Emerson Rosemount 936 User manual

Reference Manual
00809-0100-4036, Rev AD
October 2021
Rosemount™ 936
Toxic Open Path Gas Detector

Legal notice
The Rosemount system described in this document is the property of Emerson.
No part of the hardware, software, or documentation may be reproduced, transmitted, transcribed, stored in a retrieval system,
or translated into any language or computer language in any form or by any means without prior written permission of Emerson.
While great efforts have been made to ensure the accuracy and clarity of this document, Emerson assumes no responsibility
resulting from any omissions in this document or from misuse of the information obtained herein. The information in this
document has been carefully checked and is believed to be entirely reliable with all the necessary information included. Emerson
does not assume any liability arising out of the application or any use of any product or circuit described herein; neither does it
convey license under its patent rights or the rights of others.
WARNING
All individuals who have or will have responsibility for using, maintaining, or servicing the product must read this manual
thoroughly.
WARNING
Physical access
Unauthorized personnel may potentially cause significant damage to and/or misconfiguration of end users’ equipment. This could
be intentional or unintentional and needs to be protected against.
Physical security is an important part of any security program and fundamental to protecting your system. Restrict physical access
by unauthorized personnel to protect end users’ assets. This is true for all systems used within the facility.
CAUTION
The source and detector are not field-repairable due to the meticulous alignment and calibration of the sensors and the respective
circuits.
Do not attempt to modify or repair the internal circuits or change their settings, as this will impair the system's performance and
void the Emerson product warranty.
Glossary and abbreviations
Abbreviation Meaning
Analog video Video values are represented by a scaled signal.
ATEX Atmosphere explosives
AWG American wire gauge
BIT Built-in test
CMOS Complementary metal oxide semiconductor image sensor
Digital video Each component is represented by a number representing a discrete quantization.
DSP Digital signal processing
EMC Electromagnetic compatibility
EMI Electromagnetic interference
HART®Highway addressable remote transducer communication protocol
IAD Immune at any distance
IECEx International Electrochemical Commission explosion
IP Internet protocol
IR3 Refers to the three infrared sensors
2

Abbreviation Meaning
LED Light-emitting diode
LNG Liquified natural gas
mA MilliAmps (0.001 amps)
Modbus®Master-slave messaging structure
N/A Not applicable
NPT National pipe thread
NTSC National Television System Committee (a color encoding system)
PAL Phase alternation by line (a color encoding system)
PN Part number
ppm Concentration in parts per million. Defines the amount of gas molecule parts per million molecules of
atmospheric
ppm.m Integral of concentration in ppm units times the distance in meters.
RFI Radio frequency interference
RTSP Real time streaming protocol
SIL Safety integrity level
UNC Unified coarse thread
UV Ultraviolet
Vac Volts alternating current
Vdc Volts direct current
µm Micrometer
3

4

Contents
Chapter 1 Product overview.......................................................................................................7
Chapter 2 Technical description................................................................................................. 9
2.1 Features.......................................................................................................................................9
2.2 Applications...............................................................................................................................10
2.3 Principle of operation.................................................................................................................10
2.4 Product certifications.................................................................................................................12
2.5 Models and types.......................................................................................................................14
2.6 Ordering information.................................................................................................................14
2.7 Description................................................................................................................................ 17
Chapter 3 Operating modes..................................................................................................... 19
3.1 Operational modes.................................................................................................................... 19
3.2 Visual indicators.........................................................................................................................20
3.3 Output signals........................................................................................................................... 21
3.4 System setup............................................................................................................................. 22
Chapter 4 Specifications...........................................................................................................25
4.1 General specifications................................................................................................................25
4.2 Electrical specifications..............................................................................................................26
4.3 Mechanical specifications.......................................................................................................... 27
4.4 Environmental specifications..................................................................................................... 28
Chapter 5 Installation...............................................................................................................31
5.1 Introduction.............................................................................................................................. 31
5.2 General considerations.............................................................................................................. 31
5.3 Preparations for installation....................................................................................................... 34
5.4 Certification instructions........................................................................................................... 35
5.5 Install conduits and cables......................................................................................................... 40
5.6 Mount detector and source to tilt mount...................................................................................41
