Net Safety Monitoring ST3 XChems Operating Manual

Reference Manual

XChem Electrochemical Sensors

Part Number: MAN-0132, rev. 10

Release: April 2016

Important Instructions

Installing, operating or maintaining a Net Safety Product improperly could lead to serious injury or
death from explosion or exposure to dangerous substances. Comply with all information on the
product, in this manual, and in any local and national codes that apply to the product. Do not allow
untrained personnel to work with this product. Use Net Safety parts and work procedures specified in
this manual.

Net Safety Monitoring, Inc (Net Safety) designs, manufactures and tests products to function within
specific conditions. Because these products are sophisticated technical instruments, it is important
that the owner and operation personnel must strictly adhere both to the information printed on the
product nameplate and to all instructions provided in this manual prior to installation, operation, and
maintenance.

Notice

The contents of this publication are presented for informational purposes only, and while every effort
has been made to ensure their accuracy, they are not to be construed as warranties or guarantees,
expressed or implied, regarding the products or services described herein or their use or applicability.
All sales are governed by Net Safety’s terms and conditions, which are available upon request. We
reserve the right to modify or improve the designs or specifications of such products at any time.

Net Safety does not assume responsibility for the selection, use or maintenance of any product.
Responsibility for proper selection, use and maintenance of any Net Safety products remains solely with
the purchaser and end user.

To the best of Net Safety’s knowledge the information herein is complete and accurate. Net Safety
makes no warranties, expressed or implied, including implied warranties of merchantability and fitness
for a particular purpose with respect to this manual and, in no event, shall Net Safety be liable for any
incidental, punitive, special or consequential damages including, but not limited to, loss of production,
loss of profits, loss of revenue or use and costs incurred including without limitation for capital, fuel and
power, and claims of third parties.

Product names used herein are for manufacturer or supplier identification only and may be
trademarks/registered trademarks of these companies.

Net Safety and the Net Safety logo are registered trademarks of Net Safety Monitoring, Inc. The
Emerson logo is a trademark and service mark of the Emerson Electric Company.

Copyright © 2016 by Rosemount, Shakopee, MN

All rights reserved. No part of this work may be reproduced or copied in any form or by any means - graphic,
electronic, or mechanical without first receiving written permission of Rosemount, Shakopee, MN

Warranty

Limited Warranty

Resale Products

Limitation of Remedy and Liability

1.

and Liability) herein, Seller warrants that (a) the licensed firmware embodied in the Goods will
execute the programming instructions provided by Seller; (b) that the Goods manufactured by
Seller will be free from defects in materials or workmanship under normal use and care; and (c)
Services will be performed by trained personnel using proper equipment and instrumentation
for the particular Service provided. The foregoing warranties will apply until the expiration of
the applicable warranty period. Sensors and detectors are warranted against defective parts
and workmanship as per Section
to Buyer (
Buyer agrees that Seller has no liability for Resale Products beyond making a reasonable
commercial effort to arrange for procurement and shipping of the Resale Products. If Buyer
discovers any warranty defects and notifies Seller thereof in writing during the applicable
warranty period, Seller shall, at its option, (i) correct any errors that are found by Seller in the
firmware or Services; (ii) repair or replace FOB point of manufacture that portion of the Goods
found by Seller to be defective; or (iii) refund the purchase price of the defective portion of the
Goods/Services. All replacements or repairs necessitated by inadequate maintenance; normal
wear and usage; unsuitable power sources or environmental conditions; accident; misuse;
improper installation; modification; repair; use of unauthorized replacement parts; storage or
handling; or any other cause not the fault of Seller, are not covered by this limited warranty and
shall be replaced or repaired at Buyer’s sole expense and Seller shall not be obligated to pay
any costs or charges incurred by Buyer or any other party except as may be agreed upon in
writing in advance by Seller. All costs of dismantling, reinstallation, freight and the time and
expenses of Seller’s personnel and representatives for site travel and diagnosis under this
limited warranty clause shall be borne by Buyer unless accepted in writing by Seller. Goods
repaired and parts replaced by Seller during the warranty period shall be in warranty for the
remainder of the original warranty period or 90 days, whichever is longer. This limited
warranty is the only warranty made by Seller and can be amended only in a writing signed by an
authorized representative of Seller. The limited warranty herein ceases to be effective if Buyer
fails to operate and use the Goods sold hereunder in a safe and reasonable manner and in
accordance with any written instructions from the manufacturers. THE WARRANTIES AND
REMEDIES SET FORTH ABOVE ARE EXCLUSIVE. THERE ARE NO REPRESENTATIONS OR
WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, AS TO MERCHANTABILITY, FITNESS FOR
PARTICULAR PURPOSE OR ANY OTHER MATTER WITH RESPECT TO ANY OF THE GOODS OR
SERVICES.

. Subject to the limitations contained in Section 10 (Limitation of Remedy

7.4. Products purchased by Seller from a third party for resale

) shall carry only the warranty extended by the original manufacturer.

2.

