2 Control Measures Engineering Controls Engineering controls are those that mitigate the dangers of accidents through the use of design and separation. They can be placed in three categories:SubstitutionIsolationVentilation
3 Control Measures Engineering Controls Substitution includes the use of a less hazardous material, a change in the process equipment used, or a change in the process itself. Care must be taken to ensure that the substitution actually does result in less hazardous conditions.
4 How to Perform a Substitution. Develop Evaluation Criteria It order to select a substitution chemical the teacher must consider a variety of issues. Some of the criteria of concern are listed below.Waste generatedPhysical state, quantity and characteristics of the wastesCostEquipment, chemicals, waste disposal, etc.Ease of implementationTeaching objectivesDoes the alternative alter the experiment’s teaching objectives significantly?Raw material neededQuantity and characteristics of the raw materials
5 How to Perform a Substitution. Screen Alternatives Screen the alternatives to eliminate those that are not feasible for the UniversitySome preliminary information on each alternative will be neededScreen using an evaluation matrix with the selected criteriaSelect favorable alternatives
6 How to Perform a Substitution. Detailed Evaluation of Alternatives Quantitative/Qualitative Detailed EvaluationNot needed if only one alternative remains after the initial screeningUsed as a fine tuning to determine which of the remaining alternatives might result in the most favorable for pollution preventionPilot TestingTest alternative before its full implementation
7 Example Evaluation Criteria Alternatives Educational value Safety risksInput materials Waste materialsCost ResourcesEase of implementation OthersAlternativesFor Experiment A1. Chemical substitution2. Microscale3. Scale down4. Alternatives 1 and 3For Experiment B1. Ag identification and recovery using ascorbic acid2. Alternative method for Ag identification using KI
8 Control Measures Engineering Controls Isolation is a method of limiting exposure to those students and teachers who are working directly with the hazard, often by enclosing them within a containment structure. While isolation will reduce the risk to those outside the isolated area, it should be accompanied by appropriate controls to ensure that those within are not faced with an increased exposure to the hazard.
9 Control Measures Engineering Controls The most common example of isolation is the elimination of anyone from the laboratory other than those who must be there. Additional students in the room not only create additional distractions and opportunities for accidents but are also potential victims should an accident occur.
10 Control Measures Engineering Controls Ventilation is most important for the control of airborne hazards. It involves the removal (from the laboratory) of air that contains a hazardous contaminant and its replacement with uncontaminated outside air. There are two types: local exhaust and general dilution. A properly designed local exhaust system can capture a contaminant where it is generated and remove it before it is dispersed into the work environment.
11 Control Measures Engineering Controls Local exhaust is accomplished in most laboratories with the use of a fume hood. These devices are critical for the removal of potentially dangerous gases and vapors for the room.General dilution is accomplished thorough the use of Heating Ventilation and Air Conditioning Systems. The more air changes occur in the laboratory the less likely that a dangerous exposure level will occur. Experiments should never be conducted in poorly ventilated spaces.
12 Engineering Controls Fume Hoods Space is always an issue but do not use fume hoods as storage cabinets. A variety of accidents can happen
13 Engineering Controls Fume Hoods Fume hoods should be checked and certified as functioning properly. A white card should be placed on the fume hood with the certification date. (If a fume hood is operating marginally, a yellow caution sign should be posted on the hood; if the hood fails completely, a red warning sign must be posted.)
14 Engineering Controls Fume Hoods Many fume hoods have air flow alarms. However, alarms occasionally fail or are deliberately silenced.One suggestion is taping tissue to the fume hood sash to provide a visual indication of air flow.
15 Engineering Controls Fume Hoods Some rules of thumb when using fume hoods:Keep objects at least 6” inside the hoodLarger objects should be up on blocks or feet to allow air flow to travel underneathToo much air flow is not necessarily a good thing. Eddies can occur which will force the contaminant back on to the user. Call maintenance if you suspect the fume hood is pulling too much airIf your fume hood is loud, it may indicate that mechanical attention is needed. Call maintenance for a hood evaluation.
