Sierra Monitor Corporation 4105 User Manual

MODEL 4105 SERIES

GAS SENSOR MODULE

WITH DIGITAL DISPLAY AND

NON-INTRUSIVE CALIBRATION

4-20 mA

Sierra Monitor Corporation

1991 Tarob Court, Milpitas, CA 95035

[phone] [phone]

Fax: [phone]

E-Mail: [e-mail]

MODEL 4105 SERIES

GAS SENSOR MODULE

WITH DIGITAL DISPLAY AND

NON-INTRUSIVE CALIBRATION

4-20 mA

APPLICABILITY & EFFECTIVITY

This manual provides instructions for the following Sierra Monitor products:

Model Description

4105-02 Combustible Gas Sensor Module with Non-Intrusive Calibration
4105-03 Oxygen Gas Sensor Module with Non-Intrusive Calibration
4105-04 Carbon Monioxide Gas Sensor Module with Non-Intrusive Calibration
4105-05 Hydrogen Sulfide Gas Sensor Module with Non-Intrusive Calibration
4105-06 Chlorine Gas Sensor Module with Non-Intrusive Calibration
4105-07 Hydrogen Gas Sensor Module with Non-Intrusive Calibration
4105-10 Sulfur Dioxide GasSensor Module with Non-Intrusive Calibration
4105-12 Nitrogen Dioxide Gas Sensor Module with Non-Intrusive Calibration
4105-21 Hydrogen Chloride Gas Sensor Module with Non-Intrusive Calibration
4105-22 Hydrogen Cyanide Gas Sensor Module with Non-Intrusive Calibration
4105-25 Ammonia Gas Sensor Module with Non-Intrusive Calibration
4105-26 Hydrogen Flouride Gas Sensor Module with Non-Intrusive Calibration

The instructions are effective for the above models as of April 1, 1998

Instruction Manual Part Number: T13008

Rev. E1

TABLE OF CONTENTS

SECTION PAGE

1. PRODUCT DESCRIPTION 1

1.1 Introduction 1

1.2 Application 1

1.3 Configuration 1

1.3.1 Electronics 1

1.3.2 Sensor 1

2. CAUTIONS WARNINGS & RECOMMENDATIONS 2

2.1 Introduction 2

2.2 Wiring 2

2.3 Sensor Modules - General 2

2.4 Preventative Maintenance 2

3. QUICK START 3

3.1 Overview 3

3.2 Wiring 3

3.3 Module Installation 3

3.4 Wiring Connection 3

3.5 Transmitter Installation 3

3.6 Start-up & Operation 3

4. OPERATION 4

4.1 Introduction 4

4.2 Signal Value 4

5. CALIBRATION 5

5.1 Frequency of Calibration 5

5.2 Calibration Process 5

5.3 Equipment Required 5

5.4 Calibration Procedure 5

5.5 Fault Supervision 5

6. SERVICE 6

6.1 Sensor Module Configuration 6

6.2 Enclosure Replacement 6

6.3 Transmitter Replacement 6

6.4 Sensor Replacement 6

7. INSTALLATION 8

7.1 Sensor Locations 8

7.2 Sensor Mounting 8

7.3 Explosion Proof Installation 8

7.4 Power Supply 8

8. SPECIFICATIONS 10

9. REPLACEMENT PARTS 13

10. WARRANTY 13

11. APPENDICES 14

1. PRODUCT DESCRIPTION

5.42"

2.81"

1.75"

4.50"

7.25"

1.1 Introduction

Model 4105 Series Gas Sensor module features non­intrusive calibration, 4-20 mA output signal and local
continuous display of the gas concentration in ppm
(toxics), % LEL (Combustibles), or % vol (Oxygen). It
is designed for use with industry standard control in­struments.

This manual provides instructions for 4105 series gas
sensor modules that utilize common packaging and
transmitter electronics with different sensors for de­tection of various gases. The full model number of
the gas sensor module includes a suffix, 4105-XX,
where “XX” is a number that identifies a gas type.

1.2 Application

The Model 4105-XX Gas sensor is intended for use in
ambient monitoring applications. It is designed for
fixed installation and for continuous operation.

Instruction Manual

Figure 1.1 Model 4105 Gas Sensor Module

Optional fittings and adapters can be supplied by Si­erra Monitor to provide continuous sample delivery
to the sensor module.

1.3 Configuration

The gas monitor is comprised of a NEMA-7/4 enclo­sure which contains the transmitter electronics and a
gas sensor which is installed in one of the two 3/4"
conduit hubs.

FAULT /KEYPAD

MODEL 4105-02

Combustibles

% LEL

5.50"

Unity SPAN ZERO

Ph. 408-262-6611

Milpitas, CA

CAL

1.3.1 Electronics

When installed, the transmitter electronics will be con­nected to a power supply and control device via three
wire cable.

The electronics provide a 4-20 mA current loop which
is proportional to the full sensitivity of the sensor.
Integral features include:

- L.C.D. readout of ppm of gas concentration.

- Magnetic switches for non-intrusive calibration.

- Visual indicators for fault condition.