DELAY IN PERFORMANCE. THE REMEDIES OF BUYER SET FORTH IN THE AGREEMENT ARE
EXCLUSIVE. IN NO EVENT, REGARDLESS OF THE FORM OF THE CLAIM OR CAUSE OF ACTION
(WHETHER BASED IN CONTRACT, INFRINGEMENT, NEGLIGENCE, STRICT LIABILITY, OTHER
TORT OR OTHERWISE), SHALL SELLER’S LIABILITY TO BUYER AND/OR BUYER’S CUSTOMERS
EXCEED THE PRICE TO BUYER OF THE SPECIFIC GOODS MANUFACTURED OR SERVICES
PROVIDED BY SELLER GIVING RISE TO THE CLAIM OR CAUSE OF ACTION. BUYER AGREES THAT
IN NO EVENT SHALL SELLER’S LIABILITY TO BUYER AND/OR BUYER’S CUSTOMERS EXTEND TO
INCLUDE INCIDENTAL, CONSEQUENTIAL OR PUNITIVE DAMAGES. THE TERM
“CONSEQUENTIAL DAMAGES” SHALL INCLUDE, BUT NOT BE LIMITED TO, LOSS OF
ANTICIPATED PROFITS, REVENUE OR USE AND COSTS INCURRED INCLUDING WITHOUT
LIMITATION FOR CAPITAL, FUEL AND POWER, AND CLAIMS OF BUYER’S CUSTOMERS.

. SELLER SHALL NOT BE LIABLE FOR DAMAGES CAUSED BY

Reference Manual Table of Contents

Table of Contents I

Section 1 : Introduction ............................................................................................... 1

Section 2 : Installation ................................................................................................. 2

Section 3 : Operation ................................................................................................. 10

Section 4 : Maintenance ............................................................................................ 13

Section 5 : Electrostatic sensitive device ..................................................................... 17

Section 6 : Wire resistance table ................................................................................ 18

Section 7 : Specifications ........................................................................................... 19

MAN-0132, Revision 10 April 2016

Contents

1.1 Models covered .................................................................................................................. 1

1.2 Service support ................................................................................................................... 1

1.3 Return of material............................................................................................................... 1

1.4 Product recycling/disposal .................................................................................................. 1

2.1 Unpacking and inspection .................................................................................................. 2

2.2 Locate sensor ..................................................................................................................... 2

2.3 Sensor direct mount or sensor separation ........................................................................... 2

2.3.1 Sensor direct mount ............................................................................................. 2

2.3.2 Sensor separation ................................................................................................. 2

2.4 Dimensions ........................................................................................................................ 4

2.5 Mounting ........................................................................................................................... 5

2.6 Wiring ................................................................................................................................ 6

2.6.1 Field installation .................................................................................................... 6

2.6.2 Sensor separation distance ................................................................................... 7

2.6.3 Installation to transmitter or junction box ............................................................. 7

2.6.4 Sensor wiring ........................................................................................................ 7

2.6.5 External ground .................................................................................................... 8

2.7 Calibration .......................................................................................................................... 9

2.8 Installation checklist ........................................................................................................... 9

3.1 Sensor configuration settings ........................................................................................... 10

3.2 Sensor power up ............................................................................................................... 10

3.3 Sensor end of life diagnostic ............................................................................................. 10

3.4 Sensor communication ..................................................................................................... 11

3.5 Net Safety Millennium II Basic transmitter configuration ................................................... 11

3.5.1 Hydrogen sulfide sensor (ST320) ........................................................................ 12

3.5.2 Carbon monoxide sensor (ST360) ....................................................................... 12

3.6 Fault conditions ................................................................................................................ 12

4.1 Cross sensitivities ............................................................................................................. 13

4.1.1 Hydrogen sulfide sensor (ST320) ........................................................................ 13

4.1.2 Carbon monoxide sensor (ST360) ....................................................................... 14

4.2 Bump testing .................................................................................................................... 14

4.3 Sensor replacement procedure ......................................................................................... 14

4.4 Troubleshooting ............................................................................................................... 16

4.5 Storage ............................................................................................................................ 16

4.6 Spare parts and accessories .............................................................................................. 16

7.1 Performance ..................................................................................................................... 19

7.1.1 Response time .................................................................................................... 19

7.1.2 Accuracy ............................................................................................................. 19

7.1.3 Zero Drift ............................................................................................................ 19

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II Table of Contents

Section 8 : Certifications ............................................................................................ 22

Section 9 : Ordering information ................................................................................ 23

April 2016 MAN-0132, Revision 10

7.1.4 Repeatability ...................................................................................................... 19

7.1.5 Detection Range ................................................................................................. 19

7.1.6 Calibration Frequency ......................................................................................... 20

7.1.7 Unpowered storage time .................................................................................... 20

7.2 Environmental .................................................................................................................. 20

7.2.1 Storage temperature .......................................................................................... 20

7.2.2 Operating temperature ...................................................................................... 20

7.2.3 Relative humidity ................................................................................................ 20

7.2.4 Metallurgy (housing) .......................................................................................... 20

7.2.5 Ingress protection ............................................................................................... 20

7.2.6 Weight ............................................................................................................... 20

7.3 Electrical ........................................................................................................................... 21

7.3.1 Voltage ............................................................................................................... 21

7.3.2 Power Consumption ........................................................................................... 21

7.4 Separation ........................................................................................................................ 21

7.5 Warranty .......................................................................................................................... 21

8.1 North America .................................................................................................................. 22

8.2 IECEx ................................................................................................................................ 22

8.3 EMI/EMC ........................................................................................................................... 22

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MAN-0132, Revision 10 April 2016

Section 1: Introduction

1.1 Models covered

The Net Safety XChem electrochemical toxic gas sensors are designed specifically for use with the Net
Safety Millennium II Transmitter (models M21, M22, or M2B). This sensor is both versatile and reliable
for fast, accurate, and continuous monitoring of gases in extreme environments.

