Detcon DM-700 User Manual

INSTRUCTION MANUAL

Detcon Model DM-700

DM-700 Toxic Gas Sensors

DM-700 O2Deficiency Sensors

This manual covers all ranges of electrochemical and O2deficiency sensors

offered in the Detcon Product Line

DETCON, Inc.

4055 Technology Forest Blvd.,

The Woodlands, Texas 77381

Ph.281.367.4100 / Fax [phone]

www.detcon.com

Dec. 25, 2013 • Document #3207 • Revision 4.0

Model DM-700

Page intentionally blank

Model DM-700 ii

Shipping Address: 4055 Technology Forest Blvd., TheWoodlands Texas 77381

Mailing Address: P.O. Box8067, The Woodlands Texas 77387-8067

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

Model DM-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 Intelligent Plug-in Electrochemical Gas 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

2.7.1 Toxic Gas Sensors........................................................................................................................ 11

2.7.2 O2Deficiency Sensors.................................................................................................................. 12

3. Operation....................................................................................................................................................13

3.1 Programming Magnet Operating Instructions................................................................................... 13

3.2 Operator Interface............................................................................................................................. 14

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

3.4 Calibration Mode .............................................................................................................................. 16

3.4.1 AutoZero....................................................................................................................................... 16

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

3.5 Program Mode .................................................................................................................................. 19

3.5.1 View Sensor Status....................................................................................................................... 19

3.5.2 Set AutoSpan Level...................................................................................................................... 21

3.5.3 Set Serial ID ................................................................................................................................. 21

3.5.4 Set Range...................................................................................................................................... 21

3.5.5 Signal Output Check..................................................................................................................... 22

3.5.6 Restore Factory Defaults.............................................................................................................. 22

3.6 Program Features .............................................................................................................................. 23

3.6.1 Operational Features..................................................................................................................... 23

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 Intelligent Plug-in Sensor ....................................................................................... 29

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

5.6 Replacement of DM-700 Sensor Assembly...................................................................................... 31

6. Troubleshooting Guide...............................................................................................................................32

7. Customer Support and Service Policy........................................................................................................35

7.1 Warranty Notice................................................................................................................................ 35

8. DM-700 Sensor Warranty ..........................................................................................................................36

9. Appendix ....................................................................................................................................................37

9.1 Specifications.................................................................................................................................... 37

9.2 Interference Table ............................................................................................................................. 40

9.3 Proper Application and Maintenance of Acrylonitrile Sensor.......................................................... 46

9.4 Spare Parts, Sensor Accessories, Calibration Equipment................................................................. 47

9.5 Model DM-700 Engineering Drawings ............................................................................................ 47

Model DM-700 iii

Model DM-700

10. Revision Log ......................................................................................................................................... 48

Table of Figures

Figure 1 Construction of Electrochemical Toxic Sensor...................................................................................... 1

Figure 2 Construction of Galvanic Cell................................................................................................................ 2

Figure 3 ITM Circuit Functional Block Diagram................................................................................................. 2

Figure 4 Sensor Assembly Front View ................................................................................................................ 3

Figure 5 Sensor Assembly Breakaway................................................................................................................. 3

Figure 6 Intelligent Plug-in Sensor....................................................................................................................... 4

Figure 7 ATEX Approval Label........................................................................................................................... 5

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

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

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

Figure 11 Magnetic Programming Tool............................................................................................................. 13

Figure 12 Magnetic Programming Switches...................................................................................................... 13

Figure 13 DM-700 Software Flowchart ............................................................................................................. 15

Figure 14 Sensor Assembly................................................................................................................................ 29

Figure 15 Sensor Cell and ITM Mating ............................................................................................................. 30

Figure 16 Sensor Cell and ITM Mating ............................................................................................................. 32

List of Tables

Table 1 Wire Gauge vs. Distance....................................................................................................................... 10

Table 2 Modbus™ Registers.............................................................................................................................. 27

