Description
Cone joint DURAN (Form B) NS 12/21 is a precision-ground standard joint intended for secure, interchangeable connections in laboratory glass apparatus. Fabricated from borosilicate glass 3.3, it combines high chemical resistance with excellent thermal-shock stability, making it suitable for distillation, reflux, vacuum and reaction setups. The joint size is NS 12/21, the tube diameter measures 11 mm and the wall thickness is 1,5 mm, while the overall length reaches 125 mm at a net weight of only 0,012 kg. These dimensions ensure a lightweight yet robust component that mates reliably with matching sockets. Supplied as a single piece from manufacturer Rettberg, the Form B cone geometry follows established laboratory norms and supports leak-tight seals when used with appropriate grease or PTFE sleeves. The material’s low coefficient of expansion permits repeated heating and cooling cycles without stress cracking, which is essential in analytical chemistry, organic synthesis and educational laboratories. Precision grinding guarantees consistent taper and surface finish, reducing assembly force and the risk of chipping. This DURAN-quality ground joint integrates easily into modular glassware systems and custom apparatus, providing a durable, reusable connection element for solvents, reagents and gases under both ambient and moderate vacuum conditions.
This article is part of Distillation heads, adapters & columns, in Distillation & extraction glassware.
Key features
- Pack size: 1 pc
- Joint size: NS 12/21
- Material: Borosilicate glass 3.3
- Tube diameter: 11 mm
- Length: 125 mm
- Wall thickness: 1,5 mm
- Technical Information Sheet:
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Questions about Joint cone/DURAN (shape B) size 12/21
What is this article?
Joint cone/DURAN (shape B) size 12/21 is the article on this page. Luminix Health distributes Rettberg for laboratory use. It sits in Distillation heads, adapters & columns, inside Distillation & extraction glassware, in Labware.
A still head, an adapter or a column is the glass between the boiling flask and the condenser. A Vigreux or packed column gives the vapour a surface so a closer-boiling mixture can separate. The joint sizes at both ends have to match the flask and the condenser.
Distillation separates liquids by boiling point. A condenser turns the vapour back into liquid: Liebig, coil and cold-finger shapes differ in how much cooling surface they offer. A still head and a column sit between the flask and the condenser. A Soxhlet extractor washes a solid again and again with the same solvent. Ground joints have a standard size, and the joint, not the flask, is what has to match. The pieces are indexed under ISO laboratory glassware.
Which category should I open next?
The category is Distillation & extraction glassware. The sub-category is Distillation heads, adapters & columns. The catalogue is Labware.
Shelves beside this one are Condensers, Ground-joint glassware (other) and Soxhlet & extraction apparatus.
What should I check before I order?
When this page shows a safety data sheet, use that manufacturer file. Hazard text does not belong in the sales description. For a pack size, a grade or a certificate that is not on the page, send a quote request or contact the team.
How does ordering and shipping work?
Luminix Health distributes this article from the heart of Europe. Articles in stock ship within 2–5 business days. Standard delivery is free from €250 excl. VAT. Cold-chain goods and dangerous goods under ADR are never included in that free delivery. The terms are in the Shipping Policy. The full brand index is on shop by brand. Who we are is on about us.
Which other categories should I open?
The seven catalogues are Labware, Lab chemicals, Lab instruments, Lab consumables, Chromatography equipment, Lab safety equipment and Life Science & Microbiology.