Health and Safety - Section 7

A person is considered to be working alone when they are by themselves and cannot be seen or heard by another person, and when help is not readily available in case of an emergency, injury, or illness. This can apply even in busy workplaces, like a researcher working in a remote lab room or working after hours, if no one else is nearby or aware of their presence. It’s not just about physical isolation, but also about the ability to get assistance quickly if something goes wrong.

7.1.1. General Guidelines on Working Alone

Working alone should be avoided, especially after hours, whenever possible.

Working alone requires Supervisor and Principal Investigators (PI) knowledge and approval. The Supervisor/PI must conduct a risk assessment of the activity before allowing researchers to work alone. Researchers should participate in this risk assessment.  Consider what can go wrong and how adverse impacts can be eliminated or reduced, taking into consideration the hazard involved in the work, the consequences in case of an accident, access to help, and the researcher's level of training and experience. This assessment is documented using the Working Alone Form.

Implement a buddy system: check in with a designated person at the start and end of your lab session, and maintain regular contact while working alone. 

Some activities are prohibited when working alone at the University of Waterloo, such as working with acutely toxic, water-reactive and pyrophoric materials, the use of open flame associated with flammable solvents, or machines and power tools that may cause critical injury (e.g., lathe, table saw, etc.). Please refer to the Working Alone Standard for details.

Working in a research laboratory often involves dealing with hazardous chemicals, biological material, and high-energy equipment. If not properly managed, these hazards can result in serious injuries, such as chemical burns, biological infections, or mechanical injuries. Personal protective equipment (PPE) is a key barrier, protecting researchers from direct exposure and reducing the risk of accidents or contamination. Although proper lab design, engineering controls, and procedural protocols form the foundation of a safe environment, PPE adds a personal layer of protection, tailored to specific tasks and settings.

Supervisors and PIs are responsible for assessing PPE requirements for the labs under their responsibility. This assessment is completed before the work starts, as part of the Safety Report, and when new hazards are introduced to the laboratory.  Supervisors are also responsible for providing the appropriate PPE, and ensuring that employees have received the necessary training.

Researchers are responsible for following the PPE requirements.

• Completing PPE-specific training sessions;
• Wearing PPE as required;
• Cleaning and maintaining PPE as trained;
• Informing the supervisor of the need to repair or replace PPE.

7.2.1. Typical Laboratory PPE 

Lab Coats: Lab coats provide a protective barrier against spills, splashes, and contamination. They must be worn whenever hazardous materials are handled. Lab coats should be properly fastened and removed before leaving the laboratory.

Eye Protection: Safety glasses must be worn at all times in areas designated as requiring eye protection, including all laboratories where hazardous materials are stored or used. Safety glasses protect against chemical splashes, flying debris, and particulate hazards. Additional protection, such as chemical splash goggles or a face shield, may be required when handling concentrated corrosives or performing procedures with an elevated risk of splashing or projectiles.

Footwear and Clothing: Closed‑toe, slip‑resistant footwear is required in all laboratories. Open‑toe shoes, sandals, and mesh footwear are not permitted. Clothing must cover the legs to provide basic protection from spills and splashes.

Hair, Clothing, and Accessories: Long hair, beards, loose clothing, scarves, neckties, and dangling jewelry must be secured. These items can become entangled in rotating equipment or come into contact with flames, chemicals, or other hazards.

Disposable Gloves: Disposable nitrile gloves protect the hands from incidental chemical contact. They are not suitable for immersion or prolonged exposure to chemicals. Gloves must be removed immediately after contamination and must never be worn outside the laboratory or when touching common surfaces such as door handles or keyboards.

7.2.2. Activity Specific PPE

Chemical Splash Protection: Rubber or PVC splash apron must be worn when handling larger volumes of corrosive materials.

Flame‑Resistant Lab Coats: Flame‑resistant (FR) lab coats must be worn when working with open flames larger than a Bunsen burner, when sparks may be generated, or when handling pyrophoric, water‑reactive, or air‑reactive materials.

