Vacuum Refresh Procedure

The vacuum pump for IGRINS is only good for low-pressure use.

If IGRINS was recently opened in the cleanroom, then a larger roughing-pump will be required to get started.

At McDonald the VIRUS pump can be used if the vacuum was compromised.

To refresh the vacuum on IGRINS when it is being stored at McDonald:

• Let the cryostat warm to ambient temperature and document the pressure on the pressure gauge.
• Plug the vacuum pump into UPS power.
• Attach the vacuum pump and turn it on, letting the vacuum line be fully evacuated with the turbo pump running.
  
• Slowly open the vacuum valve. There will not be a noticeable change in the noise since IGRINS is already at low pressure.
• Leave IGRINS on the pump for 3-4 days. If the vacuum is good, only a few hours may be required.
• In the event of a power failure with the valve open and the pump running, the person who started the pump needs to immediately close the valve. If UPS power was also lost and the vacuum may have been compromised, then contact Greg or Hwi. The instrument should be put back on the vacuum pump once power is restored and the system safety is verified. 
• After IGRINS has been pumped at room temperature the valve should be closed and the pump removed prior to cooling.
• To remove the pump: 
  • Close the valve
  • Shut down the pump and let the turbo spin down
  • Disconnect the vacuum hose
• IGRINS should not be left in the warm, valve-closed state for more than a few minutes. Cooling should be started immediately following removal of the vacuum pump. 
• If power is lost while IGRINS is cooling, it may be necessary to pump again before resuming the cooldown. Please contact Greg or Hwi before action is taken.