ROSEMOUNT 975 Flame Detector

ROSEMOUNT 975 Flame Detector

1. Product Overview

The Rosemount 975 Flame Detector series represents Emerson’s advanced portfolio of optical flame detection solutions, engineered to deliver rapid fire identification across a broad range of industrial applications. Designed for both indoor and outdoor deployment, the Rosemount 975 series combines multiple sensing technologies—ultraviolet/infrared (UV/IR) and multi-spectrum infrared (MSIR)—to achieve superior detection range, response speed, and false alarm immunity-.

Each unit in the Rosemount 975 family integrates heated optics to maintain clear visibility under snow, ice, and condensation conditions, along with broad operating temperature capabilities spanning from -67°F to 185°F (-55°C to 85°C)-. Multiple output options, including 0–20 mA stepped current, HART® protocol, RS-485 Modbus, and three relays (Alarm, Fault, and Auxiliary), provide flexible integration with existing control and alarm systems-1.

The series fulfills Safety Integrity Level (SIL) 2 requirements in a single-channel configuration and can achieve SIL 3 when deployed in a redundant architecture per IEC 61508, with TÜV certification-.

2. Rosemount 975 Series Model Variants

The Rosemount 975 series includes four distinct models, each optimized for specific fire detection scenarios and hazardous materials:

2.1 Rosemount 975UR Ultraviolet Infrared Flame Detector

The Rosemount 975UR UV/IR Flame Detector utilizes an integrated dual-sensor design that senses radiant energy in the short-wave ultraviolet (0.185–0.260 μm) and infrared (4.4–4.6 μm) portions of the electromagnetic spectrum-40. The signals from both sensors undergo analysis for frequency, intensity, and duration; simultaneous detection of radiant energy in both UV and IR bands triggers an alarm output. The UV sensor incorporates a solar-blind logic circuit that effectively rejects false alarms caused by solar radiation, welding arcs, and other non-fire UV sources-1.

Key detection ranges for the Rosemount 975UR (at highest sensitivity, 1 ft² pan fire):

Gasoline: 66 ft (20 m)

Diesel fuel: 50 ft (15 m)

Methane: 39 ft (12 m)

Response time is typically 3 seconds, with field of view measuring 100° horizontal and 95° vertical-40.

2.2 Rosemount 975MR Multi-Spectrum Infrared Flame Detector

The Rosemount 975MR Multi-Spectrum Infrared Flame Detector employs four separate IR sensors operating across spectral bands between 4 μm and 5 μm, enabling precise analysis of multispectral signals emitted by hydrocarbon gas and liquid fires-. The 975MR achieves maximum detection range of 300 ft (90 m) for a 1 ft² gasoline pan fire at the highest sensitivity setting, with response time under 50 milliseconds-2. Six sensitivity levels allow configuration across diverse application environments-2.

2.3 Rosemount 975UF Ultra Fast Ultraviolet Infrared Flame Detector

The Rosemount 975UF Ultra Fast UV/IR Flame Detector provides the fastest response time in the series—under 20 milliseconds for flash fire detection-. Beyond hydrocarbon-based fuel and gas fires, the Rosemount 975UF also detects hydroxyl and hydrogen fires, as well as metal and inorganic fires, offering expanded coverage for specialized industrial hazards-4. Three sensitivity levels provide adaptability across applications-4.

2.4 Rosemount 975HR Multi-Spectrum Infrared Hydrogen Flame Detector

The Rosemount 975HR Multi-Spectrum Infrared Hydrogen Flame Detector is specifically engineered for detection of both hydrocarbon and hydrogen flames—a critical capability given hydrogen’s near-invisible flame characteristics-. The Rosemount 975HR detects gasoline pan fires at 215 ft (65 m) and hydrogen flames at 125 ft (38 m), with six sensitivity levels and response time under 50 milliseconds-31.

3. Technical Specifications (Rosemount 975 Series)

3.1 General Specifications

3.2 Electrical and Communication Specifications

3.3 Hazardous Area Certifications

The Rosemount 975 series carries comprehensive global hazardous area approvals:

ATEX and IECEx:

Ex II 2 G D

Ex db eb op is IIC T4 Gb

Ex tb op is IIIC T110°C Db

Ta -50°C to +85°C, IP66/IP68

FM/FMC:

Class I, Division 1, Groups B, C, D, T4A

Class II, III, Division 1, Groups E, F, G, T4A

Class I, Division 2, Groups A, B, C, D, T4

Ta -50°C to +85°C, Type 6P, IP66/68 (2m for 45 minutes)

CSA/US:

