Ramsay grease is a vacuum grease, used as a lubrication and a sealant of ground glass joints and cocks on laboratory glassware, e.g. burettes. It is usable to about 10−2 mbar (about 1 Pa) and about 30 °C.[1] Its vapor pressure at 20 °C is about 10−4 mbar (0.01 Pa).[2] It is named after Sir William Ramsay.[3]

Different grades exist (e.g. thick or viscous, soft). The viscous one is used for standard stopcocks and ground joints. The soft grade is for large stopcocks and ground joints, desiccators, and for lower temperature use. Ramsay grease consists of paraffin wax, petroleum jelly, and crude natural rubber, in ratio 1:3:7 to 1:8:16. Due to the rubber content it has less tendency to flow.[4]

One recipe for a grease usable up to 25 °C consists of 6 parts of petroleum jelly, 1 part of paraffin wax, and 6 parts of Pará rubber.[5]

The dropping point of Leybold-brand Ramsay grease is 56 °C; its maximum service temperature is 25-30 °C. Its vapor pressure at 25 °C is 10−7 torr (0.013 mPa), at 38 °C it is 10−4 torr (13 mPa).[6]

An equivalent of Ramsay grease can be made by cooking lanolin with natural rubber extracted from golf balls.[7]

References

  1. ^ "Losimol GmbH Hannover - Vacuum Greases (Laboratory Use)". losimol.de. Retrieved 2017-01-08.
  2. ^ "BDL Czech Republic s.r.o." Archived from the original on 2016-09-22. Retrieved 2017-01-08.
  3. ^ Senning, A. (2006). Elsevier's Dictionary of Chemoetymology: The Whys and Whences of Chemical Nomenclature and Terminology. Elsevier Science. p. 335. ISBN 9780080488813. Retrieved 2017-01-08.
  4. ^ Brauer, G. (2012). Handbook of Preparative Inorganic Chemistry. Elsevier Science. p. 29. ISBN 9780323161275. Retrieved 2017-01-08.
  5. ^ Krell, E. (1982). Handbook of Laboratory Distillation. Elsevier Science. p. 488. ISBN 9780080875491. Retrieved 2017-01-08.
  6. ^ Roth, A. (2012). Vacuum Technology. Elsevier Science. p. 391. ISBN 9780444598745. Retrieved 2017-01-08.
  7. ^ Royal Society (Great Britain) (1986). Notes and Records of the Royal Society of London. Royal Society of London. ISSN 0035-9149. Retrieved 2017-01-08.
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