6. Physics Laboratory Safety Specifications
In this section:
Given the inherent dangers in the laboratory study of electricity, safeguards and safety procedures need to be in place for students and teachers. Consider the following safety specifications in working with electricity:
- Know where the master switch is for electricity in the laboratory in case of an emergency.
- Make students aware of the appropriate use of electricity and dangers of misuse and abuse.
- When using batteries, always inspect them first for cracks, leaking, etc. Discard in an environmentally appropriate way if any of these conditions occur.
- When unplugging cords, always pull cords from the plug at the electrical receptacle and never pull the cords from the wire.
- Use only ground fault interrupt circuits (GFI) protected circuits!
- Remove all conductive or metallic jewelry before working with electricity.
- Prevent trip and fall hazards by placing wires away from places where people walk.
- For routine maintenance like changing bulbs, make sure the device is unplugged before initiating the work.
- Review OSHA's lockout/tagout standard (29CFR 1910.147 and 1910.333) prior to working on any electrical device.
- Never open a battery. The contents are corrosive and can be toxic or poisonous.
- When storing batteries, never allow the terminals to touch or short circuit.
- Be water phobic when working around electricity. Never use water or have wet hands when dealing with cords, plugs or electrical equipment. Never run a cord near or over a sink.
- Utility pipes such as water and gas are grounded. Do not touch an electrical circuit and utility pipes at the same time.
- Never plug damaged electrical equipment into a wall receptacle. This includes frayed wires, missing ground pin and bent plugs.
- Never overload circuits as they will overheat and cause power outages or fires.
B. Electrostatic Generators:
Electrostatic generators such as Van de Graaff generators are a real attention getter for students in the study of electrostatics. The following prudent safety procedures are in order, however:
- The generator should only be operated by and under the direction of the teacher.
- Electronic circuit or devices such as cell phones, computers and cameras can be permanently damaged by the machine's sparks. Keep them at least 50 feet (12 meters) away.
- Always use a surge protector inline with the generator's power cord.
- Students with epilepsy, heart or nervous system conditions, or pacemakers should never operate or be in the proximity of an electrostatic generator.
- Never operate the generator near flammable or combustible materials.
- Never leave the machine operating unattended.
C. Ionizing Radiation:
Although the use of ionizing radiation sources in high school science laboratories is not advocated, some physics courses do, in fact, provide these kinds of laboratory activities. When considering having students work with ionizing radiation at the high school level, it is necessary to have planned safety protocols in place. The following safety procedures should be reviewed and adopted prior to dealing with radioactive materials:
- Select only low-level alpha and beta emitters.
- To prevent accidental entry of radioactive materials into the body, high standards of cleanliness and good housekeeping must be maintained in all laboratories where radioactive materials are present and/or used.
- Visitors are not allowed without approval of chemical hygiene officer or school system safety compliance officer.
- Table and bench tops should be of a nonporous, chemical resistant material. Working surfaces shall be covered with absorbent paper regardless of the type of surface.
- Eating or drinking in laboratories that deal with radioactive materials is unsafe and forbidden. Refrigerators will not be used jointly for foods and radioactive materials.
- One or more trial runs beforehand with nonradioactive materials are recommended for new procedures and new personnel to test effectiveness of procedures and equipment.
- Do not work with radioactive materials if there is a break in the skin below the wrist.
- Always use gloves when handling more than a few hundred counts per minute. Wear protective clothing (lab coats, masks, shoe covers) as needed.
- When work is completed each person will clean up his own work area and arrange for disposal or proper storage of all radioactive materials and equipment.
- Wash hands and arms thoroughly before handling any object that goes to the mouth, nose or eyes (e.g., cosmetics, foods). Keep fingernails short and clean.
- Laboratories shall provide special radioactive waste containers. These shall bear the words “Caution, Radioactive Waste” and a warning to janitors against handling.
The study of mechanics in physics provides many touchstones to everyday applications. However, laboratory activities in this area are not without danger. Students and teachers can be injured if hit by rapidly moving objects or projectiles.
Always use caution when dealing with projectiles, falling objects, moving equipment, exposed belts, powerful permanent magnets, sharps such as Exacto knives and razor blades, and springs.
Special attention should be given to the following safety procedures when working with model rockets.
Use only lightweight, nonmetal parts for the nose, body and fins of the rocket.
- Use only commercially made model rocket engines.
- To prevent accidental eye injury, place launchers so that the end of the launch rod is above eye level or cap the end of the rod when it is not in use.
- Always use either safety glasses or safety goggles with an ANSI Z-1 rating when launching rockets.
- Do not tamper with rocket engines or use them for any purposes except those recommended by the manufacturer.
- Launch rockets outdoors, in an open area and in safe weather conditions with wind speeds no greater than 20 mph.
- Use a recovery system such as a flame-resistant or fireproof streamer or parachute so that it returns safely and undamaged and can be flown again.
- Launch rockets with an electrical launch system and electrical motor igniters.
- The launch system should have a safety interlock in series with the launch switch, and will use a launch switch that returns to the "off" position when released.
- Use a safe launch distance of at least 15 feet (6 meters) away from the launch pad for rockets with up to "D" size engines. Use 30 feet (1 meters) when launching larger rockets engines.
- If the rocket misfires, remove the launcher's safety interlock or disconnect its battery. Wait 60 seconds after the last launch attempt before allowing anyone near the rocket.