Class I, Division 1, Groups B, C, D, T4

Class II, III, Division 1, Groups E, F, G, T4

Class I, Division 2, Groups A, B, C, D, T4

Ta -50°C to +85°C, Type 6P, IP66/68 (2m for 45 minutes)

TR CU (EAC):

1 Ex db eb op is IIC T4 Gb X

Ex tb op is IIIC T110°C Db X

-55°C to +85°C ambient

Performance and Reliability Standards:

EN 54-10 (VdS certified)

FM 3260 approved

Designed to meet IEC 61508, SIL 3 (TÜV)

MED “Wheelmark” (DNV) marine approval

IP66 and IP67 per EN 60529, NEMA 250 6P

The series also meets MIL-STD-810C for humidity, salt fog, vibration, mechanical shock, high temperature, and low temperature testing-40.

4. Key Features Across the Rosemount 975 Series

Heated Window Technology: The Rosemount 975 flame detectors feature heated optical windows that prevent condensation, icing, and snow accumulation, ensuring uninterrupted operation in harsh weather conditions-.

Built-In Test (BIT): Both automatic and manual built-in test capabilities verify continued reliable operation. The detector continuously monitors input voltage levels, internal regulator voltages, sensor circuitry integrity, 0–20 mA output level, relay and heater operation, processor watchdog, software, and memory during normal operation-10.

Solar Blind UV Sensing: The UV sensor incorporates a special logic circuit that prevents false alarms caused by solar radiation, welding arcs, lightning, and X-rays, significantly reducing nuisance trip events-1.

User Programmability: All configuration parameters—including sensitivity levels, response time, heated optics functionality, alarm delay, and accessory relay options—can be modified remotely via HART® 7 communicator or RS-485 Modbus Manager-10.

Dual Enclosure Options: The Rosemount 975 flame detectors are available in either stainless steel 316L with electro polish finish or heavy-duty copper-free aluminum with polyurethane painted finish, providing material selection based on environmental corrosion requirements-1.

5. Applications and Industry Use Cases

The Rosemount 975 series is deployed across industries where rapid, reliable flame detection is mission-critical:

In refinery environments, combustible gases, catalyst dust accumulation, and static electricity discharge present persistent fire risks. The Rosemount 975 flame detectors provide fast detection even over long distances and under challenging conditions including extreme temperatures and high winds-24.

6. Ordering Information and Model Number Breakdown

The Rosemount 975UR model number 975UR4U6A3A1Y7 is structured as follows:

This complete model number 975UR4U6A3A1Y7 represents a stainless steel enclosure Rosemount 975UR flame detector with 0–20 mA/HART output, three-relay configuration, stainless steel tilt mount, and 1/2–14 NPT cable entry, suitable for demanding hazardous area installations requiring maximum corrosion resistance and communication flexibility.

7. Compliance and Regulatory Standards

The Rosemount 975 series complies with multiple international regulatory frameworks:

NFPA 72E / NFPA 72 (National Fire Alarm and Signaling Code)

EN 54-10 (European fire detection standard)

FM 3260 (Factory Mutual performance standard)

IEC 61508 (Functional safety for SIL 2 / SIL 3 applications)

ATEX Directive 2014/34/EU

IECEx Scheme

FM and FMC approvals

CSA certification

MED “Wheelmark” marine equipment directive (DNV)

EAC (TR CU) Customs Union certification

8. Installation and Configuration Guidelines

To ensure optimal performance, the Rosemount 975 flame detectors should be installed in accordance with NFPA 72E and applicable local regulations-10. Key installation considerations include:

Fire size at the required detection distance

Types of flammable materials present in the protected area

Proximity to potential false alarm sources (solar radiation, arc welding, lightning)

Environmental conditions (temperature extremes, icing, condensation, wind)

The detector features a continuous feature test that runs during normal operation, automatically indicating a fault condition if any internal failure is detected-10. Field reconfiguration and diagnostics can be performed using the USB RS-485 harness kit (P/N 00975-9000-0011), which enables connection to any PC or laptop for parameter adjustment and health monitoring of all Rosemount 975 series flame detectors-.

9. Conclusion

The Rosemount 975 flame detector series delivers a comprehensive solution for industrial fire detection, combining multiple sensing technologies, extensive hazardous area certifications, and flexible communication options. From the ultra-fast 20 ms response of the Rosemount 975UF to the long-range 300 ft detection capability of the Rosemount 975MR and the specialized hydrogen detection of the Rosemount 975HR, the series provides application-specific optimization without compromising on reliability or false alarm immunity. With SIL 2/SIL 3 functional safety certification, heated optics for extreme weather operation, and minimum 150,000-hour MTBF, the Rosemount 975 flame detectors are engineered for mission-critical deployment where failure is not an option.