Navigating the Key Challenges of Optical Flame Detection

What do mobile phones, the internet, personal computers, and optical flame detection have in common? Their origins date back some 50 years. In the decades since, of course, these devices have become an essential part of our world.

Is Game-Changing Fire Protection Coming?

As technology continues to evolve, optical flame detection is gaining relevance in fire protection.
The innovations of tomorrow, however, must start with understanding the challenges of today. So, let’s review some of the optical flame protection challenges facing fire protection professionals right now.

Challenge #1: Field Installation

Perhaps the biggest challenge encountered by end users of optical flame detection is deciding where to install the detectors. Many factors are involved in optimizing detector installation, so here’s a checklist of a few considerations for installation of optical flame detectors in the field.

Mounting Location/Optical Alignment

Optical flame detectors are proven performers in helping protect people and equipment within high-hazard areas—however, performance can suffer if they’re not installed in an optimal location. Unknown or unidentified locations for detector mounting and optical misalignment can defeat the purpose of having detectors in the first place.
“There’s a delicate balance between mounting optical flame detectors to ensure proper coverage and protection versus having the detectors accessible for troubleshooting and maintenance. Mounted in the wrong location and there’s a potential for not having enough coverage. Mounted for coverage but without regard for maintenance and it’s likely that they’ll be too far out of reach and not receive the recommended maintenance,” says Dave Opheim, Business Development Manager for MSA Flame & Gas Detection. “Before you can accurately answer the question, ‘Where do we put these things?’ we recommend working with a flame application engineer who can perform a coverage mapping study or job site survey.”

In addition, improperly installing optical flame detectors can lead to other problems, such as improper optical alignment.  The flame detector mounting bracket can play a significant role.
 “While the bracket may look basic,” says Opheim, “it’s anything but. In fact, this bracket is quite ingenious because you can mount it vertically or horizontally. This enables much more installation flexibility, especially with complex job sites that have a lot of equipment in a small space.”

Mounting and alignment recommendations include:
•    Mounting to solid structural steel using proper mounting fasteners.
•    Aiming the device at a 5 to 15 degree downward angle to help prevent dust collection on the detector face.
•    Employing flexible conduit or armored cabling within 18 inches of the device to allow for aiming adjustments.
•    For outdoor installations, utilize a weather guard accessory to keep the optics clean and clear of optical contaminants.
Field-of-View (FOV)/Coverage
Different optical flame detectors offer varying detection ranges and field-of-view (FOV). To help achieve the best coverage, Opheim suggests matching the environment with the device specifications.
“Aligning the FOV coverage with the actual job site is important,” says Opheim. “Depending on the environment and the application, that may mean placing the detector near the potential ignition source or it may be positioning the detector further away. This is another good reason for performing a mapping study or jobsite survey.”
When it comes to installation, the two most common approaches are geographic coverage and scenario coverage. With the geographic coverage approach, coverage is assessed within a defined geographic fire ignition zone covered by one or more detectors. With the scenario coverage approach, coverage is assessed on likely fire scenarios within a detection zone with consideration given to frequency and catastrophic magnitude.

Configuration/Logging

During field installation, it’s also important to be very clear with detector configuration settings, such as sensitivity and time delay parameters. Again, a mapping study can assist in identifying the ideal settings for these.
As a next-generation detector, the FL5000 MSIR Flame Detector features Bluetooth technology that easily enables configuration, modification of detector settings, and diagnostics via the exclusive MSA Flame Connect app.
“The Bluetooth capabilities and internal diagnostics within the FL5000 Flame Detector are especially meaningful and useful,” says Opheim. “The FL5000 Flame Detector gives end users the ability to use Bluetooth communications to make changes to detector settings. It also allows users to retrieve time-based event logging wirelessly. In other words, the FL5000 Flame Detector provides useful information that’s also easy
 to retrieve.”

Power Wiring and Electrical Interference

Another challenge present in some installations is long electrical cabling distances that may exist from a centrally located 24 VDC power supply to the farthest detector location.  Long cable runs may create a voltage drop resulting in insufficient operating voltage at a far location if improper cabling is utilized.  It is recommended to always measure the longest cable run distance from the power supply to the detector location and then select the proper conductor size and type that will ensure delivery of a steady 24 VDC operating voltage to all of the detectors.  Also, if an existing power supply is planned for use on a system expansion, it is recommended to always calculate the total maximum power load of the additional detectors and devices plus all existing powered devices to ensure the existing power supply has the capacity to support both the existing load plus the new device power load from a cold start up.
Many industrial jobsites include significant sources of electromagnetic interference (EMI) due to strong magnetic fields that may emanate from high horsepower turbine engines, electric motors, compressors, and other rotating equipment. For this reason, Opheim recommends using electrically-shielded industrial grade cabling of the proper type and wire gauge size that is properly grounded to ensure maximum EMI protection.  Also, he recommends routing all safety system cable runs in a way to minimize parallel proximity exposure to known strong EMI field emitters such as variable frequency drive (VFD) power conductors.  