The sensor assembly consists of a factory sealed explosion proof enclosure (housing) rated for
hazardous locations and a replaceable sensor module. This sensor must only be used with a Net Safety
Millennium II series transmitter. If the sensor is connected to any other model of transmitter, it will not
function and may result in the sensor or transmitter being damaged.

1.2 Service support

Technical support for this product can be provided by contacting your local Emerson Process
Management/Net Safety representative or by contacting the Net Safety Technical Support department
at [phone] or [e-mail]

.

1.3 Return of material

To expedite the repair and return of this product, proper communication between the customer and
the factory is important. Before returning a product for repair, call [phone] or e-mail

[e-mail]

On the return of the equipment, include the following information:

1. RMA number provided to you by Net Safety

2. Company name and contact information

3. Ship all equipment, prepaid to:

Rosemount
6021 Innovation Blvd.
Shakopee, MN 55379

4. Mark all packages with the RMA number and type of return (e.g. return for evaluation).

Pack items to protect them from damage and use anti-static bags or aluminum-backed cardboard as
protection from electrostatic damage.

All equipment must be shipped prepaid. Collect shipments will not be accepted.

for a Return Material Authorization (RMA) number.

1.4 Product recycling/disposal

Recycling of equipment and packaging should be taken into consideration and disposed of in
accordance with local and national legislations/regulations.

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Section 2: Installation

2.1 Unpacking and inspection

Carefully remove all of the components from the packaging and verify them against the enclosed
packing list. Inspect all components for any obvious damage such as broken or loose parts. If you find
any components missing or damaged, notify your local Net Safety representative or the factory
immediately.

Recycling of packaging should be taken into consideration and disposed of in accordance with local and
national legislations/regulations.

2.2 Locate sensor

Prior to installing the sensor, a plan should be developed for placement of the sensor. Although there
are no absolute rules for determining the quantity of detectors or location of a sensor, the following
points should be considered when planning the installation.

• Carefully locate the sensor in an area where gases may potentially accumulate, considering that

light gases tend to rise and heavy gases tend to fall and accumulate in low areas.

• Use redundant systems to enhance protection and reliability.

• Consider air movement patterns in the facility.

• Consider the construction of the facility such as trenches where heavy gases or peaks where light

gases may accumulate.

• Seek advice from experts knowledgeable about the gas to be detected.

• Refer to the regulatory publications that discuss guidelines for your industry.

2.3 Sensor direct mount or sensor separation

2.3.1 Sensor direct mount

The sensor can be directly attached to a Net Safety Millennium II transmitter and placed in an
appropriate location for detecting the target gas, or the sensor can be separated and remotely
mounted away from the Net Safety Millennium II transmitter. The sensor should be accessible for
calibration and maintenance purposes. The transmitter should be located where it is accessible and
visible.

2.3.2 Sensor separation

If the sensor is to be remotely mounted from the transmitter, the sensor must be connected to a
certified junction box. In this case, the transmitter is typically located near eye-level for easy access and
the sensor is mounted where the gas is likely to accumulate.

In order to ease the calibration process a calibration cup (CCS-1) can be attached to the bottom of the
sensor housing and calibration tubing run from the calibration cup to a convenient place for applying
the calibration gas, eliminating the need to access the sensor directly. In this case, to compensate for
the effect of distance, consider decreasing the calibration tubing length to some length where the end
of the tubing to the gas canister is still accessible or increase the calibration gas flow rate between the

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Figure 2-1 Sensor separation example

MAN-0132, Revision 10 April 2016

calibration gas cylinder and sensor. Refer to Figure 2-1 for an example of the sensor separation. For
tubing lengths less than 10 feet (3 meters), use a 0.5 LPM regulator and for lengths greater than 10 feet
(3 meters) use a 1.0 LPM regulator. On initial install, always confirm readings directly at the transmitter
by applying a known gas concentration to the sensor and compare the output from the transmitter.
Readings should be accurate to the gas concentration applied taking into account the sensor accuracy
specifications in Section 7.1.2.

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Figure 2-2 Net Safety Millennium II (M21 or M22) enclosure and sensor dimensions

A B C D E F G H

April 2016 MAN-0132, Revision 10

2.4 Dimensions

The following tables outline the dimensions of the sensor when connected to either the Net Safety
Millennium II Transmitter (Figure 2-2) or the Net Safety Millennium II Basic Transmitter/Junction Box
(Figure 2-3). Both the transmitter and sensor enclosures are offered in stainless steel and aluminum.

in mm in mm in mm in mm in mm in mm in mm in mm

Stainless Steel 5.9 150 5.1 130 4.6 117 8.9 226 6.0 152 5.8 147 2.6 66 2.9 74

Aluminum 6.3 160 5.6 142 5.4 137 9.7 246 6.0 152 5.7 145 2.6 66 2.9 74

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Figure 2-3 Net Safety Millennium II Basic (M2B) or junction box (JB) enclosure and sensor dimensions

A B C D E F G H I J

MAN-0132, Revision 10 April 2016

in mm in mm in mm in mm in mm in mm in mm In mm in mm in mm

Stainless
Steel

Aluminum 4.8 122 3.6 91 3.6 91 4.8 122 5.1 130 0.3 7.6 2.6 66 2.9 74 3.0 76 9.0 229

4.7 119 3.6 91 3.6 91 4.7 119 5.1 130 0.3 7.6 2.6 66 2.9 74 2.8 71 8.9 226

2.5 Mounting

Prior to mounting the sensor to the transmitter or junction box enclosure apply suitable grease (jet
lube, etc.) to the threading of the 3/4” FNPT (female NPT) conduit entry of the enclosure as well as the
threading on the sensor 3/4” MNPT (male NPT) fitting. This aids in protecting the enclosures from
water ingress. After the grease has been applied properly, fit and tighten the sensor to the transmitter
or junction box enclosure by using appropriate tools.

