Laboratory work requires a wide variety of apparatus and equipment. This page describes basic safety principles. Before using any piece of equipment, specific training on operating that equipment is required. Users must also be familiar with safe operating procedures and be able to demonstrate these to the supervisor. Select a topic below for more information.

General equipment safety requirements:
Equipment and apparatus:

Machine guarding

Devices, equipment, and apparatus that have exposed moving parts require guards to limit contact with these parts. In most cases an evaluation must be made to address the level of hazard and need for guarding. 

Most laboratory equipment is purchased with appropriate guards, however, it is the supervisor’s responsibility to ensure that the guarding in place is protective of workers operating the equipment. Once guards have been put in place, they are not to be moved or altered by any person other than those trained and authorized to perform work on the machines without guards. Maintenance procedures must be carried out by individuals who are trained to perform maintenance safely.

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    Autoclaves are pressurized sterilizing chambers generally used to sterilize glassware, instruments, gloves, liquids in bottles, biological waste, and other materials by steam under pressure.

    Autoclaves are typically at pressures a little under two atmospheres and temperatures of up to 135°C. When working with autoclaves, workers need to be aware of potential hazards such as explosions. The stored energy in the steam is tremendous and autoclaves differ from other steam receivers in that they have to be opened frequently, and residual pressure may not be detectable by the pressure gauge.

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      Centrifuges are laboratory instruments that have the potential to cause serious injury and considerable damage if safe operating and maintenance procedures are not followed. All lab workers operating centrifuges must be adequately trained in safe centrifuge operation.

      The principal investigator is responsible for ensuring that workers are trained, that rotor use logs are maintained, and that rotors are retired when required.

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      Fume hoods

      Fume hoods reduce levels of hazardous products produced or used during experiments by confining them to an area separate from the laboratory, diluting them with large quantities of air, and expelling them long distances from the building.

      There are several different types of fume hoods at the University of Waterloo. Among these are:

      In addition, there are special fume hoods for perchloric acid and radioisotopes. Therefore, one must ensure that the appropriate hood is used for each specific reaction or process involving specific chemicals. This information must be provided to students by the laboratory supervisor or laboratory assistants.

      Typical bypass fume hoods

      A typical modern fume hood consists of the following components:

      bypass fumehood partsAirfoil: Located at the bottom and sides of the fume hood entrance the airfoil reduces turbulence in the air entering the hood near the edges.

      Air baffle and adjustable slots: Air baffle and adjustable slots are used to insure a laminar flow through the hood and to decrease turbulence.


      Sliding sash: Allows full access to the fume hood when setting up an experiment and partial or full closing while running the experiment to insure proper evacuation of hazardous products.

      Bypass slots: Bypass slots are sequentially uncovered as the sliding sash is closed, allowing more air to enter through the bypass slots and less through the sash opening. This keeps the face velocity relatively constant. If there are no bypass slots the velocity through the fume hood opening would increase as the sash is closed to a point where turbulence would force hazardous materials out of the fume hood ant into the laboratory. Flow rates could also increase to the point at which experiments are physically disrupted by the air flow.

      Exhaust duct and damper: The exhaust duct damper is used to set the face velocity of the fume hood. This is normally set between 80 and 120 FPM with the sash set at normal working height. All fume hoods are to be ducted as per regulation 308 in the Environmental Protection Act.

      Construction: Material used in construction should be non-porous and impervious to materials used or produced. For example stainless steel is very good for most radioactive material because it is easily cleaned but will break down when halogenated acids such as hydrogen chloride are used.

      Walk-in fume hood

      Walk-in fume hoods are basically a ventilated room with an air baffle at the back and adjustable slots to insure laminar flow. Access is normally gained by sliding or folding doors. These fume hoods are mainly used to set up large-scale experiments or processes. Experiments are erected in the walk-in fume hood, the doors are closed, and the experiment is monitored or controlled remotely. No protection is provided to persons while inside the walk-in fume hood.

      Self-contained fume hoods (ductless)

      Self-contained fume hoods are designed similar to conventional by-pass fume hoods but are not ducted to the outside. The air is instead passed through activated charcoal for organic compounds or through a HEPA filter for particulate material and the clean air is returned to the laboratory.