Enhanced Eye and Face Protection: Chemical splash goggles or a face shield are required when working with concentrated acids and bases or when performing operations with a high risk of splashing or flying particles.

Chemical‑Resistant Gloves: Use heavy‑duty chemical‑resistant gloves (e.g., neoprene, butyl, Viton, thick nitrile and PVC) when handling corrosives, solvents, oxidizers, or any chemical that can permeate disposable nitrile gloves. Selection must follow manufacturer compatibility charts.

Thermal‑Protection Gloves: Wear heat‑resistant gloves when handling hot equipment, glassware, or materials above 60 °C, including ovens, furnaces, steam lines, and heated reaction vessels.

Cryogenic Gloves: Cryogloves are required when handling liquid nitrogen, dry ice, or other cryogenic materials. Gloves must be loose‑fitting to allow quick removal in case of a spill.

Cut‑ or Impact‑Resistant Gloves: Use cut‑resistant or impact‑resistant gloves when working with sharp tools, metal edges, broken glass, or equipment that poses crush or pinch hazards.

General Notes: Gloves must be selected based on the specific hazard, removed immediately if contaminated, and never worn outside the laboratory or on common surfaces.

Lab PPE can be purchased on Campus from Chem Stores or from one of the regular lab equipment suppliers such as VWR, Fischer Scientific.

Laboratory housekeeping refers to the ongoing practice of keeping research spaces clean, organized, and free from hazards. It is a proactive approach that supports safety, efficiency, and regulatory compliance. Effective housekeeping includes controlling clutter, maintaining clear work areas, ensuring proper storage and labelling of chemicals and equipment, disposing of waste regularly, and keeping emergency equipment stocked and accessible.

Good housekeeping reduces the risk of incidents such as spills, fires, chemical exposures, and injuries caused by slips or falling objects. It also ensures unobstructed access to emergency equipment, supports efficient work by making tools and materials easy to locate, and helps maintain research integrity by minimizing contamination.

Housekeeping is a shared responsibility. While the Supervisor/PI is accountable for overall laboratory conditions, all lab members are expected to maintain tidy work areas and participate in routine cleaning and maintenance.

Laboratory spaces must be kept free of clutter, trash, unused equipment, and empty or outdated chemical containers. This applies to benches, fume hoods, refrigerators, cabinets, chemical storage areas, sinks, and waste receptacles. All chemical spills must be cleaned up immediately, regardless of the substance. When cleaning a spill, check surrounding surfaces, such as equipment, cabinets, doors, and countertops, for splashes. Refer to section 6.4. Hazardous Materials Spills for detailed guidance. 

7.3.1. Laboratory Housekeeping Guidelines.

• All work areas, walkways and aisles must be kept clean and free of obstructions. Maintain clear, unobstructed aisles and pathways (minimum of 1.1 m wide) to allow for safe movement and emergency egress.
• Keep areas around emergency equipment and devices clean, free of clutter, and obstacles. This includes items such as eyewash/emergency showers, exits, electric power panels, fire extinguishers, and spill cleanup supplies.
• Keep work surfaces (benches, fume hoods, balance areas) clear of unnecessary items. Only have materials needed for the immediate task present. Chemicals and equipment should be returned to their proper storage location immediately after use.
• Assign specific locations for all chemicals, equipment, and supplies. Ensure all containers, shelves, and storage areas are clearly labelled. "A place for everything, and everything in its place."
• Use shelving and cabinets efficiently, placing heavier items on lower shelves and lighter items overhead, ensuring shelves are secured and not overloaded.
• Establish a schedule for wiping down of work surfaces and periodic deep cleaning of the entire lab, including less-frequently accessed areas and equipment. Clean up all spills immediately, regardless if the chemical is hazardous or not. When cleaning up a chemical spill, look for any splashes that may have resulted on nearby equipment, cabinets, doors, etc.
• Chemicals should always be segregated and stored according to their chemical hazardous classification. Storage of chemicals and equipment in the fume hoods and on bench tops should be kept to a minimum. Consult the Chemical Storage and Segregation section for more information.

