GB/T 19870-2018: Industrial Inspecting Thermal Imagers – A Comprehensive Technical Overview

GB/T 19870-2018, officially titled “Industrial Inspecting Thermal Imagers”, is a national standard of the People’s Republic of China issued by the State Administration for Market Regulation (SAMR) and the Standardization Administration of China (SAC) on May 14, 2018, with implementation starting from December 1, 2018. This standard supersedes the previous version GB/T 19870-2005, introducing updated requirements and specifications to adapt to the rapid development of infrared thermal imaging technology and its expanding industrial applications. Covering terminology, classification, technical requirements, test methods, and inspection rules, GB/T 19870-2018 serves as a foundational guideline for the design, production, testing, and application of industrial thermal imagers across key sectors such as power, metallurgy, coal mining, and petrochemicals.

1. Scope and Core Definitions

The standard applies to industrial inspecting thermal imagers—devices that convert infrared radiation from object surfaces into visible images through infrared optical systems, infrared detectors, and electronic processing systems. These instruments are characterized by temperature measurement capabilities, enabling quantitative mapping of surface temperature distributions with pseudo-color coding of grayscale images. GB/T 19870-2018 defines critical terms to ensure uniformity in technical communication and application, including:

• Noise Equivalent Temperature Difference (NETD): The temperature difference between a target and its background when the video signal-to-noise ratio (S/N) is 1, serving as an objective parameter for evaluating detection sensitivity and noise levels.
• Spatial Resolution: The ability to distinguish fine details of an object’s geometric shape, typically expressed as Detector Angular Subtense (DAS) or instantaneous field of view, calculated as (2π×horizontal field of view angle (°))/(360°×number of horizontal pixels) in radians (rad).
• Frame Sampling Rate: The reciprocal of the time interval between two consecutive image captures, measured in hertz (Hz), which determines the ability to capture dynamic temperature changes.
• Minimum Resolvable Temperature Difference (MRTD): A subjective parameter integrating temperature and spatial resolution, representing the minimum temperature difference between a target and background at which an observer can distinguish a four-bar target at a specific spatial frequency.

2. Product Classification and Basic Parameters

2.1 Classification Criteria

GB/T 19870-2018 classifies industrial inspecting thermal imagers based on two key criteria:

1. Installation Type
   1. Offline Thermal Imagers: Handheld, battery-powered devices with image display, storage, and analysis functions, requiring high temperature measurement accuracy for real-time temperature and distribution monitoring.
   2. Online Thermal Imagers: Fixed-installed instruments for continuous online temperature measurement, featuring external power interfaces, long-term stable operation capabilities, and adaptability to complex industrial environments.
2. Detector Type, categorized by resolution and sensitivity:
   1. High-Resolution, High-Sensitivity Type: Resolution of 640×480 (640×512), 1024×768 pixels, or higher.
   2. High-Sensitivity Type: Resolution of 320×240 (384×288) pixels.
   3. Standard Type: Resolution of 160×120 pixels or lower.

2.2 Basic Parameter Requirements

The standard specifies essential parameters to ensure performance consistency and application suitability:

• Spatial Resolution: 0.2 mrad~0.7 mrad for long-distance observation, 1.0 mrad~5.0 mrad for close-range large targets.
• Frame Sampling Rate: Minimum 25 Hz for general applications; minimum 50 Hz for high-speed dynamic target detection.
• Field of View (FOV): Configurable via interchangeable lenses—small FOV (≤10°), medium FOV (10°~38°), and large FOV (≥38°).
• Working Wavelength Range: Preferred long-wave band (7.5 μm~14 μm) for optimal industrial detection performance.
• Temperature Measurement Range: -40 °C to +2000 °C, selectable based on specific industrial needs while maintaining accuracy.

