ATI Technologies C12-17 Operation And Maintenance Manual

O & M Manual

C12-17

Combustible Gas Transmitter

Home Office European Office

Analytical Technology, Inc. ATI (UK) Limited
6 Iron Bridge Drive Unit 1 & 2 Gatehead Business Park
Collegeville, PA 19426 Delph New Road, Delph
Phone: [phone] Saddleworth OL3 5DE
610-917-0991 Phone: [phone]
Fax: [phone] Fax: + 44 (0)1457-874-468
Email: [e-mail] Email: [e-mail]

Fax: [phone] Fax: + 44 (0)1457-874-468

Web: www.Analyticaltechnology.com

C12-17 Combustible Gas Transmitter

TABLE OF CONTENTS

INTRODUCTION ..................................................................................................................................... 4

SPECIFICATIONS .................................................................................................................................... 5

INSTALLATION ...................................................................................................................................... 6

SENSOR LOCATION ................................................................................................................ 7

INTERFERENCES ..................................................................................................................... 7

ELECTRICAL CONNECTIONS - TRANSMITTER ................................................................ 8

ELECTRICAL CONNECTIONS - SENSOR ............................................................................. 9

DUAL CONDULET SYSTEM ................................................................................................... 10

OPERATION ............................................................................................................................................. 11

CALIBRATION .......................................................................................................................... 11

TRANSMITTER ZERO .............................................................................................................. 12

TRANSMITTER SPAN .............................................................................................................. 13

TRANSMITTER FAULT INDICATION ................................................................................... 13

CALIBRATION FOR OTHER COMBUSTIBLE GASES ........................................................ 14

SENSOR RESPONSE TEST ...................................................................................................... 15

SENSOR REPLACEMENT ........................................................................................................ 15

DISPLAY & RELAY OPTION................................................................................................................. 16

ALARM ADJUSTMENT ........................................................................................................... 18

TROUBLE FUNCTION ............................................................................................................. 18

C12-17 TRANSMITTER W/O DISPLAY SPARE PARTS LIST ............................................................ 19

C12-17 TRANSMITTER WITH DISPLAY SPARE PARTS LIST ......................................................... 20

TABLE OF FIGURES

FIGURE 1 - TYPICAL SYSTEM DIAGRAM (ATI-0145) ............................................................................... 4

FIGURE 2 - COMBUSTIBLE GAS SENSOR/TRANSMITTER DIMENSIONS (ATI-046) ............................ 6

FIGURE 3 - TRANSMITTER CUSTOMER CONNECTIONS (ATI-0237) .................................................... 8

FIGURE 4 - SENSOR CONNECTIONS TO TRANSMITTER (ATI-0144) .................................................... 9

FIGURE 5 - DUAL CONDULET CONNECTIONS (ATI-0579) ................................................................... 10

FIGURE 6 - DUAL CONDULET TYPICAL INSTALLATION ....................................................................... 10

FIGURE 7 - SENSOR/TRANSMITTER CONNECTORS, CONTROLS AND TEST POINTS (ATI-0143) . 12

FIGURE 8 - ENCLOSURE WITH DISPLAY DIMENSIONAL DRAWING (ATI-0569) ................................ 16

FIGURE 9 - TRANSMITTER WITH DISPLAY CUSTOMER CONNECTIONS (ATI-0570) ........................ 17

FIGURE 10 - STANDARD COMBUSTIBLE TRANSMITTER ECPLODED VIEW (ATI-0146) ................... 19

FIGURE 11 - STANDARD COMBUSTIBLE TRANSMITTER EXPLODED VIEW (ATI-0571) ................... 20

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C12-17 Combustible Gas Transmitter

INTRODUCTION

Series C12-17 sensor/transmitters combine catalytic bead type gas sensors and an electronic
amplifier that transmits gas concentration using a standard 4-20 mA signal. They are designed to
continuously monitor combustible gas concentrations in ambient air near process tanks or piping, or in
enclosed spaces where combustible gases may accumulate. C12-17 transmitters are available in two
versions, one containing an integral display and single alarm relay, and a second that is a simple “blind
transmitter” with no display or alarm functions.

Gas sensors are housed in a corrosion resistant stainless steel shell with a sintered metal flame
arrestor isolating the sensing elements from the ambient air. A 3/4" NPT thread at the back of the sensor
mates with the threaded entry on the explosion-proof transmitter enclosure. Series C12-17 sensor
transmitters are designed for use in Class 1, Division 1, Groups A, B, C, or D locations.

A typical installation for the C12-17 is shown in Figure 1 below.

