Other Engineering Controls
Centrifuges
Only trained personnel should operate centrifuges. They must be properly installed according to manufacturer recommendations. It is important that the load is balanced each time the centrifuge is used and that the lid be closed while the rotor is in motion. The disconnect switch must be working properly to shut off the equipment when the top is opened, and the manufacturer’s instructions for safe operating speeds must be followed. For flammable and/or hazardous materials, ensure the centrifuge is under negative pressure and connected to a suitable exhaust system.
Glove Boxes
A glove box is a sealed container used to manipulate materials where a separate atmosphere is desired. They are commonly used to protect workers from hazardous materials or to protect chemicals and materials that may be sensitive to air or water vapor.
Heating Devices
Most labs use at least one type of heating device, such as ovens, hot plates, heating mantles and tapes, oil baths, salt baths, sand baths, air baths, hot-tube furnaces, hot-air guns and microwave ovens. Steam-heated devices are generally preferred whenever temperatures of 100o C or less are required because they do not present shock or spark risks and can be left unattended with assurance that their temperature will never exceed 100o C. Ensure the supply of water for steam generation is sufficient prior to leaving the reaction for any extended period of time.
Pressure & Vacuum Systems
Working with hazardous chemicals at high or low pressures requires planning and special precautions. Procedures should be implemented to protect against explosion or implosion through appropriate equipment selection and the use of safety shields. Only perform high-pressure operations in pressure vessels appropriately selected for the operation, properly labeled and installed, and protected by pressure-relief and necessary control devices. Vacuum work can result in an implosion and the possible hazards of flying glass, splattering chemicals and fire. All vacuum operations must be set up and operated with careful consideration of the potential risks.
Refrigerators & Freezers
The potential hazards posed by laboratory refrigerators and freezers include release of vapors from the contents, the possible presence of incompatible chemicals, and spillage. Only refrigerators that have been specified for laboratory use should be utilized to store chemicals.
Stirring & Mixing Devices
The stirring and mixing devices commonly found in laboratories include stirring motors, magnetic stirrers, shakers, small pumps for fluids and rotary evaporators for solvent removal. These devices are typically used in laboratory operations that are performed in a hood, and it is important that they be operated in a way that precludes the generation of electrical sparks.
Elephant Trunks
An elephant trunk is a flexible duct or hose connected to an exhaust system. It can only capture contaminants that are very close to the inlet of the hose, typically less than a distance equal to one half of the diameter of the duct.
Canopy Hoods
A canopy hood in a laboratory is constructed in a similar fashion to the overhead canopy hoods seen in kitchens. In order for the canopy hood to be able to capture contaminants, the hood requires a relatively large volume of air movement, making them somewhat costly to operate. The canopy hood works best when the thermal or buoyant forces exist to move the contaminant up to the hood capture zone.
Slot Hoods
There are many types of slot hoods, each suited for different types of operations. In general, a slot hood requires less airflow than a canopy hood and is much more effective than an elephant trunk or canopy hood, when installed properly. Slot hoods are best used for operations that require more working room than a fume hood and where a limited number of low toxicity chemicals are used.
Downdraft Tables
Downdraft hoods or necropsy tables are specially designed work areas with ventilation slots on the sides of the work area. This type of system is useful for animal perfusions and other uses of chemicals with vapor densities heavier than air.
Toxic Gas Cabinets
Highly toxic or odorous gases should be used and stored in gas cabinets. In the event of a leak or rupture, a gas cabinet will prevent the gas from contaminating the laboratory. Gas cabinets should be connected to laboratory exhaust ventilation using hard duct, rather than elephant tubing, since such tubing is more likely to develop leaks.
Biosafety Cabinets
Biological Safety Cabinets (BSC) are an effective piece of safety equipment when used, maintained and located properly.
Ductless Fume Hoods
Use of a "ductless fume hood" is strongly discouraged. These devices work by using a fan to draw air into a chamber, through one or more filters, and back into the laboratory.
Clean Benches
Clean benches are similar to appearance as a fume hood however do not exhaust air from the laboratory. A clean bench is a device that draws air from the lab through a HEPA filter and vents the filtered air downwards onto a work surface to keep the materials within free from particulate contamination.
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