The transmitter and junction box have mounting holes to allow mounting to a flat surface or pole as
desired. Mounting kit accessories are available to aid in mounting the detector to a flat surface or a
pole. Contact your local Net Safety representative for detailed information.

The sensor must always be mounted vertically such that its mouth is pointed in the downward position
as shown in Figure 2-4.

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Figure 2-4 Net Safety XChem Sensor mounted to Net Safety Millennium II series transmitters

Failure to follow these installation guidelines could result in death or serious injury. Ensure that only
qualified personnel perform the installation.

Electrical shock could cause death or serious injury. Use extreme caution when making contact with
the leads and terminals.

Do not open the transmitter, sensor, or junction box enclosure when in a classified area or when an
explosive atmosphere may be present unless the power to the transmitter and sensor has been
removed.

April 2016 MAN-0132, Revision 10

Net Safety Millennium II

Sensor mouth

2.6 Wiring

Transmitter

3/4” NPT

3/4” NPT

ATEX locking
collar

Sensor
pointing
downwards

Net Safety Millennium II Basic

Transmitter &

Junction Box

Sensor
pointing
downwards

3/4” NPT

3/4” NPT

ATEX locking
collar

Sensor mouth

2.6.1 Field installation

Wiring codes and regulations may vary. Wiring must comply with all applicable regulations relating to
the installation of electrical equipment in a hazardous area and is the responsibility of the installer. If in
doubt, consult a qualified official before wiring the system.

When separating the sensor from the transmitter, the use of shielded cable is highly recommended to
protect against interference caused by extraneous electrical or electromagnetic noise. To meet
EN50270:2006 requirements follow the recommendations on cable choice and guidelines as outlined
in the Net Safety Millennium II Transmitter manual (MAN-0076) or Net Safety Millennium II Basic
transmitter manual (MAN-0082). In applications where the wiring is installed in conduit, the conduit
must not be used for wiring to other equipment.

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Do not open the transmitter, sensor, or junction box enclosure when in a classified area or when an
explosive atmosphere may be present unless the power to the sensor has been removed.

Figure 2-5 Terminal connection

Table 2-1 Sensor wire colors and terminal definition

Wire color

Marking

Function

MAN-0132, Revision 10 April 2016

2.6.2 Sensor separation distance

The maximum separation distance between the sensor and the transmitter is limited by the resistance
of the connecting wiring, which is a function of the gauge of the wire being used. Net Safety
recommends that sensor separation must not exceed 2000 feet (610 meters) while using 16AWG
(1.31mm

2

) wire. Refer to Section 6 for wire gauges and resistance values.

2.6.3 Installation to transmitter or junction box

The Net Safety XChem sensor is supplied with a 3/4” NPT male conduit connection and is intended to
be mounted directly to an available 3/4” NPT conduit entry on a Net Safety Millennium II Transmitter or
remotely using a certified junction box. Net Safety has an available offering of certified junction boxes
designed specifically to work with this sensor. Please contact your local Net Safety representative for
further information.

2.6.4 Sensor wiring

When connecting cable wires, use a small flathead screwdriver to gently press down and hold the
spring connector open. Insert the appropriate wire into the open connector hole, releasing the
screwdriver to secure the wire. Refer to Figure 2-5 below.

Connect the sensor wires to the Net Safety Millennium II Transmitter or junction box as per the
appropriate transmitter or junction box manual. Figure 2-6 outlines the connections to a M21 Net
Safety Millennium II transmitter. Table 2-1 outlines the wire colors and their purpose.

White Red Blue Black Green

+Vdc Sig A Sig B COM

10.5-32Vdc
Connection

Communication

signal A

Communication

signal B

Common / supply

ground

Earth ground

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Figure 2-6 Net Safety Millennium II M21 sensor wiring

Figure 2-7 External grounding point

April 2016 MAN-0132, Revision 10

2.6.5 External ground

In order to ensure proper operation of the sensor, an external ground is required. Net Safety
recommends that the external ground be connected to the grounding point on the enclosure
according to IECEx requirements. Refer to Figure 2-7 for grounding connection location.

External Earth
Ground point

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MAN-0132, Revision 10 April 2016

2.7 Calibration

The Net Safety XChem sensor should be powered up for at least twenty-four (24) hours prior to
completing the first calibration.

Although the sensor has been factory calibrated, this calibration may have been disrupted after
shipment and calibration after installation is necessary to ensure performance.

Calibration cycles are recommended to be completed every three (3) months to ensure the proper
operation of the sensor.

Refer to the respective Net Safety Millennium II transmitter manual (MAN-0076 or MAN-0082) for the
calibration procedure.

