8 | Installation
Controlled Rate Freezer
Installation
Selecting a Location
A six foot liquid nitrogen transfer hose with 1/2" flare fittings is
supplied with the unit. The use of a transfer hose longer than
six feet may degrade system performance as it may prevent
liquid nitrogen from reaching the unit in the volume needed to
properly control the temperature profile run.
The unit should be located within the reach of the transfer
hose to the liquid nitrogen supply, allowing enough space for
source tank replacement. A gauge to measure the remaining
contents in the source tank should be easily viewable and
read before each run to ensure that enough liquid nitrogen is
available for successful temperature profile completion.
A dedicated source tank is recommended for optimum
performance.
Unit should be located in a well-ventilated area of the
laboratory. Place the unit on a table/bench which is capable
of supporting the unit’s weight (see
), with adequate
workspace available. Allow clearance for the door on the front
of the unit, for the hose and power connections on the back
and the exhaust vent on the left side of the unit. Refer to
for rear side connections.
Behind the electronics housing is a 1/4" OD overflow drain
tube from the drain pan placed under the inlet solenoids.
Although most of the frost will melt and evaporate within the
drain pan, it is possible that a small amount of water may drip
out of the drain tube.
Figure 3. Rear view of the unit
WARNING:
Nitrogen gas can cause suffocation
without warning. Store and use liquid nitrogen
only in a well-ventilated place. As the liquid
evaporates, the resulting gas displaces the
normal air in the area. (The cloudy vapor that
appears when liquid nitrogen is exposed to the
air is condensed moisture, not the gas itself. The
issuing gas is invisible.) In closed areas,
excessive amounts of nitrogen gas reduces the
concentration of oxygen and can result in
asphyxiation. Because nitrogen gas is colorless,
odorless, and tasteless, it cannot be detected by
the human senses. Breathing an atmosphere that
contains less than 19.5% (or) 20% oxygen can
cause dizziness and quickly result in
unconsciousness and death. Therefore, the use
of oxygen monitoring equipment is strongly
recommended.
WARNING:
Contact of liquid nitrogen with the
skin or eyes may cause serious (freezing) injury.
CAUTION:
Use proper 2-person lifting
techniques when handling the unit (refer to
Specifications section for approximate unit
weight.
WARNING:
Do not block nor tamper with the
exhaust vent opening! Provide ample clearance
around the exhaust vent to allow the gases to
escape freely, otherwise an increase of gas
pressure inside the chamber will forcibly open the
door possibly causing damage to the unit and
risking sample integrity.
CAUTION:
If moisture cloud is seen exiting the
drain tube, turn off the unit, shut off the liquid
nitrogen supply source valve, and immediately
call for service.
Fan
PC Interface (RS232)
Power Inlet
Remote Alarm
Safety Valve
LN
2
Connection
Drain Tube