Safety 35 Visual Flame Imaging Flame Detectors
Visual flame detectors employ standard charged couple device (CCD) image sensors, commonly used in closed circuit television cameras, and flame detection algorithms to establish the presence of fires. The imaging algorithms process the live video image from the CCD array and analyse the shape and progression of would be fires to discriminate between flame and non-flame sources. CCTV visual flame detectors do not depend on emissions from carbon dioxide, water, and other products of combustion to detect fires, nor are they influenced by fire’s radiant intensity. As a result, they are commonly found in installations where flame detectors are required to discriminate between process fires and fires resulting from an accidental release of combustible material.
Despite their advantages, visual flame detectors cannot detect flames that are invisible to the naked eye such as hydrogen flames. Heavy smoke also impairs the detector’s capacity to detect fire, since visible radiation from the fire is one of the technology’s fundamental parameters.
Industrial Process and Plant Flame Detection Requirements
When configuring a flame detection system and evaluating the various technology alternatives available, it is useful to consider the following detector performance criteria:
False Alarm Immunity False alarm rejection is one of the most important considerations for the selection of flame detectors. False alarms are more than a nuisance — they are both a productivity and cost issue. It is therefore essential that flame detectors discriminate between actual flames and radiation from sunlight, lightning, arc welding, hot objects, and other non-flame sources.
Detection Range and Response Time
A flame detector’s most basic performance criteria are detection range and response time. Depending on a specific plant application environment, each of the alternative flame detection
technologies recognises a flame within a certain distance and a distribution of response times. Typically the greater the distance and the shorter the time that a given flame sensing technology requires to detect a flame, the more effective it is at supplying early warning against fires and detonations.
Field of View (FOV)
Detection range and FOV define area coverage per device. Like a wide angle lens, a flame detector with a large field of view can take in a broader scene, which may help reduce the number of flame detectors required for certain installations. Most of today’s flame detector models offer fields of view of about 90° to 120°.
Self Diagnostics
To meet the highest reliability standards, continuous optical path monitoring (COPM) diagnostics are often built into optical flame detectors, like those manufactured by General Monitors. The self-check procedure is designed to ensure that the optical path is clear, the detectors are functioning, and additionally, the electronic circuitry is operational. Self-check routines are programmed into the flame detector’s control circuitry to activate about once every minute. If the same fault occurs twice in a row, then a fault is indicated via the 0-20 mA output or a digital communications protocol like HART or Modbus.
Conclusions
After gaining a better picture of the potential flame hazard, the principles of flame detection, and the types of flame detection technologies available today, users will be in a better position to select a flame detector. Defining the requirements for an application is also essential, as such factors as the type of fuel, minimum fire size to be detected, and the configuration of the space to be monitored can influence the choice of instrument.
Portable Gas Detection Portfolio Extended with the Addition of Single Gas Monitor
Scott Safety (USA) have announced the introduction of the Protégé ZM Single Gas Monitor – a zero maintenance single gas monitor that is easy to use and delivers high performance in a small, ergonomically designed package. The Protégé ZM is a zero maintenance solution, meaning no battery charging and no sensor calibration is necessary to operate the monitor. The monitor has a high performance battery which provides two years of operation. In typical conditions, calibration will not be necessary during the operational lifetime. Three single gas models are available including Oxygen, Carbon Monoxide and Hydrogen Sulphide.
The Protégé ZM is small, lightweight, ergonomically designed and meets IP66/67 requirements for ingress protection. “We designed this monitor with ease of use and comfort in mind. The unique “Protégé profile” fits your hand nicely making the monitor comfortable to hold. It’s so lightweight and small, you will forget you’re wearing it while it protects you,” says Mel Gerst, Scott Safety’s Global Product Line Manager for Portable Gas Detection. “The monitor is very simple to use. Just turn it on for the first time, and it does the rest. Using the default settings from the factory there is no need to set up or program the monitor.”
The Protégé ZM features plenty of customisable settings to meet your specific needs. For example, a hibernate mode is available on the CO and H2S models. The hibernate mode puts the monitor in a deep sleep for up to one year to extend the operating life beyond two years. Users can customise the alarm set
points themselves or order monitors with custom alarm set points programmed by the factory. Users can also set up custom bump and calibration reminders if they desire. The monitor has the option to display continuous gas readings, life remaining or both. The monitor has a three point alarm (audible, visual, and tactile) and data logging capabilities.
The Protégé ZM monitor is supported by a portfolio of accessories including a four-bay test station and IR Connect programmer. The test station supports bumping, calibrating, hibernating and programming of up to four monitors simultaneously, and is available in both portable and table-top versions. The IR Connect allows programming and hibernating of individual monitors.
Mr. Gerst explained, “The Protégé ZM Single Gas Monitor adds to Scott Safety’s 80-year legacy of working with customers to bring innovative solutions to market. Our customers asked us for an easy to use single gas monitor that enabled them to focus on the task at hand instead of maintaining equipment. We are excited to expand the Protégé family of gas detection instruments with the introduction of the Protégé ZM.” Scott Safety is a premier manufacturer of innovative respiratory and other personal protective equipment and safety devices and offers a broad range of globally certified gas detection solutions including single gas, multi-gas and fixed gas detection systems.
For More Info, email:
25034pr@reply-direct.com
When Every Second Counts
The new Afriso (Germany) ZAG 01 additional alarm unit can be used to display and transmit alarm signals from Afriso alarm units or leak detectors as well as other switching equipment. ZAG 01 can be connected to a voltage-free output contact or to a 230 V alarm output of an alarm unit via a signal cable. The alarm unit generates visual and audible alarm signals; the audible alarm can be muted by means of an Acknowledge button. The visual alarm remains active until the cause of the alarm has been remedied. The ZAG 01 alarm signal can also be transferred to external equipment (alarm devices, communication devices, building control units, etc.) via two output relays. (2 voltage-free changeover contacts, 1 can be acknowledged). A test button allows for function checks (it is recommended to perform a function check at regular intervals). The control unit in an impact-resistant plastic housing contains all display elements and controls as well as all electronic components for evaluating the alarm signal. ZAG 01 is suitable for ambient temperatures from
-10 to +60 °C and supplied with AC 230 V. The alarm unit is designed for wall-mounting; however, an optional mounting frame also allows for easy integration into panels. A sealing kit (IP 54) is available for rough application conditions. The additional alarm unit is fast and easy to install and commission.
For More Info, email:
25095pr@reply-direct.com
OCTOBER / NOVEMBER 2013 •
WWW.PETRO-ONLINE.COM
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
