Custom Fused Quartz Tubes for Furnaces

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Quartz Tubes - Custom Tubing

When your process pushes past what alumina, borosilicate, or metal tubes can tolerate, quartz tubing is usually the next call. Sentro Tech manufactures fused quartz tubes in standard and custom dimensions for laboratory and production furnaces; the kind of work where contamination, thermal cycling, or a poor seal isn’t an inconvenience but a ruined run.

Our standard quartz is 99.99% pure and available in diameters from 3/16″ to 10″ (2 mm to 250 mm) and lengths up to 72″ (1828 mm). If your furnace flange or vacuum system needs something outside those dimensions, that’s a custom job we’re set up to handle.

Why Engineers Specify Quartz Tubing for Furnaces

Quartz earns its place in semiconductor processing, CVD reactors, UV systems, and analytical labs for a few reasons that matter on the bench.

Extremely Low Thermal Expansion

Fused quartz has one of the lowest coefficients of thermal expansion of any commercially available tubing material. That’s what allows a quartz tube to come out of an active furnace and into ambient air without shattering; the kind of quenching that would split most ceramics. For semiconductor diffusion work and any process that involves rapid ramps, this property is the whole reason the material is on the spec sheet.

Chemical Resistance to Acids and Solvents

Quartz shrugs off the acids and solvents that attack metal and many ceramics: sulfuric, nitric, hydrochloric, and most organics, even at elevated temperatures. The two exceptions matter, though: hydrofluoric acid and strong alkalis (especially hot caustics) will etch quartz. If your process involves either, talk to us before you order. We’ll help you determine whether quartz is the right material or whether one of our alumina or silicon carbide options is a better fit for your chemistry.

High-Purity Material

At 99.99% purity, our fused quartz minimizes the metallic ion inclusions and bubbles that absorb energy and create hot spots in lower-grade material. That matters in any application where the tube is part of an optical or thermal pathway and stray absorption would distort the process.

Dimensional Consistency For Vacuum-Sealed Systems

Tube furnaces with O-ring flanges leave very little margin for variance in OD or wall thickness. We’ll match dimensions to your existing hardware on custom orders. Send us the flange spec or a sample part and we’ll confirm what’s achievable before quoting.

Custom Quartz Tubing for Furnaces: Non-Standard Dimensions Welcome

Most of the calls we get about quartz tubing for furnaces are about sizes that aren’t on a standard catalog page: longer lengths to fit a specific hot zone, heavier wall thicknesses for vacuum work, or matched sets for multi-zone reactors. We handle that work routinely. Send us your dimensions, drawing, or rendering, and we’ll come back with a quote and lead time.

To understand where quartz fits among the materials we offer, you may also want to read our overview of what ceramic tubing is and how the major types compare.

A 20-year lab furnace industry leader, Sentro Tech guarantees our materials to be the best for your particular applications.
Contact us for a quote on your quartz tubing and quartz ware today!

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Standard Quartz Tube Sizing

American Unit 99.99% Quartz Tube

  Outside Dia. Inside Dia.
Sentro Tech Catalog # inch mm inch mm
STQ-0250 0.25″ 6.4mm 0.37″ 9.4mm
STQ-0500 0.50″ 12.7mm 0.62″ 15.7mm
STQ-0750 0.75″ 19.1mm 0.87″ 22.1mm
STQ-1000 1.0″ 25.4mm 1.12″ 28.4mm
STQ-1500 1.5″ 38.1mm 1.66″ 42.1mm
STQ-2000 2″ 50.8mm 2.16″ 54.8mm
STQ-2500 2.5″ 63.5mm 2.66″ 67.5mm
STQ-3000 3″ 76.2mm 3.19″ 81.2mm
STQ-3500 3.5″ 89mm 3.70″ 94mm
STQ-4000 4″ 102mm 4.21″ 107mm
STQ-4500 4.5″ 114mm 4.70″ 119mm
STQ-5000 5″ 127mm 5.20″ 132mm
STQ-5500 5.5″ 140mm 5.75″ 146mm
STQ-6000 6″ 152mm 6.22″ 158mm
STQ-6500 6.5″ 165mm 6.73″ 171mm
STQ-7000 7″ 178mm 7.32″ 186mm
STQ-7500 7.5″ 191mm 7.83″ 199mm
STQ-8000 8″ 203mm 8.31″ 211mm
STQ-8500 8.5″ 216mm 8.82″ 224mm
STQ-9000 9″ 229mm 9.33″ 237mm
STQ-9500 9.5″ 241mm 9.80″ 249mm
STT-10000 10″ 254mm 10.31″ 262mm

Frequently Asked Questions

What’s the maximum continuous operating temperature before devitrification sets in?

Quartz softens around 1650°C, but that’s not the practical limit. Held above roughly 1100°C for extended periods, fused quartz begins to devitrify. The amorphous structure starts re-crystallizing into cristobalite, which makes the tube cloudy, brittle, and prone to cracking on the next cool-down. For continuous service, plan on 1100°C as the working ceiling. Short excursions higher are tolerable; sustained operation above that range is where tubes fail.

Is the quartz high-purity, and how does that affect UV/IR transmission?

Our standard tubing is 99.99% pure fused quartz. That purity level supports clean transmission for the UV and into the near-IR; relevant for UV sterilization lamps, photochemical reactors, and CVD systems where the tube is part of the optical path. Lower-grade quartz carries metallic impurities and entrapped bubbles that absorb energy, create localized heating, and interfere with whatever the light is supposed to be doing.

Can quartz tubes handle rapid thermal cycling and quenching?

Yes, this is one of the best reasons to specify quartz in the first place. The coefficient of thermal expansion is low enough that you can pull a tube from a hot furnace into ambient air without it cracking. That said, “quench-resistant” isn’t the same as “indestructible.” Mechanical shock, surface scratches, and prior devitrification all reduce the margin. Inspect tubes regularly if you’re cycling aggressively.

How does quartz react to hydrofluoric acid or strong alkalis?

Poorly. HF dissolves quartz at room temperature, and strong bases (sodium hydroxide, potassium hydroxide) etch it, especially when hot. If either is part of your process or your cleaning protocol, quartz is the wrong material. Contact us, and we’ll talk through whether one of our alternative ceramic options fits, or whether your chemistry calls for a different material category entirely.

What are the standard tolerances for OD and wall thickness?

Tolerances depend on tube diameter and whether it’s a standard or custom item. For O-ring-sealed vacuum systems, where small variances can compromise the seal, the right approach is to match the tube to you

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