Agilent Technologies TwisTorr 74 FS Notice De Mode D'emploi page 320

17 Technical Information
Inlet screen installation
prevent the rotor blades from being damaged by debris. The inlet
screen, however, does reduce the pumping speed as per following
table:
X3502-68000
X3502-68001
The inlet screen is fitted in the upper part of the pump, as shown in
the figure.
Figure 30
320/352
Reduction in pumping speed (%)
Ar N
2
20% 18%
TwisTorr 74 FS User Manual / 87-901-053-01 (A.00)
He H
2
7% 5%