Emerson Rosemount 935 Manuale utente
Quick Start Guide
00825-0100-4035, Rev AB
November2023
Rosemount™ 935
Open Path Combustible Gas Detectors
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
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 transmitter and receiver are not field-repairable due to the meticuluos 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
Digital video Each component is represented by a number representing a
discrete quantization.
DSP Digital signal processing
EMC Electromagnetic compatibility
EMI Electromagnetic interference
EOL End of line
FOV Field of view
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2 Emerson.com/Rosemount
Abbreviation Meaning
HART®Highway addressable remote transducer communication
protocol
IAD Immune at any distance
IECEx International Electrochemical Commission explosion
IP Internet protocol
IPA Isopropyl alcohol
IR Infrared
IR3 Refers to the three infrared sensors
JP5 Jet fuel
Latching Refers to relays remaining in the On state even after the On
condition has been removed.
LED Light-emitting diode
LEL Lower explosive limit: The minimum concentration of a
substance (gas/vapor) in air mixture that can be ignited. This
mixture is different for every gas/vapor, measured in % of
LEL.
LEL.m Integral of concentration in LEL units (1 LEL = 100% LEL) and
the operation distance in meters (m).
LNG Liquefied natural gas
LPG Liquefied petroleum gas
mA MilliAmps (0.001 amps)
Modbus®Master-slave messaging structure
N.C. Normally closed
N.O. Normally open
N/A Not applicable
NFPA National Fire Protection Association
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
RFI Radio frequency interference
RTSP Real time streaming protocol
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Quick Start Guide 3
Abbreviation Meaning
SIL Safety integrity level
UNC Unified coarse thread
Vac Volts alternating current
Vdc Volts direct current
µm Micrometer
Contents
Installation instructions.............................................................................................................. 5
Operation....................................................................................................................................22
Product certifications................................................................................................................ 29
Wiring configurations................................................................................................................31
Declaration of Conformity........................................................................................................ 35
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4 Emerson.com/Rosemount
1 Installation instructions
1.1 General considerations
1.1.1 Personnel
Only employ suitably qualified personnel who are familiar with the
local codes and practices and trained for gas detection maintenance.
Ensure that wiring is only performed and supervised by someone
with knowledge of electronics and, in particular, wiring installation.
1.1.2 Site requirements
When installing the Rosemount™ 935, take into account the weight of
the monitored gas compared to that of the surrounding air and the
individual site requirements.
Ensure that the site selected gives the receiver a direct view to the
transmitter. The mounting point for each item should be secure and
stable with minimal vibrations. Mount the equipment in a position
where it cannot be knocked out of alignment and is guarded from
physical impact.
1.1.3 Transmitter and receiver
Select the appropriate receiver for the length of open path to be
monitored.
To allow for aging of the transmitter and a reduction of the
infrared signal due to adverse weather, Emerson recommends using
a receiver that is not at the limit of its operating range. The
general recommendation is to install the receiver at a distance
from the transmitter of not more than 75 percent of the specified
operating distance. In severe weather conditions, such as offshore
oil production and exploration, reduce this distance to 50 percent.
Keep the open path between the transmitter and receiver clear of
any obstacles that might hinder the free movement of air in the
protected area or block the infrared beam.
1.1.4 Tips for gas detector locations
To provide the best detection coverage, install the detector:
•Below potential leak source for gases heavier than air.
•Above potential leak sources for gases lighter than air.
•Near to leak sources along the expected leak trajectory, taking
into account prevailing wind directions.
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Quick Start Guide 5
CAUTION
For optimal performance, avoid placing the detector in locations
frequently covered by steam.
1.1.5 Separation distances
To avoid crosstalk between adjacent open path gas detector (OPGD)
systems where transmitters are installed on the same side, keep the
relevant separation distance between the neighboring OPGD systems
according to the installation lengths as listed in Table 1-1.
