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The function and life of an ultralow-temperature
(ULT) freezer depend on proper usage and preven-
tive maintenance. Some elements of proper use
start at the very beginning of ownership and others
last until a ULT’s last days. However, getting them
all right ensures getting the best performance from
start to nish.
Some of the keys steps to using a ULT the correct
way only take minimal eort. Part of that is knowing
the right steps. “Having a checklist is a good thing
to do,” says Buckner Richardson, Vice President of In-
ternational Sales at NuAire. Those steps should lead
a lab manager to use a ULT as designed, and it all
begins with where it goes.
Freezer location
Proper usage starts with the placement of a ULT
in a lab. If the room is hotter than 90°F (32°C), it is
much too hot for a ULT. “This happens in laboratories
without air conditioning,” says Richardson, “and the
freezer cannot breathe.”
Respectable ULT manufacturers test how much
heat a ULT can endure. “The manufacturer puts an
air-cooled ULT in a room at 110°F (43°C) and tracks
performance until the freezer fails,” says Richardson.
“NuAire has had one such an occurrence with a ULT
operating in a high temperature environment for a
year, but they are designed for no hotter than 90°F
(32°C).”
Despite the guidelines that go with any ULT, buyers
still put some of the units in the improper location.
When it comes to placing a ULT where it’s too hot,
Richardson says, “that is a common mistake.”
The temperature is one part of placement, but there
is more. If there is more than one ULT in a room, it
creates even more heat, and the ULTs need space
for ventilation. That means following the manufac-
turer’s guidelines for spacing. NuAire, for example,
recommends clearance of 8 inches (203 millimeters)
above a ULT and 5 inches (127 millimeters) on the
sides and back. The NuAire guidelines add: “Avoid
side by side spacing unless a ULT freezer is located
in a specially designed freezer farm. There should be
no storage on top of a ULT freezer.”
If the options for placing a ULT cannot meet the envi-
ronmental requirements, water-cooled condensers
may be added. That can overcome some of the con-
straints. Even then, as many placement guidelines as
possible should be followed. At the very least, a lab
manager should keep a ULT out of direct sunlight.
Still, there are other aspects of proper use to consider.
Best Practices
From placement and power to racks and routines, it pays to use an
ultralow freezer right.
Mike May