- Electrical fault (0 mA) to controller.
The transmitter electronics assembly includes a

printed circuit assembly and a cover plate which con­tains the L.C.D. readout and magnetic switches for
calibration.

1.3.2 Sensor

The gas sensor cell is enclosed in a threaded housing
and is plugged into a signal card located in the enclo­sure. This configuration allows for easy field replace­ment of the sensor cell.

Figure 1.2 Outline View - Gas Sensor Module

Model 4105 Gas Sensor Module (12/02)

Combustible: The gas sensor is a catalytic bead type.
Toxics & Oxygen: The gas sensor is an Electro Chemi-

cal type.

Page: 1

Instruction Manual

2. CAUTIONS WARNINGS &
RECOMMENDATIONS

2.1 INTRODUCTION

Although the sensor module is designed and con­structed for installation and operation in industrial
applications including “hostile” environments, cau­tion should be taken to insure that the installation is
in compliance with this instruction manual and that
certain procedures and conditions are avoided.

READ AND UNDERSTAND THIS INSTRUCTION
MANUAL BEFORE OPERATING OR SERVICING
THIS EQUIPMENT.

Wire Gauge Maximum Length

20 AWG 2,000 Ft.
18 AWG 3,000 Ft.
16 AWG 4,000 Ft.
14 AWG 6,500 Ft.
12 AWG 9,000 Ft.

Table 2.1

Recommended Wire/Cable Gauge

NOTE: Temperature rating of cable wire insulation

must be above 75oC (85oC or greater rated wiring is
recommended). If cable runs through higher tempera­ture environments, it should be specified for that en­vironment.

2.2 WIRING

Electro magnetic and radio frequency interference to
the analog communication between the sensor and
the controller may occur. The manufacturer recom­mends that extra caution be taken where the installa­tion is near any sources of these interferences:

Avoid running sensor cable close to high power
cables, radio transmission lines, or cables subject to
pulses of high current. Avoid running cables near
large electric motors or generators.

Use shielded cable in any location which may be ex­pected to be electrically noisy or where cable is ex­pected to be in close contact with AC wiring. The
shield should be connected to the controller com­mon, one side only.

The wiring should be run in either a cable tray or
conduit as required by applicable code and area clas­sification. Control wiring should not be installed in a
cable tray or conduit with higher voltage and AC cir­cuits. See Table 2.1 for recommended wire gauge.

Wiring connections at the gas sensor module are as
follows:

Wire# Function Terminal

1 Power PWR
2 Signal SIG OUT
3 Ground GND

Connect an earth ground to the ground screw pro­vided in the base of the gas sensor module enclo­sure.

All splices must be via either a lug and terminal sys­tem or soldered. Improperly spliced cable can result
in corrosion, resistance changes and system errors.

2.3 SENSOR MODULES - GENERAL

Sensors should be facing down. Avoid installing sen­sor modules where they will be unnecessarily exposed
to wind, dust, water (esp. direct hose down), shock,
or vibration. Observe temperature range limitations.

Sensors may be adversely affected by prolonged ex­posure to certain materials. Loss of sensitivity, or
corrosion, may be gradual if such materials are present
in low concentrations. These materials include: Ha­lides (compounds containing chlorine, fluorine, bro­mine, or iodine), silicones, acid vapors, caustic liq­uids or vapors.

Sensor modules must not be painted. Paint may con­tain compounds which will contaminate the sensor.
Paint will also cause clogging of the sintered metal
cup and will cause difficulties during attachment of
the calibration fitiing. The module should be tagged
“DO NOT PAINT”.

When sensors are replaced the thread on the sensor
housing must be lubricated with an antizieze com-
pound non-silicone based to avoid metal to metal
binding which will damage the housing threads.

2.4 PREVENTATIVE MAINTENANCE

DUST AND DIRT CONTROL: When calibration is
performed the controller and sensors should be
checked visually to determine if dust or dirt build up
needs to be removed. This cleaning should be done
with dry instruments such as compressed air, cloth
wipes or wisk broom.

WIRING OR CABLE CONDITIONS: Any wiring or
cables which are not in conduit should be checked
once a year for damage to insulation or corrosion
of splice or terminal points.

Page: 2

Model 4105 Gas Sensor Module (12/02)

3. QUICK START

MODEL 4105-05

3.1 Overview

The gas sensor module has been supplied factory cali­brated and ready for immediate installation and opera­tion. An installer familiar with installation and opera­tion of gas detection products can use this section to
begin immediate use of the monitor.

3.2 Wiring

Provide three conductor wiring from the power sup­ply/control device to the sensor module location. See
section 2.2 for wiring specifications.

3.3 Module Installation

Remove spring on electromechanical sensor prior to
installation. See Figure below.

Instruction Manual

PPM

HS PPM

2

GAS MONITOR

Unity

Typical Vertical Mounting on Conduit

FAULT

ZEROSPAN

Figure 3.1

The module can either be installed on the end of a
3/4" conduit, or attached to a vertical surface using
the mounting flange on the enclosure.

WARNING:

- The installation must meet any hazardous envi­ronment codes for electrical equipment.

