A high vacuum grade grease, which is for use at system pressures lower than 10⁻⁶ mbar.
This grease is an excellent lubricant for sliding elastomer seals, and exhibits the chemical inertness typical of the PFPE range. It has a very low vapour pressure and is suitable for use in the presence of gaseous and liquid oxygen under severe conditions.
The general purpose AR555 grease offered by Edwards has the basic properties of Fomblin® PFPE, but the vapour pressure is not specifically controlled. The vapour pressure is < 10⁻⁷ mbar at 20 °C.
DuPont Krytox® fluorinated greases are a family of multipurpose lubricants intended for use in speciality applications at elevated temperatures or in aggressive environments.
Waxes and sealing compounds (mineral based)
Apiezon® wax W is a low vapour pressure wax for sealing joints in high vacuum systems. This wax softens at 80-90 °C and has a vapour pressure at 80 °C of 10⁻³ mbar and at 20 °C of 10⁻⁸ mbar. Apiezon® wax W40 is similar to type W, but has a lower softening point which makes it very suitable for flow sealing in or around vacuum joints. It is not recommended for use at temperatures above 30 °C. • It has a vapour pressure at 20 °C of 10⁻⁷ mbar.
Apiezon® sealing compound Q remains firm for temperatures up to 30 °C, but is sufficiently pliable to permit easy moulding into position. It is an excellent material for shielding or blanking off sections of apparatus. The compound is easily applied and can be readily removed. It has a vapour pressure at 20 °C of 10⁻⁴ mbar.
A range of Apiezon® greases is offered for use on high vacuum systems and for many general applications in the laboratory. These high purity greases are non-toxic, easy to apply, easy to clean off and have long shelf lives. Applications include:
• Lubrication of glass and metal taps in vacuum systems
• Sealing polymer joints in vacuum systems
• Leak detection
• Protecting metal contacts in vacuum-encapsulated relays
• Sealing polished and ground glass/ metal surfaces
• Optical surfaces in vacuum systems and laser systems – does not cause clouding (L and M greases only)
• Non vacuum uses include lubrication of glass and metal taps in laboratory, medical and industrial applications
• Good ‘gettering’ qualities (absorbs grease and chemical impurities) – ideal for electronics industry Choice of grease depends largely on operating temperature (see below).