Select a backing-pump in accordance with the capacity and starting method (simultaneous 
starting, starting after generating roughing vacuum) suitable for the vacuum equipment you use. 
5.  Connect the STP pump and the backing-pump using stainless steel or aluminum alloy tubing, 
flexible tubing, vacuum rubber or Teflon tubing, and other. The following measures can be used 
to avoid the transmission of the vibration of the backing-pump to the STP pump and the vacuum 
equipment: 
• DO NOT place the backing-pump on the same floor as the vacuum equipment. 
• Locate the backing-pump on a vibration-proof table. Attain 1/3 or less of the rotational speed of 
the backing-pump, when adjusting the inherent frequency of the backing-pump installed on a 
vibration-proof table. 
• Attach a weight to the piping from the backing-pump, or secure the piping to a rigid, heavy 
object free of vibration. 
• Use a tube of high flexibility. 
6.  Depending upon the type of the backing-pump used, oil vapour may contaminate the inside of 
the STP pump. Some oil viscosity could cause a malfunction when there is a strong reverse flow 
of oil. Take the following measures to ensure the correct flow of oil: 
• Attach a vacuum valve to the middle of the piping between the STP pump outlet port flange and 
the backing-pump. 
• Attach an adsorption trap adjacent to the vacuum valve. 
 
2.3.5  Vacuum piping method 
1.  Attach the inlet port to the high vacuum side. 
(Refer to "TECHNICAL DATA" in the STP Pump Instruction Manual (B) for maximum working 
pressure). 
2.  Attach the outlet port to the inlet port flange of the backing-pump (primary side pump). 
(Refer to "TECHNICAL DATA" in the STP Pump Instruction Manual (B) for allowable backing 
pressure). 
 
Note:  Maximum flow for water cooled and TMS unit are applicable under the condition listed in 
"TECHNICAL DATA" and “TMS unit” in the STP Pump Instruction Manual (B). 
Note:  To attain the ultimate pressure, set the pressure at the outlet port flange to 1.3 Pa (10
-2
 Torr) 
or  less.  Refer  to  "TECHNICAL  DATA"  in  the  STP  Pump  Instruction  Manual  (B)  for  the 
ultimate pressure.