YK10-0015-DI-002-03
46
APPENDIX 1 TECHNICAL NOTE
The following is a short note of the knowledge required in using a mechanical booster pump.
APPENDIX 1.1 Designing Pumping System
The mechanical booster pump cannot be started at the atmospheric pressure and must always be
used in combination with a backing pump (Dry pump/Oil rotary pump). Therefore, the vacuum
chamber and the piping must be rough-pumped by the methods shown in the below figure and the
mechanical booster pump must be started after the pressure has lowered to its operating range.
The rough-pumping methods include those shown by (1) and (2) in Fig.12.
The method (1) carries out rough-pumping through the mechanical booster pump. This method is
used when the vacuum chamber is small in size, that is, when a long time can be spent for
rough-pumping. Since the mechanical booster pump does not operate when rough-pumping is
under way, the gas to be exhausted is discharged through the clearances between the rotors in the
mechanical booster pump. This increases the pumping resistance (decreases conductance) and a
long rough-pumping time is required.
In the method (2), a rough-pumping path is provided in the mechanical booster pump. This
method is used when the vacuum chamber is large in size, that is, when it is desired to shorten the
rough-pumping time.
Rough-pumping is carried out with the main valve and the roughing valve opened and, when the
specified pressure is attained, the mechanical booster pump is actuated and the roughing valve is
closed for high vacuum pumping.
Fig. 12 Evacuation by mechanical booster pump (example)
Summary of Contents for PMB-040C
Page 2: ......
Page 27: ...YK10 0015 DI 002 03 7 2 3 Dimensional drawing Fig 3 Dimensional drawing PMB 040C...
Page 28: ...YK10 0015 DI 002 03 8 Fig 4 Dimensional drawing PMB 060C...
Page 29: ...YK10 0015 DI 002 03 9 Fig 5 Foundation Drawing Model PMB 040C...
Page 30: ...YK10 0015 DI 002 03 10 Fig 6 Foundation Drawing Model PMB 060C...
