Taylor-Wharton LABS Series - Manual (Page 10)

WARNING:
When working with
Liquid Nitrogen,
make sure to
observe all safety
guidelines and wear
the appropriate
safety gear to avoid
personal injury,
asphyxiation and
possibly death.
8
LABS
Initial Fill
The LABS Cryostorage System comes preset for vapor phase storage from the
factory. The liquid nitrogen supply pressure at the inlet to the refrigerator should be
in the range of 10 psig (0.7 bar/69 kPa) to 22 psig (1.4 bar/152 kPa) for optimum
performance. Higher operating pressures will increase transfer losses and create
excessive turbulence of the liquid in the refrigerator which can generate false signals
to the liquid level controller causing the refrigerator to under fill. In “liquid phase”
storage applications, excessive turbulence can cause splashing which could result in
personal injury.
Operating Parameters
When materials are immersed in liquid nitrogen, they will assume the temperature
of the liquid (-196ºC/-320ºF). When material is stored in the vapor phase over the
liquid, the liquid nitrogen is still a very cold refrigerant, but the refrigerator’s interior
temperature increases somewhat as product is stored higher over the liquid. This
temperature differential is not significant in many biological storage applications,
and is affected by the amount of product stored in the refrigerator, the type and size
of inventory control system, and the liquid level in the unit.
Liquid Phase Storage
Liquid phase storage is normally utilized when liquid nitrogen temperatures are
required to maintain stored product viability and the storage medium is adequate
for storage in liquid nitrogen. To reconfigure the system’s setting for liquid phase,
review the operating instructions for the specific controller you have selected to use
with your LABS unit.
Thermocouple Positioning
The thermocouple is a separate sensor used to monitor and control the temperature
within the refrigerator. The factory-supplied thermocouple in most of the LABS
Cryostorage Systems is positioned to monitor the temperature 1.75 in. (44.45 mm)
below the top of the carousel.
Adding an Inventory Control System
The purpose of the inventory control system is to bring order to the storage of many
small samples, and to allow direct retrieval of the particular sample you need at any
time. It is important to be aware that when you lift an ICS rack from the refrigerator
it is being moved to a warmer environment. Learn to locate your sample quickly to
avoid unnecessary warming of your stored product. Keep ICS inserts (drawers or
boxes) and dividers in good repair. Replacement inserts and dividers are available
from your Taylor-Wharton distributor to keep your system as efficient as possible.
Always wear gloves when handling ICS racks or stored product, as they are very
cold. Read all of the precautions in the Safety section of these instructions and in the
Taylor-Wharton publication TW-10 “Handle With Care” for more detail on handling
product stored in liquid nitrogen.
When removing ICS racks to retrieve product, protect the labels, plastic, and electronic
areas of the refrigerator from liquid nitrogen that may spill from the rack inserts. These
parts of the refrigerator are subject to damage from the extreme low temperature of the
refrigerant.
Do not let ice or debris collect in the bottom of the freezer. Schedule periodic clean
out if racks no longer stand upright.
WARNING:
If the fill fails to
stop for any reason,
quickly close the
liquid supply valve
to prevent overfilling
until the cause of
the problem can be
determined.
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