Description
UV & lamp tubes are selected by quartz grade and spectral transmission rather than by dimension alone. The quartz composition determines which ultraviolet wavelengths pass through the tube wall, which is what differentiates germicidal, ozone-generating, ozone-free and excimer lamp tubing from general fused quartz tube stock.
The dimensional range and end-processing methods follow the general Fused Quartz Tubes specification. This page focuses on grade selection and UV transmission behavior.
Quartz Grades
| Quartz Grade | UV Behavior | Typical Use |
|---|---|---|
| Electrically Fused Quartz | Metallic impurities limit deep-UV transmission; practical transmission begins around 200 nm and longer wavelengths | General UV-C and lamp applications where very-deep UV transmission is not required |
| Natural Clear Fused Quartz, Undoped | Transmits both 185 nm and 254 nm | Ozone-generating UV lamps and sleeves |
| Titanium-Doped Quartz | Blocks transmission below approximately 200–220 nm while passing 254 nm | Ozone-free and low-ozone germicidal systems |
| Synthetic Fused Silica | Higher purity; transmission extends to approximately 170 nm | 172 nm excimer and VUV applications |
For VUV optical use, low-OH synthetic fused silica may be specified with OH content controlled to ≤50 ppm under a production standard requiring this limit.
Spectral Transmission
| Application Band | Wavelength | Tube Requirement |
|---|---|---|
| Germicidal UV-C | 254 nm | >85% transmittance; electrically fused or synthetic quartz |
| Ozone-Generating | 185 nm | Undoped natural or synthetic quartz; synthetic quartz provides higher 185 nm transmission than natural quartz |
| Excimer Curing / Cleaning | 172 nm | Synthetic low-OH quartz; synthetic fused silica extends transmission to approximately 170 nm |
| Ozone-Free / Low-Ozone | 253.7 nm pass; 185 nm blocked | Titanium-doped quartz; blocks below approximately 200–220 nm while retaining high transmission at 253.7 nm |
Ozone-Free vs UV-Filtering vs Ozone-Generating
Ozone-Free / Low (L) — Titanium-doped quartz suppresses the 185 nm line while transmitting the 253.7–254 nm germicidal line. It is used in HVAC, enclosed-space disinfection and other UV systems where ozone generation is undesirable.
Ozone-Generating / Very High (VH) — Clear natural or synthetic quartz passes both 185 nm and 254 nm. The 185 nm output supports ozone generation where ozone is part of the treatment process.
Custom-Split Tube — A controlled length ratio of doped and undoped tubing can be joined to create an intermediate ozone-output level when neither fully ozone-free nor fully ozone-generating behavior is required.
Lamp Use
| Lamp Type | Typical Tube Specification | Selection Driver |
|---|---|---|
| Germicidal Lamp Sleeve | Titanium-doped tube; stated supplier OD range 2.2–80 mm | 254 nm transmission with 185 nm suppression |
| 172 nm Excimer Lamp, Narrow Tube | Discharge vessel OD approximately 6–12 mm | Synthetic low-OH fused silica required for the discharge vessel wall |
| 172 nm Excimer Lamp, Double Cylinder | Outer diameter approximately 25 mm | High deep-UV transmission at the 172 nm excimer line |
| Ozone-Generating UV Lamp | Undoped natural or synthetic quartz tube | Transmission of both 185 nm and 254 nm |
Tube ends are cut, ground, fire-polished, sealed or welded according to the lamp assembly geometry. See the Fused Quartz Tubes hub for the general end-processing capability range.
UV Tube Selection
| Requirement | Recommended Quartz Type | Key Spectral Condition |
|---|---|---|
| 254 nm germicidal output without ozone | Titanium-doped quartz | Pass 253.7–254 nm; block 185 nm |
| 185 nm ozone generation | Undoped natural or synthetic quartz | Pass 185 nm and 254 nm |
| 172 nm excimer output | Synthetic low-OH fused silica | Deep-UV transmission extending to approximately 170 nm |
| Intermediate ozone output | Custom split doped / undoped construction | Controlled active length of ozone-generating section |
Related Material & Tube Processing
Low-OH Fused Quartz — For IR-sensitive UV systems and deep-UV / VUV applications where hydroxyl content is a controlled material parameter, grade selection should be made from the dedicated low-OH fused quartz material specification.
General Tube Fabrication — OD, ID, wall thickness, length, cutting, grinding, fire polishing, drilling, sealing and quartz welding follow the Fused Quartz Tubes hub unless the lamp design has a more restrictive requirement.