5.7 Install detector wiring................................................................................................................ 44
5.8 Wiring to detector terminals......................................................................................................45
5.9 Wiring to ultraviolet (UV) source................................................................................................45
5.10 Align detector..........................................................................................................................47
Chapter 6 Operation................................................................................................................ 51
6.1 Operating the open path system............................................................................................... 51
6.2 Safety precautions..................................................................................................................... 51
6.3 Power up................................................................................................................................... 51
6.4 Verifying signal.......................................................................................................................... 52
6.5 Zero calibrate............................................................................................................................ 54
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6.6 Functional check........................................................................................................................57
Chapter 7 Maintenance............................................................................................................59
7.1 General maintenance................................................................................................................ 59
7.2 Periodic maintenance................................................................................................................ 59
Chapter 8 Troubleshooting...................................................................................................... 61
8.1 Maintenance call........................................................................................................................61
8.2 NQ Ratio below the permitted limit........................................................................................... 61
8.3 NQ Ratio above the permitted limit........................................................................................... 62
8.4 Ratio out of the limit.................................................................................................................. 62
8.5 Voltage less than 16 Vdc............................................................................................................62
Appendix A Wiring configurations.............................................................................................. 63
A.1 RS-485 communication network............................................................................................... 67
Appendix B SIL-2 features........................................................................................................... 69
B.1 Safety relevant parameters........................................................................................................ 69
B.2 General conditions for safe use.................................................................................................. 69
Appendix C Support....................................................................................................................71
C.1 Return of material......................................................................................................................71
Appendix D Short range model................................................................................................... 73
Appendix E Declaration of Conformity........................................................................................75
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1 Product overview
The Rosemount 936 Gas Detector employs an advanced xenon flash source and
integrated electronics package, both housed in stainless steel housings to provide high
quality and performance, fast response, and line of sight gas monitoring. The source/
detector is backed by a three year warranty.
The detector is manufactured with heated optical windows to improve performance in
icing, snow, and condensation conditions. The programmable functions are available
through a HART® port used with an intrinsically safe (I.S.) handled unit.
The source and detector unit enclosures are ATEX and IECEx approved Exd flameproof with
an integral segregated rear and an Exe terminal compartment to prevent exposing the
sensors and electronics to the surrounding environment. The detector also has a plug
interface for connection to a HART Field Communicator, which is intrinsically safe.
This Manual provides a full description of the detector and its features and contains
instructions on installing, operating, and maintaining the detector.
TheRosemount 936 detects and monitors toxic gases, such as NH3 and H2S at ppm.m
concentrations in the air. The detector's response time is no more than ten seconds to
T90.
The open path system uses an open path beam of flash light pulses that provide a long line
of sight coverage equivalent to many point detectors along the path. The transmitter
beam covers a UV spectrum from 200 nm to 300 nm. The detector continuously monitors
for gas through the collimated beam over an optical path from 17 ft. (5 m) up to 200 ft.
(60 m).
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2 Technical description
2.1 Features
•Long range gas detection from 17 ft. (5 m) up to 200 ft. (60 m)
•High sensitivity and fast response to toxic gases
•Heated optics to improve performance in icing, condensation, and snow conditions
•Continuous operation in extreme and harsh environmental conditions
•Solar blind and immune to industrial environments
•Withstands extreme vibration conditions
•Standard 0-20 mA output
•Maintenance call (3 mA)
•HART® protocol: communication protocol
•RS-485 output Modbus®-compatible for personal computer (PC) communication
network for a maximum of 247 systems
•Simple one person installation, alignment, and calibration
•ATEX and IECEx per
Ex II 2(2) G D
Ex db eb ib [ib Gb] IIB + H2 T4 Gb
Ex tb [ib Db] IIIC T135 °C Db
Ta = -55 °C to 65 °C
•TR CU approved per:
1 Ex db eb ib [ib Gb] IIB + H2 T4 Gb X
Ex tb IIIC T135 °C Db X
-55 °C ≤ Ta ≤ 65 °C
•CSA C/US approved per:
Canada
Ex db eb ib [ib Gb] IIB+H2 T4 Gb
Ex tb [ib Db] IIIC T135 °C Db
Ta = -55 °C to + 65 °C
USA
Class I Zone 1 AEx db eb ib [ib Gb] IIB+H2 T4 Gb
Zone 21 AEx tbm [ib Db] IIC T135 °C Db
Ta = -55 °C to +65 °C
•TUV approved per SIL2 requirements.
•Inmetro (UL) approved.