• Dispose of waste and hazardous waste regularly. Equipment and materials no longer being used must be disposed of following proper waste removal procedures. Consult the Waste Disposal section for more information.

A fume hood is an essential engineering control in a research lab, primarily used to protect researchers from exposure to hazardous airborne contaminants. A fume hood should be used whenever there is a possibility of generating or releasing substances that could pose a health or safety risk if inhaled or released into the lab environment.

The fume hood draws air away from the user and into the hood using a powerful exhaust system. The transparent sash, usually made of safety glass, acts as a shield between the user and the experiment. It helps protect against chemical splashes, fires, and minor explosions. The contaminated air is vented outside the building to remove hazardous substances. This ensures that toxic or flammable vapours are not recirculated into the laboratory environment.

Here are the key situations and types of materials that necessitate fume hood use:

• Hazardous Vapours, Fumes, Gases, and Particulates:

Volatile Toxic Chemicals: Any chemical with significant vapour pressure that is toxic or harmful if inhaled. This includes many organic solvents, acids, and bases.

Corrosive Materials: Strong acids (e.g., concentrated hydrochloric acid, nitric acid) and bases that can release corrosive vapours (e.g., ammonium hydroxide).

Asphyxiating Gases: Gases that can displace oxygen and lead to asphyxiation.

Fine Particulates/Dusts: Operations that generate fine powders or dusts that can become airborne and inhaled.

Noxious Odours: Chemicals with strong or unpleasant odours, even if not highly toxic, should be handled in a fume hood to prevent nuisance and maintain a comfortable lab environment.

• Processes that Generate Contaminants:

Transfers of Volatile Liquids: Pouring or transferring significant quantities of volatile or hazardous liquids from one container to another.

Reactions that Produce Gases: Any chemical reaction that is expected to release gaseous products or volatile byproducts.

Distillations or Evaporations: Processes that concentrate volatile compounds, increasing their vapour pressure and potential for release.

Digestion Procedures: Especially those involving strong acids or heat.

• Physical Hazards:

The fume hood sash provides a physical barrier and can offer protection from splashes, splatters, or minor explosions in case of an unexpected reaction. Use it as a shield by keeping the sash as low as possible during experiments. If an explosion hazard exists, anchored barriers, shields or enclosures of sufficient strength to deflect or contain the explosion should be installed.

• When Safety Data Sheets (SDS) Indicate Need:

Always consult the SDS for any chemical you plan to use. If the SDS has warnings such as "Toxic by inhalation," "Do not breathe dust, fumes or vapours," or recommends "use in a well-ventilated area/fume hood," then a fume hood is required.

7.4.1. Fume Hood Work Practices

• Verify Operation:

Before starting any work, always ensure the fume hood is operating correctly. Fume hoods in the Department of Chemical Engineering are equipped with airflow indicators or alarms that alert users if the hood is not functioning properly, ensuring continuous protection. In case the fume hood is not working properly, please contact pltops.maintenance@uwaterloo.ca to request maintenance.

Building	E6	QNC	DWE
Airflow Indicator/ Alarm
Normal Operation	Green light is ON. Face velocity > 100 ft/min.	Green light is ON. Face velocity > 100 ft/min.	Power switch is in the ON position (bottom right).
Testing	Open the sash above the mark to trigger the alarm.	Open the sash above the mark to trigger the alarm.	Press “TEST” button to trigger the alarm.
Notes	Sash height determines damper opening to maintain face velocity > 100 ft/min. EMERGENCY PURGE (EEE) activates emergency mode, fully opening the damper	Sash height determines damper opening to maintain face velocity > 100 ft/min.	No damper control. Exhaust is either ON or OFF. Always test before using. Some fume hoods require manual restart after power failure.

• Sash Management:

Remember that the sash acts as a physical barrier. Keep it as low as possible during experiments, and completely lowered when the experiment is unattended or when the hood is not in use. This protects from splashes and projectiles, and helps conserve energy. Extend only hands and arms into the hood and avoid leaning against it. Never allow your head to enter the plane of the hood opening.

