Ground fat
Schliffett (tap grease, desiccator grease ) is used to seal and to keep joints glide in laboratory glassware.
There is a wide variety of grinding greases with different properties. In addition to the commonly used silicone greases, there are also water-soluble grinding greases - both those that become more viscous instead of thinner as the temperature rises, as well as grinding greases that still retain good lubricity at low temperatures instead of becoming hard or Teflon pastes for sealing ground joints on contact with very aggressive substances. Joint greases partly correspond in composition and properties to valve grease .
The fats are mainly distinguished in terms of their viscosity . Basically, sections must be greased before assembling a glass apparatus. Joint grease is particularly important when working at low temperatures or in high vacuum (high vacuum grease). It is also used in ground glass taps.
Instead of ground surfaces coated with grease, sealing rings , ground joint sleeves and ground joint collars made of the resistant plastic PTFE (often referred to as Teflon ) are increasingly being used. While grease has to be topped up more often, plastic seals require little maintenance and make it easier to loosen the connections.
literature
- Bruno P. Kremer, Horst Bannwarth: Introduction to laboratory practice. Basic skills for newcomers to the laboratory . 2nd, updated and expanded edition. Springer, Berlin et al. 2011, ISBN 978-3-642-17073-7 , pp. 238 ( limited preview in Google Book search).
Individual evidence
- ↑ Working under inert conditions ( Memento from August 1st, 2012 in the web archive archive.today ) at the FU Berlin .
- ↑ Safe working in chemical laboratories ( Memento of the original dated April 30, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 4.1 MB) at the FU Berlin, page 28.