•Programmable configuration via the Field Communicator
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•Fast connections to intrinsically safe (I.S.) approved hand-held diagnostic/calibration
unit
•Three-year warranty
2.2 Applications
You can use the Rosemount 936 system to monitor toxic gas concentrations in various
applications, such as:
•Petrochemical, pharmaceutical, and other chemical storage and production areas
•Toxic chemical storage sites and hazardous waste disposal areas
•Detecting H2S in desulfurization processes at refineries, oil platforms, pipelines,
refueling stations, and fuel storage facilities
•Transportation depots and shipping warehouses of degreasing and cleaning solvents
•Styrene monomer, polymers, and plastic industries
•NH3 production facilities, storage, and transportation
•Air conditioning, refrigeration, and agriculture application areas for NH3 and
derivatives
•Semiconductor industry in which NH3 concentration monitoring is required
2.3 Principle of operation
The system detects gases through dual-spectral range monitoring, analyzing the
absorption of radiation caused by gases in the atmosphere and comparing it (ratio) to
background atmospheric absorption.
2.3.1 Spectral fingerprint
Each hazardous material is detected at a specific wavelength selected according to its
specific spectral absorption or fingerprint.
The detection process involves two separate sensors, one that absorbs a particular gas and
one that is not sensitive to it.
2.3.2 Optical path
The Rosemount 936 detects the presence of toxic airborne vapors, gases, or aerosols in a
monitored area when the defined substance crosses/enters the optical path between the
radiation source unit and the detector.
Toxic gases/vapors present in the atmosphere cause absorption of the radiation pulse at
specific wavelengths in the optical path between the radiating source and the detector.
This causes a change in the signal intensity received by the detector, which is translated
into an output related to the detector's measurement scale.
The system analyzes the defined open path at the spectral bands specific to the materials
being monitored. The automatic gain control (AGC) unit compensates for environmental
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disturbances, such as fog, rain, etc., through a constant comparison with its dual spectral
beam.
2.3.3 Detected gases
The Rosemount 936 detects the following toxic gases and vapors according to their
unique spectral absorption in the UV solar blind range:
Ammonia (NH3)
A flammable and toxic gas that is highly irritating and colorless with a pungent odor.
The early detection of NH3 is essential to prevent its toxic effects, such as respiratory tract
paralysis. In the ultraviolet (UV) band, NH3 has a typical strong absorption in the solar blind
range of 189 nm to 210 nm that enables its fast and reliable detection at low
concentrations.
Hydrogen sulfide (H2S)
A flammable, poisonous gas with a characteristic smell of rotten eggs.
H2S is heavier than air and very dangerous to humans, causing collapse, coma, and death
from respiratory failure within a few seconds of inhalation.
Early detection of H2S is essential to prevent its toxic influence.
In the UV band, H2S has characteristically strong absorption in the solar blind range of
189 nm to 270 nm, which enables fast and reliable detection at low concentrations.
2.3.4 Ultraviolet (UV) source
The Rosemount 936 employs the latest generation of Xenon UV flash bulbs to provide
extended installation distance and maximum reliability.
2.3.5 Heated optics
The Rosemount 936 includes heated optics for the detector and source.
The heater increases the temperature of the optical surface by 5 to 8 °F (3 to 5 °C) above
the ambient temperature to improve performance in icing, condensation, and snow
conditions. Emerson has configured the heated optics to automatically operate when the
change in temperature requires heating (default).
However, you can also define the heated optics as one of the following modes:
1. Not operated (not an option source unit)
2. On continuously
3. Automatic, per temperature change (default)
See System setup.
When operated in Automatic mode, you can define the start temperature below which the
window will be heated (default 41 °F [5 °C]). You can define this temperature between 32
°F (0 °C) and 122 °F (50 °C). The heating stops when the temperature is 27 °F (15 °C) above
the start temperature.
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2.3.6 HART® protocol
The Rosemount 936 uses the HART protocol.
This is a field communications protocol used to communicate between intelligent field
instruments and the host system.
HART is the global standard for smart instrumentation, and most smart field devices
installed in plants worldwide are HART-enabled. HART technology is easy to use and very
reliable.
Through the HART connection, the detector can:
•Set up
•Troubleshoot
•Display health and status
You can connect the HART communication on the 0-20 mA line or thought the intrinsically
safe (I.S.) connection with a standard Field Communicator loaded with Emerson's host
software and attached by a special harness.
2.3.7 Modbus® RS-485
For more advanced communications, the Rosemount 936 has an RS-485 Modbus-
compatible output that provides data communication.
This feature enables simple commissioning, maintenance, and configuration.
2.3.8 Tilt mount
The stainless steel tilt mount provides a small installation footprint that can conform to
limited space constraints, while the sturdy construction maintains alignment even in
constant vibration.
The X and Y axis adjustments provide quick and easy alignment for installation and
maintenance.