16 Engineering Controls Fume Hoods Remember -- adequate ventilation is important in any room in which chemicals are used or stored. Inadequate ventilation limits the kinds of activities that can be done and the chemicals used in the laboratory. An adequate ventilation system should change the room air 4-12 times per hour. All air from laboratories should be exhausted outdoors and not re-circulated in the building. The ducts should be situated so that exhausted air does not enter fresh air intakes.
17 Engineering Controls Fume Hoods Lack of odor is not an adequate criteria of good ventilation since many chemicals have no odor at hazardous levels. A knowledge of the hazardous chemicals being used helps reduce risk from exposure. If the presence of hazardous vapors is suspected, monitoring should be done. Emergency auxiliary ventilation should put a negative pressure on the room so air moves into the room and prevents vapors from being re-circulated through the building.
18 Engineering Controls Fume Hoods Chemical storerooms should have ventilation adequate to keep atmospheric levels of chemicals below their hazardous limits (threshold limit value (TLV) or permissible exposure limit (PEL)). As with room ventilation, 4-12 air changes per hour are recommended on a continuous basis to prevent buildup of toxic or hazardous concentrations of vapors. All ventilation systems should be regularly evaluated to ensure they are operating properly.
19 Engineering Controls Fume Hoods Fume hoods are intended to keep flammable gases, toxic vapors, or noxious odors from entering the general room atmosphere. The American Conference of GovernmentIndustrial Hygienists (ACGIH) recommends that hoods be used when working with chemicals having a TLV of 50 ppm or less. The concentrations of vapors in the room must be below the TLV listed in the MSDS for the chemical(s) used. Microscale procedures in which smaller quantities of chemicals are used can reduce exposure to hazardous and noxious vapors.
20 Mechanical Systems Ventilation LOCAL EXHAUST FANSUse local exhaust fans and fume hoods to prevent air pollutants and moisture from accumulating in, or spreading beyond, the local area or classroom. Local exhaust fans may be used to exhaust entire rooms (for example, bathrooms or locker rooms). Fume hoods are appropriate for activities that generate significant quantities of pollutants in a local area within a room.
21 “Other” Control Measures Protective Equipmentrespirators, goggles, gloves, lab coatsSafety Equipmentspill kits, safety showers, eyewashes, fire extinguishers, first aid kits, explosion-proof refrigeratorsLaboratory Maintenance and InspectionHousekeeping, safety audits, chemical storage, container labeling, spills, etc.
22 “Other” Control Measures Clean and well organized lab and storage areas decrease the numbers of opportunities for accidents. Good housekeeping includes proper cleaning of glassware, orderly arrangement of chemical containers, pre-staged tools and many other measures.Laboratory Maintenance and InspectionPerhaps one of the least discussed yet most important area of safety management is housekeeping.
24 Fire Detection Systems Fire Alarms and Heat/Smoke Detectors in classrooms and storage areas provide advanced notice of an incipient fire. Ionization and photoelectric detectors have the capability of saving lives and property if they are installed and maintain correctly. Some general recommendations associated with heat and smoke detectors include:Don’t install them in corners of walls or ceiling.Don’t paint them.Don’t install them in air pathways for vents.Never cover a detector with a plastic bag or other device.
25 Fire Sprinkler Systems Fire Sprinkler systems are extremely effective tools for the protection of life and property. They have the best safety record of any fire control device according to the National Fire Protection Association. A note here about how they work.A sprinkler head is a water outlet that is sealed closed with a cap and a fusible device such as a glass crystal or fusible link. They operate at a given ambient temperature and operate one at a time directly of the seat of the fire. They cause significantly less damage than a fire might.
