Automatic Pre-cooling System Overview for myself
(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??)
(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.