2.4 Product certifications
2.4.1 ATEX and IECEx
The Rosemount 936 is approved per:
Ex II 2(2) G D
Ex db eb ib [ib Gb] IIB+H2 T4 Gb
Ex tb [ib Db] IIIC T135 °C Db
Ta = -55 °C to +65 °C
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2.4.2 SIL-2
The Rosemount 936 is TUV approved for SIL-2 requirements per IEC61508.
The alert condition according to SIL-2 can be implemented by alert signal via 0-20 mA
current loop.
2.4.3 TR CU
The Rosemount 936 is in compliance with the standard TR CU 012/2011 per:
1Ex db eb ib [ib Gb] IIB + H2 T4 Gb X
Ex tb IIIC T135 °C Db X
-55 °C ≤ Ta ≤ +65 °C
For more details, see TR CU Certificate number TC RU C-US.M ю 62.B.05535.
2.4.4 INMETRO
The Rosemount 936 is in compliance with the standards ABNT NBR IEC 60079-0, ABNT
NBR IEC 60079-1, ABNT NBR IEC 60079-7, ABNT NBR IEC 60079-11, ABNT NBR IEC
60079-28, ABNT NBR IEC 60079-31, and INMETRO decree No. 179 as of May 18th, 2010.
Further details may be found on the Certificate of Compliance Number UL-BR 19.0726X.
2.4.5 CSA C/US
The Rosemount 936 is approved per CSA C/US for hazardous and ordinary locations:
Canada
Ex db eb ib [ib Gb] IIB+H2 T4 Gb
Ex tb [ib Db] IIIC T135 °C Db
Ta = -55 °C to +65 °C
USA
Class I Zone 1 AEx db eb ib [ib Gb] IIB+H2 T4 Gb
Zone 21 AEx tb [ib Db] IIIC T135 °C Db
Ta = -55 °C to +65 °C
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The Rosemount 936 is a "Class 1 Laser Product" per IEC 60825-1: 2014 ed. 05.
2.5 Models and types
The Rosemount 936 is available as three transmitter models, determining the detection
distance, with two possible detectors, detecting H2S or ammonia. This allows for
detection at distances from 17 to 200 ft. (5 to 60 m).
Table 2-1 lists the various options.
Table 2-1: Rosemount 936 source (transmitter) installation distances
Model number Source (transmitter)
option code
Minimum installation
distance
Maximum installation
distance
936 T1 17 ft. (5 m) 52 ft. (16 m)
936 T2 46 ft. (14 m) 132 ft. (40 m)
936 T3 115 ft. (35 m) 200 ft. (60 m)
Related information
Short range model
2.6 Ordering information
You can order the Rosemount 936 as separate parts: source (PN TXT00XXXX), detector
(PN-RT12XXXXX), and commissioning kit.
2.6.1 Online product configurator
Many products are configurable online using our product configurator.
Visit our website to start. With this tool's built-in logic and continuous validation, you can
configure your products more quickly and accurately.
2.6.2 Model codes
Model codes contain the details related to each product.
Exact model codes will vary; an example of a typical model code is shown in Source
(Transmitter) and Detector (Receiver).
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Source (Transmitter)
936T1T00F002SA1
Detector (Receiver)
936R1T262SA1
2.6.3 Specifications and options
See Specifications for more details on each configuration.
Specification and selection of product materials, options, or components must be made
by the purchaser of the equipment.
2.6.4 Source (Transmitter)
Required model components
Model
Code Description
936 Toxic Open Path Gas Detector Source (Transmitter)
Transmitter range
Code Description
T1 Transmitter - Range of 17 to 52 ft (5 to 16 m)
T2 Transmitter - Range of 46 to 132 ft (14 to 40 m)
T3 Transmitter - Range of 115 to 200 ft (35 to 60 m)
Gas calibration
Code Description
T00 Transmitter
Housing style / conduit
Code Material Measurement
2S Stainless steel ¾-in NPT
4S Stainless steel M25
Product certifications
Code Description
A1 ATEX and IECEx
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Code Description
A3 CSA
E2 INMETRO
EM CU TR (EAC)
2.6.5 Detector (Receiver)
Required model components
Model
Code Description
936 Toxic Open Path Gas Detector (Receiver)
Receiver selection
Code Description
R1 Receiver
Gas calibration
Code Description
T26 Hydrogen sulfide (receiver)
T27 Ammonia (receiver)
Housing style / conduit
Code Material Measurement
2S Stainless steel ¾-in NPT
4S Stainless steel M25
Product certifications
Code Description
A1 ATEX and IECEx
A3 CSA
E2 INMETRO
EM CU TR (EAC)
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2.7 Description
The Rosemount 936 comprises two main units:
•Ultraviolet source
•Detector
The Rosemount 936 detects gases over an open path transmitted from the source to the
detector.