26 Fire Sprinkler Systems Some simple procedures will ensure that the sprinkler system will work effectively and not cause undue damage.Never hang anything from a sprinkler head.Never paint a sprinkler head.Avoid sprinkler heads when conducting experiments involving high heat.Do not store anything within 18 inches of the sprinklers.In the event a sprinkler activates accidentally, evacuate the room (the first water at the end of the pipe is usually filthy and stagnate) and attempt to control flooding.
27 Electrical SystemsGround fault interrupters are designed to protect from electrical shock by interrupting a household circuit when there is a difference in the currents in the "hot" and neutral wires. Such a difference indicates that an abnormal diversion of current from the "hot" wire is occurring. Such a current might be flowing in the ground wire, such as a leakage current from a motor or from capacitors. More importantly, that current diversion may be occurring because a person has come into contact with the "hot" wire and is being shocked. When a circuit is functioning normally, all the return current from an appliance flows through the neutral wire, so the presence of a difference between "hot" and neutral currents represents a malfunction which in some circumstances could produce a dangerous or even lethal shock hazard.
28 Electrical SystemsGFCIs are sensitive and trip easily. To reset them first ensure that there is no electrical hazard and then simply push the reset button located in the middle of the receptacle. In some cases normal duplex receptacles are wired to one GFCI. If this case you will have to locate the GFCI and reset it. Any failure or a GFCI to reset or if you cannot find it, contact facilities maintenance.Ground fault interrupters are subject to aging and may need replacing after a number of years. The GFCI ordinarily trips off and cannot be reset using the Reset button. If this occurs, notify facilities maintenance to test and/or replace the GFCI.
29 Electrical SystemsTo test a GFCI, press the “test” button. The power should shut off.Occasionally GFCIs fail to work as designed (even though pressing the “test” button shuts off the power).To ensure a GFCI is working properly, contact Maintenance for testing.
30 Electrical SystemsExtension cords are not permitted in labs except for temporary (one day) use.Check to see that all power cords are in good condition.Replace or repair those with cracked housing, missing grounding pugs, etc.
31 Electrical SystemsElectrical panels should be labeled and must have clear access. Access will be important in the event there is an urgent need to shut power off to a particular appliance of area. Breaker panels for the lab may be locked.
32 Electrical SystemsAny time rewiring or renovation is performed it is a good idea to check to see that all outlets are grounded and that the polarity is correct. A simple circuit checking tool can do this.
33 Emergency ShutoffsFlorida Statutes require that “Each space equipped with unprotected gas valves accessible to students has an approved master cut-off readily accessible to the teacher” The teacher should be aware of the location of the gas shut-offs in their laboratory classroom. Shutoff is sometimes accomplished with a quarter turn valve and sometimes with an electrical gas valve.
34 Safety Inspection Findings Let’s look at some photos of laboratory inspections in schools. See how many problems you can find.
50 This is a tricky one. Plastic tubing should not extend below the rim of a sink unless the faucet is equipped with an anti-siphon device (see arrow, inset).Soap and towels must be readily available.