2.8 Installation checklist

Review the following checklist prior to turning the power on to the sensor after installation has been
completed:

□ Ensure that the transmitter and sensor are properly and firmly mounted
□ Ensure that stopping plugs are securely tightened on any unused conduit entries
□ Ensure that the transmitter and sensor are not obstructed such that they are accessible and the

target gas is not inhibited from reaching the sensor

□ Remove the red protective plastic cap/cover from the sensor mouth
□ If IP filters are fitted to the sensor, check for any damage or debris
□ If calibration cups or splash guards are fitted to the sensor, ensure that they are properly fitted
□ Ensure adherence to applicable local guidelines and requirements on wiring and sealing of

equipment in hazardous and non-hazardous areas

□ Ensure that proper shielding and grounding practices are adhered to and local codes are being

followed

□ Check system operational voltage and conditions and ensure that they are within the applicable

specifications of the sensor

□ Verify wiring at all termination and junction points (transmitter, junction box, and power supply)
□ If the sensor housing has been opened, ensure that the sensor module is properly seated and

making a good connection. Refer to Section 4.3 for more details.

□ Perform initial calibration as per Section 2.7.

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Tip

Refer to the relevant transmitter manual prior to attempting a

Figure 3-1 Net Safety Millennium II display examples





April 2016 MAN-0132, Revision 10

Section 3: Operation

3.1 Sensor configuration settings

All configuration settings for the Net Safety XChem sensor are accessed through the Net Safety
Millennium II series of transmitters. When using the Net Safety Millennium II Transmitter, configuration
settings are accessed by selecting menu options through the main display.

calibration.

3.2 Sensor power up

When power is applied to the sensor by the transmitter, a warm-up routine will begin where the sensor
will automatically be tested to ensure its proper operation. The warm-up time for the Net Safety
XChem sensor is typically between thirty (30) and ninety (90) seconds depending on the sensor type;
the ST341 oxygen sensor could take up to an hour to warm-up. During the warm-up period, the Net
Safety XChem sensor may not provide accurate results and gas concentration levels may fluctuate
during the warm-up period. Refer to the Net Safety Millennium II transmitter manual (MAN-0076) or
the Net Safety Millennium II Basic transmitter manual (MAN-0082) for status indicators during this
period. Confirm that the Net Safety Millennium II transmitter display properly shows ppm on the
display as shown in Figure 3-1. If the display reads xxx, then the sensor cell is not seated properly in the
sensor housing. Refer to Section 4.3 for more information.

3.3 Sensor end of life diagnostic

An automatic test of the sensor will be performed daily to ensure the sensor’s integrity. This test will be
completed one (1) hour after initial power-up and then every twenty four (24) hours following that.

Note that sensor end of life indication is not available on the Oxygen (ST340 or ST341) sensors.

During the test cycle, a period of ten (10) seconds, it is expected that the sensor response time will
increase to less than sixty (60) seconds.

If a sensor end of life indication fault is generated, the analog output of the associated transmitter will
be 2.5mA (fault condition) for a period of ten (10) seconds. The analog output will then return to its

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MAN-0132, Revision 10 April 2016

operational state (4mA with no gas present) for a period of fifty (50) seconds. This cycle will continue
until the sensor has been replaced. When using the M21 or M22 transmitter, the display will read
“Sensor Reached Life End” on the respective channel and the gas concentration will not be shown.

If used with a Net Safety Millennium II transmitter with relay capabilities, the sensor end of life
diagnostic will be indicated through the fault relay. The fault relay will change states (de-energize,
indicating a fault condition, upon the detection of the end of life condition. The fault relay will stay de­energized as long as the fault condition is present. When the sensor has detected an end of life
condition, the alarm relay will not provide an alarm condition if gas is present, therefore, it is
recommended that the sensor be replaced as quickly as possible. For further information on the
operation of the relays, please refer to the associated transmitter manual (MAN-0076 or MAN-0082).

Net Safety Monitoring recommends that if a fire and gas system or other control system is used, that
the fault signal (2.5mA) and fault relay (if available) are monitored to indicate sensor faults.

Due to the electrochemical sensor technology used in the Net Safety XChem sensors, the sensor end of
life diagnostic may indicate a sensor with decaying response or a non-responding sensor. It is
recommended that the sensor be replaced when this fault message is indicated.

Please contact Net Safety Monitoring for replacement sensor modules.

3.4 Sensor communication

The Net Safety XChem sensor uses a proprietary protocol to communicate with the Net Safety
Millennium II series of transmitters. This sensor should never be connected to any device other than
the Net Safety Millennium II series of transmitters. Selected DIP switches and menu options allow
communication between the transmitter and sensor. Configuration settings are stored in the memory
of the sensor. Incorrect settings will cause the sensor to not communicate properly with the
transmitter. If any problems develop, please refer to the troubleshooting section (4.4) of this manual.

3.5 Net Safety Millennium II Basic transmitter

configuration

When using the Net Safety XChem electrochemical toxic sensor with the Net Safety Millennium II Basic
Digital transmitter model (M2B-D), the sensor’s range can be changed by accessing a specific Modbus
register. The user should write to register 40027 using the preset single register command 0x06. The
desired range can then be entered in the register. Refer to 7.1.5 for the available ranges.

When using the Net Safety XChem electrochemical toxic sensor with the Net Safety Millennium II Basic
Analog (M2B-A), Analog/HART (M2B-AH), and Relay (M2B-R) transmitter models the sensor’s range can
be changed to facilitate the need to accurately detect different gas concentrations. This is done by
making use of the transmitter’s DIP Switch 2 positions as seen in the tables below. Select the
transmitter’s DIP Switch 2 position that gives the range of gas to be detected.

