SCS LABCOTER 2 - Vacuum Levels; Vacuum Pumps; Gas Flow

Rev 37 Operator’s Manual OM-610-1002-1
page 14 SECTION 5 OPERATION PDS-2010
TABLE 5-1
Equivalence Table for Pressure/Vacuum Measurement
Vacuum Torr milliTorr PSIA Inches Hg Atmosphere
Atmosphere 760 760 000 14.7 29.92 1.0
Low 100 100 000 1.93 3.94 0.132
Low 1 1000 0.019 0.0394 0.00132
Med. 0.100 100
1.93x10
-3
3.94x10
-3
1.32x10
-4
Med. 0.010 10
1.93x10
-4
3.94x10
-4
1.32x10
-5
High 0.001 = (10
-3
) 1
1.93x10
-5
3.94x10
-5
1.32x10
-6
Very High (10
-6
) 0.001 (10
-3
)
1.93x10
-8
3.94x10
-8
1.32x10
-9
Ultra High (10
-9
) (10
-6
)
1.93x10
-11
3.94x10
-11
1.32x10
-12
5.2.3 Vacuum Levels
Vacuum is usually divided into five levels, qualitatively labeled: Low, Medium, High, Very High, and Ultra
High. A Low vacuum related to having a relatively high pressure and a Very High vacuum having a relatively
low pressure.
Low Vacuum represents pressure above 1 Torr absolute. Flow in this range is viscous, as represented by most
common fluids. Mechanical vacuum pumps are used for low vacuum, and represent the large majority of
pumps in industrial practice.
Medium Vacuum represents pressures between 1 and 1x10
-3
Torr absolute. This is a transition range between
viscous and molecular flow. Most pumps serving this range are also mechanical. The 2010 performs the
Parylene deposition process in the medium vacuum range.
High Vacuum represents pressures between 1x10
-3
and 1x10
-6
-Torr absolute. Flow in this region is molecular,
with very little interaction between individual molecules. Many specialized applications for the semiconductor
manufacturing industry fall in this range. Diffusion pumps, turbomolecular, and cryopumps are typically used
in this range.
Very High Vacuum represents absolute pressures between 1x10
-6
and 1x10
-9
Torr.
Ultra High Vacuum represents absolute pressure below 1x10
-9
Torr.
5.2.4 Vacuum Pumps
A vacuum pump is a device that is used to reduce and maintain the gas pressure in a vessel below atmospheric
pressure. The 2010 Parylene Deposition System uses an EDWARDS RV 8 (60 HZ) or EDWARDS RV12 (50
HZ) vacuum pump.
5.2.5 Gas Flow
When a closed container at atmospheric pressure is evacuated by virtue of a vacuum pumping system, the
flow of gas through the container will pass through one or more flow regimes. The flow regime in a container