- Launch a rocket from a launch rod, tower, or rail that is pointed within 30 degrees of the vertical to ensure the rocket flies nearly straight up.
- Use a blast deflector to prevent the engine's exhaust from hitting the ground.
- Do not launch rockets at targets such as tall buildings, power lines or near airplanes.
- Never put any flammable or explosive payload in a rocket.
- Do not attempt to recover rockets from power lines, tall trees or other dangerous places.
E. Nonionizing Radiation – Lasers:
Nonionizing radiation consists of electromagnetic radiation that lacks sufficient energy to ionize matter. These may include the use of lasers, microwaves and infrared radiation in the physics laboratory. Nonionizing radiation can cause injury if handled improperly.
The most common nonionizing radiation equipment used in physics laboratories is the laser. Safety specifications vary depending on the class of laser instrument being used. The following general safety specifications provide prudent advice and direction for use in high school physics courses:
- Before operation, warn all individuals present of the potential hazard.
- Use the laser away from areas where the uninformed and curious might be attracted by its operation.
- In conspicuous locations inside and outside the work area and on doors giving access to the area, place hazardous warning signs indicating that a laser is in operation and may be hazardous.
- Remove all watches and rings before changing or altering the experimental setup. Shiny jewelry can cause hazardous reflections.
- Practice good housekeeping in the lab to ensure that no device, tool or other reflective material is left in the path of the beam.
- Before a laser operation, prepare a detailed operating procedure outlining operation.
- Cover all exposed wiring and glass on the laser with a shield to prevent shock and contain any explosions of the laser materials. Be sure all nonenergized parts of the equipment are grounded.
- Set up the laser so that the beam path is not at normal eye level, i.e., below 3 feet (9 meters) or above 5 feet (2 meters).
- Use shields to prevent strong reflections and the direct beam from going beyond the area needed for the demonstration or experiments.
- Whenever a laser is operated outside the visible range (such as a CO2 laser), a warning device must be installed to indicate its operation.
- A key switch to lock the high voltage supply should be installed.
- View holograms only with a diverged laser beam. Be sure the diverging lens is firmly attached to the laser.
- Illuminate the area as brightly as possible to constrict the pupils of the observers.
- The target of the beam should be a diffuse material capable of absorbing the beam and reflection
- Do not at any time look into the primary beam of a laser.
- Do not aim the laser with the eye. Direct reflection can cause eye damage.
- Do not look at reflections of the beam. These, too, can cause retinal burns.
- Do not use sunglasses to protect the eyes. If laser safety goggles are used, be certain they are designed for use with the laser being used.
- Report any afterimage to a doctor, preferably an ophthalmologist who has had experience with retinal burns. Retinal damage is possible.
- Do not leave a laser unattended.
- Note on laser pointer use: Connecticut has the following general statute relative to laser pointers:
Connecticut General Statutes (C.G.S.)
§ 53-206e. Limitation on sale and use of laser pointers
(a) As used in this section, "laser pointer" means a hand-held device that emits a laser light beam and is designed to be used by the operator to indicate, mark or identify a specific position, place, item or object.
(b) No person shall sell, offer to sell, lease, give or otherwise provide a laser pointer to a person under eighteen years of age, except as provided in subsection (d) of this section.
No person under eighteen years of age shall possess a laser pointer on school grounds or in any public place, except as provided in subsection (d) of this section.
(d) A person may temporarily transfer a laser pointer to a person under eighteen years of age for an educational or other lawful purpose provided the person to whom the laser pointer is temporarily transferred is under the direct supervision of a parent, legal guardian, teacher, employer or other responsible adult.
(e) No person shall shine, point or focus a laser pointer, directly or indirectly, upon or at another person in a manner that can reasonably be expected to cause harassment, annoyance or fear of injury to such other person.
(f) Any person who violates any provision of this section shall have committed an infraction.
F. Pressurized and Vacuum Systems:
Pressurized gas cylinders can explode. Bell jars can implode. Use only pressurized or evacuated items that are designed for such an activity.
Working with vacuums has the potential of an implosion and the possible hazards of flying glass, splattering chemicals and fire. Potential risks must be carefully considered. Equipment at reduced pressure can be prone to rapid pressure changes forcing liquids through an apparatus.
For safety prevention, adopt the following safety protocols when dealing with pressurized and vacuum systems:
- Always use safety glasses or goggles with ANSI Z81 ratings.
- Procedures should always be effected inside a hood.
- Place vacuum apparatus out of harm's way so an accidental hit is minimized. Placement of transparent plastic around the apparatus helps prevent injury from flying glass in case of an explosion.
- Protect vacuum pumps with cold traps and vent the exhaust into an exhaust hood.
- Assemble vacuum apparatus in a manner that avoids strain, particularly to the neck of the flask.
- Do not allow water, solvents and corrosive gases to be drawn into vacuum systems.
- Avoid putting pressure on a vacuum line to prevent stopcocks from popping out or glass apparatus from exploding.
- Avoid using mechanical vacuum pumps for distillation or concentration operations when dealing with volatile materials. A water aspirator should be used.
Usually physics laboratory equipment and activities do not normally produce noise levels requiring use of hearing protection. The OSHA Occupational Noise Standard (29 CFR 1910.95) has established a noise action level of 85 decibels (dBA) averaged over eight hours. Wind tunnels, motors, engines and other laboratory equipment used in physics laboratories have the potential to exceed the action level. Science teachers should monitor sound levels and provide hearing protection for themselves and students. It is advised that this be applied even below the action level.