VICI NP2 - Manual (Page 4)

3
Installation and Operation
This procedure describes a chromatographic installation. Although that is not
the only possible application, it is the most common. It is up to the user to
determine whether the purifier is suitable for a particular application based
upon the specifications of the purifier.
Installation
The Valco HP2 and NP2 are two part systems comprised of the purifier and
the power supply. The purifier must be installed in a vertical position to
eliminate the possibility of channeling. For best results, do not modify the
fittings or tubing lengths; small particles which might be generated by such
modifications are difficult to remove and can restrict the flow.
1. Connect the input line (tagged INLET) to a carrier gas cylinder with a
high purity regulator. (Save the caps to seal the purifier whenever you
remove it from the system.)
2. Purge the system for 15 to 30 minutes at 20 to 30 mL/min to eliminate
air from the getter material.
CAUTION: The getter material should never be heated
when air is present.
3. Connect the barrel connector of the power supply to the purifier.
4. Connect the power supply to mains (115/230 VAC). The LED on the
power supply should come on to confirm power output.
5. Connect the purifier output line to the chromatographic system’s carrier
gas input line using a 1/16" union (Valco Product Number ZU1).
Activation
When the purifier reaches operating temperature (usually in about 2½
hours) the getter will be activated. Once the getter is activated, active
gaseous impurities such as H
2
, O
2
, H
2
O, CO, and CO
2
(plus N
2
for the HP2)
are captured and chemisorbed on the getter surface. Only noble gas atoms
are not affected. Once adsorbed, oxygen, carbon, and nitrogen atoms
cannot be released by the getter material even at its melting point (1400°C),
due to the formation of strong chemical bonds with the alloy atoms.
Hydrogen atoms behave quite differently, diffusing into the getter material
bulk more quickly than the other atoms and becoming almost uniformly
distributed within the bulk. However, hydrogen sorption occurs below 250°C,
achieved through the temperature gradient of the trap assembly.