Table 3 Modbus™ Special Registers ................................................................................................................. 28

Table 4 Sensor Specific Data ............................................................................................................................. 39

Table 5 Interfering Gasses.................................................................................................................................. 40

Table 6 Cross Interference Table pg.1 ............................................................................................................... 41

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 DM-700 iv

1. Introduction

Detcon Model DM-700 toxic gas and O2deficiency sensors are non-intrusive
“Smart” sensors designed to detect and monitor a wide range of toxic gasses in air.
Ranges of detection for toxic gasses are from 0-1ppm up to 0-10,000ppm. Ranges
for O2deficiency are 0-100ppm up to 0-25% by volume. The sensor features an
LED display of current reading, fault and calibration status. The Sensor 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, called the ITM (Intelligent Transmitter
Module). The ITM includes a four character alpha/numeric LED used to display
sensor readings, and the sensor’s menu driven features when the hand-held
programming magnet is used.

Model DM-700

1.1 Description

Electrochemical Sensor Technology

The Toxic gas sensors are based on electrochemical cells. Each cell consists of three electrodes embedded in
an electrolyte solution all housed beneath a diffusion membrane. Sensitivity to specific target gasses is
achieved by varying composition of any combination of the sensor components. Good specificity is achieved
in each sensor type. The cells are diffusion limited via small capillary barriers resulting in a long service life
of up to three or more years. The electrochemical cell is packaged as a field replaceable intelligent plug-in
sensor.

Figure 1 Construction of Electrochemical Toxic Sensor

The O2deficiency sensor technology is a two electrode galvanic metal air battery type cell, which is housed as
a field replaceable intelligent plug–in sensor. The cell is diffusion limited and functions as a direct current
generator proportional to the amount of oxygen adsorption. The sensors are temperature compensated and
show good accuracy and stability over the operating temperature range of –20° to 50°C (-4° to +122°
Fahrenheit). The sensor is warranted for two years and has an expected service life of up to 2.5 years in
ambient air at 20.9% oxygen.

DM-700 Instruction Manual Rev. 4.0 Page 1 of 48

Model DM-700

RS-4854-

20mA

Display

Intrinsically

Safe Barrier

Analog 4

-

20mA Out

Power Supply

Figure 2 Construction of Galvanic Cell

1.2 Sensor Electronics Design

Intelligent Transmitter Module

The DM-700 Intelligent Transmitter Module (ITM) is a fully encapsulated microprocessor-based package that
is universal in design and will accept any Detcon intelligent plug-in electrochemical gas sensor. The ITM
design uses an internal intrinsically safe barrier circuit that lifts the requirement for use of flame arrestors to
achieve Class 1, Division 1 (Zone1) area classification. This facilitates fast response times and improved
calibration repeatability on highly corrosive gas types. The ITM circuit functions include extensive I/O circuit
protection, on-board power supplies, internal intrinsically safe barrier circuit, microprocessor, LED display,
magnetic programming switches, a linear 4-20mA DC output, and a 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 IIC.

Intelligent

Plug-In

Sensor

Micro-

Processor

I/O

Circuit

Protection

Modbus™ RS-485 Output

Power In

Figure 3 ITM Circuit Functional Block Diagram

DM-700 Instruction Manual Rev. 4.0 Page 2 of 48

Model DM-700

LED Display

Program Switch #2

Program Switch #1

Splashguard Adapter

detcon inc.

detcon inc.

MODEL

DM-700

H2S Sensor

Locking Set-Screw

Figure 4 Sensor Assembly Front View

1.3 Modular Mechanical Design

The Model DM-700 Sensor Assembly is completely modular and is made up of four parts (See Figure 5 for
Assembly Break-away):

1) DM-700 Intelligent Transmitter Module (ITM)

2) Intelligent Plug-in Sensor (varies by gas type and range)

3) Model DM-700 Splash Guard Adapter

4) Splash Guard.