- The sensor module enclosure mounting must be
far enough from any vertical surface to allow re­moval and replacement of the sensor assembly
which is threaded into the second 3/4" conduit
hub.

3.4 Wiring Connection

To gain access to the I/O PCB for wiring or mounting
purposes, loosen the two captive thumb screws in the
4105-XX front panel and remove the PANEL/CPU PCB
assembly as far as is allowed by the ribbon cable.

Terminal positions on the I/O printed circuit assembly
are labeled PWR (power), OUTSIG (signal), GND (TB2).
Make the corresponding connections to the control
device/power supply.

The sensor harness should remain connected to the
I/O assembly at “TB1”.

3.5 Transmitter Installation

To install the front panel assembly, align the two thumb
screws with their mating stand-offs and firmly hand
tighten. Be sure the front panel is centered in the
4105-XX housing opening.

WARNING:

- If the sensor transmitter is installed in a classi­fied hazardous area, replace the threaded cover
prior to providing power.

3.6 Start-up & Operation

To begin operation of the sensor module provide 21-30
VDC from a regulated power supply.

Model 4105 Gas Sensor Module (12/02)

Page: 3

Instruction Manual

FAULT /KEYPAD

Milpitas, CA

Ph. 408-262-6611

FAULT /KEYPAD

Milpitas, CA

Ph. 408-262-6611

4. OPERATION

4.1 Introduction

Under normal conditions the sensor module does not
require operator or technician intervention. The fol­lowing are conditions under which the module requires
attention:

- Routine periodic calibration.

- Calibration after a high gas alarm.

- Sensor replacement on a planned schedule or
when a sensor failure occurs.

- Periodic cleaning as necessary.

- Unanticipated maintenance.

4.2 Signal Value

During normal operation the current loop of the sen­sor module and the controller will be between 4 mA
indicating no presence of gas, and 20 mA indicating
that the full scale concentration of gas is present. The
signal value is proportional to the concentration of
gas present.

Page: 4

MODEL 4105-02

Combustibles

Unity SPAN ZERO

CAL

% LEL

Figure 4.1

Transmitter Cover Plate

Unity

MODEL 4105-05
HS2PPM

SPAN ZERO

CAL

Model 4105 Gas Sensor Module (12/02)

5. CALIBRATION

5.1 Frequency of Calibration

Instruction Manual

The manufacturer recommends that the gas sensor
module be calibrated every ninety days.

5.2 Calibration Process

The output signal of the gas sensor module is cali­brated using a span mixture containing a known con­centration of the gas of interest. The concentration
of the span gas must be within the full scale of the
sensor module and should be either 50% of the full
scale, or approximately equal to the lowest alarm level.

Calibration requires application of the span gas to the
sensor and adjustment of the “SPAN” magnetic switch
making the module signal output and display equiva­lent to the concentration of sample gas. The 4-20 mA
output is held at 1.5 mA while activated for calibration
to prevent alarms being tripped by calibration gas
application.

5.3 Equipment Required

The following tools and equipment will be required
for calibration:

- Magnetic tool

- Gas Sensor Calibrator, Model 1260-XX
or Model 1200-26 or permeation tube

- Calibration Gas

- Disbursing Calibration Adapter (Model 5358-

01)

5.4 Calibration Procedure

Routine calibrations are easily performed using the
magnetic tool provided with each sensor.

Briefly hold the magnet tool close to the small dot
located on the lower edge of the front panel. The
arrow on the upper left side of the LED will illuminate
and the 4-20 mA output is locked at 1.5 mA, indicating
that the sensor module is ready for calibration. Sim­ply expose the sensor to a ZERO gas and observe the
L.C.D. readout. In normal situations, simply exposing
the sensor to an atmosphere free of the gas of interest
is satisfactory. If it does not return to the correct
ZERO reading, a ZERO adjustment is required. Hold
the magnet close to the UP ZERO or DOWN ZERO
indicators and adjust the reading to the correct ZERO
reading.

Connect the calibration adapter and expose the sen­sor to an appropriate SPAN gas using a span mixture
containing a known concentration of the gas of inter­est at a minimum flow rate of 300 cc/minute. (Use per­meation tube for 4105-25) Allow 3-5 minutes before
making any adjustments.

If the L.C.D. does not display the correct SPAN value,
a SPAN adjustment is required. With the arrow still
flashing, hold the magnet close to the UP SPAN or
DOWN-SPAN indicators and adjust the reading to the
correct SPAN value. (The 4-20 mA out is automati­cally adjusted.)

The monitor is now calibrated. Deactivate calibration
by holding the magnet close to the small dot again.
This releases the 1.5 mA lock.

5.5 Fault Identification

A Fault condition is detected if the sensor output drifts
far enough negative to cause the 4-20 mA output to

reach 1.5 mA (±15% of full scale) or the sensor failure.
The sensor module demonstrates that a fault condi­tion exists by illuminating the RED LED on the front
panel and by holding the 4-20 mA output at 0 mA.
These conditions will exist until the fault is corrected.

