Detcon FP-700 User Manual

INSTRUCTION MANUAL

Detcon Model FP-700

FP-700 Combustible Gas Sensor

0-100% LEL

0-50% LEL

DETCON, Inc.

4055 Technology Forest Blvd.,

The Woodlands, Texas 77381

Ph.281.367.4100 / Fax [phone]

www.detcon.com

February 28, 2014 • Document #3168 • Revision 3.0

This page left intentionally blank

Model FP-700

Model FP-700 ii

Model FP-700

Table of Contents

1. Introduction ..................................................................................................................................................1

1.1 Description.......................................................................................................................................... 1

1.2 Sensor Electronics Design .................................................................................................................. 2

1.3 Modular Mechanical Design............................................................................................................... 3

1.4 Plug-in Replaceable Sensor ................................................................................................................ 4

2. Installation....................................................................................................................................................5

2.1 ATEX Operational Guidelines for Safe Use....................................................................................... 5

2.2 Sensor Placement................................................................................................................................ 6

2.3 Sensor Contaminants and Interference ............................................................................................... 7

2.4 Mounting Installation.......................................................................................................................... 7

2.5 Electrical Installation .......................................................................................................................... 8

2.6 Field Wiring........................................................................................................................................ 9

2.7 Initial Start Up................................................................................................................................... 11

3. Operation....................................................................................................................................................12

3.1 Programming Magnet Operating Instructions................................................................................... 12

3.2 Operator Interface............................................................................................................................. 13

3.3 Normal Operation ............................................................................................................................. 15

3.4 Calibration Mode (AutoZero and AutoSpan) ................................................................................... 15

3.4.1 AutoZero....................................................................................................................................... 15

3.4.2 AutoSpan...................................................................................................................................... 16

3.5 Program Mode .................................................................................................................................. 18

3.5.1 Navigating Program Mode ........................................................................................................... 18

3.5.2 View Sensor Status....................................................................................................................... 18

3.5.3 Set AutoSpan Level...................................................................................................................... 19

3.5.4 Set Gas Factor............................................................................................................................... 20

3.5.5 Set Cal Factor ............................................................................................................................... 21

3.5.6 Set Serial ID ................................................................................................................................. 22

3.5.7 Set Bridge Voltage........................................................................................................................ 22

3.5.8 Signal Output Check..................................................................................................................... 23

3.5.9 Restore Factory Defaults.............................................................................................................. 23

3.6 Program Features .............................................................................................................................. 24

3.6.1 Operational Features..................................................................................................................... 24

3.6.2 Fault Diagnostic/Failsafe Features ............................................................................................... 24

4. RS-485 Modbus™ Protocol .......................................................................................................................27

Content Description.............................................................................................................................................27

5. Service and Maintenance............................................................................................................................29

5.1 Calibration Frequency....................................................................................................................... 29

5.2 Visual Inspection .............................................................................................................................. 29

5.3 Condensation Prevention Packet....................................................................................................... 29

5.4 Replacement of Plug-in Combustible Gas Sensor............................................................................ 29

5.5 Replacement of ITM......................................................................................................................... 30

5.6 Replacement of FP-700 Sensor Assembly........................................................................................ 30

6. Troubleshooting Guide...............................................................................................................................31

7. Customer Support and Service Policy........................................................................................................34

8. FP-700 Sensor Warranty ............................................................................................................................35

9. Appendix ....................................................................................................................................................36

9.1 Specifications.................................................................................................................................... 36

9.2 Spare Parts, Sensor Accessories, Calibration Equipment................................................................. 38

9.3 Model FP-700 Engineering Drawings .............................................................................................. 38

10. Revision Log..........................................................................................................................................39

Model FP-700 iii

Model FP-700

Table of Figures

Figure 1 Sensor Cell Construction ....................................................................................................................... 1

Figure 2 Wheatstone Bridge................................................................................................................................. 2

