Consists of esters or specially selected hydrocarbon fractions. They were developed for vapor-diffusion pump fluids:
- High purity, very low pressure, very stable
- Pressures lower than 10-7 torr obtainable
- No need for cold trap
- Good pumping speed
- No corrosive deposits or vapors
Physical Properties of Apiezon Oils
|
Diffusion Pump Oils |
|
Type B |
Type BW |
Type C |
Vapor Pressure,vtorr @20°C |
10-6 |
10-6 |
10-7 |
Boiling Point,°C @ 1 torr |
220 |
225 |
225 |
Flash Point (open cup)°F |
470 |
480 |
510 |
Pour Point(ASTM) °F |
15 |
10 |
5 |
Density, g/ml @ 20°C |
0.872 |
0.882 |
0.875 |
@ 40°C |
0.859 |
0.869 |
0.863 |
Viscosity, kinematic,cS @ 20°C |
142 |
361 |
283 |
@ 50°C |
49.3 |
98.1 |
90 |
@ 100°C |
7.0 |
10.1 |
10.6 |
Coefficient of Expansion per °C over 20-30°C (ASTM) |
0.00073 |
0.00070 |
0.00069 |
Thermal Conductivity Btu/in |
0.91 |
0.89 |
0.96 |
Invoil Oil B
Good for small or large vapor diffusion pumps. Good pumping speed and high backing pressure. If a cold trap is used, oil B can obtain a higher vacuum than oil C does.