Model Gas Min. Flow Rate

(cc/min)

4105-02 CH
4105-03 O

4

2

100

100
4105-04 CO 150
4105-05 H2S 300
4105-06 Cl
4105-07 H
4105-10 SO
4105-12 NO

2

2

2
2

300

300

300

300
4105-21 HCl 300
4105-22 HCN
4105-25** NH

*

3

300

400
4105-26 HF 500

*Note: SO2 may be used instead of HCN to
calibrate: 10ppm SO2 = 16 ppm HCN
*Note: H2S may be used instead of HCl to
calibrate: 10 ppm H2S = 20 ppm HCl

** Note: Use permeation tube for 4105-25

Model 4105 Gas Sensor Module (12/02)

Table 4.1

Calibration Span Gas Flow Rates

Page: 5

Instruction Manual

6. SERVICE

6.1 Sensor Module Configuration

The gas sensor module is comprised of the following
sub assemblies:

4105-XX Gas Sensor Module

-SPM25002 Transmitter Assembly

-SPT25013 Combustible Gas Sensor
Module Transmitter Assembly

-SPM25003 Oxygen and Toxic Gas Sensor
Module Transmitter Assemby
(must specify gas type)

-4205-XX Sensor Assembly

[Where "xx" is the suffix to the gas sensor
module number (Table 6.1)]

There is no field servicable components below
the sub assembly level.

Warning: Prior to removal of the trans­mitter assembly, remove system power at
the controller or other power source.

Model Gas Module

4105-02 Combustible
4105-03 Oxygen
4105-04 CO
4105-05 H2S
4105-06 Cl
4105-07 H
4105-10 SO
4105-12 NO

2

2

2

2

4105-21 HCl
4105-22 HCN
4105-25 NH

3

4105-26 HF

Table 6.1

Model Numbers

6.3 Transmitter Replacement

The transmitter assembly should be replaced when it
is determined that it is unreliable, noisy or cannot be
adjusted for calibration. This may occur due to age,
corrosion or failed components.

To replace the transmitter assembly:

1. Remove the cover of the main enclosure.

2. Remove the front panel by loosening the two cap­tive thumb screws in the 4105-XX front panel and
remove the PANEL/CPU PCB assembly as far as is
allowed the by the ribbon cable.

3. Unscrew the sensor harness from the transmitter
(TB1).

4. Remove the three wires from the P,S,G terminals
(TB2).

5. Remove the I/O PCB.

6. Reverse the preceding steps to install the new
transmitter.

7. Restore power and allow a minimum of 30 minutes
for stabilization before re-calibration.

6.4 Sensor Replacement

The sensor should be replaced when it is determined
that:

- It is no longer possible to obtain correct Zero and
Span values at the test points or at the controller.

- The sensor output signal is noisy, causing errone­ous gas level readings.

To replace the sensor:

1. Remove the gas sensor module enclosure lid.

2. Remove the front panel by loosening the two cap­tive thumb screws in the 4105-XX front panel and
remove the PANEL/CPU PCB assembly as far as is
allowed the by the ribbon cable.

3. Unscrew the sensor wires from the transmitter..

6.2 Enclosure Replacement

The enclosure should be replaced if the lid threads or
conduit threads have been damaged, or if the enclo­sure has corroded sufficiently that it no longer meets
the required NEMA classification.

To replace the enclosure follow the transmitter and
sensor assembly removal instructions, remove the
damaged enclosure from it’s conduit or wall mount­ing, install a new enclosure and continue the trans­mitter and sensor assembly replacement instructions.

Page: 6

4. Unscrew the old sensor assembly from the enclo­sure conduit hub. Remove the sensor assembly
with its harness.

5. Reverse the preceding steps to install the sensor
assembly.

Model 4105 Gas Sensor Module (12/02)

6.4a.Combustibles

Instruction Manual

1. Verify the voltage across A to R equals 2 volt. If
not, adjust volts potentiometer R11

2. Verify the voltage from GND (TB2) to VOUT
equals 0.4 volts. If not adjust BAL potentiom­eter (R2)

3. Verify that the voltage at VOUT is equal to the
voltage desired.

• The VOUT test point on the I/O PCB has a range

of 0.4-2 volts for 0-100% of the measurement
range. Therefore, 0%=0.4 volts, 25%=0.8,
50%=1.2 volts, 75%=1.6 volts, 100%=2 volts.

• Selecting the jumper at JP1 assigns one of four

different sensitivity ranges to the module. The
JP1 positions are labeled 1, 2, 3 & 4. JP1 jumper
set the coarse up scale SPAN values by affect­ing the gain of the analog circuit. JP1 is set
correctly if an application of 50% of full scale
reads between 1.0 & 1.4 volts on VOUT. Fine­tuning of these setting is done later by adjust­ing the 4105-02 magnetic control.

JP1 gain values are as follows:

JP1 with jumper in position 1 = GAIN = 51
JP1 with jumper in position 2 = GAIN = 26
JP1 with jumper in position 3 = GAIN = 12.5
JP1 with jumper in position 4 = GAIN = 7
JP1 with no jumper = GAIN = 1

• The 4105-XX has 4 fixed ranges of sensitivity,

which are selectable via JP1.