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Table 3-1 Net Safety Millennium II Basic transmitter DIP switch 2 positions for the ST320 sensor

Position 1

Position 2

Position 3

Position 4

Range(Setting)

ON

OFF

OFF

OFF

Range 1 (20ppm)

OFF

ON

OFF

OFF

Range 2 (50ppm)

OFF

OFF

ON

OFF

Range 3 (100ppm)

Table 3-2 Net Safety Millennium II Basic transmitter DIP switch 2 positions for the ST360 sensor

Position 1

Position 2

Position 3

Position 4

Range(Setting)

ON

OFF

OFF

OFF

Range 1 (500ppm)

OFF

ON

OFF

OFF

Range 2 (1000ppm)

Fault condition

Analog output

Fault relay output

April 2016 MAN-0132, Revision 10

3.5.1 Hydrogen sulfide sensor (ST320)

3.5.2 Carbon monoxide sensor (ST360)

3.6 Fault conditions

The Net Safety XChem sensor will provide a number of fault conditions that the Net Safety Millennium II
transmitter will translate into an analog or fault relay output. These fault conditions are outlined in the
following table.

Sensor zero drift 2.5mA Fault

Memory fault 2.5mA Fault

Sensor nearing end of life Alternating 2.5mA for ten (10)

Calibrate Sensor 2.5mA Fault

seconds and normal level fifty
(50) seconds

Alternating 2.5mA for ten (10)
seconds and normal level fifty
(50) seconds

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noted that some cross interference break through will occur if gas is applied for a longer period of time.

Table 4-1 List of cross sensitive gases/compounds

Cross sensitive gas

Cross sensitive gas concentration

Reading

MAN-0132, Revision 10 April 2016

Section 4: Maintenance

4.1 Cross sensitivities

This relates to the fact that certain compounds and or gases can cause a reaction and hence some
effects or response from the sensor. See the tables below for a list of these cross sensitive
gases/compounds. For more information, please contact Net Safety.

The values listed below are typical values and should not be used as a basis for cross calibration. Cross
sensitivities may not be linear and should not be scaled either. The data provided is based on gassing
for a minimum of five (5) minutes using the gas sensor manufacturers test equipment. It should be

4.1.1 Hydrogen sulfide sensor (ST320)

Carbon monoxide 300 ppm <3 ppm

Sulfur dioxide 5 ppm <1 ppm

Nitrogen dioxide 5 ppm <± 0.5ppm

Nitric oxide 50 ppm <1 ppm

Hydrogen 100 ppm <1 ppm

Chlorine 1 ppm 0 ppm

Ethylene 100 ppm 0 ppm

Carbon dioxide 5000 ppm 0 ppm

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Table 4-2 List of cross sensitive gases/compounds

Cross sensitive gas

Cross sensitive gas concentration

Reading

Do not open the transmitter, sensor, or junction box enclosure when in a classified area or when an
explosive atmosphere may be present unless the power to the sensor has been removed.

Avoid touching any electronic components, as they may be susceptible to electrostatic discharge
(ESD). Refer to Section 5 for further information and proper handling instructions of electronic
components.

April 2016 MAN-0132, Revision 10

4.1.2 Carbon monoxide sensor (ST360)

Hydrogen sulfide 15 ppm < 0.1 ppm

Sulfur dioxide 5 ppm 0 ppm

Nitrogen dioxide 5 ppm -0.5ppm

Nitric oxide 35 ppm <7 ppm

Hydrogen 100 ppm <60 ppm

Chlorine 1 ppm 0 ppm

Ethylene 100 ppm <90 ppm

4.2 Bump testing

As part of the site preventative maintenance program Net Safety recommends that a bump test of the
sensor is completed every three (3) months. Bump testing consists of a visual inspection of the sensor,
applying a known gas concentration to the sensor verifying the accuracy of the response to the
specifications of the sensor, and alarm system simulation. If the response is outside of the
specifications of the sensor a calibration should be completed. Refer to Section 2.7 for more
information. After a calibration has been completed, it is recommended that a bump test be
completed to verify accuracy and response of the sensor.

4.3 Sensor replacement procedure

Sensors are pre-calibrated at the factory; however, field calibration must be performed as a part of
commissioning. When the sensor end of life diagnostic is indicating a fault condition, a calibration can
no longer be performed, or the sensor is not operating properly, the sensor module may need to be
replaced. Refer to steps below for replacing the sensor module.

1. Remove power from the sensor.

2. Remove the locking ring by loosening the set screws with 1.5 mm Allen Key tool.

3. Remove the bottom part of the sensor enclosure by turning it in a counter clockwise rotation to

expose the sensor module.

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MAN-0132, Revision 10 April 2016

4. Carefully remove the sensor module from the sensor housing by pulling the module straight out of

the housing. NOTE: DO NOT TWIST THE SENSOR MODULE.

5. Properly dispose of the old sensor module as per local guidelines and regulations.

6. Remove the replacement sensor module from its packaging ensuring not to touch any electronic

components as this may cause problems due to an unwanted electrostatic discharge (ESD).

7. Rotate replacement sensor module until it aligns with the guide posts. Once aligned, press firmly

into place.

8. Install and hand-tighten the bottom part of the sensor enclosure by turning it in a clockwise

direction.

9. Install the locking ring by tightening the set screws with 1.5 mm Allen Key tool.

10. Restore power to sensor via the transmitter.

11. Verify that the display shows ppm and not xxx as shown in Figure 3-1. If the display is showing xxx,

then the sensor module is not seated properly. In this case, repeat all steps within this procedure.