Figure 1 - Typical System Diagram (ATI-0145)

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C12-17 Combustible Gas Transmitter

SPECIFICATIONS

Range: 0-100% LEL (Lower Explosive Limit) Standard
0-50% LEL Optional

Response Time (T90) 10 Seconds
Sensitivity: 1% LEL
Zero Drift: < 2%/Month
Power: 10-28 VDC, 24 VDC at 100mA nominal
Output: 4-20 mA DC, 200 ohms maximum load at 12 VDC

800 ohms maximum load at 24 VDC

1000 ohms maximum load at 28 VDC
Display: Optional 2 ½ digit LCD
Alarm: Single setpoint or Trouble with SPDT, 1A, 125VAC; 1A, 30VDC alarm relay
Temperature Limits: -40° to + 70° C.
Sensor Materials: 316 Stainless Steel
Enclosure (Blind): Galvanized Cast Iron for blind transmitter

Area Classification: NEC Class 1, Division 1, Groups B, C, & D

Enclosure (for Display): Extruded Aluminum with glass window
Area Classification: NEC Class 1, Division 1, Groups A, B, C, & D

Connections: 3 wire, 20 AWG, 500 feet max. (150 m.)
Sensor Cable Length: Maximum 50 feet for separation between sensor and transmitter
Weight: 3 lbs. (1.4 Kg.)

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C12-17 Combustible Gas Transmitter

INSTALLATION

Combustible gas sensor/transmitters are explosion-proof assemblies that are normally mounted
directly to suitable explosion-proof conduit. To maintain the explosion-proof integrity of the transmitter, a
suitable cable entry seal must be used in accordance with the applicable electrical code.
Sensor/transmitters should be mounted with the sensor facing down as shown in Figure 2.

NOTE: Gas sensors are shipped with a protective plastic cap over the end. This cap should be left in
place to avoid damage to the sensor during installation. If the detection system is to be activated within a
few days of installation, the cap should be removed when installation is complete. Otherwise, leave the
cap in place until the system is to be placed in service. Be sure to leave the protective cap on the
sensor if painting is to be done in the area of the sensor.

Series C12-17 transmitters require connection to a DC power supply and connection of the 4-20
mA output to a receiving device such as a computer, recorder, or data logger. A 3-conductor cable may
be used for this purpose and is made at the terminals marked TB1 on Figure 3. Transmitters with the
optional display and relay may use a 2-wire connection if only the local relay is to be used. If the 4-20 mA
output is to be used, a 3-wire connection is needed.

Figure 2 - Combustible Gas Sensor/Transmitter Dimensions (ATI-046)

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C12-17 Combustible Gas Transmitter

SENSOR LOCATION

Combustible gas sensors are used to detect a variety of gases or vapors. The proper sensor
location will depend on what type of gas is expected. For gases that are lighter than air, such as
methane, sensors should be located near the ceiling. For gases that are heavier than air, such as
butane, sensors should be mounted near the floor. If the gas or vapor has a density near that of air,
locate the sensor about 5 feet off the floor in enclosed areas. Gas sensors mounted outdoors should be
located near anticipated leak sources (valves, flanges, compressors, etc.) and the location will depend on
normal wind patterns and anticipated employee activity areas.

The following are a few common combustible gases, along with their relative density (air = 1.00).
Densities less than one indicate gases that are lighter than air while those with densities greater than one
are heavier than air. Combustible vapors from most solvents, such an Benzene, n-Hexane, Methanol,
Ethanol, and MEK, are heavier than air and will tend to accumulate near the floor in enclosed spaces with
little air movement.

Methane 0.55
Butane 2.11
Propane 1.55
Hydrogen 0.07
Ammonia 0.60

INTERFERENCES

Combustible gas sensors contain two heated elements. One of these elements is active, and will
allow combustible gases or vapors to burn on its catalytic surface. The other is passive, and does not
react to gases. These two elements form two legs of a Wheatstone bridge measuring circuit. When
combustible gas contacts the sensor, the active element burns this gas and the temperature of this
element increases, changing its resistance. The transmitter measures the imbalance in the bridge circuit
and transmits the data to the receiver for display and alarming purposes.

Combustible sensors are adversely affected by a few compounds that may be present in a given
application. Probably the worst of these are silicone vapors from silicon based lubricants or sealants.
High silicon vapor concentrations can cause complete loss of sensitivity in as little as a few hours. These
sensors should not be used where silicon vapors are normally present, and sensors should be protected
from these vapors if such compounds are in use temporarily.

Lead compounds and high levels of hydrogen sulfide can also cause degradation of combustible
sensors. While lead vapors are not commonly encountered, they can also cause complete sensor failure
if encountered. Hydrogen sulfide will cause reduced sensitivity over the first few weeks of exposure, but
then will level out. The effect of hydrogen sulfide can normally be compensated for by re-calibration after
the first few weeks of use.

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C12-17 Combustible Gas Transmitter

Important: If the loop output is not used to

ELECTRICAL CONNECTIONS - TRANSMITTER

External connections to the C12-17 transmitter can be made using 3 conductor cable. A 3­conductor cable uses a single conductor for the common of both the power supply and the output signal.
Figure 3 shows typical connections to a power supply and a panel indicator running off the 4-20 mA
signal from the C12-17 transmitter.

ZERO

LEL Transmitter

SPAN

drive an external device, jump the
LOOP terminal to the COM
terminal

Figure 3 - Transmitter Customer Connections (ATI-0237)

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