Detcon DM-400IS User Manual

detcon inc.

Detcon Model Series

DM-400IS

Explosion Proof and Intrinsically Safe Toxic Gas Sensors

Operator’s Installation & Instruction Manual

November 8, 2010 • Document #2432 • Version 1.5.8

phone [phone] • fax [phone] • www.detcon.com • [e-mail]

Table of Contents

3.0 Description

3.1 Principle of Operation

3.2 Application

3.3 Specifications

3.4 Installation

3.5 Start-up

3.6 Calibration

3.7 Trouble Shooting Guide

3.8 Spare Parts List

3.9 Warranty

3.10 Service Policy

DM-400IS Toxic Gas Sensors PG.2

This manual covers the following Models...

Model # Gas Name Symbol

DM-400-C2H3O Acetyldehyde C2H3O
DM-400-C2H2 Acetylene C2H2
DM-400-C3H3N Acrylonitrile C3H3N
DM-400-NH3 (-20°C) Ammonia NH3
DM-401-NH3 (-40°C) Ammonia NH3
DM-402-NH3 (
DM-400-AsH3 Arsine AsH3
DM-400-Br2 Bromine Br2
DM-400-C4H6 Butadiene C4H6
DM-400-CS2 Carbon Disulfide CS2
DM-400-CO Carbon Monoxide CO
DM-400-COS Carbonyl Sulfide COS
DM-400-CL2 Chlorine CL2
DM-400-CLO2 (>40 ppm range) Chlorine Dioxide CLO2
DM-401-CLO2 (≤40 ppm range) Chlorine Dioxide CLO2
DM-400-B2H6 Diborane B2H6
DM-400-C2H6S Dimethyl Sulfide C2H6S
DM-400-C3H5OCL Epichlorohydrin C3H5OCL
DM-400-C2H5OH Ethanol C2H5OH
DM-400-C2H5SH Ethyl Mercaptan C2H5SH
DM-400-C2H4 Ethylene C2H4
DM-400-C2H4O Ethylene Oxide C2H4O
DM-400-F2 Fluorine F2
DM-400-CH2O Formaldehyde CH2O
DM-400-GeH4 Germane GeH4
DM-400-N2H4 Hydrazine N2H4
DM-400-H2 (ppm range) Hydrogen H2
DM-401-H2 (% LEL range) Hydrogen H2
DM-400-HBr Hydrogen Bromide HBr
DM-400-HCL Hydrogen Chloride HCL
DM-400-HCN Hydrogen Cyanide HCN
DM-400-HF Hydrogen Fluoride HF
DM-400-H2S Hydrogen Sulfide H2S
DM-400-CH3OH Methanol CH3OH
DM-400-CH3SH Methyl Mercaptan CH3SH
DM-400-NO Nitric Oxide NO
DM-400-NO2 Nitrogen Dioxide NO2
DM-400-O3 Ozone O3
DM-400-COCL2 Phosgene COCL2
DM-400-PH3 Phosphine PH3
DM-400-SiH4 Silane SiH4
DM-400-SO2 Sulfur Dioxide SO2
DM-400-C4H8S Tetrahydrothiophene C4H8S
DM-400-C4H4S Thiophane C4H4S
DM-400-C6H5CH3 Toluene C6H5CH3
DM-400-C4H6O2 Vinyl Acetate C4H6O2
DM-400-C2H3CL Vinyl Chloride C2H3CL

continuous exposure

) Ammonia NH3

DM-400IS Toxic Gas Sensors PG.3

3.0 DESCRIPTION

Construction of Electrochemical Sensor

Reference Electrode

Counter Electrode
Electrolyte Reservoir

Sensing Electrode

Diffusion Barrier

Detcon Model series DM-400IS, toxic gas sensors are designed to detect and continuously monitor for toxic gas in the
ppm range. Method of detection is by diffusion/adsorption requiring no moving parts. The sensor assembly consists of
an electrochemical fuel cell mounted in an Intrinsically Safe stainless steel and ABS plastic housing that includes an
integral rain-shield, a universal signal conditioning control transmitter circuit, a base connector board and an explosion
proof junction box.

Typical ranges of detection are 0-10ppm, 0-25ppm, 0-50ppm and 0-100ppm. Other ranges are available and all ranges are cov­ered by this manual. To find out the specific gas type and range of detection of your sensor(s), refer to the label located on
the stainless steel sensor housing.

3.0.1 Sensor Technology

The sensors are electrolytic chemical cells. Each cell consists of three electrodes embedded in an electrolyte solution all
housed beneath a diffusion membrane. Sensitivity to specific target gases 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 long service life of up to 3 or more years. The fuel cell is packaged as a field
replaceable plug-in sensor via gold plated pins. Pre-amplifier and intrinsically safe barrier circuits are epoxy potted in the
stainless steel housing and include the mating sockets for the sensor.

DM-400IS Toxic Gas Sensors PG.4

3.0.2 Control Transmitter Circuit

T

E

X

A

S

H

O

U

S

T

O

N

SIGNAL

Model DM-4xx

ZERO

FINE

COARSE

Gas Sensor

detcon inc.

