The equipment in nearly every lab includes an appliance to keep things cool. That almost
always includes a refrigerator, probably one with a freezer section. Many labs also use dedicated freezers that can keep samples even colder. If there’s one key characteristic that unifies this disparate collection of cooling devices, it’s that they all need maintenance.
In fact, the need for more maintenance in lab refrigerators and freezers might be an epidemic. When asked which maintenance for lab refrigerators and freezers is neglected most often, Allison Paradise, CEO at My Green Lab (Los Gatos, CA), says, “All maintenance is neglected.” Although she says that with a smile, she means it.
Much of that maintenance depends on getting off to the right start. Paul Foote, energy efficiency/ conservation specialist at the University of Illinois at Urbana-Champaign (UIUC), says labs should “properly install the unit for good ventilation and cool operating temperature.” Then, all along the way, he recommends “managing the samples and keeping the unit clean inside and out.”
For the most part, maintaining a fridge or freezer is not difficult. It’s just a hassle and not always convenient. Plus, few labs make it a priority, but more should.
Caring for the coils
“Lab freezers should be regularly maintained by vacuuming the outer condenser coils,” Paradise explains. How do you know when it’s time to vacuum the condenser coils? It is probably now. A somewhat more scientific answer is that the coils should be free of dust and anything else that blocks the intended heat exchange.
So, why do so many coils look so filthy? “Very few labs vacuum the condenser coils, as most don’t know that this is something they are supposed to do,” Paradise says.
And when it comes to refrigeration, that coil cleaning is really all you need to do. As a University of California (UC) HVAC technician says, “For the refrigerator, not much is needed in terms of maintenance except making sure that the condenser coils are clean.” With dirty coils, a cooling unit just won’t work as designed. “When the coils are full of dust and grime, it costs energy and reduces [the] life of the unit,” says Brian Jacobson, assistant director of the food and bioprocessing pilot plant at UIUC. So, a little cleaning goes a long way in a lab’s cooling needs now and over time.
Don’t delay defrosting
Some scientists, says Paradise, believe a buildup of ice in a freezer is good, providing insulation. It’s not good. “Freezers run most efficiently in the absence of ice buildup,” she says.
The UC HVAC tech notes, “For a -20° C freezer, just make sure that there is no more than one-quarter inch of ice buildup.” For more than that, he recommends a 24-hour shutdown for defrosting and making sure that everything is dry before a restart.
A -80° C freezer takes more maintenance. In addition to defrosting, the filter media should be removed and washed every three months. When the UC HVAC tech looks at those freezers, he finds that “the filter is usually completely plugged, and there is so much ice buildup that it is difficult to close the door.” As he says, “There should only be frost on the inner door, and it needs to be scraped off every few days.”
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