      Perchloric acid fume hoods

      Perchloric acid fume hoods are to be installed and used whenever processes involve the production of perchloric acid fumes. This type of hood is designed to prevent the deposition and build up of perchloric salts on the hood or duct surfaces. Perchloric acid hoods are designed with wash down devices that periodically (after each use) rinse the fans ducts and fume hoods surfaces with water. The fume hood and duct work is made of stainless steel and the duct work is kept straight, vertical and as seamless as possible to aid in washing away perchloric salts.

      • Heating perchloric acid should be undertaken with extreme caution.
      • Do not use oil baths or open flames to heat perchloric acid.
      • Do not dry filter paper used to collect perchloric acid precipitates.
      • Keep perchloric acid away from organic chemicals especially alcohols and glycerol.
      • Store perchloric acid in ceramic trays.

      General fume hood information

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              Glassware is used in almost every type of chemical and biological lab. Depending on the processes being performed, specific safety precautions should be taken to reduce breakage and implosions.

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              Heating baths

              Often materials used in heating baths are flammable and excessive temperatures could result in a fire. 

              • DO NOT LEAVE ON OVER NIGHT.
              • Heating bath containers should be durable, non-breakable, and set up with a firm support so they will not tip over.
              • Do not place heating baths near either flammable or combustible material.
              • Move heating baths only when the liquid is cool, to avoid risk of burning.
              • Set the thermostat well below the flash point of the heating liquid in use.
              • Keep a thermometer placed in the bath at all times it is in use to provide a visual indication of the actual temperature of the bath.

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              Heating mantles

              stirring heating mantleHeating mantles are composed of an electrical element surrounded by layers of fiberglass. These are generally safe pieces of equipment, provided the following:

              • Ensure that the coating around the fiberglass is not worn or broken and that no electrical components are exposed. It is also advisable to ground the outer metal case to protect against an electric shock if the heating element inside the mantle shorts against the metal case. 
              • fabric heating mantleAlways use a heating mantle with a variable autotransformer (VIAT) to control the input voltage. Never plug them directly into a 110-V line.
              • Be careful not to exceed the input voltage recommended by the mantle manufacturer. Higher voltages will cause it to overheat, melt the fiberglass insulation and expose the bare heating element.

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              Ovens are used in laboratories for baking or curing materials, out-gassing, removing water from samples, drying glassware, or in some cases providing a controlled, elevated temperature for an experiment. Follow these guidelines:

              • Equip every oven with a back-up thermostat or temperature controller which will either control the unit or shut the oven down should the primary one fail.
              • Do not use a unit with only a single thermostat for long, unattended processes. A backup system should be used in case the first thermostat fails.
              • Do not use an oven to heat any material from which a toxic vapour or gas would be expected to evolve unless provisions are made to exhaust the fumes, as would be done with a fume hood.
              • Do not use mercury thermometers in ovens.

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              Refrigerators and freezers

              Refrigerators and freezers used for chemical storage must have signs indicating their purpose.

              Food and beverages are not permitted in a refrigerator containing chemicals.

              To reduce odour build-up in a refrigerator seal all containers tightly and wipe any spilled material from the container prior to storing in the refrigerator. All containers must be clearly and legibly labelled (i.e. WHMIS labels).

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              Rotary evaporators

              Evaporation by using a rotary evaporator is the most common method used to separate a solvent. These are often known as "rotovaps", and operate by placing a flask under a vacuum while heating and spinning it. This allows solvent to evaporate more quickly.

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              Solvent stills

              Solvent stills are used to purify flammable liquids into pure, dry solvent. If safety precautions are not observed, a solvent still is very dangerous. The chemicals used in solvent stills are air/water-reactive and flammable, and pose a significant risk of serious injury and damage due to fire if not handled properly. Deactivation/neutralization procedures are particularly sensitive. All workers in the lab should be trained on the general hazards of solvent stills, and users must be trained and competent in all aspects of use.

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              Mercury-containing equipment and thermometers

              Mercury thermometers have been banned at UW since 2015.

              Follow these steps if your lab has mercury thermometers: 

              1. Bag them tightly
              2. Seal the bag
              3. Transport them to the waste facility during your normal waste drop-off

              Contact if you have any questions. 

              Mercury-containing equipment

              Equipment that contains mercury should be placed in a secondary containment/tray, if possible, to contain any potential spills. If not possible, contact the Safety Office to develop a spill plan, in advance.

              Mercury spills

              If you have a mercury spill, the mercury itself is not an emergency. 

              1. Close off the area 
              2. Put a sign on the door
              3. Call the spills team via the Special Constables Service during regular office hours for help cleaning the spill

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