Joint sleeve
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A joint sleeve is a PTFE sleeve used to seal ground glass joints in processes where the reagents can attack silicone grease, such as distillation of nitric acid.
Contents
General
PTFE joint sleeves are hollow conical frustum-shaped sheets of PTFE, which come in two versions: rigid and flexible. The rigid sleeve is thick, while the flexible one is thinner and can be deformed by hand. While the thinner ones are often preferred, they are also easier to damage. PTFE joint sleeves can handle temperatures up to 280 °C.
Availability
PTFE joint sleeves can be purchased from lab suppliers, though they are a bit pricey. Usually they're sold in packs of 10.
DIY joint sleeve
You can make your own joint sleeves by carefully cutting a Teflon sheet in the form of a cone frustum projection, then carefully attach it to the male ground glass joint, before carefully placing it in the female ground glass joint. If your PTFE sheet gets wrinkled, it may not seal properly.
Alternatively, a simple PTFE strip wrapped around the ground glass joint can be used instead, although one has to replace it after every use.
Projects
- When using a pouring adapter, a PTFE joint sleeve is better than grease
- Distillation of nitric acid