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

Plug-In
replaceable
Sensor Cell

O2 Sensor

Magnetic
Programming
Switches

Splash Guard

Splashguard

Adapter

O-Rings

Housing Bottom
Locking Set-Screw

Figure 5 Sensor Assembly Breakaway

DM-700 Instruction Manual Rev. 4.0 Page 3 of 48

Lens and LCD
Display

DM-700-O2

detcon inc.

MODEL

Interconnect

Wiring

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

Model DM-700

1.4 Intelligent Plug-in Electrochemical Gas Sensor

The Detcon family of electrochemical gas sensors are field proven, intelligent plug-in sensors with over-sized
gold-plated connections that eliminate corrosion problems. The intelligent design provides automatic
recognition of gas type, units, full-scale range, and calibrations data when a new sensor is plugged in. The
sensor can be accessed and replaced in the field very easily by releasing the locking setscrew and unthreading
the Splashguard Adapter. Detcon’s family of toxic sensors have a long shelf life and are supported by an
industry-leading warranty.

PLUG-INO
ALIGN AR
WITH LED

ntents on skin

Figure 6 Intelligent Plug-in Sensor

DM-700 Instruction Manual Rev. 4.0 Page 4 of 48

Model DM-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 7 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.

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. 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.

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 6g6h having yield strength of greater than 40,000 PSI, typical
80,000 PSI. If screw requires replacement, only an identical screw may be used.

7. Do not substitute components that are not authorized by the scope of the safety approval. This may
impair the intrinsic safety rating.

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.

DM-700 Instruction Manual Rev. 4.0 Page 5 of 48

Model DM-700

NOTE:

10. The sensor power supply common (black wire) must be referenced to the metal enclosure body
(ground) during installation.

11. These sensors meet EN60079-0:2009, EN60079-1:2007, EN60079-11:2012 and EN 50020

12. These sensors have a maximum safe location voltage of Um=250V.

13. These sensors pass dielectric strength of 500VRMS between circuit and enclosure for a minimum of 1
minute at a maximum test current of 5mA.

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) Additional placement considerations

Density

Placement of sensors relative to the density of the target gas is such that sensors for the detection of heavier
than air gasses should be located within 4 feet of grade as these heavy gasses will tend to settle in low lying
areas. For gasses lighter than air, sensor placement should be 4-8 feet above grade in open areas or in pitched
areas of enclosed spaces.

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.

All installations of the gas sensor should point straight down (refer to Figure 9).

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

DM-700 Instruction Manual Rev. 4.0 Page 6 of 48

Model DM-700

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.

Mount 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

Electrochemical toxic gas may be adversely affected by exposure to other airborne gasses. Depending on the
cross-sensitivity relationship, there may be a positive or negative impact on the reading.

The most commonly present gasses that potentially cause interference problems are listed in Table 6 Cross
Interference Table (refer to Section 9).

The presence of cross-interference gasses in an area does not preclude the use of this sensor technology,
although it is possible that the sensor could experience a false high or false low reading should exposure occur.

Cross-Interference Data Table

Table 6 Cross Interference Table (refer to Section 9) lists the gasses typically found in industrial environments
that may cause a cross-interference response on members of the Detcon family of toxic gas sensors. Review
Table 6 in Section 9 for the correct gas and then scan across the list for possible interference gasses.
Determine the magnitude of cross-interference that may occur.

2.4 Mounting Installation

The DM-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 DM-700 should be vertically oriented so that the sensor points straight down. 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 8 below). 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.

DM-700 Instruction Manual Rev. 4.0 Page 7 of 48

Model DM-700

NOTE:

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.)

5.5"

4.95"

3/4" NPT

Ø0.265" x2

Mounting Holes

3.675"

12.7"

5.25"

8.06"

5.53"

2"

8-32 Thread
Ground Point

Explosion Proof Enclosure

Junction-Box

(Detcon's Junction-Box shown)

Use Spacers to move

the J-Box and Sensor

detcon inc.