• The JP1 positions are labeled 1, 2, 3 & 4.

• JP1 jumper set the coarse up scale SPAN values

by affecting the gain of the analog circuit.

• JP1 is set correctly if a 50% of full-scale gas

read between 1.0 & 1.4 volts on VOUT.

• Fine-tuning of these settings is done later by

adjusting the 4105-XX via magnetic control.

• Select the jumper at JP1 as required. JP1 gain

values are as follows:

JP1 with jumper in position 1 = GAIN = 5.5
JP1 with jumper in position 2 = GAIN = 4
JP1 with jumper in position 3 = GAIN = 2.3
JP1 with jumper in position 4 = GAIN = 1.5
JP1 with no jumper = GAIN = 1

• More than one jumper may be installed to allow

additional gain value. Multiple jumper are addi­tive in relation of the gain value. For example, if
a gain of 6.5 is needed, jumper should be placed
in positions 2 and 3 to provide a gain of 6.3.

Note: Allow the new sensor to stabilize for a mini­mum of 30 minutes and then calibrate using the
procedure in Section 5.

• More than one jumper may be installed to allow

additional gain value. Multiple jumper are addi­tive in relation of the gain value. For example, if
a gain of 20 is needed, jumper should be placed
in positions 3 and 4 to provide a gain of 20.

6.4b LEL Sensor Fault Supervision

The typical failure mode of catalytic bead sensors
is the reference or active beads open circuit. In
rare cases a short circuit may develop. The 4105­02 is equipped with fault detection circuitry that
detects either condition. A FAULT is also signaled
if the output drifts below -10% of full scale. The
4105-02 signals a FAULT condition exists by over­writing the LCD with a FLt message, flashing the
red LED on the front panel and clamping the 4­20mA output at 0mA. These conditions remain until
the FAULT is corrected.

6.4c Electrochemical (Oxygen and Toxics)

Verify that the voltage VOUT is equal to the volt­age as desired.

• The VOUT test point on the I/O PCB has a range

of 0.4-2 volts for 0-100% of the measurement
range.

6.4d Missing Electromechanical Sensor Fault Supervision

Many electromechanical sensor housings allow for
easy replacement of defective sensors by making the
sensors 'plug in'. A problem is that if the sensor is
removed, many transmitters continure to display the
safe reading of 0 PPM. The 4105-XX is equipped with
fault detection circuitry that detects a missing sensor.
Within several minutes of removing an EC sensor, the
4105-XX will signal a FAULT condition. A FAULT is
also detected if the sensor output drifts below -10%
of full scale. the Model 4105-XX demonstrates a
FAULT condition exists by overwriting the LCD read­ing with FLt, illuminating the red LED on the front
panel and by clamping the 4-20mA output at 0mA.
These conditions exist until the FAULT is corrected.

Model 4105 Gas Sensor Module (12/02)

Page: 7

Instruction Manual

7. INSTALLATION

7.1 Sensor Locations

Select locations for each of the sensors based on the
following:

- Consider the density of the gas to determine
height of sensor above floor or ground level.

- Sensors should be placed close to the potential
source of gas.

- Sensors should be placed in areas accessible for
calibration.

- Sensors must be pointed down and the conduit
should include an inverse trap to reduce mois­ture (condensation) from accumulating in the elec­tronics enclosure. See Figure 7.1.

7.2 Sensor Mounting

Where possible sensor modules should be installed
with the sensor facing vertically down. The lid of the
sensor module should face out for easy access.

Sensors may be mounted directly onto the end of a
vertical conduit, or bracketed to a vertical surface us­ing the two mounting flanges. Insure that the body of
the enclosure is at least 1" from the wall so that the
sensor assembly can be rotated for removal and re­placement. See Figure 6.1 for installation configura­tions.

7.3 Explosion Proof Installation

Where area classification requires explosion proof
(NEMA-7) installation a sealing fitting will be required
immediately above the gas sensor module enclosure.

7.4 Power Supply

The power supplied by the controlling device or an
external power supply must meet the following speci­fications:

Voltage: 21-30 VDC
Current: 180 mA (Combustibles)

40 mA (Oxygen & Toxics)

Page: 8

Figure 7.1

Gas Sensor Module Installation

Model 4105 Gas Sensor Module (12/02)

Instruction Manual

ELECTROCHEMICAL SENSORS

T B 2

P 1
R I B B O N C A B L E

T O C P U A S S Y .

U 2

1 3 2 4

R 2

J P 1

U 5

U 4

Combustible

V O U T

U 1

V O U T

P 1

R I B B O N C A B L E

T O C P U A S S Y .

U 2 U 7

R A C

T B 1

Sensor Pwr./Sig.

V O L T S B A L

U 3

R 1 1

Black

Brown

1 3 2 4

J P 1

Red

U 4

V O U T

ST-46A/EC I/O PCB FOR

P 1

R I B B O N C A B L E

T O C P U A S S Y .

U 2 U 7

1 3 2 4

J P 1

U 5

U 1

J P 2

R 1 9

S C R

T B 1 T B 2

Sensor Pwr./Sig.

