Reducing the Total Cost of Biological Safety Cabinet Ownership

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 Reducing the Total Cost of Biological Safety Cabinet Ownership

Cell culture laboratories rely on biological safety cabinets (BSCs) to maintain the viability and integrity of cell cultures, ensuring safe handling of samples outside of the CO2 incubator environment. BSCs also serve the important role of protecting laboratory personnel and the environment by containing the release of infectious or otherwise dangerous aerosols generated during microbiological procedures. BSCs are classified into three categories according to their capabilities and performance attributes. Class I units protect users and the environment but not products, making them suitable when working with low- and moderate-risk biological agents. Class II and III cabinets take a holistic approach to safety, protecting products, users, and the environment; their main difference being that the former are appropriate for handling lowand moderate-risk biological materials, whereas the latter are necessary when working with biohazardous agents requiring high containment. Cell culture laboratories most commonly use Class II units, which are available in four different types depending on the level of protection they offer (Table 1).

Table 1 – Classes and types of BSCs

BSCs are often energy-intensive and can emit large amounts of heat into the laboratory, creating the need to install and use powerful ventilation and cooling systems. As a result, the operation of an inefficient BSC can significantly increase the operating costs associated with a laboratory’s daily contamination-control efforts. The electricity, ventilation, and cooling costs a BSC can incur vary depending on its class and type, as well as on the way the system is used. In general, the total cost of operation of a Class II BSC can equal the unit’s purchase price in as little as two or three years, with Type B2 cabinets being more costly to operate than Type A2 units. This is because Type B2 units consume more energy and emit more heat, thus having an increased carbon footprint and higher total cost of operation. The total cost of ownership increases proportionally with the extended operation of the safety cabinet 24 hours a day, seven days a week.

Like any business, cell culture laboratories constantly look for ways to improve productivity while minimizing operational costs. One way to achieve this is by investing in a BSC that has been designed to reduce the total cost of ownership without compromising on cell safety. Designed to deliver optimized efficiency, performance, and ergonomics, these units can generate considerable cost savings.

Facilitating a balanced, uninterrupted airflow

Class II BSCs protect cell cultures, operators, and the environment by maintaining a constant, unidirectional flow of air, which is filtered using high-efficiency particulate air (HEPA) filtration technology. By precisely controlling the balance of inflow and downflow at the front opening of the unit, the BSC’s fans prevent airborne contaminants from the external environment from reaching the sample chamber, while eliminating the danger of biological aerosols escaping the cabinet.

Conventional Class II BSCs operate on alternating current (AC) motors, designed to run at a certain speed, based on the supply current. When necessary, these motors can slow down, but this is done by electrically reducing the force at the motor, something that is achieved by chopping the current. This process wastes energy and releases heat into the surrounding environment.

Modern units incorporate electronic direct current (DC) motors, also known as electronically commutated motors (ECMs), which are capable of adjusting their speed and force as required by the supplied current. These motors always turn at the speed and force needed to push the right amount of air through the BSC’s HEPA filters. As the filters load, the motor adjusts to run at a higher speed and with more force to maintain the same amount of air going through the loaded, and thus higher-resistance, filters. By quickly compensating and maintaining critical airflows, this technology reduces the potential for contamination due to unbalanced airflow.

Class II BSCs protect cell cultures, operators, and the environment by maintaining a constant, unidirectional flow of air, which is filtered using high-efficiency particulate air (HEPA) filtration technology. By precisely controlling the balance of inflow and downflow at the front opening of the unit, the BSC’s fans prevent airborne contaminants from the external environment from reaching the sample chamber, while eliminating the danger of biological aerosols escaping the cabinet.

Conventional Class II BSCs operate on alternating current (AC) motors, designed to run at a certain speed, based on the supply current. When necessary, these motors can slow down, but this is done by electrically reducing the force at the motor, something that is achieved by chopping the current. This process wastes energy and releases heat into the surrounding environment.

Modern units incorporate electronic direct current (DC) motors, also known as electronically commutated motors (ECMs), which are capable of adjusting their speed and force as required by the supplied current. These motors always turn at the speed and force needed to push the right amount of air through the BSC’s HEPA filters. As the filters load, the motor adjusts to run at a higher speed and with more force to maintain the same amount of air going through the loaded, and thus higher-resistance, filters. By quickly compensating and maintaining critical airflows, this technology reduces the potential for contamination due to unbalanced airflow.