Figure 3 Response Curves.................................................................................................................................... 2

Figure 4 ITM Circuit Functional Block Diagram................................................................................................. 2

Figure 5 Sensor Assembly Front View ................................................................................................................ 3

Figure 6 Sensor Assembly Breakaway................................................................................................................. 3

Figure 7 FP Replaceable Sensor Cell................................................................................................................... 4

Figure 8 ATEX Approval Label........................................................................................................................... 5

Figure 9 Outline and Mounting Dimensions........................................................................................................ 8

Figure 10 Typical Installation.............................................................................................................................. 9

Figure 11 Sensor Wire Connections................................................................................................................... 10

Figure 12 Magnetic Programming Tool............................................................................................................. 12

Figure 13 Magnetic Programming Switches...................................................................................................... 13

Figure 14 FP-700 Software Flowchart ............................................................................................................... 14

Figure 15 Sensor Assembly................................................................................................................................ 29

Figure 16 Plug-in Sensor (Bottom View)........................................................................................................... 31

List of Tables

Table 1 Protection vs. Wire Gauge..................................................................................................................... 10

Table 2 Gas/Cal Factors..................................................................................................................................... 20

Table 3 Modbus™ Registers.............................................................................................................................. 27

Table 4 Modbus™ Special Registers ................................................................................................................. 28

Shipping Address: 4055 Technology Forest Blvd., The Woodlands Texas 77381

Mailing Address: P.O. Box 8067, The Woodlands Texas 77387-8067

Phone: [phone] • Fax: [phone] • www.detcon.com • [e-mail]

Model FP-700 iv

Model FP-700

1. Introduction

1.1 Description

Detcon Model FP-700 combustible gas sensors are non-intrusive “Smart” sensors
designed to detect and monitor combustible gases in air. Range of detection is 0-100%
LEL or 0-50% LEL. The sensor features an LED display of current reading, fault and
calibration status. The unit is equipped with standard analog 4-20mA and Modbus™
RS-485 outputs. A primary feature of the sensor is its method of automatic calibration,
which guides the user through each step via fully scripted instructions displayed on the
LED display.

The microprocessor-supervised electronics are packaged in an encapsulated module and
housed in an explosion proof casting. The unit includes a 4 character alpha/numeric
LED used to display sensor readings, and the sensor’s menu driven features when the
hand-held programming magnet is used.

Catalytic Bead (Pellistor) Sensor Technology

The sensor technology is a poison-resistant catalytic bead type. Catalytic bead sensors show a strong response
to a long list of combustible gases. The sensor is supplied as a matched-pair of detector elements mounted in a
plug-in replaceable module. One bead is a catalytically active detector and the other is a non-active reference
detector. Each detector consists of a fine platinum wire coil embedded in aluminum oxide. A catalytic
mixture is applied to the active detector while the reference detector is treated so that oxidation of the gas does
not occur. The technique is referred to as non-selective and may be used to monitor most any combustible gas.
Detcon catalytic bead sensors are specifically designed to be resistant to poisons such as sulfides, chlorides,
and silicones. The sensors are characteristically stable and capable of providing reliable performance for
periods exceeding 5 years in most industrial environments.

Platinum Wire

Cataly st

Alum ina Bead

Co nstruc tio n

o f Detec to r

Bead

Figure 1 Sensor Cell Construction

Cataly tic Beads

M ain Ho u sing Insert

Printed C irc uitBo ard
G o ld Plated Pins

Principle of Operation

Method of detection is by diffusion/adsorption. Air and combustible gases pass through a sintered stainless
steel filter and contact the heated surface of both the active and reference detectors. The surface of the active
detector promotes oxidation of the combustible gas molecules while the reference detector has been treated not
to support this oxidation. The reference detector serves as a means to maintain zero stability over a wide range
of temperature and humidity.

