Proper storage of pharmaceutical and laboratory products becomes increasingly critical as the value of these products increase. The laboratory refrigerator plays a crucial role in protecting such products from degradation in development, manufacturing, and clinical use environments.
In these applications a household refrigerator should never be used as a
laboratory refrigerators. Lab refrigerators are designed and constructed to high standards, containing monitoring equipment that keeps track of internal temperature variations and signals when set parameters are exceeded. These refrigerators come in several sizes, the decision of which depends on the needs of the user.
Aside from size, purchasers of a
laboratory refrigerators should have an understanding of the types of refrigerators that are available.
One decision relates to purchasing a manual or an automatic defrost model. While one cannot dispute the convenience of an auto-defrost refrigerator, they consume more electricity to run the condenser and air recirculation fans. This can also cause samples to dry out unless they are protected in sealed containers. The continuous forced air circulation in auto defrost models maintains good temperature uniformity throughout the cabinet. However, minor temperature fluctuations do occur during the defrost cycle. Some models feature user-controlled auto-defrost whereby lab personnel can define the frequency and duration of the auto-defrost cycles and even shut them off completely if there is a need to maintain a constant temperature.
Refrigerant in manual defrost refrigerators passes through copper tubing in the walls, forming a “cold wall”. There is no fan to circulate the air, thus the temperature is lower near the cold wall than elsewhere in the cabinet. The cold wall also can result in condensation pooling at the bottom of the unit. This water can be removed by a defrost drain. Defrost cycles are set and controlled by lab personnel who should place temperature-critical contents into another cold storage unit during the operation.
Another important decision, one that might be overlooked but could result in severe consequences, is determining if a flammable laboratory refrigerator or an explosion proof lab refrigerator is needed.
A flammable lab refrigerator is absolutely essential to personnel and property safety when dealing with volatile vapors and gases. These units are designed to keep flammable vapors or gases from contacting internal ignition sources. These sources include compressors, thermostats, defroster timer housings and interior lights that can provide sparks to ignite vapors and gases. It is not unknown that these explosions can scatter refrigerator contents across the lab floor. The risk of injuring or perhaps killing anyone unfortunate enough to be in the way of such an event makes a strong case for specifying a flammable lab refrigerator when volatile vapors and gases are stored inside.
Explosion proof lab refrigerators are the solutions of choice when the laboratory environment surrounding the units may harbor flammable vapors or gases. This is accomplished by separating internal and external environments.
Another difference between flammable and explosion proof lab refrigerators is that the former can be plugged into a wall outlet but the latter must be hard-wired into the building’s electrical system
When making a choice between less-costly flammable safe and more costly explosion proof refrigerators the deciding factor is whether or not the atmosphere outside the unit is as hazardous as the environment inside.
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4 March 2010
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