• Proper Placement of Materials and Equipment:

Always conduct experiments and place all chemicals and equipment at least 6 inches (15 cm) behind the plane of the sash (the front edge of the hood). This ensures proper containment.

• Do Not Obstruct Airflow:

Keep the baffles (openings at the top and rear of the hood) and airfoil (front bottom edge) clear of obstructions. Do not block the slots and avoid overcrowding the hood. Only place materials and equipment necessary for the immediate experiment. Place large equipment on blocks or risers (approximately 2 inches or 5 cm) to allow air to flow underneath and around it, maintaining smooth airflow.

• Storage of materials in the Fume Hood:

Minimize material storage in the fume hood, as it can adversely affect the air flow and containment provided. In addition, the fume hood is often used for the most hazardous activities in the laboratory, and the presence of stored flammables or highly toxic materials can worsen explosions or fire in the hood and may spill during emergency response.

Materials requiring ventilated storage (e.g., volatile and highly toxic, or odorous substances) may be stored in a hood if they are properly segregated and the hood is not used for experimental work.

• Know Your Hood's Limits: 

Standard chemical fume hoods are designed for controlling chemical fumes and vapours. They must not be used for biological materials (use a biological safety cabinet), for handling nanomaterials (use a HEPA‑filtered glove box), or for specialized reactions requiring dedicated infrastructure. For example, perchloric acid heated above room temperature requires a perchloric‑acid‑rated hood with wash‑down capability.

Fume hoods are not designed to contain high‑velocity releases. Gases or vapours escaping from pressurized systems may exit the hood before being captured. Because a typical fume hood exhausts directly outdoors, equipment and processes must include appropriate condensers, traps, or scrubbers to prevent the release of hazardous substances into the environment.

7.4.2. Other Laboratory Exhaust Systems

• Snorkels:

Snorkel exhaust systems or canopy hoods are used in research labs when localized ventilation is needed to capture fumes, vapours, dust, or heat directly at the source. They’re not ideal for high-hazard materials, as their capture efficiency depends heavily on proper positioning, but they’re especially useful when:

Working with small-scale chemical processes that emit nuisance vapours or low-hazard contaminants.

Using equipment like gas chromatographs or the end of equipment tubing that releases fumes at specific points.

Performing tasks that don’t require a full fume hood, but still need targeted exhaust, such as soldering, gluing, or working with volatile non-hazardous solvents.

Venting heat, steam, or non-toxic vapours from large or open equipment that can’t be enclosed in a traditional fume hood (e.g. autoclaves).

• Glove Boxes:

Glove boxes are sealed enclosures that are designed to protect the user, the process or both, by providing total isolation of the contents from the outside environment. They are usually equipped with at least one pair of gloves attached to the enclosure. The user manipulates the materials inside using the gloves. Typically, a glove box has an antechamber that is used to take materials in and out of the box. Negative pressure models prevent contaminants from escaping, protecting the user, while positive pressure versions protect sensitive materials from external contamination.

A controlled environment glove box (dry glove box) is a sealed enclosure designed to maintain low levels of moisture and oxygen, creating a stable, inert atmosphere for sensitive work. These glove boxes are typically purged with dry inert gases like nitrogen, argon, or helium, and are used when even trace amounts of air or humidity could compromise materials or reactions.

A ventilated glove box (filtered glove box) features a high-efficiency particulate air (HEPA) or ultra-low particulate air (ULPA) filtered inlet and outlet air to provide a physical barrier between personnel and hazardous materials.  Unlike sealed dry boxes that maintain an inert atmosphere, ventilated glove boxes allow for continuous airflow.

• Biosafety Cabinets:

Biosafety cabinets (BSC) are specialized, ventilated workspaces designed to safeguard laboratory personnel, the work conducted within, and the surrounding environment from exposure to infectious agents and hazardous materials. BSCs are essential in microbiology, virology, and anywhere that safe handling of biohazards is critical.

Class I Cabinets Provide personnel and environmental protection by HEPA‑filtering exhaust air. They do not protect the product and are suitable for low‑ to moderate‑risk work where sterility is not required.