When combustible gas molecules oxidize on the surface of the active detector, heat is generated, and the
resistance of the detector changes. Electronically, the detectors form part of a balanced bridge circuit. As the
active detector changes in resistance, the bridge circuit unbalances. This change in output is conditioned by
the amplifier circuitry, which is an integral part of the sensor design. The response and clearing characteristics
of the sensor are rapid and provide for the continuous and accurate monitoring of ambient air conditions.

FP-700 Instruction Manual Rev. 3.0 Page 1 of 40

Model FP-700

RS-4854-

20mA

Display

Control

Pre-Amp

Power Supply

Sen so r

Inp u t

Vo lta g e

Z ero

Adju st

C ell

O u tpu t

C o m p ens ato r /
Ref e re nc e B ea d

De te c to r /
Ac tive B ea d

Figure 2 Wheatstone Bridge

Performance Characteristics

The detector elements maintain good sensitivity to combustible gas concentrations in the Lower Explosive
Limit (LEL) range, as shown in the response curves in Figure 3. However, for gas concentrations significantly
above the LEL range (100% LEL = 5% by volume Methane), the bridge output begins to decrease.
Ambiguous readings above the LEL range dictate that alarm control logic be of the latching type, wherein
alarms are held in the “ON” position until reset by operations personnel.

Figure 3 Response Curves

1.2 Sensor Electronics Design

Intelligent Sensor Module

The Intelligent Transmitter Module (ITM) is a fully encapsulated microprocessor-based package that accepts a
plug-in field replaceable combustible gas sensor. Circuit functions include extensive I/O circuit protection,
sensor pre-amplifier, bridge voltage (temperature) control, on-board power supplies, microprocessor, LED
display, magnetic programming switches, linear 4-20mA DC output, and Modbus™ RS-485 output. Magnetic
program switches located on either side of the LED Display are activated via a hand-held magnetic
programming tool, thus allowing non-intrusive operator interface with the ITM. Calibration can be
accomplished without declassifying the area. Electrical classifications are Class I, Division 1, Groups B C D
and Class I, Zone 1, Group IIB+H2.

Plug-In

Sensor

Element

Temperature

Micro-

Processor

I/O

Circuit

Protection

Analog 4-20mA Out

Modbus™ RS-485 Output

Power In

FP-700 Instruction Manual Rev. 3.0 Page 2 of 40

Figure 4 ITM Circuit Functional Block Diagram

Model FP-700

LED Display

Program Switch #2

Program Switch #1

Splashguard Adapter

Lockdown Set-Screw

detcon inc.

MODEL

FP-700

LEL Sensor

Figure 5 Sensor Assembly Front View

1.3 Modular Mechanical Design

The Model FP-700 Sensor Assembly is completely modular and made up of four parts (See Figure 6 for
Assembly Break-away):

1) FP-700 Intelligent Transmitter Module (ITM)

2) Field Replaceable Plug-in Combustible Gas Sensor

3) Model 700 Housing Bottom Assembly (contains the Housing Bottom, Flame Arrestor, Retaining Ring,
and rubber O-Rings)

4) Splash Guard.

NOTE: All metal components are constructed from electro-polished 316 Stainless Steel in order to maximize
corrosion resistance in harsh environments.

Splashguard
Adapter

Plug-In replaceable
H2S Sensor

LEL Sensor

Splash Guard

Magnetic

O-Rings

Housing Bottom
Locking Set-Screw

Programming
Switches

Figure 6 Sensor Assembly Breakaway

FP-700 Instruction Manual Rev. 3.0 Page 3 of 40

Lens and LCD
Display

detcon inc.

detcon inc.

FP-700

MODEL

Interconnect

Wiring

Intelligent Transmitter Module
(ITM) Microprocessor controlled
circuit encapsulated in an
explosion proof housing

Model FP-700

1.4 Plug-in Replaceable Sensor

The Detcon combustible gas sensor is a poison-resistant and field proven design. It is packaged as true plug-in
replaceable type sensor with over-sized gold-plated connections that eliminate corrosion problems. It can be
accessed and replaced in the field very easily by releasing the locking screw and unthreading the housing
bottom. The Detcon combustible gas sensor has an infinite shelf life, and is supported by a 2-year warranty.
The expected service life is 3-5 years.