Table 1-1: Minimum Separation Distances
Installation line of sight distance Minimum separation
33ft. (10m) 3.3ft. (1m)
66ft. (20m) 5 ft. (1.5 m)
98ft. (30m) 6.5 ft. (2 m)
131ft. (40m) 11.5 ft. (3.5 m)
164ft. (50m) 15 ft. (4.5 m)
197ft. (60m) 16.5ft. (5m)
230ft. (70m) 20ft. (6m)
262ft. (80m) 23ft. (7m)
295ft. (90m) 26ft. (8m)
328ft. (100m) 28 ft. (8.5 m)
361ft. (110m) 29.5ft. (9m)
394ft. (120m) 33ft. (10m)
427ft. (130m) 34.5 ft. (10.5 m)
459ft. (140m) 38 ft. (11.5 m)
492ft. (150m) 42.5ft. (13m)
525ft. (160m) 47.5 ft. (14.5 m)
558ft. (170m) 49ft. (15m)
591ft. (180m) 51 ft. (15.5 m)
693ft. (211m) 52.5ft. (16m)
656ft. (200m) 54 ft. (16.5 m)
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6 Emerson.com/Rosemount
1.1.6 Wiring
For wiring, use color-coded conductors or suitable wire markings or
labels.
•The wire cross-section must be between 28 to 14 AWG (0.5 mm2
to 2.5 mm2).
•Select the wire gauge based on the number of detectors used
on the same loop and the distance from the control unit. The
maximum number of wire connections in one terminal is two wire
cross-sections, each 1 mm2.
•To fully comply with electromagnetic compatibility (EMC) directive
and protect against interference caused by radio frequency
interference (RFI) and electromagnetic interference (EMI), the
cable to the detector must be shielded, and the detector must
be grounded. Ground the shield at the detector end.
1.2 Preparations for installation
It is important to ensure that installation complies with local,
national, and international regulations and norms as applicable to
gas detectors and approved electrical devices installed in hazardous
areas.
1.2.1 Equipment
The system should include the following (in addition to the Quick
Start Guide):
Figure 1-1: Box Contents
Commissioning kit not pictured.
A. Transmitter or receiver (per box)
B. Tilt mounts
•Receiver unit: 935-R1F01XXXX
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Quick Start Guide 7
•Transmitter unit: 935-TXFXXXXXX
•Two tilt mount bases (one for the transmitter and one for the
receiver)(1)
•Extended Commissioning Kit
•Commissioning kit, three options when ordered:
—For methane calibration
—For propane calibration
—For ethylene calibration
The commissioning kit includes:
•Alignment tool kit
•Function check filters
•HART® hand-held harness kit
Other accessories are available (per customer request):
•5-in. pole mount kit
•2 to 3-in. pole mount
•Wall mount
•Protective cover
Note
See the Rosemount™ 935 Product Data Sheet for accessory part
numbers.
1.2.2 Required tools
Install the device using the following general purpose common tools
and equipment.
Table 1-2: Tools
Tool Function
Alignment kit Provides tools to install fine alignment tool.
Hex key 8 mm Mounts the detector on the tilt mount.
Hex key 3/16-in. Aligns the detector.
Hex key 5/16-in. Screws ¾ stop plug.
Flat screwdriver 4 mm Connects ground terminal.
(1) If you order a transmitter or receiver separately, then you will receive one tilt
mount.
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8 Emerson.com/Rosemount
Table 1-2: Tools
(continued)
Tool Function
Flat screwdriver 2.5 mm Connects wires to the terminal block.
1.3 Certification instructions
WARNING
EXPLOSION
Do not open the detector, even when isolated, in a flammable
atmosphere.
•The cable entry point may exceed 182°F (83°C). Take suitable
precautions when selecting the cable.
•The equipment may be used with flammable gases and vapors
with apparatus groups IIA and IIB+H2 T4 in the ambient
temperature range: -67°F (-55°C) to 149°F (65°C).
•Only suitably trained personnel shall install the detector in
accordance with the applicable code of practice, e.g., EN
60079-14: 1997.
•Only suitably trained personnel shall inspect and maintain this
equipment in accordance with the applicable code of practice,
e.g., EN 60079-19.
•Only suitably trained personnel shall repair this equipment
in accordance with the applicable code of practice, e.g., EN
60079-19.
•The certification of this equipment relies upon the following
materials used in its construction:
—Enclosure: Stainless steel 316
—Windows: Sapphire glass
—Seals: EPDM
•If the equipment is likely to come into contact with aggressive
substances, then it is your responsibility to take suitable
precautions that prevent it from being adversely affected, thus
ensuring that the type of protection provided by the equipment is
not compromised.
—Aggressive substances: For example, acidic liquids or gases
that may attack metal or solvents that may affect polymeric
materials.
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Quick Start Guide 9
—Suitable precautions: For example, regular checks as part of
routine inspections or establishing from the material's Safety
Data Sheets that it is resistant to specific chemicals.
Quick Start Guide November2023
10 Emerson.com/Rosemount
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