Even the premium gas detector field has been in a rut—with the same technologies operating in the same ways with the same limitations for many years.
To break out and provide plug-and-play, set-and-forget detection, Emerson has launched the Rosemount 625IR fixed gas detector. It’s designed to deliver greater reliability with less required maintenance, and employs advanced, temperature-compensated, optical-absorption detection for faster detection of methane, propane and other hydrocarbon gases without false alarms, even in hazardous environments and all weather conditions.
“One of the traditional limits for gas detectors was the amount of maintenance they required, such as optical drift that lead to frequent visits and calibrations,” says Paul Tillyer, global product manager for flame and gas at Emerson. “So, we integrated multiple hardware and software revisions in a new gas-detector design that could address these issues, and remove the need for onsite calibration.”
For instance, Rosemount 625IR uses specialized, solid-state, dual infrared (IR) sources and dual IR receivers, and transmits through a sapphire lens. The IR sources and receivers are monitored in real time to perform continual cross-checks and internal adjustments, which enables the detector’s factory-set calibration to be maintained for its life. Heaters on its optical surfaces dissipate moisture, while multiple optical-protection accessories provide continuous detection without causing unplanned downtime.
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Rosemount 625IR is also simpler to install and maintain because it retains its initial factory calibration for life thanks to its advanced, drift-monitoring capability and health-monitoring diagnostics. When retrofitting 625IR to replace another manufacturer’s detector, you can internally configure the 0-4 mA warning and fault levels, which means no changes are needed to the control system. Multiple accessories also make function testing fast and easy using test gas or a gas-free test filter that greatly reduces maintenance time and expense.
“Gas function tests typically require real gas, which usually means bringing a compressed-gas cylinder to the site,” explains Tillyer. “To solve this difficulty, we developed a plug-in, gas-free test filter for 625IR for required gases, which can simulate the presence of hydrocarbons. It attenuates the measurement wavelength of the gas being tested for, but not the reference wavelength, which indicates the actual gas presence. This turns a 30- to 90-minute visit into a 5-minute visit.”
Rosemount 625IR has a standard operating range of -40 °F to 167 °F (-40 °C to +75 °C), while its ingress protection levels are IP66/67 and NEMA 4X. At 77 °F (25 °C), its accuracy is ±2% of full scale (FS), while its repeatability is ±1% of FS.
The detector is rated for use in hazardous areas, including North America Class 1, Division 1, Groups B, C and D, as well as INMETRO/ATEX/IECEx - Ex db ib IIC T5 Gb. It’s also certified for marine applications, and is SIL 2 rated in accordance with IEC61508, and SIL3 rated when used in a 1oo2 voting configuration. It also has a five-year, proof-test interval that lets users confidently reduce scheduled maintenance visits.
“While most detectors have a 9- or 10-second response time with a splashguard fitted, Rosemount 625IR is less than 2 seconds with its splashguard fitted. This means faster detection and less risk of a shutdown,” adds Tillyer. “It can presently detect hydrocarbons like methane, propane, ethylene and many others, but more hydrocarbon gases and CO2 detection will be added in the future.”
Other accessories, such as an environmental shield, mosquito net and adaptor plate, further simplify installing Rosemount 625IR in various applications and settings, making it usable in extractive, gas-detection applications. Duct-mounted, extended-probe versions are also available 15 cm (5.9 inch) and 35 cm (13.8 inch) lengths to provide fast, accurate and representative detection across ducts or voids.