MODEL

DM-700

CO2 Sensor

2.125"

Assembly away from the

wall at least 0.25-0.5" to

allow access to Sensor

Sensor Assembly

Splash Guard

Figure 8 Outline and Mounting Dimensions

Bolt

Mounting

Spacer

Wall (or other

mounting surface)

2.5 Electrical Installation

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 IIC area 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 9 and Figure 10 for proper electrical installation.

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

Figure 9.

In Figure 9, the drain allows water 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.

DM-700 Instruction Manual Rev. 4.0 Page 8 of 48

Model DM-700

NOTE:

NOTE:

NOTE:

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

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

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

Conduit

"T"

Drain

Customer

Supplied Wiring

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

N/U

A(+)

B(-)

(+)

(-)

mA

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

Blu

Blk

Grn

Red

(+)mA(-)

Wiring to

Sensor Assembly

Wht

A(+)

B(-)

DM-700

Sensor

Assembly

6-Pin Pheonix Plug

P/N 306-175705-100

Plug any unused

Explosion Proof

Housing

(J-Box)

detcon inc.

MODEL

DM-700

H2S Sensor

ports

Figure 9 Typical Installation

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 DM-700 toxic gas sensors assemblies require three conductor connections between power
supplies and host electronic controller’s 4-20mA output, and two conductor connections for the Modbus™ RS­485 serial interface. Wiring designations are + (DC), – (DC), mA (sensor signal), and Modbus™ RS-485 A
(+), and B (-). Maximum wire length between sensor and 24VDC source is shown in the Table 1 below.
Maximum wire size for termination in the Detcon J-Box accessory is 14 gauge.

DM-700 Instruction Manual Rev. 4.0 Page 9 of 48

AWG Wire Dia. Meters Feet

NOTE 1:

NOTE 2

NOTE 3:

22 0.723mm 700 2080 3A
20 0.812mm 1120 3350 5A
18 1.024mm 1750 5250 7A
16 1.291mm 2800 8400 10A
14 1.628mm 4480 13,440 20A

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

The supply of power should be from an isolated source with over-current protection

as stipulated in table.

Terminal Connections

Model DM-700

Table 1 Wire Gauge vs. Distance

Over-Current

Protection

highly recommended in these cases.

CAUTION: Do not apply System power to the sensor until all wiring is properly terminated. Refer to

Section 2.7 Initial Start Up

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 10 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 10. If the 4-20mA output is not used,

install a 100-250Ω resistor between the mA and (-) terminals on the Transient Protection Module.

DM-700 Instruction Manual Rev. 4.0 Page 10 of 48

Model DM-700

NOTE

NOTE

NOTE

NOTE

: If the 4-20mA output is not being used, a 100-250Ω resistor must be installed between

the mA and (-) terminals 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 10. 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 the sensor
and host. General Cable Commodore part number ZO16P0022189 is recommended.

: Install a 120-ohm 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:

2.7.1 Toxic Gas Sensors

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

b) A temporary upscale or downscale reading may occur as the sensor stabilizes. This upscale reading will

typically decrease to “0” ppm within 1-2 minutes of power-up, assuming there is no gas in the area of the
sensor.

c) Sensors that use a bias voltage require a longer time to stabilize. This can vary between 1 and 24 hours

depending on the sensor type and range. Biased sensors include NH3, NO, HCl, and VOC gasses
(ethylene oxide, ethylene, methanol, formaldehyde….etc.).

: 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 (or when zero has stabilized), the sensor should be checked to verify
sensitivity to the target 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 Span Gas; 50% of range target gas in balance N2or Air at fixed flow rate between 200-

500cc/min

: Calibration gas generators using perm tubes or electrochemical sources may be used in

place of span gas cylinders.

DM-700 Instruction Manual Rev. 4.0 Page 11 of 48

Model DM-700

a) Attach the calibration adapter to the threaded sensor housing or connect tubing to integral cal port. Apply

the test gas at a controlled flow rate of 200 - 500cc/min (500cc/min is the recommended flow). Observe
that 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”.

