Lab refrigerators and freezers are arguably the most common appliance in laboratories. Lab units are similar in construction to household refrigerators and freezers, and come in a variety of temperature ranges, shapes and sizes.
Freezer and refrigeration options fall into four general temperature categories: +4ºC refrigerators for chromatography supplies, blood storage, and pharmaceuticals; -20ºC (and below) freezers for enzymes and biochemicals; -30ºC to -40ºC for biological samples, and -80°C freezers for longterm storage and stability. Units range in size from under-counter systems as small as 3.6 cu. ft., to standalone chests as large as 70 cu. ft.
Upright models have a front-opening outer door and multiple compartments. Most also have inner doors, so that when one compartment opens cooled air does not escape from the unopened compartments. These systems also tend to be vertically-oriented and occupy less floor space than chests.
Chest style systems have a top-opening lid, one large compartment, and are generally about half the height of uprights. Because warm air rises and colder air falls, chest freezers will generally not experience as much of a temperature swing when the lid is opened as uprights. The disadvantage is that they take up more floor space and samples are not as accessible as with an upright.
Choices and trends
After considering temperature capabilities, capacity and footprint, choosing among lab refrigerators and freezers often reduces to secondary or subjective criteria. Eye-level controls, mechanisms to prevent door freezing and/or vacuum pressure build-up, space-saving insulation, automated data recording, alarms, digital temperature control, rapid temperature recovery after door openings, temperature uniformity throughout the box, and condition monitoring are differentiators. “But the reality,” says Dan Hensler, VP of sales and marketing at So-Low Environmental Equipment (Cincinnati, OH), “is that aside from temperature range, vendors offer pretty much the same features.” Purchase decisions often come down to brand name recognition, perceived reliability, price and availability. Intangible factors such as a history with a particular vendor, the manufacturer’s perceived understanding of a group’s workflow, and the ability to follow up with helpful advice without over-selling, also come into play.
Tamper-proof temperature logging and recording are desirable features for regulated industries and those called on to testify in court. Thermo Fisher Scientific (Marietta, OH) plans to offer a wireless recording/logging option in 2010, but companies have been slow to adopt such equipment due to difficulties in changing established SOPs. The traditional chart recorder is still the industry standard for temperature monitoring despite its manual requirement for frequent paper and pen changes. However, most industries are moving toward electronic temperature monitoring.
One notable development in refrigeration has been the emergence of cold storage to support vaccine work, particularly for H1N1 influenza vaccine storage. “We’ve been deluged over the last few months with requests for vaccine-worthy refrigerators,” Hensler told Lab Manager. H1N1 vaccine is stored within a narrow temperature range (35ºF to 46ºF), and health agencies mandate twice-daily temperature measurements.
Kitchen units and retrofits
Many labs use kitchen refrigerators from home appliance stores to store very low-risk laboratory materials, for example biological buffers, dried plant material, animal feed, or dilute acids or bases. But kitchen units are designed for low-traffic use and lack the precise temperature control and refrigeration capabilities of lab-designed units. Several vendors have nevertheless made a business of refurbishing and retrofitting home-appliance cooling chests for labs. Common upgrades include alarms, controllers, door locks and special shelving.
Thermo Fisher Scientific offers both laboratory-designed refrigerators/ freezers with upgraded insulation and compressors, and retrofitted kitchen-designed units. Explosion- and fireproofing are also common retrofits. Retrofit refrigerators are quite common for storing flammable or volatile organic compounds, says Gordon Shields, director for cold storage at Thermo Fisher.
Cool, green and validatable
Energy efficiency has become a key driver in refrigerator/freezer purchase decisions. Many vendors, including Thermo Fisher Scientific and New Brunswick Scientific (Edison, NJ) have been working with the U.S. Environmental Protection Agency to establish industry-wide Energy Star standards for lab refrigerators and freezers, which surprisingly do not yet exist. Beginning in late 2008, vendors began submitting energy efficiency and performance data to EPA, from which the agency will eventually issue guidelines for the coveted Energy Star designation. Energy consumption for “always-on” appliances is a serious concern for large organizations like pharmaceutical companies and universities.
“The key is to reduce overall energy usage while maintaining performance,” Shields commented. “Due to their heavy usage, lab refrigerators and freezers will never be as energy efficient as units purchased for the home, but we are hoping to achieve a 15 to 20 percent energy savings compared with existing models. That can mean a lifecycle energy cost saving of $1,500 for a lab refrigerator and $2,500 for a freezer.” And, when it comes to ultra-low temperature (ULT) freezers, the energy and cost savings can be even greater. Ted Andrew, product manager at New Brunswick Scientific, says that their energy-efficient design can save up to 45 percent in operating costs over competitively sized models, which translates into up to $3,000 in energy savings over the lifetime of a single freezer.