In addition to establishing a balanced and uninterrupted airflow within the cabinet, dc motors allow for energy savings of up to 75%,1 reducing the BSC’s operational costs and its environmental impact. Moreover, less heat is released into the laboratory, lowering the air-conditioning costs and providing a more comfortable working environment.

Energy-efficient, unattended operation

Cell culture laboratories tend to operate their Class II BSCs continuously to maintain cleanliness in the sample chamber, reduce airborne contamination in the laboratory, and comply with relevant internal policies and guidelines. There are times when users will need to stop their work in the BSC in order to perform other activities, or when leaving for the day. In those instances, the front sash of the BSC should remain closed to limit the effects of foot traffic and room air currents on the contained cell cultures. When the sash is closed, a lower fan speed is sufficient to achieve the necessary safety levels while consuming less energy.

To address specific operation needs as they arise, BSCs should be able to adjust their performance. This is not possible with traditional Class II units using AC motors, since they only have a moderate capability to adjust their fan speed. Advanced BSCs with DC motors are capable of quickly adapting to changing conditions and can run at reduced fan speeds with the window closed. Due to this capability, these units offer optimal sample protection, while reducing energy consumption and heat output for cost savings.

Preprogrammable UV disinfection capability

Germicidal UV lights are commonly used in Class II BSCs for disinfection purposes when the units are not in use. UV radiation can break chemical bonds and denature DNA and RNA, meaning that prolonged exposure to samples can lead to dysfunctional genetic material and eventual cell death. As such, most exposure recommendations for surface biological decontamination are one to three hours with standard surface intensity. In addition to risking sample loss, prolonged use of UV lights also results in higher energy usage and more rapid wear of the lamps, adding to the overall cost of ownership of the BSC.

For many years, Class II BSCs were equipped with germicidal UV lights featuring manual on and off switches. At the end of a typical working day, users were required to decide between leaving the UV lights on overnight or remaining at the laboratory one to three hours longer so that they could turn the lamps off once the disinfection cycle was complete. Current BSCs, both those fitted with cross-beam UV lights and those using standard single lamps, offer a preprogrammable UV disinfection capability. Depending on the specific application requirements, operators can schedule a disinfection cycle to run automatically at a prespecified time and duration. As a result, less energy is consumed, lamp life is extended, and the undesirable effects of UV radiation on cell cultures are minimized.

Improved ergonomics

Electricity, ventilation, and cooling costs—although very important and easily measurable—are not the only elements that contribute to the total cost of operation of a Class II BSC. BSCs with a restrictive opening height make it difficult for operators to manipulate cell cultures and laboratory tools, while limiting their ability to reach interior surfaces for decontamination purposes. Additionally, units that feature a work surface with bends and corners are susceptible to the accumulation of contamination. Poor ergonomics can therefore increase the time and effort invested in accessing and cleaning the BSC.

To overcome these limitations, BSC vendors are increasingly moving away from traditional designs in favor of more user-friendly approaches. Different window designs, such as front-hinged or with the ability to be lowered, allow for easy access to formerly hard-to-reach surfaces of the sample chamber. Combined with a flat work surface, this facilitates the daily activities of BSC users, improving comfort levels and helping them implement all necessary cleaning and disinfection measures.

Conclusion

Performing cell culture studies can be costly, requiring considerable time, effort, and materials to grow, treat, and maintain cell lines, and generate truly valuable results. Contamination can jeopardize the entire process, rendering cultures inappropriate for use and leading to the destruction of months of work. Class II BSCs play a crucial role in preserving the viability and integrity of cell cultures, while also protecting users and the environment from hazardous aerosols produced. However, the operation of Class II BSCs has been associated with high energy consumption, ventilation, and cooling costs, with conventional systems not always being ergonomic and easy to clean. Minimizing the total cost of BSC ownership can facilitate cost efficiencies within the cell culture laboratory and help lab managers realize their sustainability goals through energy savings and reduced heat emissions.

Reference

1. Webber, B.A. University of Michigan field study of Class II biological safety cabinet energy consumption costs. Amer. Biotechnol. Lab. 2008, 26(9), 22-4; https://tools.thermofisher.com/content/sfs/brochures/ Univ%20of%20Michigan%20Energy%20Field%20Study%202008.pdf

Martin Cole is product manager, Laboratory Equipment Technologies, Thermo Fisher Scientific, Stafford House, 1 Boundary Park, Hemel Hempstead HP2 7GE, U.K.; tel.: +44 7909 992341; e-mail: [email protected];www.thermofisher.com

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