Class II Cabinets Provide personnel, product, and environmental protection, making them appropriate for microbiological and biotechnological work requiring aseptic conditions. Class II BSC types include:

• Type A1 — For non‑volatile, non‑toxic microbiological work. Minimum inflow of 75 fpm. Recirculates ~70% of air; exhausts ~30% through a HEPA filter. Not suitable for volatile or toxic chemicals.

• Type A2 — Similar to A1 but with 100 fpm inflow for improved containment. Can accommodate minute amounts of volatile chemicals when connected to the building HVAC system.

• Type B1 — Suitable for small quantities of toxic chemicals and biological agents when work is performed at the rear of the cabinet. Exhausts ~70% of air and recirculates ~30%, both HEPA‑filtered.

• Type B2 (Total Exhaust) — For work involving significant quantities of toxic chemicals and biological agents. Minimum inflow of 100 fpm. Exhausts 100% of air to the building system with no recirculation.

• Laminar Flow Cabinet:

A laminar flow cabinet is used to create a clean, particle-free environment for handling sensitive materials. It works by directing air through HEPA filters and across the work surface in a smooth, unidirectional stream—either horizontally or vertically—effectively sweeping away contaminants.

It’s important to note that laminar flow cabinets protect the product, not the user. They should never be used with hazardous chemicals or infectious agents—biosafety cabinets or fume hoods are better suited for those tasks.

• Toxic Gas Cabinets

Toxic gas cabinets are ventilated enclosures specifically designed to safely store and contain the release of toxic or odorous gases such as carbon monoxide, ammonia, hydrogen sulfide, etc. Gas cabinets are connected to laboratory exhaust ventilation and are designed to prevent the gas from contaminating the laboratory in the event of a leak or rupture. Toxic gases are required to be stored in this type of cabinet.

Research laboratories routinely utilize chemicals that may present physical, health, and environmental hazards. These hazards include toxicity, flammability, corrosivity, reactivity, oxidizing properties, and the ability to generate harmful vapors, gases, or dust. Safe chemical handling practices are essential to protect laboratory personnel, facilities, and the environment.

All laboratory personnel are responsible for understanding the hazards associated with the chemicals they use and for following established procedures to minimize risk. Safe chemical handling requires proper planning, adequate training, appropriate engineering controls, suitable personal protective equipment (PPE), and adherence to established laboratory procedures.

7.5.1. Hazard Awareness and Planning 

Before beginning any work, review the Safety Data Sheet (SDS), for each chemical and assess the associated hazards, including toxicity, flammability, reactivity, and incompatibilities.  Plan experiments in advance, identify required controls and procedures, and ensure that appropriate PPE, spill materials, and emergency equipment are available. Review these procedures with your Supervisor or PI, as described in Section 5. Safety Report and 6. Emergency Response.​

7.5.2. Safety Data Sheet (SDS)

The purpose of a Safety Data Sheet is to provide information on the hazards of working with a chemical and procedures that should be used to ensure safety. SDSs are a primary source of information regarding chemical hazards and handling. To ensure chemical safety in the workplace, SDSs must be available to all researchers who may be exposed to hazardous substances.

Researchers in the Department of Chemical Engineering use the web-based Chemical Inventory System (RSS) to access SDS for the chemicals used on Campus.

• Log in to https://app.riskandsafety.com using your WATIAM credentials.
• Use the tab “Apps” at the top of the page to access the "SDS" App.
• Search by chemical name, CAS number, or product ID, then select a chemical from the results and select the SDS from one of the vendors in the list.

7.5.3. Use of Engineering Controls 

Conduct all work involving volatile, flammable, corrosive, or otherwise hazardous chemicals inside a chemical fume hood or other appropriate containment device. See section 7.4 Fume Hoods and Laboratory Ventilation for details. Ensure that hoods are not overcrowded, airflow is unobstructed, and sash height is maintained at the designated operating level.