51 SummaryThere are a wide variety of engineering control measures that can prevent accidents but at their best they may not be able to control all hazards. It is essential therefore to act is a safe manner in support of those systems.Most engineering solutions require some level of maintenance, it is up to the users to ensure proper working condition.ReferencesGo to the Quiz
52 ReferencesASE (1996) Safeguards in the School Laboratory (10th ed..), Hatfield: ASE.Borrows, P. (1992) ‘Safety in secondary schools’, in Hull, R. (ed.), ASE Secondary Science Teachers’ Handbook, Hemel Hempstead: Simon & Shuster. (This highlights the common accidents in labs most of which involve chemicals in the eye or mouth or on the body; and describes five ‘main danger areas’ such as burns from alcohol fires and alkali metal explosions.) More recently Borrows has written: ‘Safety in science education’, in Ratcliffe, M. (ed.) (1998).DfEE (1996) Safety in Science Education, London: HMSO.Everett, K. and Jenkins, E. (1991) A Safety Handbook for Science Teachers, London: John Murray.The MSDS Hyperglossary at
53 Glossary Back to Module 29 CFR – OSHA’s Laboratory Standard also known as Title 29 of the Code of Federal Regulations Part 1910, Subpart Z, Section 1450Action Level – a concentration designated in 29 CFR part 1910 for a specific substance, calculated as an eight hour-time weighted average (TWA), which initiates certain required activities such as exposure monitoring and medical surveillance. Action levels are generally set at one half the PEL but the action level may vary from standard to standard.Acute toxicity – is the ability of a chemical to cause a harmful effect such as damage to a target organ or death after a single exposure or an exposure of short duration.American Conference of Governmental Industrial Hygienists (ACGIH) – a non-profit organization consisting of a community of professionals advancing worker health and safety through education and the development and dissemination of scientific and technical knowledge. The ACGIH develops and publishes recommended occupational exposure limits each year called TLVs for hundreds of chemicals, physical agents and biological exposure indices.American National Standard Institute (ANSI) – a non-profit organization that administers and coordinates the US voluntary standardization and conformity assessment system.Biological Materials – Biological or biohazardous materials include all infectious organisms (bacteria, fungi, parasites, viruses, etc.) that can cause disease in humans or cause significant environmental or agricultural impact.Carcinogen - A substance capable of causing cancer. Carcinogens are chronically toxic substances; that is, they cause damage after repeated or long-duration exposure, and their effects may become evident only after a long latency period.Back to Module
54 Glossary Back to Module CAS # - Chemical Abstracts Number – a unique number assigned to a chemical by the Chemical Abstracts Service.CFR – Code of Federal Regulations – contains the listings of all US Federal regulations. The CFR, compiled by the Office of the Federal Register, is divided into 50 titles, which cover broad areas subject to Federal regulation.Chemical Hygiene Officer – an employee designated by the employer who is qualified by training or experience to provide technical guidance in the development and implementation of the provisions of the Chemical Hygiene Plan. Note that these duties can be in addition to the other job functions the employee performs in the laboratory.Chemical Hygiene Plan (CHP) – a plan that addresses specific hazards in the laboratory and is required by OSHA’s Laboratory StandardCorrosive – a substance which causes damage to skin, eyes or other parts of the body on contact. Concentrated acids are examples of corrosive substances.Embryotoxin – a substance which retards the growth or affects the development of an unborn child up to and including deformities and death. Mercury compounds, certain heavy metals, aflatoxin, formamide, and radiation are known embryotoxins.Explosive – means a chemical that causes a sudden, almost instantaneous release of pressure, gas and heat when subjected to sudden shock, pressure, or high temperature.Face velocity – the average velocity of air drawn through the face of a chemical fume hood and generally calculated as the total volumetric exhaust flow rate for the hood divided by the area of the open face, less an adjustment for hood air leakage.Back to Module
