Emerson Rosemount 625IR User manual

Manual
MS-00809-0100-3625, Rev AA
January2024
Rosemount™ 625IR
Optical Infrared Gas Detector

Warnings
WARNING
If the product is not used and maintained in accordance with the manufacturer's instructions, the product may not
perform as intended.
Carefully read the manual in its entirety.
All those responsible for operating and maintaining this product must read and understand the manual.
WARNING
If the product is not used and maintained as described in this manual, warranties with respect to the product are
voided.
Warranties are also voided if the product is used outside temperature and vibration certified ranges.
Please read the general warnings in the following chapters.
WARNING
The Rosemount 625IR Optical Gas Detector is certified for and intended for use in potentially hazardous areas.
Install and use the gas detector in accordance with the appropriate local or national regulations.
WARNING
Ensure that the gas detector is properly earthed to protect against electrical shock and minimize electrical
interference.
WARNING
Test gases may be combustible.
Refer to Material Safety Data Sheets for appropriate warnings.
WARNING
Only trained and qualified personnel should install and operate the detector.
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 in protecting your system. Restrict
physical access by unauthorized personnel to protect end users’ assets. This is true for all systems used within the
facility.
NOTICE
The warranty is not valid if the detector housing is opened.
Do not open the detector housing. There are no user-serviceable parts or settings inside.
Return to service point for service or repair.
2

Related information
Abbreviations
3

Warranty
•5 (five) year limited warranty
The Rosemount 625IR warrants for normal use within gas detection, in accordance with this Manual.
Contact your supplier for further instructions on warranty and claims procedures.
Related information
Contact support
Abbreviations
Abbreviation Definition
ATEX Atmospheric explosives
EMC Electromagnetic compatibility
FS Full scale. Full gas range for the detector. For example 0 - 100% lower
explosive limit (LEL) or 0 - 100% volume.
HART®Highway addressable remote transducer communication protocol
IR Infrared light
IECEx International Electrochemical Commission Explosion
Modbus®Master-slave messaging structure
SIL Safety integrity level. This is used in accordance with the standard IEC 61508.
1oo1 One out of one. Used in an SIL context, where only one detector is used to
decide if the gas detection is valid.
1oo2 One out of two. Used in an SIL context. Two detectors are set up in a voting
configuration, where if just one detector is detecting gas, the system will
treat it as a gas incident.
4

Contents
Chapter 1 Installation.................................................................................................................................7
1.1 Install the detector...................................................................................................................... 7
1.2 Preparations and positioning considerations..........................................................................7
1.3 Positioning considerations and response time....................................................................... 8
1.4 Mounting the detector............................................................................................................. 11
1.5 Electrical connections and earthing........................................................................................17
1.6 Environment shield................................................................................................................... 19
1.7 Sunshade....................................................................................................................................21
1.8 Mosquito net..............................................................................................................................22
1.9 Blocking kit.................................................................................................................................23
Chapter 2 Configure the detector...........................................................................................................25
Chapter 3 Operation................................................................................................................................. 27
3.1 Function test.............................................................................................................................. 27
3.2 Verify detector accuracy........................................................................................................... 31
3.3 Check reaction time.................................................................................................................. 32
Chapter 4 Maintenance............................................................................................................................35
4.1 Clean optics (lens and mirror)..................................................................................................35
4.2 Inspect detector for damage................................................................................................... 35
4.3 Keeping a stable zeroing of the detector...............................................................................36
4.4 Self diagnostics..........................................................................................................................37
Chapter 5 Troubleshooting...................................................................................................................... 39
5.1 HART® status flags.....................................................................................................................39
5.2 Potential errors..........................................................................................................................52
Chapter 6 Classification of gases............................................................................................................ 55
Appendix A Description and detection principle..................................................................................... 57
A.1 Detection principle....................................................................................................................58
Appendix B Ordering information, specifications, and certifications.................................................. 59
Appendix C Dimensions.............................................................................................................................. 61
Appendix D Contact support.......................................................................................................................65
Appendix E Detecting other gases............................................................................................................ 67
Manual Contents
MS-00809-0100-3625 January2024
Rosemount 625IR 5

