Product Overview

The Fireye 95DSS3-1CEX is an explosion-proof ultraviolet flame scanner designed for industrial burner management systems in hazardous locations. This device detects the ultraviolet radiation emitted by hydrocarbon flames, providing reliable flame presence confirmation for single-burner or multi-burner applications. The scanner is certified for use in Class I Division 1 hazardous locations with Groups B, C, and D, making it suitable for oil refineries, natural gas processing plants, petrochemical facilities, and other environments where flammable gases or vapors may be present. The 95DSS3-1CEX features a robust explosion-proof housing that contains any internal ignition, preventing it from igniting the surrounding atmosphere. The scanner incorporates self-checking circuitry that periodically verifies the integrity of the UV sensor and associated electronics, ensuring fail-safe operation in safety-critical applications. This flame scanner is compatible with Fireye burner management systems and other industrial flame safety controllers.

Technical Specifications

Ultraviolet Detection Principle

The 95DSS3-1CEX utilizes a gas-filled ultraviolet sensor tube that responds to UV radiation in the wavelength range of 185 to 260 nanometers. This range corresponds to the UV emissions produced by hydrocarbon flames, including natural gas, propane, butane, oil, and kerosene. The UV sensor is sensitive only to ultraviolet light; it does not respond to visible light, infrared radiation, or hot refractory backgrounds. This selectivity is critical for reliable flame detection, as it prevents false flame signals from glowing furnace walls, hot combustion chambers, or sunlight. When UV radiation strikes the sensor tube, it ionizes the gas inside, causing a small current to flow. The scanner electronics amplify this current and produce a flame-on output signal when the UV intensity exceeds a preset threshold. The quartz viewing window is specifically selected for its high transmissivity in the UV range, ensuring that the sensor receives maximum flame radiation while maintaining mechanical strength and chemical resistance.

Explosion-Proof Design

The 95DSS3-1CEX is housed in a rugged explosion-proof enclosure certified for use in hazardous locations. The enclosure is constructed of copper-free aluminum to prevent sparking from impact, and it is coated with an epoxy finish for corrosion resistance. The design complies with the requirements of Class I Division 1, which covers locations where ignitable concentrations of flammable gases or vapors are present under normal operating conditions. The enclosure contains any internal explosion resulting from ignition of a flammable mixture inside the housing, preventing the flame from propagating to the external atmosphere. The threaded joints and flame paths are precision machined to the required lengths and clearances specified by the certification standards. The quartz viewing window is sealed and secured to withstand internal pressure without shattering. The scanner is also rated for Class II Division 1 (combustible dust) and Class III (ignitable fibers and flyings), making it suitable for a wide range of hazardous environments including grain handling facilities and chemical processing plants.

Self-Checking Safety Feature

The 95DSS3-1CEX incorporates a self-checking circuit that is essential for fail-safe operation in burner management systems. The self-checking function periodically tests the integrity of the UV sensor and the associated electronics. During the self-check, the scanner temporarily blocks the UV sensor from external radiation using an internal mechanical shutter or electronic modulation, then verifies that the sensor output drops to zero. The scanner then unblocks the sensor and verifies that the output returns to its previous level. If either test fails, the scanner enters a fault state and de-energizes the flame relay output. This self-checking cycle occurs multiple times per second, ensuring that any failure of the sensor or electronics is detected within a short time frame. The self-checking feature prevents a dangerous condition where a failed sensor might indicate flame-on when no flame is present, which could lead to fuel being admitted into an unlit furnace with explosive consequences.

Key Features and Benefits

Applications

The Fireye 95DSS3-1CEX is used in industrial burner management systems where reliable flame detection is critical for safety. Typical applications include refinery process heaters and furnaces where flammable hydrocarbon gases are present, natural gas compressor stations and pipeline heaters, petrochemical plant boilers and thermal oxidizers, offshore oil and gas platforms with hazardous area classifications, and industrial kilns and dryers fired with gas or oil.

Installation and Alignment

The 95DSS3-1CEX is typically mounted on the burner front plate or observation port using the 1 inch NPT threaded connection. The scanner must be aimed so that its field of view is focused on the flame's UV emission zone, typically the primary combustion zone near the burner tip. Proper alignment is critical for reliable flame detection. The scanner should be positioned to avoid viewing hot refractory, which emits very little UV but could cause false signals if the sensor becomes desensitized. The viewing window must be kept clean, as any contamination such as soot, oil, or dust will attenuate UV radiation and reduce sensitivity. The scanner includes a purge air connection to allow a small flow of clean instrument air to keep the window clear in dirty environments.

Standards and Certifications

The 95DSS3-1CEX is certified for hazardous locations by FM Approvals and meets the requirements of NFPA 86 (Standard for Ovens and Furnaces) and NFPA 85 (Boiler and Combustion Systems Hazards Code). The scanner complies with applicable IECEx and ATEX standards for international use.