Custom Double-Bore & Multi-Bore Quartz Tubes

Parameter	Factory Standard	Manufacturing Limit
Outer OD	3–50 mm	Up to 100 mm on request
Hole count	2–7	Up to 19, pattern-dependent
Bore diameter	0.3–10 mm per hole	Down to 0.2 mm, tolerance-dependent
Hole pitch	1.2–3× bore diameter	Tighter pitch narrows web thickness
Web thickness (between holes)	≥0.3 mm	Down to 0.15 mm on request
Length	Up to 3,000 mm	Longer via tube-to-tube welding
Hole position tolerance	±0.03–0.05 mm	Tighter, confirmed per order

Inquiry

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Quartz Glass draws quartz tubing with two or more parallel bores in a single piece — used where separate channels need to run side by side without a secondary assembly step.

Bore diameter, pitch, web thickness, and outer wall aren't independent choices — increasing bore diameter or tightening pitch directly eats into web thickness and the remaining outer wall. Send all four together on your RFQ rather than specifying one and asking us to fill in the rest.

Double-Bore, Multi-Bore and Eccentric-Bore Configurations

Double-bore — two parallel channels, equal or unequal diameter, for applications needing two isolated paths (e.g., supply and return) in one part
Multi-bore — three or more holes in a fixed pattern, typically symmetric around the tube axis
Eccentric-bore — one or more holes offset from center, used when a channel needs to sit close to the outer wall

Precision drawing and redrawing is how the hole pattern is set and held through the draw — this is a Quartz Glass quartz tubes and tubing capability, not a separate process line.

Hole Diameter, Pitch and Web Thickness

Web thickness — the quartz wall left between adjacent holes — is usually the limiting factor, not hole diameter itself. A tight pitch with large bores can leave a web too thin to survive drawing or later handling without cracking. If your design needs a thinner web than the standard figures above, tell us the application (pressure, temperature, or just space constraint) so we can confirm whether it's achievable with secondary micro-machining instead of drawing alone.

Double-Bore & Multi-Bore Quartz Tubes Factory Standard & Manufacturing Limit

The table above separates what's repeatable without added cost or lead time (Factory Standard) from what's achievable but needs confirmation and usually more inspection (Manufacturing Limit). Maximum hole count and minimum bore diameter are not simultaneously available at the tightest pitch — the more holes you need, the more that constrains how small or how close together they can be.

Cross-Section Design and Bore Position Control

Bore position is checked against the outer OD, not just against the other holes — a pattern can be internally consistent but still off-center in the tube. For eccentric or asymmetric patterns, specify position from a fixed reference point (like the OD centerline) rather than only hole-to-hole spacing, so the whole cross-section can be verified in one measurement.

End finishing is cut-to-length and fire-polish, same as standard tubing; no special end treatment is applied to multi-bore parts unless requested.

2–7Longitudinal Bores

1–3 mmCommon Bore ID

6–10 mmCommon Double-Bore OD

±0.05–0.10 mmReference Bore Tolerance

≥99.99%Natural SiO₂ · synthetic ≥99.999%

≤1100 °CContinuous Service Guideline

Specifications

Double-Bore & Multi-Bore Tube Specifications

Parameter	Reference Capability / Requirement
Outer Profile / OD	Round or drawing-specific profile; common double-bore OD 6–10 mm
Hole Count	2–7 longitudinal channels
Bore Diameter	Common ID 1–3 mm; other bores reviewed by cross-section
Bore Tolerance	Reference ±0.05–0.10 mm according to bore size and length
Hole Pitch	Center-to-center spacing dimensioned on the cross-section
Web Thickness	Controlled between adjacent bores
Hole Position	Referenced to the outer-profile datum
Length	Cut length specified with bore continuity and straightness requirements
Material	JGS2-class high-purity fused quartz

Standard Series

Multi-Bore Cross-Section Series

Layout	Reference Bore	Outer Size	Typical Function
2 bores · parallel	2 × ID 1–3 mm	OD 6–10 mm	Dual gas or liquid routing
2 bores · asymmetric	Different IDs	By drawing	Sensor plus reference channel
3 bores · inline	Equal or mixed IDs	By drawing	Electrodes and thermocouple routing
3 bores · triangular	Equal IDs	By drawing	Compact multi-channel probes
4 bores · square	Equal IDs	By drawing	Optical fiber and electrode arrays
7 bores · ring + center	Equal or mixed IDs	By drawing	Gas distribution and analytical instruments