B A

U 1

J P 2

U 5

Toxics

Short R&C

Black

Red

R 1 9

S C R

T B 1 T B 2

Sensor Pwr./Sig.

B A

Black

Red

White

Model 4105 Gas Sensor Module (12/02)

U 4

ST-46A/EC I/O PCB FOR

Oxygen

Figure 7.2

Wiring Diagram

Page: 9

Instruction Manual

8. SPECIFICATIONS

Model 4105-02 4105-03 4105-04 4105-05 4105-06 4105-07 4105-10
Gas Comb. O

2

Sensor Type Catalytic E.C. E.C. E.C E.C. E.C. E.C.
Units %LEL % Vol ppm ppm ppm ppm ppm
Range 0-100 0-25% 0-1000 0-100 0-10 0-1000 0-100
Resolution 3% F.S. 0.1% F.S. 1 0.1 0.1 2 0.5
Response Time Note 1 10 sec. 25 sec. 30 sec. 60 sec. 30 sec. 20 sec.

to 90% of signal
Sensor Life

2

3 Yrs 2 yrs 2 yrs 2 yrs 2 yrs 2 yrs 2 yrs

Operating Range
Temperature 14 to 158oF 19 to 122oF 14 to 122oF 14 to 122oF 14 to 122oF 14 to 122oF 14 to 122oF

-10 to 75oC -7 to 50oC -10 to 50oC -10 to 50oC -10 to 50oC -10 to 50oC -10 to 50oC

Relative Humidity 10-95% 5-99% 15-90% 15-90% 15-90% 10-90% 15-90%
Pressure 10% 10% 10% 10% 10% 10% 10%

Electrical Data
Input Voltage DC 19-30VDC at less than 100 mA
Output-Normal 4-20 mA DC linear
Output-Trouble 0 mA

CO H2S Cl

2

H

2

SO

2

Construction
Dimensions H: 7.6", D: 4.6", W: 4.2" (19.3 x 11.7 x 10.7 cm)

Weight (Module) 5.0 lb. (2.2 kg)
Mounting 3/4" NPT
Housing Explosion proof

(NEMA 7) / NEMA 4X Enclosure (Div. I, Class 1, Groups B, C, D)

Notes: 1. Step to 50% LEL within 10 sec, recovery to 10% LEL within 30 sec.

2. Sensor life is for use at standard temperature and pressure with occasional

exposure to the gas of interest

Page: 10

Model 4105 Gas Sensor Module (12/02)

8. SPECIFICATIONS (Continued)

Instruction Manual

Model 4105-12 4105-21 4105-22 4105-2534105-26
Gas NO

2

HCL HCN NH

3

HF

Sensor Type E.C. E.C. E.C. E.C. E.C.
Units ppm ppm ppm ppm ppm
Range 0-20 0-20 0-20 0-50 0-10
Resolution 0.2 0.5 0.1 0.1 0.5
Response Time 35 sec. 150 sec 70 sec. 45 sec. 30 sec.

to 90% of signal
Sensor Life

2

2 yrs 2 yrs 2 yrs N/A N/A

Operating Range
Temperature 14 to 122oF 14 to 122oF 14 to 122oF 14 to 113oF 14 to 113oF

-10 to 50oC -10 to 50oC -10 to 50oC -10 to 45oC -10 to 45oC

Relative Humidity 15-90% 15-90% 15-90% 20-90% 20-90%
Pressure 10% 10% 10% 10% 10%

Electrical Data
Input Voltage DC 19-30 VDC at less than 100 mA
Output-Normal 4-20 mA DC linear
Output-Trouble 0 mA

3

Construction
Dimensions H: 7.6", D: 4.6", W: 4.2" (19.3 x 11.7 x 10.7 cm)

Weight (Module) 5.0 lb. (2.2 kg)
Mounting 3/4" NPT
Housing Explosion proof

(NEMA 7) / NEMA 4X Enclosure (Div. I, Class 1, Groups B, C, D)

Notes: 2. Sensor life is for use at standard temperature and pressure with occasional exposure to the gas of interest

3. Diffusion via membrane. Dimensions are H: 10.2", D: 6.0", W: 6.0" (25.9 x 15.2x 15.2 cm)

Model 4105 Gas Sensor Module (12/02)

Page: 11

Instruction Manual

8. SPECIFICATIONS (Cont.)

Cross Sensitivities (toxic sensors)

Model Gas Reading from 100 ppm of interfering gas
Number Type CO H2S Cl

2

4105-04 CO 100 315 -15 <40 50 -55 30 2 40 <50
4105-05 H2S <0.5 100 -20 <0.1 <15 -15 0 0 0 0
4105-06 Cl
4105-07 H

2

4105-10 SO
4105-12 NO

2

2

0 <-10 100 0 0 105 0 0 0 0
<1 <20 0 100 3 0 35 3 35 85
<1 0 -40 0 100 -100 0 0 15 0