UNIVERSAL

TRANSMITTER

0

1

2

3

4

5

6

7

8

9

A

B

C

D

E

Span Adjustments

Plug-in Transmitter Circuit

Signal Test Points

BLK

BLU

YEL

WHT

MA

Sensor

4-20 mA Loop

+VDC
VDC Common

Intrinsically Safe
Sensor Head

Transmitter Electronics
in Explosion-Proof housing

The 4-20 mA DC control transmitter is equipped with zero and span adjustments accessible through a face plate allowing
one man remote calibration without communication with control room personnel. The transmitter circuit module is
plug-in replaceable, via gold plated pins, facilitating easy maintenance and repair.

3.0.3 Base Connector Board
The base connector board is mounted in the explosion proof enclosure and includes: the mating connector for the con­trol circuit, reverse input and secondary transient suppression, input filter and lugless terminals for all field wiring.

3.0.4 Explosion Proof Enclosure
The explosion proof enclosure is a Killark type HKB-GC with 3/4” NPT female entry ports. It’s constructed of cast alu­minum and given an epoxy paint finish. The enclosure is fitted with a threaded cover. Electrical classification is Class 1;
Groups B, C, D; Div. 1.

DM-400IS Toxic Gas Sensors PG.5

3.1 PRINCIPLE OF OPERATION

Functional

Block

Diagram

4-20 mA +

Sensor

Element

Preamp

I/O Circuit
Protection

4-20 mA –

(11.5-28 VDC)

Transmitter Power

Signal Conditioning

(zero/span)

Method of detection is by an electrochemical reaction at the surface of an electrode called the sensing electrode. Air
and gas diffuse through the capillary diffusion barrier. The controlling circuit maintains a small external operating volt­age between the sensing and counter electrodes of the proper bias and magnitude so that no current flows to or from
the reference electrode while its potential is maintained at the correct fixed voltage — usually ground. The electrochemi­cal reaction creates a change in current flow from the counter electrode to the sensing electrode. This change in current
is proportional to the gas concentration and is reversible. The quick response of the sensor results in continuous moni­toring of ambient air conditions. The Intrinsically Safe Housing design allows direct contact of the target gas to the
electrochemical sensor, thus maximizing response time, detectability and repeatability.

3.2 APPLICATION

3.2.1 Sensor Placement/Mounting

Sensor location should be reviewed by facility engineering and safety personnel. Area leak sources and perimeter mounting
are typically used to determine number and location of sensors. The sensors are generally located 2 - 4 feet above grade.

3.2.2 Interference Data

Detcon Model DM-400IS series electrochemical sensors are subject to interference from other gases. This interaction is
shown in the table in section 3.2.4 as the relation between the amount of the interfering gas applied to the sensor, and
the corresponding reading that will occur. All measurements are in ppm unless otherwise noted.

The table is laid out with the Model Number of each sensor in a column on the left side of the page. The interfering
gases are listed in a row across the top of the page. Each page lists all Model Numbers but 5 pages are necessary to list
all interfering gases, thus each page is a repeat of the full line of Detcon sensors. Be sure to reference each page to ascer­tain the full listing of interfering gases for a particular sensor.

As an example, the first listing shows that the Model DM-400IS-C2H30 acetyldehyde sensor will have an interference
reading of 340 ppm if 40 ppm of C2H2 (Acetylene) is applied.

NOTE:

Interference factors may differ from sensor to sensor and with life time. It is not advisable to calibrate with

interference gases. They should be used as a guide only.

3.2.3 Interference Gas List

Gas Name

Symbol

Acetyldehyde C2H3O
Acetylene C2H2
Acrylonitrile C3H3N
Alcohols Alcohols
Amines Amines
Ammonia NH3
Arsenic Triflouride AsF3
Arsenic Pentaflouride AsF5
Arsine AsH3
Boron Triflouride BF3
Bromine Br2
Butadiene C4H6
Buten-1- Buten-1
Carbon Dioxide CO2

DM-400IS Toxic Gas Sensors PG.6

Carbon Disulfide CS2
Carbon Oxide Sulfide COS
Carbon Monoxide CO
Carbonyl Sulfide COS
Chlorine CL2
Chlorine Dioxide CLO2
Chlorine Triflouride CLF3
Diborane B2H6
Dimethyl Sulfide C2H6S
Disilane Si2H6
Epichlorohydrin C3H5OCL
Ethanol C2H5OH
Ethyl Mercaptan C2H5SH
Ethylene C2H4
Ethylene Oxide C2H4O
Fluorine F2
Formaldehyde CH2O
Germane GeH4
Hydrazine N2H4
Hydrocarbons C-H’s
Hydrocarbons (unsaturated) C-H’s (u)
Hydrogen H2
Hydrogen Bromide HBr
Hydrogen Chloride HCL
Hydrogen Cyanide HCN
Hydrogen Flouride HF
Hydrogen Selenide HSe
Hydrogen Sulfide H2S
Iodine I2
Isopropanol C3H8O
Methane CH4
Methanol CH3OH
Methyl-ethyl-ketone C4H8O
Methyl Mercaptan CH3SH
Nitric Oxide NO
Nitrogen N2
Nitrogen Dioxide NO2
Ozone O3
Phosgene COCL2
Phosphine PH3
Phosphorous Triflouride PF3
Silane SiH4
Silicon Si
Silicon Tetra Flouride SiF4
Sulfur Dioxide SO2
Tetrahydrothiophene C4H8S
Thiophane C4H4S
Toluene C6H5CH3
Tungsten Hexaflouride WF6
Vinyl Acetate C4H6O2
Vinyl Chloride C2H3CL

DM-400IS Toxic Gas Sensors PG.7