Dimensional Tolerances

Bore Diameter, Pitch & Position Tolerances

Feature	Size / Condition	Reference Tolerance
Bore Diameter	Common precision bores	Reference ±0.05–0.10 mm
Hole Pitch	Center-to-center	Defined by cross-section and drawing
Web Thickness	Between adjacent channels	Controlled to preserve channel isolation
Hole Position	To outer datum	Drawing-specific
Cut Length	Finished tube	±0.5 mm standard; ±0.1 mm precision where geometry permits
End Face	All channels exposed	Ground square or fire-polished

Configurations

Bore Layouts & Outer Profiles

Parallel Double BoreTwo isolated longitudinal channels in one round tube

Asymmetric Double BoreDifferent bore diameters or offset locations

Inline Triple BoreThree channels arranged across one datum line

Triangular Triple BoreCompact three-channel cross-section

Four-Bore ArraySquare or rectangular channel pattern

Seven-Bore PatternCenter channel surrounded by six channels

Eccentric BoreSingle or multiple channels offset to a functional surface

Shaped Outer ProfileRound, square or custom outside envelope

Material Selection

Quartz Grades for Multi-Channel Tubing

Electric-Fused QuartzGrade-specific UV cut-offOH 5–150 ppm; heat treatment can adjust OH. General-purpose continuously drawn stock. Confirm UV boundary by grade datasheet.

Flame-Fused Quartz · JGS2220–2500 nmOH 120–260 ppm; UV-visible optical components.

Synthetic Fused Silica · JGS1185–2500 nmSiO₂ ≥99.999%; OH ≈1000 ppm. Selected for deep-UV transmission; strong OH absorption near 2730 nm.

Vacuum-Fused / Low-OH · JGS3Grade-specific UV–IR / 260–3500 nmVacuum-fused OH <3 ppm; JGS3-class OH ≤10 ppm. Use the lot certificate and transmission curve at the working thickness.

OH content varies by grade and batch; the lot certificate is authoritative. Compare material routes and typical transmission data.

Fabrication

Drawing, Redrawing, Cutting & End Finishing

Cross-Section DesignBore ID, pitch, web and outer datum defined together
Precision DrawingLongitudinal channels formed continuously through the tube
Profile RedrawingOuter size and bore geometry reduced under controlled heat
Cut-to-LengthEnds cut without closing or contaminating the channels
End GrindingSquare faces expose all bores for assembly and inspection
Bore InspectionChannel count, ID, pitch and continuity verified on finished parts

Applications

Multi-Bore Tube Applications

Gas DistributionSeparate channels for process, purge and reference gases

Thermocouple ProtectionMultiple insulated paths for sensor wires and junctions

Analytical InstrumentsParallel flow, reference and electrode channels

Laser & PhotonicsFiber, electrode and cooling paths in one quartz profile

Electrochemical ProbesIsolated channels for electrodes and electrolytes

Microfluidic RoutingMultiple longitudinal flow paths with a shared outer body

FAQ

Frequently Asked Questions

How many bores can be made in one quartz tube?

Reference layouts cover 2–7 channels. Bore count, diameter, pitch and web thickness must be reviewed as one cross-section.

What bore tolerance can be specified?

A reference range of ±0.05–0.10 mm is used according to bore size, length and redraw geometry.

Can the bores have different diameters?

Yes. Symmetric, asymmetric and eccentric layouts can combine different bore IDs when the remaining quartz web is sufficient.

Can you make prototype quantities?

Yes. One-piece prototypes are welcome; a dimensioned cross-section is required before production review.

Need a custom double-bore or multi-bore tube?Send the bore count, ID, pitch, web thickness, outer profile and required length.

Open the Tube Configurator

Engineering Data

Grade-Qualified Material Purity

Electric-fused / flame-fused quartz: SiO₂ ≥99.99%; synthetic JGS1-grade fused silica: ≥99.999%. Grade and lot certificate govern supplied material.

Engineering Data

Service Temperature

Transparent quartz: continuous use ≤1100 °C; short-term excursions ≤1200 °C. Opaque / milky quartz: continuous use ≤1000 °C. Load, atmosphere, support span and thermal cycling determine the application limit.

Engineering Data

Formed Stock versus Cold-Cut Dimensions

Formed stock and finished cut parts use different length tolerances. Continuously drawn transparent stock: ±1.0 mm at OD ≤50 mm / ±2.0 mm at OD >50 mm. Rotationally fused opaque stock: ±5.0 mm. Cold-cut finished parts: standard ±0.5 mm; precision ±0.1 mm only where agreed for the finished geometry.