Access

Difficult physical access or limited options for optimal mounting can create barriers to troubleshooting and maintenance.
“Access can be a big pain point,” says Opheim. “If you’ve got a working compressor station with a 10,000-horsepower engine, it can be a hot and potentially dangerous environment that nobody wants to be around. Getting detector data from the floor via the app is a huge advantage, which is why we included Bluetooth connectivity in the FL5000 Flame Detector.”

Environmental

Factors that degrade performance, such as environmental conditions, also can be a potential problem.
Before installing sensors, consideration should be given to whether there’s a potential for rain, snow, ice, humidity, or condensation on optical surfaces. Consideration should also be given to airborne particles that may land on optical surfaces, because dirt, mud, and oil mist can interfere with performance.
“To help overcome these challenges, the FL5000 Flame Detector includes Continuous Optical Path Monitoring (COPM). This feature lets the device perform a self-check every two minutes to help determine whether the optical path is clear, and that the electronic circuitry is functional. COPM does not require manual intervention.”
In addition to COPM, the FL5000 Flame Detector has heated optics, designed to melt away moisture from optical surfaces, as well as an enclosure designed to help keep windblown contaminants off the optics.  An optional Rain Guard Visor accessory can offer even greater protection against windblown contaminants.

Challenge #2: Testing and Maintenance

Having a means of physical access for optics cleaning, maintenance, testing, and routine inspection is important. If technicians cannot easily access detectors, routine maintenance becomes more of a challenge.
Opheim explains, “For example, if a detector is mounted at an elevation so high from floor that the tri-color LED status indicator cannot be seen, then it’s more likely that the detector will be out-of-sight and out-of-mind for maintenance.”

Other maintenance and testing challenges include:
•    Detectors located in places where test lamps can’t easily trigger alarms for system response testing purposes.
•    Detectors mounted in locations where cleaning optical surfaces is difficult or impossible, thereby inhibiting technicians from responding to a dirty optics fault signal.

“The FL5000 Flame Detector can provide an answer to these challenges,” says Opheim. “Not only does it provide exceptional jobsite coverage without high-elevation installation, thanks to an outstanding FOV, technicians can easily view installation locations and use a handheld test lamp for response testing with no manlift required in most situations.”

Challenge #3: Troubleshooting

The ability to easily assess the operating voltage is important for maintaining optimal performance and can help to ensure continuous fire protection. Insufficient voltage (e.g., voltage that falls below a specific threshold) can negatively impact the performance and reliability of flame detectors. Maintaining proper operating voltage helps prevent intermittent performance, reduced sensitivity, and, perhaps, total device failure.
“Having the ability to quickly identify and address voltage issues before they lead to detector malfunction can be key,” says Opheim. “The FL5000 Flame Detector’s Bluetooth communications capability, coupled with our Flame Connect app offers a convenient solution. By allowing real-time monitoring of the detector’s operating voltage without the need for physical access via lifts or ladders, not only is the reliability of the fire detection system enhanced, but maintenance can also be streamlined, downtime can be reduced, and overall safety can be improved.”
Additionally, the FL5000 Flame Detector’s capabilities include an onboard datalog for alarms, faults, and other events recorded within the detector’s history. This means that end users can easily retrieve valuable insights into device performance history, helping to enable safe and proactive maintenance and troubleshooting.

Addressing Optical Flame Detection Challenges Moving Forward

With the FL5000 Flame Detector as an example, significant technical advancements have occurred over the past decade that have improved the baseline performance of optical flame detectors. Detectors like these can respond faster, can see farther, and can be more immune to false alarm sources.
Of course, technologies will continue to evolve, which means that today’s best-in-class optical flame detectors will continue to get even better in the future.
Until then, choose wisely by exploring your options, comparing models carefully, and partnering with safety professionals who can help you properly evaluate your optical flame project with a mapping study or jobsite survey.