Veeco MS40 Operation And Maintenance Manual page 67

Purge Hose Connection: 1/4" Poly-flo tube fitting and tubing. Connects
the purge valve to the purge fitting on the internal mechanical pump.
Internal Mechanical Pump "Flex" Line: KF16 size stainless steel flex
hose. Connects the valve block to the internal mechanical pump.
Fore-line "Flex" Line: KF16 size stainless steel flex hose. Connects the
valve block to the fore-line of the turbo-molecular pump.
Purge Sintered Filter: Prevents contaminants from being drawn into the
internal mechanical pump through the purge valve.
PUMPS
External Roughing Pump: Optional equipment with the MS-40. A 7 or
16 CFM dual stage rotary vane (mechanical) pump. The pump is capable
-3
of evacuating from atmosphere to 10 Torr. Assists in providing a
-3
leak test range from 10 to 1 x 10 std cc/sec helium. The pump is
necessary when testing large objects.
Internal Roughing Pump: A 1.5 CFM dual stage rotary vane (mechanical)
pump. Used to evacuate the test port and test object. Also used to provide
"backing" of the turbo-molecular pump.
High-Vacuum Pump: A 60 liters/second turbo-molecular pump. In direct
mode testing, the pump allows the MS-40 to measure leak rates as low as
-11
4 x 10 std cc/sec helium. In this mode, the test port is directly connected
to the high-vacuum system.
When performing reverse mode testing, test port gases are channeled to the
fore-line side of the turbo-molecular pump. The turbo-molecular pump acts
to protect the mass spectrometer from these test port gases. Helium
molecules however, due to their relatively small mass, are able to "back
diffuse" through the turbo-molecular pump. Since heavier gas molecules
are trapped by the pump, only helium enters the high-vacuum system,
where the mass spectrometer is able to accurately measure the leak rate.
Vacuum Instrument Corp.
2099 Ninth Avenue
Ronkonkoma, NY 11779
631.737.0900
1109-186-00 Rev. C 3-14