2.7.1 Ultraviolet (UV) source unit
The UV source unit emits radiation pulses at the rate of one pulse per second.
The pulse width (5 to 10 µsec) is very powerful. The front of the source unit has an internal
reflector that collimates the UV beam for maximum intensity. The front window is heated
to improve performance in icing, condensation, and snow conditions.
Figure 2-1: UV Source
A. Weather shield
B. Front window section
C. Label
D. Main housing
E. Mounting plate
F. Junction box
G. Indicator light-emitting diode (LED)
H. Earth terminal
I. Cable inlet
J. Front window
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2.7.2 Detector unit
The detector receives the transmitted pulsed radiation signals from the source. The signals
are then amplified and fed into an analog to digital signal converter to be processed by the
internal microprocessor.
When the signals drop below a prescribed level, the internal microprocessor compensates
for them. This allows the signals to be maintained even in severe weather conditions. The
data is sent to the output interface section.
The front window of the detector is heated to improve performance in icing,
condensation, and snow conditions.
There is one detector type that is suitable for the H2S version and one for the NH3 version.
Figure 2-2: Detector
A. Front window
B. Handheld fast connection
C. Weather shield
D. Front window section
E. Label
F. Main housing
G. Mounting plate
H. Junction box
I. Back cover
J. Indicator light-emitting diode (LED)
K. Earth terminal
L. Cable inlet
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3 Operating modes
3.1 Operational modes
The Rosemount 936 has four operational modes:
•Normal mode
•Maintenance call mode (3 mA output)
•Fault mode
•Zero calibration mode (1 mA output)
3.1.1 Normal mode
This mode is used for gas detection. In Normal mode, the following statuses are possible:
•Normal (N): Signal received from gas detection is at safe levels.
•Warning (W): Gases have been detected at warning levels.
•Alarm (A): Gases have been detected at alarm levels.
NOTICE
For the standard 0-20 mA output, the warning and alarm levels are not relevant. Choose
these alarm levels at the controller. The output detector is at 4 mA at zero reading and 20
mA for full-scale reading.
If using the RS-485 output, the detector changes its status from N to W at Warning level
and to A at Alarm level.
3.1.2 Maintenance call mode (3 mA output)
This mode indicates low signal that may be caused by a dirty window, misalignment, or
poor source or if one of the detector's parameters is at the limit value.
The detector continues to function, but provides a (3 mA) pre-warning signal (via HART®
and Modbus®) that a maintenance procedure is required.
3.1.3 Fault mode
In the fault status, there are three fault types.
•Fault 1 (2 mA output) - non-critical
If this occurs, it is due to blockage, very low signal, partial obscuration, or full beam
block. In this situation, detection is no longer possible. The detector's proper operation
can be restored (auto reset) during operation if the condition causing the problem is
removed or resolved. This mode occurs after a delay of 60 seconds from the moment
of the fault. This delay is important to eliminate momentary obscuration due to
passing through the beam.
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•Low voltage fault (1 mA output)
In this situation, detection is disabled due to low voltage being supplied to the
detector. The detector returns to proper operation only when proper voltage level is
restored.
•Fault 2 (1 mA output)
In this situation, the detection is disabled due to an electrical/software operational
failure or a central device (memory or processor) fault. Such a fault causes the detector
to cease operation. If there is a fault in the 0-20 mA loop, the output is 0 mA.
3.1.4 Zero calibration mode (1 mA output)
This mode zeroes the base level from which the detector reads gas.
Only do this when:
•No gases are present.
•There is a clear path between the source and the detector.
•Weather conditions are clear.
Use the Field Communicator of host software on your personal computer (PC) to zero
calibrate after installation, re-alignment, and window cleaning. In parallel, while the
detector is connected to the Field Communicator, the magnetic mode selector can be
used for zero calibration.
Related information
Zero calibrate
3.2 Visual indicators
One three color light-emitting diode (LED) indicator is located in the back side of the
detector/source and can be seen through the back cover window.
See Figure 2-1 and Figure 2-2.
The detector statuses are listed in Table 3-1.
Table 3-1: Detector LED indications
Detector status LED color LED mode
Fault Yellow 4 Hz - flashing
Alignment / Standby Yellow 1 Hz - flashing
Zero calibration Yellow Constant
Normal Green 1 Hz - flashing
Warning Red 2 Hz - flashing
Alarm Red Constant
The source statuses are listed in Table 3-2.
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