Ultra-low temperature (ULT) freezers are crucial for storing a laboratory’s most precious asset: samples. Freezer failure can be devastating, as compromised temperature control can destroy years of work and threaten future experiments. Innovative technology offers reliable and efficient solutions for ULT storage. Choosing a reliable and efficient unit ensures samples are safe, and saves on operating costs allowing scientists to invest in their research.
The History of Reliability
The innovative technology driving modern freezers was conceived over 200 years ago by Robert Stirling, and patented as the Stirling engine in 1816. After decades of development in the modern era, the free-piston Stirling engine design was perfected by Stirling Ultracold, the only ULT freezer manufacturer that offers this alternative technology designed to deliver reliable, efficient, high-performance cooling. Compressor-based ULT systems are designed with numerous moving parts, each with the potential to fail. The free-piston engine design has far fewer moving parts, eliminating failure modes that are known to shorten the operating life of traditional systems. The unique free-piston Stirling engine design features no mechanical linkages, with only two moving parts supported by gas bearings that eliminate contact friction and prevent wear. Unlike start-stop characteristics of compressor technology, the free-piston Stirling engine operates continuously with adaptive control, eliminating surge currents and other potential points of failure. Valves, oil, and lubrication requirements are also eliminated, resulting in a robust solution.
Superior Energy Performance Delivers Long-Term Savings
Budgetary constraints are ubiquitous among laboratories. Often overlooked is the total cost of ownership of a particular piece of equipment. A standard compressorbased ULT freezer requires about the same amount of energy as an entire US household and operates continuously. This is a significant energy cost for laboratories and facilities with numerous ULT freezers operating at all times. As such, even a low initial investment may be offset by high operating costs. Standard compressor-based freezers also release large amounts of heat into the surrounding room environment, increasing HVAC demands and further contributing to the ongoing cost of operation.
Without standards for direct comparison, identifying the most energy-efficient freezer was once a difficult task. The newly developed industry-standard Final Test Method and Environmental Protection Agency (EPA) ULT freezer category allow buyers to compare manufacturers and identify ENERGY STAR® certified models. Stirling engine technology delivers excellent efficiency, and their upright model received the industry’s top ENERGY STAR®-certified rating.
In addition to lower operating costs, energy-efficiency reduces the operating carbon footprint of equipment and supports sustainability initiatives. There is still room for improvement on the sustainability front; however, as most freezers require harmful refrigerants that are potent greenhouse gases, including chlorofluorocarbons. Fortunately, newer options are available and do not require harmful refrigerants, relying instead on natural hydrocarbons, which have a dramatically lower global warming potential.
The Functionality Your Laboratory Requires
Following reliability and cost considerations, several other factors can be used to assess the functionality of a ULT freezer to find the appropriate solution for a laboratory.
Compressor-based ULT freezers require routine system maintenance to ensure optimal performance and operating life. Maintenance may be costly, and the associated downtime can interfere with the flow of daily operations. Even with regular maintenance, compressor-based freezers are not designed for longevity. Alternatively, freezers with free-piston Stirling engines require minimal routine maintenance as the gas bearing design prevents wear and uses no oil in the system, ensuring safe samples for years.
Laboratory space is an asset, and must be allocated to facilitate efficient workflows and ensure safety. As samples accumulate, freezer space is at a premium, and in some cases an additional unit is required. Opting for a well-designed freezer ensures maximum sample storage in a given amount of floor space, and may eliminate the need for an additional unit. Because the Stirling engine cooling system is much more compact than compressorbased systems, leaving more cabinet space for storing samples, up to 50 percent more storage capacity is available in the same floor space area when compared to traditional ULT models. This storage density advantage can be even greater if high-density storage racks are used.
The benefits of versatile equipment are clear. Projects evolve, applications change, and flexible equipment supports new endeavors. ULT freezers may be required for long-term sample storage; however, various applications necessitate higher temperatures. Freezers that offer a wide cooling temperature range are an adaptable solution, another advantage of the Stirling engine alternative with its -86°C to -20°C capability.
Reliability, efficiency, storage volume, and total cost of ownership are the key features of a ULT freezer. Opting for a unit that incorporates the free-piston Stirling engine with maximum sample storage space per square foot will offer reliability and energy savings. The future of your research depends on properly stored samples. Keep your valuable assets in a freezer that delivers reliability, efficiency, and most importantly, peace of mind.
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