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The operator should perform routine cleaning and maintenance. For maximum performance and efficiency, it is recommended that the unit be checked and calibrated periodically by a qualified service technician.

The following is a condensed list of suggested preventive maintenance requirements. Refer to the owner’s manual for specific details for each piece of equipment. Cleaning and calibration adjustment intervals are dependent on use, environmental conditions, and accuracy required.

• Fill an upright by starting at the bottom near the probe and add racks to one shelf at a time. Allow freezer to recover to set point between shelves.
• Fill chest freezer by starting at the left side near the probe. Filling with room temperature racks will result in long pull-down time.
• Fill the unit with frozen product to help overall performance, frozen water jugs, for example.
• Always make certain the vacuum relief port is free of frost and ice, to allow for timely re-entry into the freezer after a door opening.
• Unit needs space to breathe, 6” is a good general rule, could be less per the owner’s manual.
• Unit must be connected to properly sized and dedicated breaker.
• Inspect all probe ports, make sure they are sealed during and after use. Do not drill/screw the case in any way without consulting the manufacturer.

*Dispose of batteries properly through Environmental Health and Safety

**Dollar/paper test: Close freezer door on dollar bill or piece of paper. If door seals properly, you should have difficulty removing the dollar or paper. If it is easy to remove paper, the gasket may need to be replaced.

To minimize ice build-up inside of freezer:

• Locate the freezer away from drafts and heating/cooling units.
• Keep the number of door openings to a minimum.
• Minimize the length of time door is open.
• Make sure the door latches securely after opening.

Read your owner’s manual and follow the steps recommended by the freezer manufacturer.

The recommendations below are only basic guidelines.

• Remove all contents and transfer to alternate ULT.
• Following the manufacturer's instructions, turn the unit off and disconnect from power.
• Turn off the battery switch (back-up battery).
• Check owner's manual to determine whether the unit has a drain.

Whenever possible, move ULTs to a location with a floor drain. This provides a safe path for the water to drain. If ice is allowed to melt in a lab without a floor drain (or other precautions), areas located below the lab may receive water damage

Check defrosting ULTs periodically, at a minimum every 2 hours while ice is present

For chest freezers, open the lid and remove the sub-lids. If there is ice build-up on the sub-lids, place on towels.

• If there is no drain, place towels on the chamber floor and along the hinge.
• If there is a drain, place a pan under the drain and open the drain.

For upright freezers, open the outer and all inner doors.

• If there is no drain, place towels inside each compartment.
• If there is a drain, place a pan under the drain and open the drain.

Allow the ice to melt and become loose. Loose ice can be placed in a sink or pan to melt. DO NOT REMOVE ICE USING A SCREWDRIVER, ICE PICK, OR SIMILAR DEVICE.

Do not dispose of ice in biohazard waste. If concerned about biological contamination, decontaminate per biowaste management guidelines.

• Use secondary bin to catch water as ice thaws in an upright freezer.
• Safety staff can supply cotton rags to help absorb water in the freezer.

Allow ULT to defrost for 24 hours. This allows both the interior and refrigerant system to warm to room temperature. Continue to check on melting ice, and ensure the water is contained and soaked with towels or other absorbents.

Once ULT is at room temperature, clean with a mild soap solution or a solution of sodium bicarbonate and warm water. Bleach is often not recommended for freezers that will be kept in service. However, if used, follow with a soap and water solution.  Rinse with clean water and dry with a cloth or towel.

• NOTE: For disposal, use bleach for decontamination of biological materials.

Close the door/lid of the ULT and restart the freezer. Allow it to come to temperature before reloading with your contents (some manufacturers recommend 24 hours).

If you have valuable and/or irreplaceable materials that rely on the mechanical equipment to maintain appropriate temperature, then you should install a monitor or alarm. There are two types of monitor/alarm systems in use at �պ����� that alert lab personnel to storage conditions that exceed lab-defined parameters. Either can be used for freezers, refrigerators, LN2 dewars, warm rooms and other equipment and space.

1. Sensaphone: are installed by �պ����� Physical Plant. Submit a Planon Service Request. This system uses �պ����� network connection, which labs may need to pay to be installed and/or activated. There is an initial purchase price as well as costs for PPD to install. PPD does not respond to these monitors/alarms.
2. Minus80: is a system used in several institutions around the country. They provide monitoring and alert services that are customized to each lab's need. These systems report temperature fluctuations over time as well as alerts for temperatures that exceed a given range. Minus80 personnel monitor alerts along with lab personnel. These systems communicate using Minus80 telecommunications equipment. Labs pay an initial purchase cost as well as monthly service charges. Contact Minus80 for more information or to set up this service.

Consider the materials you are storing by following the flowchart in the dropdown below.

Flammable liquids that require refrigeration must be stored in a refrigerator or freezer especially designed to prevent flammable vapors from igniting.

• Never store flammable liquids in domestic refrigerators or freezers.  Explosions, injuries, and costly laboratory fires can result.
• Never store flammable materials in household appliances (Kenmore, GE, Amana, etc.)
• If a flammable material refrigerator or freezer is needed, purchase one that is U.L. listed, intrinsically safe, and specifically labeled for “flammable materials storage.”  A flammable liquid is defined by the fire code as having a flash point of less than 100 degrees Fahrenheit/38 degrees Celsius.
• Ultra low freezers (less than -40 degrees Fahrenheit) generally cannot be approved for storing flammable materials.
• Do not purchase an “explosion proof” unit. These are unnecessary and costly.

The staff of a biomedical laboratory in the Colchester Research Facility were given an unexpected demonstration of what can happen when flammable liquids are stored in household refrigerators. They came in one morning in June 2000 to find their laboratory in disarray.

Their first impulse was to call the �պ����� Police to say that their lab had been vandalized. However, as they examined the situation more closely, they observed that the doors to the laboratory were locked, and the damage was centered around the laboratory refrigerator.

Then, they remembered that they had stored about 100 mL of isopentane in the refrigerator the day before in an unsealed container.

Inside the refrigerator was also the thermostat that controlled its motor - a source of ignition if a flammable atmosphere developed inside the refrigerator.

Evidently, the fumes from the isopentane built up until the thermostat gave a spark and the whole refrigerator exploded.

The contents of the refrigerator were spewed across the lab.

The refrigerator itself bounced off the wall it was placed against and rebounded into the room.

The force of the explosion was strong enough to open the flammable storage cabinet across the lab.

Debris was found throughout the lab, although much of it did not break.

Fortunately, the materials in the refrigerator did not include acids and bases which could have done chemical as well as physical damage where they landed.

Some equipment, such as this incubator, was severely damaged by the shock wave of the explosion.

Even the ceiling tiles in neighboring rooms were affected.