HOT VT  OPERATION ON THE VARIAN 400 and 500

ATB probe on the 400 can be used from    - 80  to  + 130  C

INVERSE probe on the 500 can be used from    -100  to  + 130 C

BROADBAND probe on the 500 can be used from   -100  to   + 150 C

If you are going  above > 100  C      below < - 40  C    YOU MUST USE TANK NITROGEN

CHECK YOUR SOLVENT’s  BOILING POINT...DO NOT GO THERE!!!

IF USING TANK NITROGEN (above 100 C) 

1.   On the 500, change over the black air line from the chiller to the bucket; turn

off the chiller.

2.  Turn on the nitrogen tank at about 60 lbs  (blue line)

                   Turn off the air – yellow lever                (off is perpendicular --  on is parallel)

                   Turn on the nitrogen – red lever

IF NOT GOING ABOVE  100 C   (or after NITROGEN  is on)

1.  Type   “temp”  on the command line, to bring up window.

2.  Select a temperature, using the slide bar (start with about 35 C)  hit “reset VT”

                   button, then turn the temperature control  “on”.

3.  Check to see that the VT  flow rate on the magnet leg is ~ 10

4.  Type “su” on the command line and wait for the beep.

5.  Watch the acqstat window.  It should say “status: VT regulation” on the top and the

                   “setting: 35 C” on the bottom and the “actual temperature”.

                   (the actual temperature can also be observed on the hardware box on the 400)

DO NOT TYPE ANYTHING ELSE.....WAIT FOR THE BEEP .... the beep means that it is stable, and it will say “setup complete” in the text window.

6.  Put in your sample in the normal way.   Lock and shim.

7. Always keep your eye on the lock level and the spinning in the acqstat   window

as this is the first sign something is going wrong.  If the sample  boils, the lock level will drop  out.  

8.  You can now slowly raise the temperature and take spectra.  Increase the  

          temperature on the slide bar.  Use increments of 15 degrees or so...wait until

          each temperature is achieved before you move the slide bar again.  You should

          give the sample ~10 min to equilibrate at a different  temperature, and you

          should re-shim.   At each  new temperature do “su” and wait for the beep before

          starting the spectra  (setup in GLIDE or ”ga” if you are running manually.)

9.  When you are done,  lower the temperature control bar by increments of 20.

until you are back to 25 C.  Leave the VT on!  When you log out the VT will

stay on at 25 C, even though you are logged out.   On the 400, you can come back  ½ hour later or more and turn off the temperature control in the TEMP window.

10.  If you are using NITROGEN quickly turn off the nitrogen tank and  then the red

                   nitrogen lever, put back on the air with the yellow lever,  on the 500 switch

back to the chiller, turn it on.