7.5.4. Personal Protective Equipment (PPE) 

Wear PPE appropriate to the hazards of the task. At minimum, this includes a lab coat, safety glasses, closed‑toe footwear, and disposable gloves for incidental contact. Compatible, chemical-resistant gloves may be required for prolonged contact with chemicals.  Additional PPE, such as chemical splash goggles, face shields, or aprons, must be used when handling corrosives, reactive chemicals, or materials with a high risk of splashing. PPE must be inspected regularly and replaced when damaged or contaminated. See section 7.2. Personal Protective Equipment for details.

7.5.5. Chemical Labelling and WHMIS

Proper chemical labelling is essential to ensure that laboratory personnel can readily identify chemical hazards, implement appropriate control measures, and respond effectively during emergencies. All chemicals used, stored, or generated in Department of Chemical Engineering laboratories shall be labelled in accordance with applicable Workplace Hazardous Materials Information System (WHMIS) requirements.

• Supplier Labels:

Suppliers of hazardous products are required to apply a label that meets the WHMIS 2015 requirements. Original containers received from suppliers must retain the original supplier label. If the supplier label becomes damaged or unreadable for any reason, the label must be replaced with a workplace label.

• Workplace Labels:

Workplace labels are required for hazardous products that are produced within the workplace, received without an appropriate supplier label, or transferred into a secondary container that is not otherwise labelled.

A workplace label shall be applied when:

• A hazardous product is created or prepared within the laboratory or workplace.
• A hazardous product is received without a supplier label.
• A hazardous product is transferred from its original container into another container that does not have a label.
• The original supplier label becomes damaged, illegible, or is no longer available.

• Laboratory Samples and Special applications of WHMIS:

Laboratory samples produced within the workplace are not required to have a workplace label. However, they must be clearly identified, and laboratory personnel must receive sufficient information and training to understand the sample's contents, hazards, and safe handling requirements.

Personnel handling laboratory samples shall be able to readily access the applicable Safety Data Sheet (SDS), where available, or other hazard information necessary to safely work with the material.

Abbreviations, chemical formulas, sample codes, or personal identification systems alone are not acceptable if they do not allow a laboratory worker to readily identify the contents and associated hazards of the material. Any person entering the laboratory should be able to reasonably determine the identity of the sample and obtain the information necessary to handle it safely.

7.5.5. Transport of Chemicals

The transport of chemicals within and between laboratories shall be conducted in a manner that protects personnel, prevents environmental releases, and minimizes the risk of spills or container damage. When transporting chemicals, observe the following requirements:

• Always place chemical bottles in a shatter-proof, leak-proof secondary container, such as a safety bottle carrier or plastic tub, when moving them. Where necessary, compatible cushioning or packing material should be used to prevent containers from tipping, shifting, or breaking during transport.
• When transporting chemicals by hand, always leave one free hand for opening and closing doors safely.
• When transporting multiple containers or larger quantities of chemicals, use a sturdy wheeled cart with raised edges (minimum 1 inch lip).
• If a passenger elevator must be used, transport should be scheduled during periods of low occupancy. Where other occupants are present, they should be informed of the hazards associated with the material being transported and discouraged from riding in the elevator during transport.

This section provides essential guidelines for the safe segregation and storage of chemicals within our research laboratories. Proper chemical management is critical to prevent accidents and ensure a safe working environment.

7.7.1. Chemical Segregation and Storage Guidelines

• All chemical containers must be clearly and legibly labelled with their chemical name and hazard warnings, according to WHMIS 2015 requirements. Never leave unlabelled chemical containers in the lab.
• Always refer to the specific SDS for detailed incompatibility data and never store incompatible chemicals together. 
• Chemicals should be segregated based on their primary hazard class to prevent dangerous reactions in case of a spill or other incident.
• Purchase and store only the minimum amount of chemicals necessary for current research. Properly dispose of chemicals that are no longer needed.
• Always keep containers tightly capped when not in use to prevent spills, evaporation, and contamination. Liquid chemicals should be stored below eye level.
• Conduct regular inspections to check for damage, leaks, or signs of degradation. Remove chemical containers from shipping cans/boxes, as these may obstruct proper inspection. Immediately replace any compromised containers.
• Maintain an accurate and up-to-date inventory of all chemicals using the RSS – Chemical Inventory tool. See section 7.7.4 below.

