25
TRANSFERRING SAMPLES FROM THE MIXING CHAMBER TO THE
NMR CELL
With the sample now over pressurized to expand to fill the NMR cell internal volume,
what remains is to apply sufficient pressure to the piston such that the sample is
displaced from the mixing chamber into the NMR cell when the OUTLET / INLET
valve is opened. The following steps outline the procedure.
(1) Preset the NMR cell valve. The needle in the NMR cell valve displaces volume
during actuation. Thus the valve must be opened to the same position each time to
assure the internal volume matches the over pressurizing ratio from the previous
section. To set the position close the NMR cell valve until just snug, then open the
valve (counter clockwise) two full turns, then close (clockwise) one full turn. Be sure
to use the transfer tube provided as its internal volume is included in the over
pressurizing ratio. Connect this tubing between the NMR cell and the
OUTLET /
INLET
valve.
(2)
Open
the
PISTON BOOSTER
and
HP ALKANE TO BOOSTER
valves.
Be
sure the HP ALKANE valve is closed before performing this operation
otherwise the sample will be pushed back into the syringe pump.
This allows
the syringe pump to pressurize the piston. Increase the pressure on the piston to
2000 psi above the encapsulation pressure (this is not the current mixing chamber
pressure) or equal to the over pressurization pressure, whichever is higher.
Close
the
HP ALKANE TO BOOSTER
valve after the target pressure is reached. The
piston is now set for transfer.
(3) Reset the syringe pump pressure to the encapsulation pressure of the sample.
This is not the over pressurization pressure.
(4) Perform the sample transfer by actuating valves according to the following
(Refer to Figure 14):
i)
Open
the
OUTLET / INLET
valve; wait for two seconds.
ii)
Close
the
PISTON BOOSTER
valve.
iii)
Open
the
HP ALKANE
valve to equalize the system pressure.