Deep freezers are the testing equipment that are used to preserve and store food products, medical equipment, blood samples, medicines and injections, etc. for a long period of time. Deep Freezers are used for industrial purposes as well as for household purposes. Moreover, deep freezers are also used in restaurants and supermarkets to preserve the raw food for a long period of time. There are numerous types of deep freezers such as blood bank refrigerators, freezer drier, ultra-low deep freezer, deep freezer vertical and many more. These devices are available in different sizes and shapes sometimes it is designed with compact designs and sometimes with regular designs. The specifications and functions of the instruments varies as per the requirements of the test application.

What is Meant by Ultra-Low Temperature?

There are freezers, low-temperature freezers and ultra-low temperature freezers on the market.

Here are some examples that apply to scientific (not commercial or household) freezers.  Note that different manufacturers may define the temperature capabilities of their various models differently.

  • Scientific laboratory and pharmacy freezers can control ranges from -10⁰ to -25⁰C (+14⁰ to -13⁰F)
  • Low temperature freezers depending on the model and function: to – 25⁰, -35⁰ or -40⁰C (-13⁰, -31⁰, -40⁰F) minimum, also with a user-controlled range
  • Ultra-low temperature freezers control temperatures down to -86⁰C (-186.5⁰F) also with precise temperature control

Remember:  Colder is Not Always Better

Base your decision on the recommended storage temperature for what you put in your freezer.  Our next section provides some examples.  But keep this in mind:

Just as with your room or central air conditioner, a colder setting means a higher power consumption.  But don’t stint:  the most important consideration is the proper storage temperature of the contents.  Keep in mind as well that when you access the unit you allow ambient-temperature air to enter.  We’ll get into that later.

How the Deep Freezers work?

Mechanical or single compressor based freezers can easily reach the temperature range -40 degree Celsius or -50 degree Celsius. Apart from that a freezer which is equipped with two compressors are used to create the temperature below the mentioned limit. To utilize the efficiency of the compressors and to extend the life of the compressors, the small compressors automatically get turn off whenever the set temperature is reached whereas the big compressor should remain On continuously for maintain the consistency in temperature.

Typical Applications for Ultra-Low Temperature Freezers

Use of Ultra low Deep Freezers in Medical Laboratories

For storing Blood Samples and Medical samples 

The Ultra-Low Deep Freezers are widely used in medical laboratories and for industrial purposes to store chemicals, bloods, tissue cultures, and other medical samples that can only be stored and preserved in low temperature range. It is quite obvious that no medical samples & chemicals can be stored in high-temperatures and chemicals. These freezers are totally different from the regular freezers as they do not maintain constant temperatures but these devices helps to set different temperatures as per the test requirement. The temperature range of deep freezers can be set between 0 to -10 but the temperature of the freezers that are used in laboratories and medical industries can be set up to -60 degree Celsius.

Helps to Preserve Medicines to prevent them from Spoilage

Apart from preserving blood samples, they are used to preserve medicines and prevent the medicines from spoilage. These deep freezers are also known as Medical Refrigerators that are used to preserve stem cells of newly born baby for many years that can be used to prevent them from diseases in future.

Enhance the life of injections and Vaccines 

Ultra Low Temperature Deep Freezers are used to enhance the life of the vaccines and injections.

As to more specific examples of the above, ultra-low temperature freezers are used to store biological samples such as DNA/RNA, plant samples and insect artifacts, autopsy materials, blood, plasma and tissues, chemicals, drugs and antibiotics.

Manufacturing firms and performance testing labs use ultra-low temperature freezers to determine the ability of products and machinery to perform reliably under severe low temperature conditions such as found in Arctic and Antarctic regions.

These myriad applications suggest that ultra-low temperature freezers may house multiple and different experiments, some of which may require frequent checking while others remain undisturbed for lengthy periods of time.  And in fact if they do, this becomes a feature that can be applied to your selection process.

