12
969-13998
Complete Sensor Assembly
301-40254
4 Pin Terminal Block
8534-275
Sensor Condulet
3998-B H2S Sensor
In Stainless Steel Housing
6006 Splash Guard
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.
11.1 SERVICE P
OLICY
Detcon, Inc., as manufacturer, warrants under intended normal use each new RoughNECK™ PCB motherboard to be free from defects in material and workmanship for a period of one year from the date of shipment to the original purchaser. Detcon, Inc., further provides for a five year fixed fee service policy wherein any failed motherboard shall be repaired or replaced as is deemed necessary by Detcon, Inc., for a fixed
fee of $55.00. The fixed fee service policy shall effect any factory repair for the period following the one
year warranty and shall end five years after the date of shipment to the original purchaser. All warranties
and service policies are FOB the Detcon facility located in The Woodlands, Texas.
12.0 WIRING DIAGRAM
Detcon RoughNECK™ H2S Gas Detection & Alarm System PG.13
Shipping Address: 3200 A-1 Research Forest Dr., The Woodlands, Texas 7381
Mailing Address: P.O. Box 8067, The Woodlands, Texas 77387-8067
phone 888-367-4286, 281-367-4100 • fax 281-292-2860 • www.detcon.com • sales@detcon.com
RED
BLK
STROBE
RED 18
BLK 18
RED 18
BLK 18
HORNPWR
12VDC SENSOR 1 SENSOR 2
YEL 18
BLK 18
BLK 18
BLU 18
RED 18
WHT 18
ABCD ABCDAB
BLU 18
YEL 18
BLK 18
WHT 18
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