POST 00416E : FREEZE PROTECTION IN VACCINE REFRIGERATORS 21 January 2002
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Carib Nelson Technical Officer at Program for
Appropriate Technology in Health (PATH) is requesting your opinions on
freeze protection in refrigerators. Please send your input to both Carib
and Technet.
_______________________________________________________________________
In considering ways to reduce inadvertent cold chain freezing, some
refrigerator manufacturers are considering putting heating elements in
their vaccine refrigerators that would automatically turn on when the
internal temperature approaches freezing. This approach could keep vaccines
safe in situations where ambient temperatures within health centers fall
below zero.
If this could be combined with better controls where the refrigerator will
not cool when its temp is below 1°C--regardless of what the operator sets
it at--we might have a freeze-proof refrigerator. Obviously this is not a
fix for protecting vaccines from freezing during cold-box-with-ice-pack
transport.
We are seeking input on the heating element approach, specifically:
1. Are freezing temperatures within health centers, or wherever
refrigerators may reside, a common occurrence? (or is it improper
thermostat adjustment that causes most refrigerator freezing)?
2. What minimum temperatures should we try and protect against with this
approach -- keep in mind that these would be minimum temperatures in health
centers, or where ever the refrigerator sits, not minimum ambient
temperatures.
3. Could we come up with a specification for freeze protection
("refrigerator must maintain internal temperatures of not less that 1°C
when refrigerator is placed in -10°C environment for 48 hours....")? We are
not going to save the vaccine during a 2-week power outage in Siberia in
December, but if we could describe the more common scenarios of low
temperature exposure, manufacturers may be able to take steps to provide
some protection.
Thanks for your input.
Carib Nelson
Technical Officer
Program for Appropriate Technology in Health (PATH)
4 Nickerson Street, Seattle, WA 98109-1699 USA
Telephone: (206) 285-3500; Fax (206) 285-6619
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