Automatic Pre-cooling System Overview for myself
6/21/2006  Tokoku

  • Objective (1)Save troubles and man-power. (2)The system is necessary for MOIRCS, COMICS, and CIAO. The pre-cooling pipe of COMICS and CIAO (the same system) are made of stainless steel with welding(=tough) and that of MOIRCS is made of copper with silver soldering(=fragile). COMICS and CIAO don't mind a flow rate. COMICS takes 2 daytime operations, CIAO takes 1 daytime operation for pre-cooling. MOIRCS takes 7 daytime operations with serious care. (3)It is not clear whether this sytem will be allowed to run during night time on safty grounds.
  • Current Status (1)Mechanical : Almost done. We want to add a vacuum system for LN2 pipe for in case of high pressure inside. (2)Software : Omata-san is improving it.
  • Current Control System Liquid flow rate control with adjustment OPEN/CLOSE of the pnumatic valve. Set point(flow rate) are determined by liquid flow rate and temprature.
  • Current Problems (1)No secure measure for power failure. (2)Need backup flow meter? (to where?)
  • When is a vacuum system necessary? (1)Avoid any damage from power failure. (2)After PV1 was closed, if a puressure of G1 is too high (>10^-1 Torr??) and (3)During night time or When both tanks run out. (4)How about using only relief valve? ---> Frost inside line. ---> Vacuuming during warm-up.
  • Issues about a vacuum system in a liquid nitrogen line. (1)The same line is used for liquid and high-vacuum. (1-1)Connectors are difference. (1-2)Gauges are difference. (2) (3)