Medical Equipment Blog

Key Features of Laboratory Freezers

Wednesday, December 14, 2011

What features are built into laboratory freezers to ensure that the temperature remains constant throughout the entire interior storage space?
Unlike standard freezers used in homes or for non-laboratory or medical types of uses, warmer and colder sections of the interior a huge concern. Laboratory freezers require standard temperatures throughout the entire freezer to ensure proper storage of specimens, samples and required chemicals and compounds. Slight variations in temperature can be devastating to the storage of these types of materials and supplies.

Freezers that are rated for commercial laboratory use are designed and constructed with uniform cooling and constant temperature maintenance in mind. This includes the use of cutting edge insulation and design technology that limits the heat from the environment negatively impacting the performance of the cooling system. Increased insulation in the walls and doors of the laboratory freezer provides additional temperature control as does the specific technology used to maintain the internal temperature.

Microprocessors are used to allow the cooling unit to adjust to any changes in the internal temperature of the freezer. The cooling is also completed using either evaporative cooling or convection type cooling that eliminates the need for fans or blowers that create colder locations within the freezer unit. Finally, each lab freezer is thoroughly tested prior to shipping. The unit will come with a pull down graph of the test at the manufacturer which provides all the information about that specific unit, not general manufacturer or style performance information.

Do the freezers that mount under an existing counter require any specific clearance for air circulation around the unit and if so, how much?
Most of the new models of under the counter freezers are designed to be set for standard size countertops of 34.5 inches. However, they can also be used as stand alone freezers and will sit nicely at the end of a counter or workstation and can be used to expand the storage area. The zero-clearance feature means that there is no requirement for a specific amount of space to be maintained around the unit to provide air circulation for efficient operation of the cooling unit.

The standard height of a under the counter type of lab freezer is approximately 33.5 inches in height with a width of just under 22 inches and a depth of approximately 24 inches. This is all consistent with standard work stations, workbench or countertop measurements used in labs, clinical settings and medical facilities.

How are laboratory freezers defrosted and what specialized equipment is needed?

Since temperature control is essential for storage of medical materials, specimens and samples these freezers area all designed with a manual defrost. This ensure that a defrost cycle does not compromise or damage any samples that may be stored in the freezer. Defrosting requires no special equipment and should be done according to the manufacturer's guidelines that are sent in the product manual. If the manual is not available contacting the manufacturer directly or looking for information on their website is always the best option.

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Tips for Choosing Lab Freezers

What design features specifically make a lab freezer easy to clean and decontaminate in the event of spills or accidents?

There are actually several different features that have been developed for use in lab freezers that make them very easy to clean and decontaminate as necessary. While most labs will have very few issues with spills or accidental contamination it can and does occur. The manufacturers of medical freezers have created a molded plastic interior that has no interior seams. This means that spills and contamination is never hidden from sight in cracks or seams in the interior as you would find in a standard freezer. Since there are no hidden areas cleaning is simple and, using a standard disinfectant and cleaning solution, accidental spills or frozen materials are simple to remove. With a smooth surface internally decontamination is a snap.

In addition the specific material used for the shelves and bins is heavy gauge steel that is treated with a baked on epoxy. This ensures that there is a uniform, smooth and resistant surface area on shelves, bins and wire racks found within the unit itself.

Is there any type of freezer that is specifically designed for enzyme freezing and what features does it offer over a standard laboratory freezer?

In fact there are specific enzyme freezers that can also be used as a general freezer. There is also the option to have an enzyme freezer and a general freezer, which is a good idea in busy lab or where a lot of specimens and samples are handled on a daily basis. The specialized features of the enzyme freezer include slide out and removable drawers that can be used as an effective and very accurate inventory system of what is in the freezer at all times. This is particularly important when you are working with very small samples where individual labeling can be extremely difficult.

Another feature of the enzyme lab freezer is that it does have a slightly larger temperature range than a standard lab freezer. Usually the lower end of the range is -32 degrees Celsius in an enzyme freezer and -30 in a standard lab freezer. The upper end of the range in an enzyme freezer is -12 degrees Celsius with the laboratory freezer at -20 degrees Celsius.

What is the size and weight of a lab freezer?

There are two general sizes, a full sized unit that will be just under 21 cubic feet and a smaller under the counter sized option that is approximately 6 cubic feet. Some manufacturers also make a 7 cubic foot freezer which is similar to the larger free standing unit but is smaller in overall internal and external measurements.

Depending on the size of the unit the weight will vary the larger units, both the 7 and the 20 cubic foot models are usually about 178 pounds or 80.74 kilograms. The smaller under the counter options are just over 100 pounds or approximately 45.8 kilograms.

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Gut Sutures Q & A

Monday, December 12, 2011

How fast are gut sutures typically absorbed by the body and what factors make a difference in absorption rates?

Gut sutures are absorbed in the body at various rates. Most of the sutures will have full tensile strength for approximately 7 days after use but the tensile strength can begin to decrease slightly prior to that if infection, high levels of blood flow, taking specific medications or if the gut suture is not high quality collagen. In addition these sutures used in the mouth or in reproductive tract procedures will have a faster rate of loss of tensile strength due to faster breakdown of the collagen. High quality absorbable sutures are very uniform in size and are designed to have good flow through when suturing.

Most natural sutures will be completely absorbed by the body within 90 days. However, after day 7 the tensile strength decreases markedly and quickly, providing only limited support for the healing process.

What are the major features of gut sutures that make them a good option in a wide variety of types of procedures?

Gut sutures come pre-sterilized and packaged based on length and diameter of suture material as well as the type and size of needle required. This is a great option for a busy emergency or surgery unit or for a smaller clinic that typically is not going to complete a lot of emergency wound repairs or surgical procedures.

The nature of gut sutures also makes them very unlikely to cause reactions at the site of the suture. Plain gut is very neutral in the body and, unlike the chromic gut, there is rarely any reaction of the surrounding skin. Since the suture material is very uniform in diameter and smooth there is little if any tissue damage to the tissue during the suturing. Last but not least the suture is very easy to work with, flexible yet strong, resistant to fraying and is very effective at holding knots securely.

What options are available in absorbable sutures that will have slightly longer tensile strength in the body the standard gut sutures?

One option that many surgeons and medical practitioners prefer to plain gut is chromic gut. This is a natural suture that is treated with chromic salts prior to packaging. The chromic salts act as a barrier to the natural breakdown of the collagen in the suture. This slower ability of the body to break down the actual fibers in the sutures provides longer tensile strength. Different sizes of chromic gut and different preparations can extend the tensile strength and reduce absorption rates by days or weeks.

Although chromic gut is broken down less rapidly in the body than natural gut there are still multiple variables that can speed up or slow down the specific timeline for absorption. For this reason all types of absorbable sutures should be carefully considered before using in a specific surgical ligation or approximation. The absorption of the sutures is still a major benefit to consider in many types of procedures.

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