Initial operational tests are complete. DM-700 toxic gas sensors are factory calibrated prior to shipment, and
should 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 zero and span calibration
instructions in Section 3.4.

2.7.2 O2Deficiency Sensors

a) DM-700 display reads close to 20.9% and no fault messages are flashing.

b) The reading should stabilize within 1 to 2 minutes of power-up (assuming a ‘normal’ ambient O

concentration).

Initial Operational Tests

After a warm-up period of 5 minutes the sensor should be checked to verify response to O2deficiency.

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 Zero Gas: 100% N2 at fixed flow rate of 200-500cc/min

a) Attach the calibration adapter to the threaded sensor housing or connect tubing to the integral cal port.

Apply the test gas at a controlled flow rate of 200-500cc/min (500cc/min is the recommended flow).
Observe that the ITM display decreases to a level near zero.

b) Remove test gas and calibration adapter. The ITM display should return to a reading of 20.9%.

Initial operational tests are complete. DM-700 O2deficiency sensors are factory calibrated prior to shipment,
and should 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 zero and span calibration
instructions in Section 3.4.

2

DM-700 Instruction Manual Rev. 4.0 Page 12 of 48

Model DM-700

NOTE

3. Operation

3.1 Programming Magnet Operating Instructions

The Operator Interface of the Model 700 Series gas sensors is accomplished via two internal magnetic
switches located to either side of the LED display (see Figure 12). The two switches, labeled “PGM1” and
“PGM2”, allow for complete calibration and configuration, thereby eliminating the need for area de­classification or the use of hot permits.

Figure 11 Magnetic Programming Tool

The magnetic programming tool (Figure 11 Magnetic Programming Tool) is used to operate the magnetic
switches. Switch action is defined as momentary contact, 3-second hold, and 10-second hold. (Hold times are
defined as the time from the point when the arrow-prompt ““appears.) For momentary contact use, the
programming magnet is briefly held over a switch location. For 3-second hold, the programming magnet is
held in place over the switch location for three seconds. For 10-second hold, the programming magnet is held
in place over the switch location for 10 seconds. The 3 and 10 second holds are generally used to enter
calibration/program menus and save new data. The momentary contact is generally used to move between
menu items and to modify set-point values. Arrows (“” and “”) are used on the LED display to indicate
when the magnetic switches are activated. The location of “PGM1” and “PGM2” are shown in Figure 12.

LED Display

Program Switch #2

Program Switch #1

detcon inc.

detcon inc.

MODEL

DM-700

H2S Sensor

Figure 12 Magnetic Programming Switches

: While in the Program Mode, if there is no magnetic switch interaction after 4

consecutive menu scrolls, the sensor will automatically revert to normal operating condition.
While changing values inside menu items, if there is no magnet activity after 3-4 seconds

the sensor will revert to the menu scroll.

(Exception to this is with “Signal Output Check” mode.)

DM-700 Instruction Manual Rev. 4.0 Page 13 of 48

Model DM-700

3.2 Operator Interface

The operating interface is menu-driven via the two magnetic program switches located under the target marks
of the sensor housing. The two switches are referred to as “PGM1” and “PGM2”. The menu list consists of
three major items that include sub-menus as indicated below. (Refer to the complete Software Flow Chart
Figure 13.)

Normal Operation

Current Reading and Gas Type/Fault Status

Calibration Mode

AutoZero
AutoSpan

Program Mode

View Sensor Status

Sensor Model Type
Current Software Version
Gas Type
Range of Detection
Serial ID address
AutoSpan Level
Days Since Last AutoSpan
Remaining Sensor Life
mA Output
Input Voltage Supply
Sensor Temperature
Output
Bias Voltage
Gain Setting

Raw Counts
Set AutoSpan Level
Set Serial ID
Set Range
Signal Output Check
Restore Default Settings

DM-700 Instruction Manual Rev. 4.0 Page 14 of 48