What is the Difference Between UVA340 and UVB313 in UV Light Resistance Tester

When materials are exposed outdoors, they face constant attack from UV radiation, heat, humidity, and rain. These stresses accelerate aging, causing cracking, fading, gloss loss, brittleness, or complete structural failure. Understanding how different UV wavelengths affect material degradation is the key to accurate weathering simulation.

In UV testing, UVA340 and UVB313 are the two most commonly used fluorescent UV sources. They simulate different portions of the ultraviolet spectrum and therefore produce different aging effects. Selecting the right one ensures your test results match real-world usage conditions.Below, we explain the differences clearly and provide a full overview of the LIB UVA340/UVB313 UV light resistance tester-its technical highlights, how to use it for paint shelf-life evaluation, and complete Q&A.

UVA340 vs. UVB313 in UV Light Resistance Tester

UVA340 and UVB313 simulate different spectral ranges to reproduce different types of UV damage.
UVA340 lamps reproduce the UV spectrum of sunlight at the Earth's surface (295–365 nm), while UVB313 exaggerates short-wave UV energy (280–315 nm) to accelerate degradation. Both lamp types comply with international testing standards such as ASTM G154 (fluorescent UV exposure test). Their spectral stability enables consistent and repeatable material aging assessment.

Key Differences

Why These Differences Matter

UVA340 is ideal for products used outdoors for long periods, such as coatings, plastics, rubber, automotive parts, roofing materials.

UVB313 is better when the goal is rapid degradation screening or comparative testing under harsher UV conditions.

UVA340 provides realism, while UVB313 provides speed.

Key Technical Highlights of LIB UVA340/UVB313 UV Light Resistance Tester

LIB's UV light resistance tester integrates multiple environmental controls to simulate real-world weathering, all in a stable and repeatable laboratory environment.

Model	UV-SI-260
Internal Dimension (mm)	450*1170*500
Overall Dimension (mm)	680*1300*1500
Irradiation Source	Fluorescent UV lamps (8) - 40 W
Temperature Range	Ambient ～ 90 ℃ ±2℃
Black Panel Temperature (BPT)	35 ～ 80 ℃
Humidity Range	≥95% RH
Bandwidth	290 ~ 400nm
Irradiance Control	0.3~20 W/㎡
Distance of Specimen and lamp	50mm
Heating Element	Nichrome heater
Controller	Programmable color LCD touch screen controller
	Ethernet connection, PC Link, USB
Water Supply System	Automatic water supply, Water purification system
Interior Material	SUS304 stainless steel

Highlight 1: Precise and Stable UV Simulation

The system supports up to eight 40W QUV lamps, providing strong and uniform UV output. With lamp lifetimes up to 5000 hours and excellent spectral stability, the tester delivers reliable and repeatable results. The irradiance control range of 0.3–20 W/m² ensures accurate UV intensity settings that comply with ASTM G154 and related standards.

Highlight 2: Multi-Environment Simulation

This tester integrates UV exposure with condensation, temperature, humidity, and spray functions to simulate real-world weathering conditions. It offers precise control from room temperature to 90°C, humidity above 95% RH, and consistent spray flow from 10 nozzles. The combination accelerates material ageing while maintaining realistic environmental stress profiles.

Highlight 3: Realistic Outdoor Conditions

Black Panel Temperature (BPT) monitoring accurately reflects the sample surface condition during testing. Combined with a UV Irradiance Radiometer, the unit ensures UV levels always meet standard requirements. With 52 sample holders and optional 3D fixtures, the device supports multiple material formats and complex product geometries.

Highlight 4: Intelligent PID Touchscreen System

The touchscreen controller offers up to 120 programmable groups with 100 steps each, allowing flexible and precise test programming. Connectivity options include USB, RS232, and LAN for efficient data export and remote monitoring. An integrated alarm system and multilingual interface make operation intuitive and dependable.