3. Key Technical Requirements

3.1 Performance Requirements

Under standard ambient conditions (23 °C±5 °C), the performance indicators must meet the following criteria:

• NETD: <0.06 °C for high-resolution/high-sensitivity models; <0.08 °C for high-sensitivity models; <0.15 °C for standard models (at relative aperture of 1).
• Maximum Allowable Temperature Measurement Error: ±2 °C or ±2% of the measured temperature (whichever is larger).
• Continuous Stable Operation Time: ≥24 hours for online models (customizable per user requirements); ≥3 hours for offline models.
• Appearance: No visible scratches, dents, deformation, or paint peeling on the housing; clear and correctly positioned markings; compliant installation dimensions for online models.

3.2 Environmental Adaptability and Electromagnetic Compatibility (EMC)

Industrial thermal imagers must withstand harsh operating environments, with the standard specifying requirements for temperature, humidity, vibration, and shock resistance. Additionally, EMC compliance is mandatory to ensure immunity to electromagnetic interference and minimal interference with other industrial equipment, adhering to relevant national standards for electrical safety and EMC.

3.3 Functional Requirements

The standard mandates core functions including real-time temperature display, pseudo-color imaging, temperature alarm (for abnormal values), image storage/playback, and data export. Advanced functions such as multi-point temperature measurement, area temperature statistics, and thermal contrast adjustment are recommended for enhanced industrial applicability.

4. Test Methods and Inspection Rules

4.1 Test Equipment and Conditions

Compliance testing requires specialized equipment, including:Collimator: Focal length at least 3 times that of the tested thermal imager, with a clear aperture larger than the imager’s receiving aperture (for MRTD and NETD tests).Surface Blackbody: Temperature range -10 °C~+70 °C (relative to 20 °C), temperature resolution 0.001 °C, uniformity 0.05 °C or ΔT×1% (whichever is larger), emissivity ≥0.95, and heating/cooling rate ≥10 °C/min.

Tests are conducted under standard ambient conditions, with environmental adaptability tests performed in controlled chambers simulating extreme temperatures, humidity, and mechanical stress.

4.2 Inspection Rules

The standard defines two levels of inspection: Factory Inspection: Mandatory for each unit, covering appearance, basic performance, and functional tests to ensure product consistency before delivery.Type Inspection: Conducted during product development, design modifications, or periodic quality audits, encompassing all technical requirements, environmental adaptability, and EMC tests.

5. Marking, Packaging, and Transportation

Products must be clearly marked with the standard number (GB/T 19870-2018), product model, serial number, manufacturer, production date, and key parameters (resolution, temperature range, etc.). Packaging shall be shockproof, moisture-proof, and dust-proof to protect the instrument during transportation. Transport conditions must comply with national regulations, avoiding extreme temperatures, severe vibration, and impact.

6. Industry Significance and Application

As a unified national standard, GB/T 19870-2018 plays a pivotal role in regulating the industrial thermal imager market, improving product quality, and ensuring reliable application in safety-critical sectors. In power systems, it enables accurate detection of overheating in transformers, cables, and switchgear; in petrochemical plants, it supports leak detection and equipment condition monitoring; in metallurgy and coal mining, it enhances process control and accident prevention. By aligning technical requirements with international advanced standards, GB/T 19870-2018 also promotes the competitiveness of Chinese thermal imaging manufacturers in the global market.

GB/T 19870-2018 provides a comprehensive framework for industrial inspecting thermal imagers, integrating updated technical specifications and practical application needs. Its implementation ensures the reliability, accuracy, and interoperability of thermal imaging equipment across key industries, contributing to improved production efficiency, operational safety, and technological advancement. As infrared thermal imaging technology continues to evolve, future revisions of the standard are expected to incorporate emerging technologies such as artificial intelligence-based analysis and higher-resolution detectors, further expanding the scope and value of industrial thermal imaging applications.

References

1. GB/T 19870-2018, Industrial Inspecting Thermal Imagers (Chinese National Standard). 2. GB/T 12604.9-2008, Temperature Measurement – Part 9: Infrared Thermometry. 3. GB/T 13962-2009, General Specifications for Infrared Thermal Imaging Systems.