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16

Description

Part Number

April 2016 MAN-0132, Revision 10

4.4 Troubleshooting

Sensors and transmitters are not designed to be repaired in the field. If problems should develop, first
check for faulty wiring, confirm proper voltage to sensor, and attempt a calibration. If problems persist,
please contact Net Safety’s technical support department first by phone to try and resolve any issues. If
issues cannot be resolved, please follow the procedure in Section 1.3 Return of material.

4.5 Storage

The sensor and its electronic components/parts should be stored in locations free from dust, liquid
spills, contaminants, and moisture. The storage temperature should be well within the limits of the
certified temperatures of the equipment. See Section 7 for certified temperatures.

4.6 Spare parts and accessories

Calibration cup/splash guard CCS-1

Calibration Kit CAL-KIT-1

Calibration Gas CAL-CYL-AIR (103L Air)

CAL-CYL-H2S-10 (58L, 10ppm, H
CAL-CYL-H2S-25 (76L, 25ppm, H
CAL-CYL-H2S-50 (76L, 50ppm, H
CAL-CYL-H2S-A-10 (58L, 10ppm, H
CAL-CYL-H2S-A-25 (58L, 25ppm, H
CAL-CYL-H2S-A-50 (58L, 50ppm, H

CAL-CYL-CO-250 (103L, 250ppm, CO)

Calibration cup CCS-1

Separation kit JB-MPD-A - aluminum

JB-MPD-S - stainless steel

Replacement sensor module ST320-100 (H2S)

ST341-25 (O

)

2

ST360-1000 (CO)

Ingress protection filter IPF-001

2” Pole mounting kit UN-MK-32

Duct mounting kit UDM-001 (1m sampling pipe)

UDM-002 (1.5m sampling pipe)
UDM-003 (direct mount to duct)

S, nitrogen balanced)

2

S, nitrogen balanced)

2

S, nitrogen balanced)

2

S, oxygen balanced)

2

S, oxygen balanced)

2

S, oxygen balanced)

2

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MAN-0132, Revision 10 April 2016

Section 5: Electrostatic sensitive device

Definition: Electrostatic discharge (ESD) is the transfer, between bodies, of an electrostatic charge
caused by direct contact or induced by an electrostatic field.

The most common cause of ESD is physical contact. Touching an object can cause a discharge of
electrostatic energy (ESD). If the charge is sufficient and occurs near electronic components, it can
damage or destroy those components. In some cases, damage is instantaneous and an immediate
malfunction occurs. However, symptoms are not always immediate—performance may be marginal or
seemingly normal for an indefinite period of time, followed by a sudden failure.

To eliminate potential ESD damage, review the following guidelines:

• Handle boards by metal shields—taking care not to touch electronic components.

• Wear grounded wrist or foot straps, ESD shoes or heel grounders to dissipate unwanted static

energy.

• Prior to handling boards, dispel any charge in your body or equipment.

• Ensure all components are transported and stored in static safe packaging

• When returning boards, carefully package in the original carton and static protective wrapping

• Ensure ALL personnel are educated and trained in ESD Control Procedures

In general, exercise accepted and proven precautions normally observed when handling electrostatic
sensitive devices. A warning label is placed on the packaging, identifying product using electrostatic
sensitive semiconductor devices.

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18

Distance
Feet (Meters)

AWG #20

0.5mm

2

AWG #18

0.8mm

2

AWG #16

1.0mm

2

AWG #14

2.0mm

2

April 2016 MAN-0132, Revision 10

Section 6: Wire resistance table

100 (30.5) 1.02 0.64 0.40 0.25

200 (61) 2.03 1.28 0.80 0.51

300 (91.4) 3.05 1.92 1.20 0.76

400 (121.9) 4.06 2.55 1.61 1.01

500 (152.4) 5.08 3.20 2.01 1.26

600 (182.9) 6.09 3.83 2.41 1.52

700 (213.4) 7.11 4.47 2.81 1.77

800 (243.8) 8.12 5.11 3.21 2.02

900 (274.3) 9.14 5.75 3.61 2.27

1000 (304.8) 10.20 6.39 4.02 2.53

1250 (381) 12.70 7.99 5.03 3.16

1500 (457.2) 15.20 9.58 6.02 3.79

1750 (533.4) 17.80 11.20 7.03 4.42

2000 (609.6) 20.30 12.80 8.03 5.05

2250 (685.8) 22.80 14.40 9.03 5.68

2500 (762) 25.40 16.00 10.00 6.31

3000 (914.4) 30.50 19.20 12.00 7.58

3500 (1066.8) 35.50 22.40 14.10 8.84

4000 (1219.2) 40.60 25.50 16.10 10.00

4500 (1371.6) 45.70 28.70 18.10 11.40

5000 (1524) 50.10 32.00 20.10 12.60

5500 (1676.4) 55.80 35.10 22.10 13.91

6000 (1828.8) 61.00 38.30 24.10 15.20

6500 (1981.2) 66.00 41.50 26.10 16.40

7000 (2133.6) 71.10 44.70 28.10 17.70

7500 (2286) 76.10 47.90 30.10 19.00

8000 (2438.4) 81.20 51.10 23.10 20.20

9000 (2743.2) 91.40 57.50 36.10 22.70

10000 (3048) 102.00 63.90 40.20 25.30
Resistance shown is one way. This figure must be doubled when determining closed loop resistance.