Figure 7 FP Replaceable Sensor Cell

FP-700 Instruction Manual Rev. 3.0 Page 4 of 40

Model FP-700

2. Installation

2.1 ATEX Operational Guidelines for Safe Use

1. Install sensor only in areas with classifications matching with those described on the ATEX approval
label. Follow all warnings listed on the label.

Figure 8 ATEX Approval Label

2. Ensure that the sensor is properly threaded into a suitable explosion-proof rated junction box with a
downward pointing female ¾” NPT threaded connection. The sensor should be threaded up at least 5
full turns until tight, with the LED display facing forward. Avoid use of Teflon Tape, or any type of
non-conductive pipe thread coating on the NPT threaded connection.

3. A good ground connection should be verified between the sensor’s metal enclosure and the junction
box. If a good ground connection is not made, the sensor can be grounded to the junction box using
the sensor’s external ground lug. Also verify a good ground connection between the junction box and
earth ground. Installer shall use ring terminal to make connection to earth ground to be secured by
screw and lock washer on sensor housing.

4. Ensure that the Housing Bottom and plug-in sensor are installed during operation. The Housing
Bottom should be threaded tightly to the Intelligent Transmitter Module. The locking setscrew (M3.5
x 0.6 6g6h Stainless Steel Allen set screw cup point with yield strength of greater than 40,000 PSI,
typical 80,000 PSI) should then be tightened down to keep the Housing Bottom from being
inadvertently removed or from becoming loose under vibration. The locking setscrew ensures that
Housing Bottom is only removable by authorized personnel with the use of special tools. A M1.5
Allen Wrench is required. If screw requires replacement, only an identical screw may be used.

5. Removal of the Housing Bottom violates the Ex d protection method and hence power must be
removed from the sensor prior its safe removal.

6. The screws holding down the retaining plate label are special fasteners of type Stainless Steel Phillips
Pan-head Machine screw, M3 x 0.5, 6g6hhaving yield strength of greater than 40,000 PSI, typical
80,000 PSI. If screw requires replacement, only an identical screw may be used.

7. Proper precautions should be taken during installation and maintenance to avoid the build-up of static
charge on the plastic components of the sensor. These include the splashguard and splashguard
adapter.

8. Do not operate the sensor outside of the stated operating temperature limits.

9. Do not operate the sensor outside the stated operating limits for voltage supply.

10. These sensors meet EN60079-0:2009, EN60079-1:2007.

FP-700 Instruction Manual Rev. 3.0 Page 5 of 40

Model FP-700

NOTE:

NOTE:

2.2 Sensor Placement

Selection of sensor location is critical to the overall safe performance of the product. Six 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.
(6) Personal Exposure.

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.

Methane and Hydrogen are lighter than air. Most other combustible gases are heavier
than air. Compare the molecular weight, density, or specific gravity of the target gas(es) with
that of air to determine appropriate placement.

Leak Sources

The 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 providing easy access for maintenance personnel. Consideration should also
be given to the consequences of close proximity to contaminants that may foul the sensor prematurely.

In all installations the gas sensor should point straight down, refer to Figure 10.

Improper sensor orientation may result in false readings and permanent sensor damage.

Additional Placement Considerations

The sensor should not be positioned where it may be sprayed or coated with surface contaminating substances.
Painting sensor assemblies is prohibited.

Although the sensor is designed to be RFI resistant, it should not be mounted in close proximity to high­powered radio transmitters or similar RFI generating equipment.