Contents Manual
January2024 MS-00809-0100-3625
6 Emerson.com

1 Installation
WARNING
Ensure that the area for which the detector will be installed is in accordance with the
certification of the detector and with the standards of the appropriate authority in the
country concerned.
WARNING
If the service temperature of the installation may exceed +158 °F (+70 °C), ensure the
following:
Cable glands are certified for the given temperature range.
Cables are suited for use at temperatures above +172 °F (+78 °C).
1.1 Install the detector
Prerequisites
Emerson recommends reading the procedures in IEC 60079-29-2: Explosive atmospheres gas
detectors - Selection, installation, use, and maintenance of detectors for flammable gases and
oxygen.
Procedure
1. Verify that the detector is mounted in a horizontal orientation with tight bolts as
described in Mounting the detector.
2. Verify correct wiring of the terminals as described in Electrical connections and
earthing.
3. Verify that the cable gland is a suitable type and has the appropriate certification.
4. Verify cable shielding has been correctly terminated.
5. Verify correct earthing to external earthing point on the detector housing as
described in Electrical connections and earthing.
1.2 Preparations and positioning considerations
The Rosemount 625IR is a point gas detector, and qualified personnel should carefully
assess its chosen location. However, each installation is unique, and the operators must
make detailed considerations locally in order to get the best coverage. Below are some
general matters to consider.
•Place the detector where maintenance, such as cleaning of optics, can be easily
performed.
•Take into account the relative weight of the target gas compared to air when deciding
the optimum installation height. Methane is lighter than air, and in this case the gas
detector may have to be placed above a potential leak source. If measuring other
hydrocarbons, such as propane, that are heavier than air, it might be better to place the
detector at a lower level, in many instances close to the floor.
Manual Installation
MS-00809-0100-3625 January2024
Rosemount 625IR 7

•The concentration of a gas cloud may quickly reduce with the distance from the
leak source. Therefore, consider placing the detector as close as possible to potential
leakage sources.
•No known limitations to air velocity found, but pressure building up in a duct or
similar applications will change the gas reading with the same relative amplitude as
the pressure changes. This is how physics works for all optical detectors.
•Do not mount the detector in areas where it can be drenched by water.
•Consider the fact that gas quickly dilutes when released into the air and the impact of
wind. As illustrated in Figure 1-1, with a leak point at position A, the gas will spread in
the direction of the wind and be detected at position C (downstream), but not detected
at position B. The wind speed has no effect on the detector.
Figure 1-1: Impact of wind
A. Leak point
B. Detector out of range
C. Detector in range
D. Wind direction
1.3 Positioning considerations and response time
IEC 60089-29-1 mentions three methods that can be used to test response time:
•Flow (tested by manufacturer)
•Diffusion by immersion (tested by manufacturer)
Installation Manual
January2024 MS-00809-0100-3625
8 Emerson.com

•Diffusion by containment (tested by FM)
In sampling systems, the response time T90 can be as low as 1.3 seconds, but for other
applications it takes more time for the gas to completely fill the sampling volume in the gas
detector.
Especially for laminar flows, the response time can vary depending on how the gas
detector is mounted, and this can be relevant for air intakes and ventilation systems with
a laminar flow in one specific direction. The flow method is a test illustrating laminar flow
and is in Table 1-1 for the fastest and slowest orientations.
Table 1-1: Response times by test method
Test method Description of test method T90 (seconds)
No
accessories
Environment
shield
Flow using the gas test kit This is close to the fastest possible response, and is an
easy method for the end user to produce. This response
represents use in aspiration/gas sampling systems.
1.3 (gas flow > 5 lpm)
Diffusion by immersion For this method, use a chamber filled with moving gas and
record the time it takes to detect gas after removing the
cup. This setup emulates the detector surrounded by a gas
cloud.
These results are used in the Specifications sheet.
The detector's orientation did not have a significant impact
on the results
1.4 4
Diffusion by containment
(used in FM test)
FM used this method to test the response during the
performance certification tests.
For this method, use water to force the gas with a
specific speed and direction. With the laminar gas flow,
the response time depends on the detector's orientation.
The fastest and slowest orientations are indicated in
parentheses.
2.1 (fast)
2.5 (slow)
4.6 (fast)
15.5 (slow)
Manual Installation
MS-00809-0100-3625 January2024
Rosemount 625IR 9

For the shortest response time, orient the detector so the air flow is directed directly into
the opening of the gas detector as illustrated in Figure 1-2.
Figure 1-2: Detector orientation
A. Recommended orientation
B. Air flow
Installation Manual
January2024 MS-00809-0100-3625
10 Emerson.com