7.7.2. Segregation and Storage by Hazard Class

Chemicals should be segregated based on their primary hazard class to prevent dangerous reactions in case of a spill or other incident, as shown in the Figure below.  The WHMIS pictograms on the Chemical Label are a good indicator of the classification of the chemical for storage purposes.  Keep in mind that these are general guidelines and the chemical SDS should always be consulted for specific information about incompatibility.  For example, sodium hypochlorite (bleach) and ammonium hydroxide (ammonia solution) are both weak inorganic bases, but they may create highly toxic gases when combined.

• Chemical Hazard Classes Requiring Exclusive Cabinets or Shelves:

Explosives: Store only small amounts (< 50 g) of these chemicals in the lab in an exclusive cool, dry cabinet, away from heat sources, ignition sources, and direct sunlight. Do not store with any other class of chemicals.

Note: Manufactured explosives, such as gunpowder, blasting agents, etc., are legally excluded from WHMIS labels and Safety Data Sheets and are instead regulated separately under the federal Explosives Act, and any use, handling or storage must conform to these regulations.

Pyrophorics and Water-Reactive: Store in a tightly closed container under inert atmospheres (e.g., nitrogen or argon glovebox or air-tight containers under an inert gas blanket) to prevent unwanted reactions. For some chemicals, like alkali metals, mineral oil can be used to further protect them from moisture. Storage conditions shall be maintained in accordance with the manufacturer's recommendations and laboratory-specific procedures.

Incompatibles: Certain highly reactive chemicals require dedicated storage and shall not be stored with general chemical inventories. Examples include organic peroxides, picric acid, white or yellow phosphorus, or chemicals identified by the manufacturer or SDS as requiring segregation from other hazard classes. Dedicated shelves, cabinets, secondary containment, temperature controls, or other precautions may be required depending on the material.

Oxidizing Acids: Some concentrated acids such as nitric acid, sulphuric acid, and perchloric acid are classified as Oxidizing Acids and require an exclusive cabinet. Use secondary containment for each subclass of oxidizing acids. When diluted, these acids should be stored in the Corrosives Cabinet.

Oxidizers: Do not store any other class of chemicals or combustible materials.Store these chemicals away from flammables.

• Other Chemical Hazard Classes:

Flammable Liquids: Flammable liquids should be stored in designated Flammable Liquid cabinets installed following the building code, which may include venting and grounding. Refrigerate flammable liquids only in refrigerators or freezers approved for flammable materials. The maximum container size for flammable liquids is 5 L. No more than 50 L of flammable liquids are allowed outside a flammable cabinet at any time.

Corrosive Liquids: Store these chemicals in the Corrosives cabinet with the exception of Oxidizing Acids (require exclusive cabinet) or chemicals that are corrosive and flammable (these should be stored in the Flammable Liquids cabinet. Use secondary containment for each subclass of chemicals: Inorganic Acids, Inorganic Bases, Organic Acids, and Organic Bases.

Liquids Compatible with Anything: Liquid chemicals that do not meet the criteria for a specialized storage class may be stored in a dedicated storage cabinets or shelving, in the Flammables cabinet and/or in the Corrosives cabinet, provided they are compatible with surrounding materials and do not introduce additional hazards.

Solid Chemicals: Chemicals in solid form may be stored in dedicated solid chemical storage cabinets or shelving, provided they are compatible with adjacent materials. Chemicals requiring dedicated storage, including explosives, pyrophorics, water-reactive materials, and oxidizers, must be stored according to their specific storage requirements.

Note: Chemical Storage and Segregation Guidelines posters, Cabinet Labels, and Secondary Containments are available for Chemical Engineering Labs. Please contact checoop@uwaterloo.ca for assistance.

7.7.3. Peroxide-Forming Compounds

Peroxide-forming compounds (PFCs) are chemicals that can gradually form shock-sensitive and potentially explosive peroxides, particularly when exposed to air, light, or heat during storage. To minimize this risk, PFCs should be stored in sealed, air-tight, light-resistant containers and, whenever possible, kept in their original manufacturer's packaging. If a compound has been purified to remove peroxide inhibitors, an appropriate inhibitor must be reintroduced before storage, and the addition should be documented. Where practical, oxygen exposure should be minimized through oxygen-exclusion techniques, such as purging containers with an inert gas.