FP-700 Instruction Manual Rev. 3.0 Page 6 of 40

Model FP-700

When possible in an area void of high wind, accumulating dust, rain or splashing from hose spray, direct steam
releases, and continuous vibration. If the sensor cannot be mounted away from these conditions then make
sure the Detcon Harsh Environment Splashguard accessory is used.

Do not mount in locations where temperatures will exceed the operating temperature limits of the sensor.
Where direct sunlight leads to exceeding the high temperature-operating limit, use a sunshade to help reduce
temperature.

2.3 Sensor Contaminants and Interference

Detcon combustible gas sensors may be adversely affected by exposure to certain airborne substances. Loss of
sensitivity or corrosion may be gradual if such materials are present in sufficient concentrations.

The performance of the detector elements may be temporarily impaired during operation in the presence of
substances described as inhibitors. Inhibitors are usually volatile substances containing halogen compounds.
Inhibitors include halide compounds such as Cl2, ClO2, F2, HF, HCl, Br2, vinyl chloride, and methyl chloride.
Inhibition is typically a temporary effect and the detectors generally recover after short periods of operation
back in clean air.

Some background gases may act as poisoning agents and have a more damaging effect on the sensor.
Although the sensor is designed to be poison resistant, it does have physical limits. Poisoning gases deactivate
the active detector’s catalytic ability and cause a permanent reduction in the span sensitivity. Examples of
typical poisons are: silicone oils and greases, siloxanes (HMDS), H2S, anti-knock petrol additives, and
phosphate esters. Activated carbon filters can be used to provide additional protection from poisoning in most
cases.

The presence of such inhibitors and poisons in an area does not preclude the use of this sensor technology,
although it is likely that the sensor lifetime will be shorter as a result. Use of this sensor in these environments
may require more frequent calibration checks to ensure safe system performance.

2.4 Mounting Installation

The FP-700 sensor assembly is designed to be threaded into a ¾” Female NPT fitting of a standard cast metal,
Explosion-Proof Enclosure or Junction Box. There are two wrench flats on the upper section of the sensor that
should be used to thread the sensor into the ¾” female NPT receiving connection. Thread the sensor up until
tight (5 turns is typically expected) and until the display is pointed in the direction that sensor will normally be
viewed and accessed.

The FP-700 should be vertically oriented so that the sensor points straight downward. The explosion-proof
enclosure or junction box would then typically be mounted on a wall or pole. Detcon provides a standard
selection of junction boxes available as sensor accessories (See Figure 4 below), but any appropriately rated
enclosure with a downward facing ¾” NPT female connection will suffice.

When mounting on a wall, it is recommended to use a 0.25”-0.5” spacer underneath the mounting ears of the
Detcon standard J-Box to offset the sensor assembly from the wall and create open access around the sensor
assembly. Spacing requirements for other junction boxes may vary.

When mounting on a pole, secure the Junction Box to a suitable mounting plate and attach the mounting plate
to the pole using U-Bolts. (Pole-Mounting brackets for Detcon J-box accessories are available separately.)

FP-700 Instruction Manual Rev. 3.0 Page 7 of 40

5.5"

NOTE: I

NOTE:

4.95"

Model FP-700

3.675"

3/4" NPT

Ø0.265" x2

Mounting Holes

5.25"

12.5"

5.53"

7.855"

2"

detcon inc.

MODEL

FP-700

LEL Sensor

2.125"

Figure 9 Outline and Mounting Dimensions

2.5 Electrical Installation

8-32 Thread
Ground Point

Explosion Proof Enclosure

Junction-Box

(Detcon's Junction-Box shown)

Use Spacers to move

the J-Box and Sensor

Assembly away from the

wall at least 0.25-0.5" to

allow access to Sensor

Sensor Assembly

Splash Guard

Bolt

Spacer

Mounting

Wall (or other

mounting surface)

The Sensor Assembly should be installed in accordance with local electrical codes. The sensor assemblies are
CSA/NRTL approved (US and Canada) for Class I, Division 1, Groups B, C, & D area classifications, and are
ATEX Approved for Class I, Zone 1, Group IIB+H2area classifications.