55 Glossary Back to Module Irritant – a chemical which may cause reversible inflammation upon contact.Laboratory -Any facility where the "laboratory use of potentially hazardous chemicals" occurs. It is a room where relatively small quantities of potentially hazardous chemicals are used during scientific experimentation.Flammable – means a chemical that falls into one of the following categories:aerosol flammable is an aerosol that when tested by the method in 16 CFR , yields a flame protection exceeding 18 inches at full valve opening, or a flashback (a flame extending back to the valve) at any degree of valve openinggas flammable is a gas that at ambient temperature and pressure, forms a flammable mixture with air at a concentration of 13% by volume or less or a gas that at ambient temperature and pressure, forms a range of flammable mixtures with air wider than 12% by volume, regardless of the lower limit.liquid flammable means any liquid having a flashpoint below 100°F (37.8°C), except any mixture having components with flashpoints of 100°C or higher, the total of which make up 99 percent or more of the total volume of the mixture.solid flammable means a solid, other than a blasting agent or explosive as defined in (a), that is liable to cause fire through friction, absorption of moisture, spontaneous chemical change, or retained heat from manufacturing or processing, or which can be ignited readily and when ignited burns so vigorously and persistently as to create a serious hazard. A chemical will be considered a flammable solid if, when tested by the method described in 16 CFR , it ignites and burns with a self-sustained flame at a rate greater than one-tenth of an inch per second along its major axis.Back to Module
56 Glossary Back to Module FM 200 – a Halon replacement extinguishing agent which is a chemical blend (heptafluoropropane), stored as a liquid within the agent cylinder similar to that of Halon-type cylinders. It will not corrode sensitive electronic equipment, and contains no particulates or oily residues. In fact, it leaves very little residue and is a quite popular extinguishing agent in use today for the protection of computer rooms.Fume Hood - a laboratory device, enclosed on five sides with a moveable sash or fixed partial enclosure on the remaining side; constructed and maintained to draw air from the laboratory and to prevent or minimize the escape of air contaminants into the laboratory; and allows chemical manipulations to be conducted in the enclosure without insertion of any portion of the employee’s body other than hands and arms.Hazardous chemical – the OSHA definition is a chemical for which there is statistically significant evidence based on at least one study conducted in accordance with established scientific principles that acute or chronic health effects may occur in exposed employees. The term "health hazard" includes chemicals which are carcinogens, toxic or highly toxic agents, reproductive toxins, irritants, corrosives, sensitizers, hepatotoxins, nephrotoxins, neurotoxins, agents which act on the hematopoietic systems, and agents which damage the lungs, skin, eyes, or mucous membranes.Hazard Communication Standard – 29 CFR was first enacted on November 25, 1983, by the OSHA. It was later modified with minor changes and technical amendments to take effect March 11, The purpose of the standard is to ensure that chemical hazards in the workplace are identified and evaluated, and that information concerning these hazards is communicated through MSDSs and labels. This standard is also known as the Right-to-Know Law.Back to Module
57 Glossary Back to Module HEPA - high efficiency particulate air filter – is a filter that is manufactured, tested and certified to meet applicable construction and efficiency standards for high-efficiency filters. The filters are manufactured from an ultra-fine glass-fiber medium designed to capture microscopic particles that can easily pass through most other filters by a combination of diffusion, interception, and inertial impaction.Health Hazard - means a chemical for which there is statistically significant evidence based on at least one study conducted in accordance with established scientific principles that acute or chronic health effects may occur in exposed employees.Inergen - It is an inert gas used for fire extinguishment. It is a mixture of three naturally occurring atmospheric gases: 52% nitrogen, 40% argon, and 8% CO2. The Inergen gas curtails and extinguishes fire by lowering the oxygen content beneath the level that supports combustion. But it should be noted that due to the CO2 present in Inergen, the brain continues to receive the same amount of oxygen in an Inergen atmosphere as it would in a normal atmosphere, for reasonable periods of time.Laboratory Scale - Working with substances in which the containers used for reactions, transfers, and other handling of substances are designed to be easily and safely manipulated by one person. Laboratory Standard – a standard (29 CFR ) issued by OSHA addressing occupational exposures to hazardous chemicals in the laboratory. All laboratories must comply with this standard.Back to Module