Researchers who manipulate PFCs must adhere to safe handling practices and procedures, which involve making effective purchasing decisions, buying only the amount that is needed to complete an experiment within the chemical's safe shelf life, storage tracking and periodic testing for peroxide, labelling containers and tracking received date, opened date, and last tested date, and proper disposal of hazardous waste following UW procedures.

The RSS Chemical Inventory System, see section 7.7.4 below, can be used to identify, track, and manage peroxide-forming compounds throughout their life cycle. For inventory management purposes, peroxide-forming compounds are classified into four groups:

• Class A (Severe Peroxide Hazard): Form explosive levels of peroxides during storage without any concentration or opening.

  • Examples: Butadiene (liquid), potassium metal, sodium amide, tetrafluoroethylene (liquid), vinylidene chloride.
  • Action: Test liquids for peroxide formation before using, and discard when peroxides are present. Dispose of the chemicals 3 months after opening or 12 months after receiving if unopened.

• Class B (Concentration Hazard): Form dangerous peroxides only when the solvent is evaporated, distilled, or concentrated.

  • Examples: Cyclohexene, diethyl ether, isopropanol, tetrahydrofuran (THF).
  • Action: Always test for peroxide formation before distillation or evaporation. Do not concentrate solutions that may contain peroxides. Test for peroxide formation every 12 months after opening. Dispose of the chemical if peroxides are above 25ppm.

• Class C (Self-polymerization): Highly reactive monomers that can undergo a runaway, explosive polymerization triggered by internal peroxide accumulation.

  • Examples: Acrylic acid, butadiene (gas), ethyl acrylate, styrene, vinyl chloride.
  • Action: Test liquids for peroxide formation before using. Test for peroxide formation every 12 months after opening. Dispose of the chemical if peroxides are above 25ppm. Uninhibited Class C chemicals should be disposed of 24 h after opening.

• Class D (Potential Peroxide Formers): Chemicals that do not fit within Classes A–C, but require special handling as they may form peroxides.

  • Examples: Allyl ether, tert-butyl methyl ether, tetrahydropyran.
  • Action: Always test for peroxide formation before distillation or evaporation. Test for peroxide formation every 12 months after opening. Dispose of the chemical if peroxides are above 25ppm.

Notes:

Class A, B, C, and D are also referred to as Class 1, 2, 3, and Unclassified.

Peroxide testing strips and peroxide-forming chemical labels are available in the Analytical Lab. Please contact checoop@uwaterloo.ca for assistance.

7.7.4. Chemical Inventory

Maintaining an accurate chemical inventory is a critical component of laboratory safety. The Risk and Safety Solutions (RSS) Chemical Inventory System is the University's centralized system for managing laboratory chemical inventories.

The RSS Chemical Inventory System supports inventory management, access to Safety Data Sheets (SDS), hazard identification, and regulatory compliance. The system also assists in identifying expired, aging, or high-risk chemicals, including peroxide-forming compounds. RFID and QR code tags can be used to facilitate chemical tracking and reduce the administrative burden associated with maintaining an accurate inventory.

Researchers are granted access to the applicable laboratory inventory as part of the onboarding process and are responsible for maintaining accurate inventory records. Chemical inventories should be updated whenever chemicals are received, transferred, consumed, relocated, or disposed of.

RSS Chemical inventory System

Notes:

• Personnel experiencing difficulties accessing a laboratory inventory should contact checoop@uwaterloo.ca for assistance.
• Laboratory chemical inventories shall be reviewed and recertified annually to verify their accuracy and completeness.
• RFID/QR code tags and scanners are available in the Analytical Lab for inventory management purposes.
• Detailed instructions for using the RSS Chemical Inventory System are available in the RSS Chemical Inventory User Guide below.

RSS Chemical Inventory User Guide