Proper electrical installation of the gas sensor is critical for conformance to Electrical Codes and to avoid
damage due to water leakage. Refer to Figure 10 and Figure 11 for proper electrical installation.

f a conduit run exits the secondary port, repeat the installation technique shown in

Figure 10.

In Figure 10, the drain allows H2O condensation inside the conduit run to safely drain away from the sensor
assembly. The electrical seal fitting is required to meet the National Electrical Code per NEC Article 500-3d
(or Canadian Electrical Code Handbook Part 1 Section 18-154). Requirements for locations of electrical seals
are covered under NEC Article 501-5. Electrical seals also act as a secondary seal to prevent water from
entering the wiring terminal enclosure. However, they are not designed to provide an absolute water-tight
seal, especially when used in the vertical orientation.

The Detcon Warranty does not cover water damage resulting from water leaking into
the enclosure. However, since the electronics are 100% epoxy encapsulated, only the wire
terminations could get wet. Moisture could cause abnormal operation and possibly corrosion
to the terminal connections, but permanent damage to the sensor would not be expected.

FP-700 Instruction Manual Rev. 3.0 Page 8 of 40

NOTE:

A conduit seal is typically required to be located within 18" of the J-Box and Sensor

NOTE:

Assembly. Crouse Hinds type EYS2, EYD2 or equivalent are suitable for this purpose.

Conduit

Model FP-700

"T"

Drain

Customer

Supplied Wiring

Transient Protection Module
(TPM) P/N 500-003087-100

N/U

A(+)

(+)

(-)

mA

B(-)

Mount TPM in Explosion

Proof Enclosure to ground

unit properly. Mount to

bottom of enclosure using

6-32 screws.

EYS Seal Fitting

Explosion

Proof

Junction Box

FP-700
Sensor

Assembly

6-Pin Pheonix Plug

P/N 306-175705-100

Blu

Blk

Grn

Wiring to

Wht

A(+)

B(-)

Red

(+)mA(-)

Sensor Assembly

Figure 10 Typical Installation

Plug any unused

Explosion Proof

Housing

(J-Box)

detcon inc.

MODEL

FP-700

LELSe nsor

ports

Any unused ports should be blocked with suitable ¾” male NPT plugs. Detcon
supplies one ¾” NPT male plug with their accessory J-box enclosures. If connections are other
than ¾” NPT, use an appropriate male plug of like construction material.

2.6 Field Wiring

Detcon Model FP-700 sensor assemblies require three conductor connections between power supplies and host
electronic controller’s 4-20mA output, and two conductor connections for the Modbus™ RS-485 serial
interface. Wiring designations are + (DC), – (DC), mA (sensor signal), and Modbus™ RS-485 A (+), and B (­). Maximum wire ohmic resistance between sensor and 24VDC source is defined below. Maximum wire size
for termination in the Detcon J-Box accessory is 14 gauge.

Max Resistance drop on red and black wire is 10 ohms. This considers wire diameter, wire length and
maximum operation temperature.

Max loop load resistance between green and black wire is 500 ohms. Minimum loop load resistance between
green and black wire is 100 ohms. This is considers wire diameter, wire length, max operating temperature
and selected termination resistor.

FP-700 Instruction Manual Rev. 3.0 Page 9 of 40

Model FP-700

NOTE 1:

NOTE 2:

NOTE 3:

Wiring table is based on stranded tinned copper wire and is designed to serve as a

reference only.

Shielded cable is required for installations where cable trays or conduit runs include
high voltage lines or other possible sources of induced interference. Separate conduit runs are
highly recommended in these cases.

The supply of power should be from an isolated source with over-current protection
as stipulated in table.

Terminal Connections

CAUTION:Do not apply System power to the sensor until all wiring is properly terminated. Refer to
Section2.7Initial Start Up

AWG Wire Dia.