58 Glossary Back to Module Laboratory use of Potentially Hazardous Chemicals - the handling or use of such chemicals in which all of the following conditions are met:1) Use of laboratory scale.2) Multiple chemical procedures or chemicals used.3) Protective laboratory practices and equipment are available and in common use to minimize the potential for student/teacher exposure to hazardous chemicals.LC50 or lethal concentration 50 – this is a measure of toxicity which corresponds to the concentration in air that kills 50% of the test population. Note that most estimates of human toxicity are based on animal studies, which may or may not relate to human toxicity.LD50 or lethal dose 50 – this is a measure of toxicity which corresponds to the dose required to kill 50% of the test population. Note that most estimates of human toxicity are based on animal studies, which may or may not relate to human toxicity. The LD50 is usually measured in milligrams of the material per kilogram of body weight of the test animal. To estimate a lethal dose for a human based on animal tests, the LD50 must be multiplied by the weight of an average person.Material Safety Data Sheets (MSDS) – is a well-established document for disseminating health and safety information about chemical products to employees, customers, emergency responders, and the public. Information contained in the MSDS includes potential health, safety, and environmental hazards, safe handling practices, and applicable regulatory information.Back to Module
59 Glossary Back to Module National Fire Protection Association (NFPA) private non-profit organization, is the leading authoritative source of technical background, data, and consumer advice on fire protection, problems and preventionOrganic peroxide - an organic compound that contains the bivalent -OO- structure and which may be considered to be a structural derivative of hydrogen peroxide where one or both of the hydrogen atoms has been replaced by an organic radical. Peroxides can be very dangerous materials and may be shock and thermal sensitive. They are also strong oxidizers. OSHA – Occupational Safety & Health Administration is part of the US Department of Labor. Its mission is to save lives, prevent injuries and protect the health of America's workers.Particularly hazardous substance – is defined by OSHA in the Laboratory Standard and includes “select carcinogens” (strongly indicative of causing cancer in humans), reproductive toxins, and substances which have a high degree of acute toxicity.Permissible exposure limit (PEL) - which represents the maximum amount or concentration of a substance that a worker may be exposed to under OSHA regulations. There are ceiling values (at no time should this value be exceeded) and 8-hour time weighted averages (an average value of exposure over the course of an 8 hour work shift)Personal Protective Equipment (PPE) – is all clothing and other work accessories designed to create a barrier against workplace hazards. Examples include safety goggles, respirators, lab coats, etc.Back to Module
60 Glossary Back to Module Pyrophoric – a pyrophoric material is one that ignites spontaneously in air and is derived from the Greek word meaning “fire-bearing”. Many of these materials will also react vigorously with water or high humidity and ignite upon contact.Physical Hazard – A hazard exhibited by certain chemicals due to their physical properties. These chemicals fall into the following classes: combustible liquids, compressed gases, explosives, flammable liquids or solids, organic peroxide, oxidizers, pyrophoric materials, and unstable (reactive) or water reactive materials.Reproductive toxins – per OSHA any chemical that affects the reproductive chemicals which affect the reproductive capabilities including chromosomal damage/mutations and effects on fetuses (teratogenesis).Select carcinogens – per OSHA any substance that meets one of the following criteria:regulated by OSHA as a carcinogenlisted under the category, “known to be carcinogens” in the Annual Report on Carcinogens published in the latest edition by the National Toxicology Program (NTP)listed under Group 1 (“carcinogenic to humans”) by the International Agency for Research on Cancer Monographs (IARC)listed in either Group 2A or 2B by IARC or under the category, “reasonably anticipated to be carcinogens” by NTP and causes statistically significant tumor incidence in experimental animals in accordance with any of the following criteria: after inhalation exposure of 6-7 hours per day, 5 days per week, for a significant portion of a lifetime to dosages of less than 10 mg/m3, after repeated skin application of less than 300 mg/kg of body weight per week, or after oral dosages of less than 50 mg/kg of body weight per day.Back to Module