1.4 Mounting the detector
In Figure 1-3, the Rosemount 625IR is shown securely mounted.
Figure 1-3: 625IR securely mounted
Mount the detector with the longitudinal axis in the horizontal direction as illustrated in
Figure 1-4. You can rotate it in any direction along this longitudinal axis. This position
reduces the accumulation of contamination on the optical parts (lens and mirror).
Figure 1-4: Mounting direction
A. Correct position
B. Incorrect position
Most often, operators mount the detector on the wall, but they can also mount it flat or in
the roof as illustrated in Figure 1-5, Figure 1-6, and Figure 1-7.
Manual Installation
MS-00809-0100-3625 January2024
Rosemount 625IR 11

Figure 1-5: Detector mounted on the wall
Figure 1-6: Detector mounted flat
Figure 1-7: Detector mounted in roof
Installation Manual
January2024 MS-00809-0100-3625
12 Emerson.com

1.4.1 Pole mounting
Figure 1-8 shows the Rosemount 625IR with the pole mount kit. A pole with a diameter of
about 3 in. (60 mm) should be sufficient.
Figure 1-8: Pole mount kit
Manual Installation
MS-00809-0100-3625 January2024
Rosemount 625IR 13

1.4.2 Mount to duct or pipe
If you are installing the Rosemount 625IR in a ventilation duct or pipe, Emerson
recommends using the mounting arrangement and accessories as shown in Figure 1-9.
To get better gas coverage inside the duct, use the 625IR Duct with extended gas sensing
section as illustrated in Figure 1-9.
Figure 1-9: 625IR with longer gas sensing section
To mount the 625IR with the duct flange kit:
Procedure
1. Fix the plate duct flange with eight bolts to the installation.
2. Make sure the O-ring is in place and not damaged.
3. Slide the 625IR into the plate duct and fix it with the two metal brackets.
Emerson can supply the duct flange kit with a nozzle to allow for gas testing without
removing the detector from the duct flange.
Installation Manual
January2024 MS-00809-0100-3625
14 Emerson.com

1.4.3 Options for mounting Rosemount 625IR in ducts or pipes
There are three possible configurations for mounting the duct flange:
Figure 1-10: Rosemount 625IR mounted in the duct flange kit
The operator can easily remove the detector from the duct to perform a gas test. The
nozzle is not used for gas testing.
Figure 1-11: 625IR mounted in duct flange with gas test line connected to the nozzle
Installed with the nozzle in front of the 625IR and a flexible tube connected from the nozzle
to the duct flange. With the environment shield installed, this solution works well when the
air is flowing in the duct. Without the environment shield, it is more difficult to do the gas
test, since the gas dilutes more quickly and therefore requires very high flow.
Manual Installation
MS-00809-0100-3625 January2024
Rosemount 625IR 15

Figure 1-12: 625IR Duct mounted in duct flange kit
You can perform a gas test through the rigid gas pipe. It can be challenging to perform gas
tests if there is air flow in the duct.
Installation Manual
January2024 MS-00809-0100-3625
16 Emerson.com

1.5 Electrical connections and earthing
Connect the Rosemount 625IR chassis to local clean earth.
Use one of the two external earthing points illustrated in Figure 1-13 using an earthing
cable ring lug.
Figure 1-13: Electrical connections and earthing
A. External earthing point
B. Electrical terminals inside rear lid
C. Cable entries
D. Internal wiring terminals
E. Wire terminals according to Table 1-2.
F. Internal earth point for an M4 screw for connection of cable lug
The electrical terminals are located inside the rear lid. Open them by unscrewing the three
screws fixing the lid to the detector. There are cable entries on both sides of the detector.
The right side of the terminals are for internal wiring. On the left side are the terminals (pin
1 at the top and pin 5 at the bottom) to be wired according to Table 1-2.
Table 1-2: Terminal Specifications
Terminal (detector wire
color)
Signal type Specification Cable requirement
1 (white) Power, positive supply
voltage
24 Vdc Defer to site standards.
Minimum cross section is
0.01 in.2 (0.14 mm2), and
maximum cross section is 0.1
in.2 (2.5mm2) (stranded) or
0.2 in.2 (4 mm2) (solid).
2 (brown) Power, supply voltage return 0 Vdc
3 (green) Analog safety signal Analog 0-20 mA DC signal
overlaid with a HART® signal.
The HART signal does not
interfere with the analog DC
signal. Maximum impedance:
500 Ω
4 (yellow) RS-485 A Two wires for connection
to digital RS-485 serial
Industrial communication
cable with shielded twisted
pair. Minimum/maximum
Manual Installation
MS-00809-0100-3625 January2024
Rosemount 625IR 17