Over-Current

Protection

22 0.723mm 3A
20 0.812mm 5A
18 1.024mm 7A
16 1.291mm 10A
14 1.628mm 20A

Table 1 Protection vs. Wire Gauge

Customer

Supplied Wiring (In)

Power from and 4-20mA

out to Control Device

Modbus RS-485 to

Host Control Device

mA

A(+)

B(-)

(+)

Explosion

Proof

Junction Box

(-)

Blu

Blk

Grn

Red

(+)mA(-)

Wiring to

Sensor Assembly

Wht

A(+)

B(-)

Customer

Supplied Wiring

(Out to next Device)

(+)
(-)
mA

A(+)
B(-)

Modbus RS-485 to

next Device

Install a 100-250 Ohm

resistor if the 4-20mA

output is not used

Figure 11 Sensor Wire Connections

a) Remove the junction box cover. Identify the terminal blocks for customer wire connections.

b) Observing correct polarity, terminate the 3-conductor 4-20mA field wiring (+, -, mA) to the sensor

assembly wiring in accordance with the detail shown in Figure 11. If the 4-20mA output is not used, the
green wire from the sensor must be connected to the (-) terminal on the Transient Protection Module.

FP-700 Instruction Manual Rev. 3.0 Page 10 of 40

Model FP-700

NOTE

NOTE

NOTE

NOTE: If the 4-20mA output is not being used, the Green wire from the sensor must be
connected to the Black wire at the (-) terminal on the Transient Protection Module to
ensure RS-485 communication is not disrupted by a 4-20mA Fault.

a) If applicable, terminate the RS-485 serial wiring as shown in Figure 11. Use the second plug (Out) as

termination point on the customer side to facilitate a continuous RS-485 serial loop

The RS-485 (if applicable) requires 24 gauge, two conductor, shielded, twisted pair cable between sensor and
host PC. General Cable Commodore part number ZO16P0022189 is recommended.

: Install a 120Ω resistor across A & B terminals on the last sensor in the serial loop.

c) Trim all exposed wire leads if they are not permanently landed in the terminal block.

d) Replace the junction box cover.

2.7 Initial Start Up

Upon completion of all mechanical mounting and termination of all field wiring, apply system power in the
range of 11.5-30VDC (24VDC typical) and observe the following normal conditions:

a) FP-700 display reads “0”, and no fault messages are flashing.

b) A temporary upscale reading may occur as the sensor heats up. This upscale reading will decrease to

0ppm within 1-2 minutes of power-up, assuming there is no combustible gas in the area of the sensor.

: The 4-20mA signal is held constant at 4mA for the first two minutes after power up.

Initial Operational Tests

After a warm up period of 1 hour, the sensor should be checked to verify sensitivity to combustible gas.

Material Requirements

 Detcon PN 613-120000-700 700 Series Splash Guard with integral Cal Port -OR-
 Detcon PN 943-000006-132 Threaded Calibration Adapter
 Detcon PN 942-520124-050 Span Gas; 50% LEL methane/balance Air at fixed flow rate of 200-

500cc/min (use with 0-100% LEL range).

 Detcon PN 942-520124-025 Span Gas; 25% LEL methane/balance Air at fixed flow rate of 200-

500cc/min (use with 0-50% LEL range).

: Do not use calibration gases in Nitrogen background gas mixtures. This will cause

significant reading inaccuracies.

a) Attach the calibration adapter to the threaded sensor housing. Apply the test gas at a controlled flow rate

of 200 - 500cc/min (200cc/min is the recommended flow). Allow 1-2 minutes for the reading to stabilize.
Observe that during the 1-2 minutes the ITM display increases to a level near that of the applied
calibration gas value.

b) Remove test gas and observe that the ITM display decreases to “0”.

FP-700 Instruction Manual Rev. 3.0 Page 11 of 40