Five Tips to Extend the Life of a ULT Freezer

Used to store precious, often irreplaceable samples, ultralow-temperature (ULT) freezers are an essential workhorse of laboratories worldwide. When used and maintained properly these specialist units typically provide 10–12 years of highly reliable service, but to get the best out of them it is important that they are treated with respect. This includes locating them wisely, ensuring they are provided with a power supply of the correct voltage, and performing essential preventive maintenance functions to keep them running optimally. We spoke with Adam Christensen, technical support/service trainer at NuAire, who shared with us his expertise in ULT freezer preventive maintenance.

“For maximum performance and efficiency, it’s recommended that a ULT freezer is checked and calibrated periodically by a qualified service technician,” he says. “However, regular cleaning and maintenance is relatively straightforward and can easily be performed by the end users. We suggest adopting a number of simple practices to extend freezer life. By making these routine it’s possible to detect and correct any potential sources of failure in timely and efficient manner.”

Minimize frost or ice build-up

“Although gradual formation of frost or ice within the inner chamber is inevitable, this can be kept to a minimum,” explains Christensen. “The room in which the unit is situated should have an ambient temperature no higher than 32oC, while exposure to direct sunlight and drafts or heating/cooling vents should be avoided. It’s also important to provide suitable spacing around the unit for effective ventilation.”

Further steps to lessen frost or ice build-up include minimizing the number and duration of door openings and checking that the door latches securely upon closure. “Periodic removal of frost or ice build-up from the door gaskets and inner chamber can be achieved by scraping,” notes Christensen. “The vacuum relief port should also be cleared regularly.”

Defrost the chamber regularly

“We recommend fully defrosting the chamber at least twice a year depending on usage and environmental conditions,” says Christensen. “This involves transferring all contents to another ULT freezer, switching off the unit, then wiping it out with a non‐chloride detergent once it has defrosted. This can be a good time to inspect door gaskets and make sure they seal properly, to clear out old stock, and to re-organize existing samples to maintain correct airflow and afford better accessibility. The unit should then be allowed to operate empty overnight before being reloaded.”

Keep the condenser clean

By transferring heat from inside the ULT freezer to outside, the condenser has one of the most important roles to play in ULT storage. Christensen explains that dust accumulation on the condenser filter can compromise its performance, adding that the condenser coil also requires regular preventive maintenance. “We suggest cleaning the condenser filter every two to three months, more frequently if the environment is particularly dusty, and the condenser coil at least once a year,” he notes.

Wipe down the door gaskets

“If frost and ice build-up isn’t removed from the inner and outer door gaskets, they can tear,” says Christensen. “This compromises the performance of the unit. Leaks are usually indicated by a streak of frost at the point of gasket failure, but by wiping down the gaskets with a soft cloth at least once a month, tearing can be avoided. Furthermore, frost and ice build-up around gasketing can wear out the outer door latch since it makes it hard to close the door.”

Understand freezer alarms

ULT freezers are often fitted with alarms to indicate a variety of sub-optimal operating conditions. These can include high temperature, power failure, low battery life, prolonged door opening, and system monitoring failure. According to Christensen, knowing what the different alarms mean facilitates swift remedial action. “It is imperative that alarms are not ignored and that a plan of action is in place for situations that require operator input. This includes labeling each freezer clearly with the details of a point of contact and back-up contact and having spare ULT freezer space available should there be a need to transfer samples to an alternative unit.”

Freezer alarms will still occur during a power outage since the display and buzzer are powered by a battery. Christensen says this should be replaced by a certified technician every 2.5 years, when the battery timer will also be reset. “The battery life of NuAire freezer alarms can be checked by entering the function code menu, however it is sufficient to simply have the battery replaced once the 2.5 years expires and the light is illuminated,” he adds. “Checking the battery timer in the function menu can be incorporated into routine cleaning and maintenance schedules to provide end users with additional peace of mind.”

A wide range of ULT freezers are available, yet they all have one thing in common—they require care and attention to keep them performing at their best. Just a few simple preventive maintenance steps will ensure the longevity of sample material while maximizing the lifetime of these vital pieces of equipment.

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