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19

Hydrogen Sulfide
(ST320)

Carbon Monoxide
(ST360)

Oxygen
(ST341)

T20

T50

T90

Hydrogen Sulfide
(ST320)

Carbon Monoxide
(ST360)

Oxygen
(ST341)

Hydrogen Sulfide
(ST320)

Carbon Monoxide
(ST360)

Oxygen
(ST341)

Hydrogen Sulfide
(ST320)

Carbon Monoxide
(ST360)

Oxygen
(ST341)

Hydrogen Sulfide
(ST320)

Carbon Monoxide
(ST360)

Oxygen
(ST341)

MAN-0132, Revision 10 April 2016

Section 7: Specifications

7.1 Performance

7.1.1 Response time

10 sec 10 sec 7 sec

15 sec 15 sec 10 sec

36 sec 30 sec 20 sec

7.1.2 Accuracy

0°C to +50°C (+32°F to +122°F)

±6 ppm or 17% of reading, whichever
is greater

-40°C to 0°C (-40°F to +32°F)
±7 ppm or 27% of reading, whichever
is greater

0°C to +50°C (+32°F to +122°F)

±13 ppm or 5% of reading, whichever
is greater

-20°C to 0°C (-4°F to +32°F)
±32 ppm or 17% of reading,
whichever is greater

7.1.3 Zero Drift

<5% full scale per year <5% full scale per year <5% full scale per year

7.1.4 Repeatability

<3% full scale <3% full scale <3% full scale

7.1.5 Detection Range

0°C to +50°C (+32°F to +122°F)

± 0.5% Vol.

-20°C to 0°C (-4°F to +32°F)
± 1.5% Vol.

20 ppm
50 ppm
100 ppm

500 ppm
1000 ppm

25% Vol.

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20

Hydrogen Sulfide
(ST320)

Carbon Monoxide
(ST360)

Oxygen
(ST341)

Hydrogen Sulfide
(ST320)

Carbon Monoxide
(ST360)

Oxygen
(ST341)

Hydrogen Sulfide
(ST320)

Carbon Monoxide
(ST360)

Oxygen
(ST341)

April 2016 MAN-0132, Revision 10

7.1.6 Calibration Frequency

Three (3) months

7.1.7 Unpowered storage time

Six (6) months

7.2 Environmental

7.2.1 Storage temperature

+3°C to +20°C
(+37°F to +68°F)

+3°C to +20°C
(+37°F to +68°F)

7.2.2 Operating temperature

-40°C to +50°C
(-40°F to +122°F)

-20°C to +50°C
(-4°F to +122°F)

7.2.3 Relative humidity

15-90% relative
humidity, non­condensing

15-90% relative
humidity, non­condensing

7.2.4 Metallurgy (housing)

316 Stainless steel and 6061 anodized aluminum.

0°C to +20°C
(+32°F to +68°F)

-20°C to +50°C
(-4°F to +122°F)

15-99% relative
humidity, non­condensing

7.2.5 Ingress protection

7.2.6 Weight

IP64

Stainless steel: 3.5 lbs, 1.4 kg
Aluminum: 1 lb, 0.4 kg

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21

Hydrogen Sulfide
(ST320)

Carbon Monoxide
(ST360)

Oxygen
(ST341)

MAN-0132, Revision 10 April 2016

7.3 Electrical

7.3.1 Voltage

10.5 to 32 Vdc

7.3.2 Power Consumption

Peak inrush 667 mA (16.0 W) at 24 Vdc 655 mA (15.7 W) at 24 Vdc 685 mA (16.4 W) at 24 Vdc

Operational 13 mA (0.3 W) at 24 Vdc 13 mA (0.3 W) at 24 Vdc 13 mA (0.3 W) at 24 Vdc

7.4 Separation

Up to 2000 feet (610 meters) with 16AWG (1.31mm2) wire.

7.5 Warranty

2 years

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22

April 2016 MAN-0132, Revision 10

Section 8: Certifications

8.1 North America

Class I Division 1 Groups B,C D T5
Ex d IIB+ H
Class I Zone 1 AEx d IIB +H

-40°C ≤ Ta + 75°C (sensor dependent)
IP 64

8.2 IECEx

II 2G Ex d IIB+H2 T5 Gb

-40°C ≤ Ta + 75°C (sensor dependent)
IP64
IECEx CSA 11.0006

T5

2

2

T5

8.3 EMI/EMC

EN 50270:2006

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MAN-0132, Revision 10 April 2016

Section 9: Ordering information

Model Description

ST Electrochemical toxic gas sensor compatible with all Net Safety Millennium II Transmitters

Type Performance

320 Hydrogen Sulfide (H2S), 0-20/50/100ppm, Field Selectable

341 Oxygen (O2), 0-25%

360 Carbon Monoxide (CO), 0-500/1000ppm, Field Selectable

Housing Enclosure Material

A Aluminum

S Stainless Steel

Range Sensor Range (Type Specific)

-100-ASSY ST320 and ST330 Only

-1000-ASSY ST360 Only

-25-ASSY ST341 Only

Americas

Europe

EmersonProcess.com/FlameGasDetection

Emerson Process Management

6021 Innovation Blvd.
Shakopee, MN 55379
T [phone]
F [phone]

[e-mail]

AnalyticExpert.com

MAN-0132

Revision 10

April 2016

Emerson Process Management AG

Neuhofstrasse 19a P.O. Box 1046
CH-6340 Baar
Switzerland
T + 41 (0) 41 768 6111
F + 41 (0) 41 768 6300

[e-mail]

Middle East & Africa
Emerson Process Management

Emerson FZE
Jebel Ali Free Zone
Dubai, UAE
P.O. Box 17033
T + 971 4 811 8100
F + 971 4 886 5465

[e-mail]

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