0 -20 90 0 0 100 0 0 -3 0

2

4105-21 HCl 0 75 -10 0 35 -2 0 100 -8 0
4105-22 HCN <0.5 -50 0 160 -190 -5 30 100 <1
4105-25 NH

0 0 0 - 40 0 0 - - -

3

4105-26 HF 0 0 9 0 9 5 - 6 - -

H

2

SO

NO

2

NO HCl HCN C2H

2

4

Page: 12

Model 4105 Gas Sensor Module (12/02)

9. REPLACEMENT PARTS

4205-02 Sensor Assembly, Combustible, Non-Intrusive
4205-03 Sensor Assembly, 4-20 mA O2, Non-Intrusive
4207-04 Sensor Assembly, 4-20 mA CO, Non-Intrusive
4205-05 Sensor Assembly, 4-20 mA H2S, Non-Intrusive
4205-06 Sensor Assembly, 4-20 mA Cl2, Non-Intrusive
4207-07 Sensor Assembly, 4-20 mA H
4207-10 Sensor Assembly, 4-20 mA SO2, Non-Intrusive
4207-12 Sensor Assembly, 4-20 mA NO2, Non-Intrusive
4207-21 Sensor Assembly, 4-20 mA HCl, Non-Intrusive
4207-22 Sensor Assembly, 4-20 mA HCN, Non-Intrusive
4207-25 Sensor Assembly, 4-20 mA NH3, Non-Intrusive
4207-26 Sensor Assembly, 4-20 mA HF, Non-Intrusive
5311-00 Rainshield

Non-Intrusive

2,

Instruction Manual

10. LIMITED WARRANTY

SIERRA MONITOR CORPORATION warrants its products
to be free from defects in workmanship or material under
normal use and service for two years after date of shipment.
SMC will repair or replace without charge any equipment
found to be defective during the warranty period. Final
determination of the nature and responsibility for defective
or damaged equipment will be made by SMC personnel.

All warranties hereunder are contingent upon proper use in
the application for which the product was intended and do
not cover products which have been modified or repaired
without SMC approval or which have been subjected to
accident, improper maintenance, installation or application,
or on which original identification marks have been removed
or altered. This Limited Warranty also will not apply to
interconnecting cables or wires, consumables (ie. calibra­tion gases, batteries, sensors), nor to any damage resulting
from battery leakage.

In all cases SMC’s responsibility and liability under this
warranty shall be limited to the cost of the equipment. The
purchaser must obtain shipping instructions for the prepaid
return of any item under this warranty provision and compli­ance with such instruction shall be a condition of this war­ranty.

Except for the express warranty stated above, SMC disclaims
all warranties with regard to the products sold hereunder
including all implied warranties of merchantability and fit­ness and the express warranties stated herein are in lieu of
all obligations or liabilities on the part of SMC for damages
including, but not limited to, consequential damages arising
out of/or in connection with the use or performance of the
product.

Model 4105 Gas Sensor Module (12/02)

Page: 13

Instruction Manual

Appendix A: Unity Gain Mode

The Unity magnetic control is available during CAL
MODE to allow the ZERO and SPAN adjustments to be
centered within their range. This is similar to setting a
potentiometer so the wiper terminal is exactly halfway
between the clockwise and counterclockwise terminals.
this is identified as the UNITY GAIN mode. In UNITY

GAIN the ZERO controls have a ± 15% of full scale
adjustment range. For example, in UNITY GAIN, if the
sensor's ZERO output has drifted so high that it reads
15% with ZERO gas applied, the DOWN ZERO magnetic
control could still bring the 4105-XX reading to ZERO.
However, it will be at the end of its adjustment range. If
the ZERO adjustment required is greater than ±10% of
full scale, a BALANCE adjustment should be performed
as described in Appendix A.

In UNITY GAIN the SPAN controls have a .5 to 2 adjust­ment range. For example, in UNITY GAIN, if a sensor's
output sensitivity has been reduced to the point where
50% SPAN gas provides only a 25% reading, the UP
SPAN magnetic control could still calibrate the reading
to the proper value of 50%. However, it will be at the end
of its adjustment range.

Appendix B: L.C.D. Readout Calibration Procedure

The 3 1/2 digit LCD meter span and decimal points
may be configured for full scale ranges such as 1­100, 0-25, 0-10.0, 0-1000 and many others. Zero per­cent of full-scale readings, or those corresponding
to 4mA, are always assumed to equal a reading of 0.
Holding the magnet over the CAL key for at least 5
seconds enters the LCD METER SPAN SETUP
MODE. After this, the current setting for 100% full
scale is displayed and may be modified using the UP/
DOWN SPAN keys. This sets the LCD reading dis­played when the 4-20mA output equals 30mA. Deci­mal points are added with the UNITY key.

Appendix C: End of Sensor Life Indication

Old sensors near the end of their service life require
higher gain settings. M4105-XX "END OF SENSOR
LIFE" (ESL) feature may be used to indicate condi­tion. A span trip point may be entered that when ex­ceeded, causes the LCD to flash and ESL reading for
2-seconds each 10 seconds. Holding the magnet to
the UNITY key for at least 5 seconds brings the LCD
a span value set-point reading for setting when the
ESL indication trips. CAL MODE GAIN adjustments
range between .5 and 2 and the ESL set-point is ad­justable between 1.5 and 2.01 with 2.01 turning the
ESL feature off. The current span setting may be
viewed on the LCD during NORMAL MODE by
touching the DOWN SPAN key.