Table 1-2: Terminal Specifications (continued)
Terminal (detector wire
color)
Signal type Specification Cable requirement
5 (grey) RS-485 B communication, Modbus®
remote terminal unit (RTU)
cross section 0.01 in.2 (0.14
mm)2/0.1 in.2 (2.5 mm2)
(stranded) or maximum 0.2
in.2 4 mm2 (solid)
Earth External earth point Use external grounding when the detector is installed in an
Ex zone.
Internal earth point Normally not used. Shield of the cable is typically connected
to instrument earth in the central control cabinet and is
normally not terminated at the detector.
If extra radio frequency interference (RFI) is required, and
the installation's grounding principles/regulations allow it,
you can terminate the shield to local ground via the internal
earth point at the detector.
Note
Minimum voltage to the 625IR is 18 Vdc.
Table 1-3: Cable size and maximum length
Cable cross section Voltage drop Maximum cable length(1)
0.03 in.2 (0.75 mm2)∼5.8 V 656 ft. (200 m)
0.04 in.2 (1.0 mm2) 820 ft. (250 m)
0.06 in.2 (1.5 mm2) 1312 ft. (400 m)
0.1 in.2 (2.5 mm2) 2133 ft. (650 m)
0.2 in.2 (4 mm2) 3281 ft. (1000 m)
(1) For a nominal power of 24 V. Longer cable can be used with higher supply voltage.
Related information
Light indicator
HART status flags
1.5.1 Boot up the detector
Procedure
Turn on the power to the detector.
The detector has a boot-up time of < 2 minutes when ambient temperature is above
-4 °F (-20 °C). During this time, the detector runs self-diagnostics and if the indicator is
configured to be active, it will be yellow.
Postrequisites
After this boot-up time, the detector is ready to detect gas, but for a very precise and
accurate test, allow the detector another 20 minutes to warm up.
Installation Manual
January2024 MS-00809-0100-3625
18 Emerson.com

1.5.2 Performing loop test
The Rosemount 625IR can perform a loop test through the HART® or Modbus® interface.
The loop test allows you to manually set the analog signal output to a selected value for a
limited time.
1.6 Environment shield
Dirt, dust, snow, and liquids gathered on the lens and mirror will reduce the amount of
infrared (IR) light used for detecting gas.
A clean detector should have about 100 percent signal strength. Over time, the optics
will get dirty and the signal strength will drop. If the signal goes below 70 percent, the
detector gives an EARLY CLEAN OPTICS warning. If you see this warning, clean the
optics. If the optics are not cleaned, more dirt will accumulate on the optics. If signal
strength drops below 55 percent, the detector will go into BEAM BLOCK FAULT. How fast
dirt accumulates on the optics depends on how dirty the environment is.
Water splash, such as from fire extinguishing systems, can also block the optics. Also, in
some cases insects and other objects can block the optics. To reduce the likelihood of
water or insects getting into the optical path, use an environment shield. The environment
shield can also extend the time before dirt and similar substances accumulate on
the optics, which can increase the cleaning intervals. Table 1-4 is an overview of the
environment shield offered.
Table 1-4: Environment shield
Type Application examples Performance effect
Environment shield The standard environment shield
comes with the Rosemount 625IR. It
gives good protection from ingress of
water and other contaminants.
Gas response time is specified with the
environment shield in place. Without
the environment shield, the response
time is slightly faster.
For the fastest response time, use the 625IR without the environment shield. In most
cases, Emerson recommends using the environment shield, since it makes the detector
more robust against water and dirt. Even with the environment shield, the detector has a
very fast response time.
The environment shield for the 625IR consists of one compact unit fitting into the gas
sensing section as illustrated in Figure 1-15. Emerson has designed the environment shield
for optimum performance of the detector. Figure 1-14 shows how the environment shield
slots into the sensing section of the 625IR. Before inserting the environment shield, visually
inspect the detector to verify that it is free from dirt and blocking substances. Ensure that
the shield is inserted all the way.
Manual Installation
MS-00809-0100-3625 January2024
Rosemount 625IR 19

Figure 1-14: Inserting the environment shield
Figure 1-15: Detector with environment shield inserted
Related information
Clean optics (lens and mirror)
Installation Manual
January2024 MS-00809-0100-3625
20 Emerson.com