Description
Replacement plug NS 18,8 PTFE is a robust spare plug for larger laboratory stopcocks that use the NS 18,8 ground joint. Made from solid PTFE, it features a 4 mm bore that accommodates higher volumetric flow while preserving chemical resistance across a wide range of solvents, acids and bases. The PTFE taper mates with standard glass barrels to restore a leak-tight seal after the original plug has become worn, deformed or chemically attacked. This component from manufacturer Witeg is supplied as a single piece and is intended for maintenance of medium- to large-scale glass apparatus such as reaction vessels, large separating funnels, vacuum manifolds and process-scale laboratory lines. The inert polymer surface resists sticking and simplifies cleaning, reducing cross-contamination between successive runs. Accurate geometry of the NS 18,8 taper and the defined 4 mm bore help maintain predictable flow behaviour in preparative chemistry, extraction work and pilot-scale operations. Laboratories that standardise on NS joints can keep this PTFE plug on hand as a ready replacement, ensuring minimal downtime when stopcock performance declines and glassware must be returned quickly to reliable service.
This article is part of Ground-joint glass stoppers, in Stoppers, caps & closures.
Key features
- Pack size: 1 pc(s)
- Material: PTFE
- Joint size: NS 18,8
- Bore diameter: 4 mm
- Product type: NS replacement plug
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Questions about stopcock ST 18,8
What is this article?
stopcock ST 18,8 is the article on this page. Luminix Health distributes Witeg for laboratory use. It sits in Ground-joint glass stoppers, inside Stoppers, caps & closures, in Labware.
A ground-glass stopper matches a ground neck of a stated joint size. A 14/23 stopper does not seal a 29/32 neck. The stopper is part of the flask's seal, and a chip on the grind is a leak.
A closure is the part that decides whether a bottle stays shut and whether the contents attack the seal. A ground-glass stopper matches a ground neck. A screw cap needs the right thread and a liner that survives the liquid. Rubber and silicone stoppers push into a mouth. The liner, not the colour of the cap, is the chemical choice. The vessels they close are indexed under ISO laboratory glassware.
Which category should I open next?
The category is Stoppers, caps & closures. The sub-category is Ground-joint glass stoppers. The catalogue is Labware.
Shelves beside this one are Screw caps & closures, Rubber & silicone stoppers, Lids & seals and Closures (other).
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.