61 Glossary Back to Module Sensitizer – a chemical which may lead to the development of allergic reactions after repeated exposure.Short term exposure limit (STEL) - which is the concentration employees can be exposed to continuously for a short period of time without suffering from irritation, chronic or irreversible tissue damage, or narcosis of sufficient degree to increase the likelihood of accidental injury, impair self-rescue or materially reduce work efficiency.Standard Operating Procedures (SOP) – is a document that describes the operations, analyses, or actions that are commonly accepted methods or the laboratory prescribed procedures for performing certain routine or repetitive tasks.Target Organ - indicate which bodily organs are most likely to be affected by exposure to a substance. Certain chemicals may bio-concentrate in the liver while other target the brain.Threshold Limit Values (TLV) – are airborne concentrations devised by the ACGIH that represent conditions under which it is believed that nearly all workers may be exposed day after day with no adverse effect. TLVs are advisory exposure guidelines, not legal standards, that are based on evidence from industrial experience, animal studies, or human studies when they exist. There are three different types of TLV's: Time Weighted Average (TLV-TWA), Short Term Exposure Limit (TLV-STEL) and Ceiling (TLV-C).Tort Law – is the law of liability and negligence. It involves that plaintiff who allegedly has been wronged and the defendant who is claimed to have perpetrated the injustice. Tort law deals with issues of property and personal injury law. Mass tort is the process of suing a major defendant on behalf of a large number of plaintiffs. Law suits involving drugs such as Vioxx are examples.Back to Module
62 Glossary Back to Module Toxicity Characteristic Leaching Procedure (TCLP) – is a procedure (Method 1311) performed on a sample within the laboratory to determine whether or not a waste is considered hazardous. A sample is extracted with a buffered acid and the resulting extraction fluid or leachate approximates the fluid that would leach from the sample if it were in a landfill.Toxicity Characteristic (TC) – regulatory limits established for 39 compounds. If a waste analyzed via the TCLP procedure detects any of these compounds above the regulatory limits then the waste is said to exhibit the toxicity characteristic.Water Reactive - these substances are dangerous when wet because they undergo a chemical reaction with water. This reaction may release a gas that is either flammable or presents a toxic health hazard. In addition, the heat generated when water contacts such materials is often enough for the item to spontaneously combust or explode.Back to Module
63 Quiz Five The first step in using a fire blanket is to: Spread it out on a table or other flat surfaceAttempt to use an extinguisher first.Shake the container to mix the chemicals.Remove it from its package.Back to StartNext Question
64 Quiz FiveWhich of the following items is one of the categories of engineering controls?IsolationSublimationSeparationDemarcationBack to StartNext Question
65 Quiz FiveOne way of continuously monitoring the proper Functioning of fume hoods is to:Tape a ribbon of tissue to the fume sash.Listen for the sound the fan makes.Routinely test the air around the hood.Regularly measure the air flow just outside the hood.Back to StartNext Question
66 Quiz Five When using a fume hood, larger items should be placed: On blocks of feet to allow air flow to travel underneathIn the front of the hood to get maximum effect.In the back of the hood to get maximum effect.Next to smaller items to aid in recognitionNone of the aboveBack to StartNext Question
67 Quiz FiveThe ACGIH recommends that fume hoods be used when working with chemicalsThat are on the extremely dangerous substances listThat have a TLV of 50ppm or less.That are inflammable.That have an ignition temperature of 451ºF or lessAll of the above.Back to StartNext Question
68 Quiz FiveOne important issue regarding smoke detectors in the laboratory or classroom is they should:Never be painted.Not be installed in corners of walls or ceilings.Not be installed in the air path of a vent.Not be covered with plastic bags.All of the above.Back to StartNext Question
69 Quiz FiveThe Fire Sprinklers located in the laboratory activate based upon heat and operate:All at once and as a deluge to drown the fireOne at a time as the fusible devices operate.In groups of three to control a rapid moving fire.With relatively low effectivenessBack to StartNext Question
70 Quiz FiveThe device that is designed to protect from electrocution by interrupting the circuit when there is a difference in the currents in the hot and neutral wires is called a(n):Circuit BreakerGround Fault Circuit InterrupterBar FuseECG deviceNone of the aboveBack to StartNext Question
71 Quiz FiveGas valves in laboratories are required to have what safety feature?An emergency shutoff.A sign that reads “Gas in Use”No available means of ignition.Doors that open only in the direction of egress.Back to StartNext Question
72 Quiz FiveWhich of the following is a good practice regarding fire sprinklers?Never hang anything from a sprinkler head.Never paint a sprinkler any color other than its original colorDo not store anything within 22 inches of the headConduct high heat experiments directly under the head of a sprinkler.Back to StartFinish