Apiezon H High Temperature Vacuum Grease, Silicone Free, 25g, CAS #8012-95-1 and CAS#68953-58-2
Apiezon H is designed for applications at higher temperatures and of all the Apiezon greases, is the formulation for the highest temperatures. Nothing in life is without trade-offs and in this case, the ultimate vapor pressure rating is a bit less attractive than Apiezon L although it is comparable to Apiezon M.
Apiezon H grease is the ideal choice of grease for use at higher temperatures in a wide variety of applications in both science and industry. Its characteristic properties would suggest it is good at high temperatures, it has decent thermal conduction properties, good "stiction" and is designed for use in the low to medium vacuum range. Whatever chemical vapors that do get produced at elevated temperatures would contain only petroleum hydrocarbons and under no circumstances would they contain silicones or halogenated compounds.
Apiezon H grease is a very tenacious grease conferring excellent cohesive strength. With Apiezon H grease, gone are the days of loose fitting glassware and mated joints coming loose.
"Stiction" power not only makes Apiezon H grease ideal for use with laboratory glassware, but combined with properties of high thermal conductivity, it is the perfect choice for the electronics and space industries where heat sink media require adhesion.
Apiezon H grease can be used over a wide range of temperatures from -10 to + 240° C, while optimum consistency is retained at between +10 and +110° C. There are a growing number of applications for Apiezon H outside of the vacuum area, for example, it is used on a heatsink fan for a computer central processing unit ("CPU").
Apiezon H grease is a relatively stiff grease which does not melt, but in fact becomes stiffer as the temperature increases. It is specifically recommended for sealing and lubrication in high temperature applications, but not for highly stressed bearings.
At the upper temperature limit: Apiezon H vs. Santovac 5GB High Vacuum Greases
Santovac® 5GB Grease has a drop point of 250°C so it will therefore operate to the same top temperature as Apiezon H (240°C).
Santovac 5GB has slightly lower vapor pressure than Apiezon H at 25°C, 4 x 10-10 Torr (Apiezon H 17 x 10-10 Torr) but these values reverse themselves at higher temperatures. The vapor pressure of Santovac 5GB rises to 1 x 10-2 Torr @ 200°C (Apiezon H, 0.8 x 10-2 Torr) and 10 x 10-2 @ 250°C Torr (Apiezon H, 5 x 10-2 Torr). Santovac 5 fluid turns into a glassy solid at +5 °C (Pour Point) so one would assume that the grease will also have the same low temperature limitations, compared to Apiezon H which can be used down to -10°C.
When it is all said and done, these two products are pretty close in properties and characteristics, that that is why both products seem to have their "fans" of users who have tried both but prefer one or the other.
Apiezon H is a filled hydrocarbon grease which exhibits excellent heat transfer properties.
Allowing heat to conduct away from a site of operation, Apiezon H grease will reduce the danger of overheating and hence will limit the risk of damage to heat sensitive components.
Apiezon H grease is manufactured from a unique feedstock containing a high proportion of branched and unsaturated hydrocarbons.
These complex structures give Apiezon H grease a very high molecular weight and consequently, strong powers of absorption, particularly for other hydrocarbon molecules.
Strong absorption properties ensures that Apiezon H grease has powerful "gettering" action, that is, the power to absorb greasy or chemical impurities on metal and glass surfaces. This is of considerable value in the electronics industry where scrupulous cleanliness of metal surfaces is required.
Apiezon H grease is extensively used in a wide variety of applications and industries. It has gained prestigious approvals from British Aerospace, the European Space Agency, and NASA.
Apiezon H grease has been approved by NASA as the only material suitable for lubricating the gold-plated threads of small variable capacitors required to operate under high vacuum from -65° C to + 125° C to prevent galling.
Apiezon H grease exhibits good vacuum properties in the lower to medium vacuum range at higher temperatures, while at lower temperatures, Apiezon H grease can be used in the high vacuum range.