Description
This capillary is defined by its material grade, not its bore geometry — low-OH quartz reduces hydroxyl-related IR absorption, which matters when the capillary itself is in the optical or IR path, not just acting as mechanical tubing.
OH Content
| Parameter | Specification |
|---|---|
| OH content | Max. 45 ppm — cited example spec |
| Comparison — standard optical grade | JGS2-equivalent, ~150 ppm OH |
| Comparison — low-OH synthetic grades | Type IV / Suprasil 300-equivalent, <1–5 ppm OH |
Why OH Content Matters
Hydroxyl (OH) groups in fused quartz cause an absorption band around 2.73 µm — lower OH content reduces this IR absorption, which matters for capillaries used in IR transmission paths, optical fiber preform manufacturing, or any application where the capillary wall sits in the light path rather than acting purely as a mechanical sleeve.
Dimensions
Follows the same OD/ID/wall range as Precision Round Capillaries (OD 0.1–10 mm, ID 0.05–9 mm) — low-OH is a material grade selection layered onto the standard dimensional system, not a separate size range.
Application
- Optical fiber preform and drawing processes where low OH content in the capillary/tube prevents contamination of the drawn fiber’s own OH level
- IR-transmission-sensitive capillary applications
- High-purity chemical/analytical use where trace metal and OH content both matter
Material Reference
See Quartz Glass Tubes Material Grades for the full Type I–IV / JGS1–3 OH-content comparison table — low-OH capillary draws from the same grade system, applied at capillary scale.
FAQ
Is “low-OH” the same across all suppliers?
No — OH ceiling varies by supplier and grade (from ~150 ppm standard optical grade down to <5 ppm ultra-low-OH synthetic). Specify your maximum acceptable OH content in ppm rather than relying on the label alone.
Do I need low-OH capillary if I’m not using it for IR transmission?
Not necessarily — low-OH mainly matters when the capillary wall itself is in an optical/IR path, or when it’s used in fiber preform manufacturing where OH contamination transfers to the drawn fiber. For purely mechanical or UV-range use, standard-grade capillary is usually sufficient.
Can low-OH be combined with a specific bore geometry, like fiber-optic or multi-hole?
Yes — OH grade is independent of bore geometry; specify both the grade and the bore type (round, multi-hole, fiber-optic, etc.) on your drawing.