European Southern Observatory New Technology Telescope

General :
Observations :
Operations :

EMMI CCD Dewar Refilling

This is the actual procedure to refill the CCD Dewar of EMMI twice a day, preferably at 8 a.m. and at 6 p.m. :

• If EMMI is not horizontal  set it manually to horizontal position.
• Push the EMMI central red interlock.
• Measure the vacuum in red and blue dewars and write them down on the log sheet.
  After checking vacuum,notify ODT if the value is above 5 x 10-4.
• Look at both Pulpo displays : temperature should be 152 K in red and 175 K in blue .
• If the previous values are noticeably different, do not refill and inform ODT.
• Write down the date, time, temperature and operator signature on the log sheets.
• If a LN2 tank is empty, IMMEDIATELY  execute NITROGEN TANK exchange procedure.
• Always discharge yourself by touching the instrument structure before touching the CCD dewar

(while holding the metallic LN2 hose in order to discharge the bottle too as it has rubber wheels).
• Introduce the tank tube into the dewar inlet.
• Screw the ring a few turns around it.
• Take care that the overflow plastic hose is not oriented toward the dewar valve or vacuumeter connector.
• Open the tank valve until liquid nitrogen overflows.
• Close the tank valve.
• Unscrew the tank tube ring with gloves and removes the hose gently from the dewar inlet :
• Remove the tank away from the instrument.
• Release EMMI central red interlock.
• Fill the log sheet in the control room..
     

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