Page: 14

Model 4105 Gas Sensor Module (12/02)

Instruction Manual

Appendix C: Combustible Gas Scaling Factors (Table 1)

Where possible, calibration gas should be the same as the gas to be detected. If this is not possible then a scaling factor
should be used to determine the “equivalent value” of the calibration gas in terms of the gas to be detected. (Note:
Concentration of calibration gas must be less than the factor number listed on Table 1).

The formula for calibration is as follows:

Display = (Cal gas) / Factor

where: Display = the span gas applied

Cal gas is the percent methane used for calibration.
Factor is a number that corresponds to the gas to be measured. (see Table 1)

Example: The application is for measurement of Propane and Methane is the calibration gas.

The factor for Propane (from Table 1) is 55.

For the example, calibration gas is Methane at 40% LEL.

Display = 40% LEL Methane / 55 = 0.73

Display = Adjust span until LCD reads 73.

Model 4105 Gas Sensor Module (12/02)

Page: 15

Instruction Manual

COMBUSTIBLE GAS SCALING FACTORS

For combustible gas monitoring, a calibration standard of Methane or Propane my be used in conjunction with scaling
factors to cause alarm function in %LEL scale of another gas as follows:

GAS METHANE PROPANE

FACTOR FACTOR

Acetaldehyde 60 109
Acetic Acid 54 98
Acetic Anhydride 46 83
Acetone 52 94
Acetylene 57 103
Alkyl Alcohol 51 92
Ammonia 126 229
n-Amyl Alcohol 33 59
Aniline 39 71
Benzene 41 74
Biphenyl 25 45
1,3-Butadiene 56 101
n-Butane 58 106
iso-Butane 52 94
Butene-1 45 82
cis-Butene-2 48 88
trans-Butene-2 51 92
n-Butyl Alcohol 34 62
iso-Butyl Alcohol 53 96
tert-Butyl-Alcohol 74 134
n-Butyl Benzene 31 57
iso-Butyl Benzene 32 58
n-Butyric Acid 38 69
Carbon Disulfide 18 32
Carbon Monoxide 75 137
Carbon Oxysulphide 93 169
Chlorobenzene 34 62
Cyanogen 89 162
Cyclohexane 41 74
Cyclopropane 62 113
n-Decane 33 59
Diethylamine 49 88
Dimethylamine 58 105
2,3-Dimethylpentane 40 72
2,3-Dimethylpropane 40 72
Dimethylsulphide 43 79
1,4-Dioxane 45 81
Epichlorohydrin 45 82
Ethane 68 123
Ethyl Acetate 51 93
Ethyl Alcohol 73 132
Ethylamine 53 95
Ethyl Benzene 36 65
Ethyl Bromide 91 165
Ethyl Chloride 57 103
Ethylcyclopentane 40 72
Ethylene 71 128
Ethylenedichloride 66 120
Ethyleneoxide 52 94

GAS METHANE PROPANE

FACTOR FACTOR

Diethyl Ether 46 84
Dimethoxyethane 42 75
Dimethyl Ether 63 113
Dimethylformamide 46 83
Ethyl Formate 44 80
Ethylmercaptan 56 102
n-Heptane 39 70
n-Hexane 37 67
Hydrazine 45 82
Hydrogencyanide 48 86
Hydrogen 77 139
Hydrogen Sulfide 41 74
Methane 100 181
Methyl Actetate 50 90
Methyl Alcohol 86 156
Methylamine 77 140
Methyl Bromide 90 162
Methyl Chloride 102 186
Methylcyclohexane 44 80
Methylenedichloride 93 168
Methylethylether 44 80
Methylethylketone 41 75
Methyl Formate 67 121
Methylmercaptan 61 110
Methylpropionate 51 93
Methyl n-propylketone 40 73
Napthalene 34 62
Nitromethane 34 62
n-Nonane 31 57
n-Octane 37 68
n-Pentane 46 83
i-Pentane 46 84
Propane 55 100
n-Propyl Alcohol 47 85
n-Propylamine 48 88
n-Propylchloride 50 90
Propylene 52 93
Propyleneoxide 46 83
iso-Propylether 44 79
Propyne 42 75
Toluene 40 73
Triethylamine 40 72
Trimethylamine 48 88
Vinylethylether 42 76
o-Xylene 36 65
m-Xylene 39 71
p-Xylene 39 71
JP-4 (Jet Fuel) 41 73

NOTES:

1. Scaling factors are not FMRC approved.

2. Base data source: EEV sensor specification catalog. (EEV claims some data is the result of specific tests,
other data is empirically derived.)

3. Display = Cal Gas / Factor = % LEL

=> must be less than 1

TABLE 1

COMBUSTIBLE GAS SCALING FACTORS

Page: 16

Model 4105 Gas Sensor Module (12/02)