How to Use LIB UVA340/UVB313 UV Light Resistance Tester to Evaluate Paint Shelf Life

Paint shelf-life testing focuses on three key points:

• Color retention (does the paint fade?)
• Gloss stability (does it lose shine?)
• Surface integrity (cracking, peeling, chalking)
• Mechanical durability (film hardness, adhesion)

Weathering simulation accelerates these changes so evaluations that normally take months outdoors can be completed in weeks.

Step 1 - Prepare Samples

Coat paint uniformly onto test panels according to standard thickness.

LIB Advantage:

Supports standard panels and custom 3D parts. Sample rack accommodates 52 specimens . Thickness compatibility up to 3.5 cm

Step 2 - Set UV Exposure Parameters

Choose UVA340 for realistic sunlight or UVB313 for accelerated fading. Typical settings based on ASTM G154: Irradiance: 0.89 W/m² at 340 nm, Temperature: 50–70°C, Cycle: UV + condensation

LIB Advantage:

Irradiance precisely controlled under closed-loop feedback. Full-range control 0.3–20 W/m²'. Stable BPT ensures consistent panel temperature

Step 3 - Add Condensation or Humidity Phase

This simulates dew and moisture cycles that cause blistering, softening, or adhesion loss.

LIB Advantage:

Bottom water basin with heating system produces 98% RH steam. Supports condensation cycle per ASTM G154

Step 4 - Optional Spray Cycle

Simulates rainfall and erosion.

LIB Advantage:

10 precision nozzles, Water-saving automatic supply, Realistic rainfall + UV combined cycle

Step 5 - Evaluate Results

Check paint for: color change, gloss loss, cracking / chalking, adhesion changes (cross-cut test)

LIB Advantage:

Data can be exported via USB. Easy comparison with historical records. Helps build long-term durability database

UVA340/UVB313 UV Light Resistance Tester Q&A

Q1: What is the purpose of water heating at the bottom of the UV chamber?
The water heating design at the bottom of the UV chamber is used to achieve the high-humidity environment required by testing standards. In UV exposure experiments, humidity must reach 98% RH or higher. Heating tubes warm the water to generate steam, enabling condensation testing and ensuring the chamber simulates real-world high-humidity conditions for evaluating weathering resistance.

Q2: Are the UV spray nozzles the same as those for xenon lamps?
Yes. The nozzles used in UV testers and xenon arc testers are identical. They maintain the same diameter, flow rate, and water spray parameters to ensure the spray effect meets relevant testing standards.

Q3: What is the maximum specimen thickness for standard racks?
The standard specimen rack in the UV chamber accommodates samples with a maximum thickness of approximately 3.5 cm, suitable for most weathering test requirements.

Q4: What are the differences between UV and xenon lamps? What are the key distinctions?
UV lamps and xenon lamps differ primarily in their light source type and spectral distribution. UV lamps use fluorescent UV light (UVA/UVB), focusing mainly on the 290–400 nm ultraviolet range, simulating the UV portion of sunlight and meeting ASTM G154 standards. Xenon lamps are gas-discharge light sources covering ultraviolet and visible wavelengths, providing a more realistic full-spectrum sunlight simulation and typically following ASTM G155 standards.

Q5: What is the maximum irradiance when all 8 lamps are on? What if 4 UVA and 4 UVB are installed?
Whether all 8 UVA/UVB lamps are turned on, or a configuration of 4 UVA and 4 UVB is used, the UV tester achieves a maximum irradiance of 20 W/m². The irradiance can be precisely controlled between 0.3–20 W/m², ensuring compliance with testing standards.

Any customization can be made. LIB offers a 3-year warranty and lifetime service. Any issues that cannot be resolved during the warranty period will be replaced free of charge. 24/7 English-speaking after-sales team. Fast shipping within 7-15 days.

For more information about UVA340/UVB313 UV light resistance testers, testing solutions, or customized equipment requirements, contact LIB Industry today. Our technical team is ready to support your project with professional guidance, reliable testing systems, and tailored configurations to meet your application needs.