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Laboratory Safety Manual

Table of Contents

Lab Safety at Princeton

Chemical Hygiene Plans

Emergency Procedures

Hazard Identification

Health Hazards of Chemicals

Controlling Exposures

-Lab Ventilation

-Protective Equipment

Chemical-Specific Issues

Anecdotes

Particularly Hazardous Substances

Reproductive Toxins

High Acute Toxicity

Lab Design Considerations

Lab Safety Management

Fire Extinguishers and Fire Safety
in a
Science & Engineering Laboratory

Introduction

Since fire is a common hazard that one faces in a science and engineering laboratory, it is important to be prepared and to know how to deal with a fire emergency. Fire extinguishers are a first line of defense, only if used properly, and under the right conditions. Fire extinguishers are appropriate for small, incipient stage fires, no bigger than a wastepaper basket. University policy states that individuals are not required to fight fires, but that those who choose to do so must have been trained in the proper use of fire extinguisher. Training is provided by the University Fire Marshall and can be arranged by calling 8-6805.

Fire Triangle

A fire needs three elements to survive: oxygen, heat and fuel. This is known as the fire triangle. Fires are extinguished by removing one of the three elements of the triangle.

Oxygen	Makes up about 21% if the air that we breathe. To sustain a fire, a ratio of 16% oxygen or greater is needed
Fuel	Can be combustible or flammable material, and may be solid, a liquid or a gas
Heat	Is needed both to initially ignite the fire and also to sustain the fire.

Fire Classifications

Fires are classified based on the type of fuel that is burning.

Class A - Wood, paper, cloth, trash and plastics
                (solid combustible materials that are not metals)
Class B - Flammable liquids such as gasoline, oil, kerosene and solvents

Class C - Electrical equipment
                (as long as it's "plugged in" it is considered a Class C fire)
Class D - Combustible Metals such as magnesium, potassium and sodium as well as organometallic reagents such as alkyllithiums, Grignards
                and diethylzine.

Types of Fire Extinguishers

1. Pressurized Water - Class A fire only

a. Water stored under air pressure - 2.5 gallon cylinder
b. Discharge approximately 1 minute, with a range of 10-20 feet
c. Extinguishes the fire by removing heat
d. WATER-FILLED EXTINGUISHERS ARE NOT ACCEPTABLE FOR LABORATORY USE. If you have a water-filled extinguisher, have it replaced immediately by calling Building Services at 8-3490.

2. Dry Chemical - Class A, B & C fires

a. Dry chemical powder (ABC - Ammonium phosphate, BC - Sodium or potassium bicarbonate) stored under nitrogen pressure
b. Discharge approximately 8 to 15 seconds, with a range of 6-15 feet
c. Extinguishes fire by removing the oxygen through smothering
d. Dry chemical fire extinguishers are suitable for labs, but can cause a tremendous mess. Dry chemical powder can infiltrate sensitive electrical equipment and ruin optics, mirrors and other laboratory equipment.

3. Carbon Dioxide (CO₂) - Class B & C fires

a. CO₂stored under pressure
b. Discharge approximately 8 to 15 seconds, range 3-5 feet
c. Extinguishes fire by reducing the amount of oxygen around the fire
d. WARNING: CO₂ can cause severe chemical burns and freezing of body parts. DO NOT HOLD THE HORN - grip the handle part of the
extinguisher.
e. WARNING: CO₂ can reduce the percent of oxygen in air when in a confined area. Use only in well ventilated areas.

4. Dry Powder (Sodium Chloride/Sand) - Class D fires

a. This agent can be stored in both extinguishers and storage bins. The agent is applied gently at a sufficient amount to cover the burning metal
b. Extinguishes fires by forming a crust over the burning metal, thus smothering it.

Components of a Fire Extinguisher

Cylinder - Holds extinguishing agent and expelling gases
Handle - Used to carry and hold extinguisher
Trigger - When pressed, releases extinguishing agent through hose and nozzle
Nozzle or Horn - Agent expelled through these items
Pressure Gauge - Shows pressure of the extinguishing agent being stored in the cylinder. The indicator should be in the green area. CO₂ extinguishers do not have a pressure gauge.

Rules for Fighting Fires

Public Safety should be notified immediately at 911
If the fire is large or spreading, alert building occupants verbally or activate the fire alarm
NEVER FIGHT A FIRE IF:

You don't know what is burning
The fire is spreading rapidly beyond the spot where it started
You don't have adequate or appropriate equipment
You may inhale toxic smoke
Your instincts tell you not to

Always position yourself with an exit or means of escape at your back before you attempt to extinguish a fire.
If the fire is not out after you have completely discharged the extinguisher, exit the building immediately.

PASS Procedure

Pull the Pin - This unlocks the operating lever and allows the agent to discharge from the extinguisher

Aim Low - Point the nozzle at the base of the fire

Squeeze the Lever - Discharge the agent from the extinguisher. If you release the lever, the discharge stops.

Sweep from Side to Side - Move carefully toward the fire, keeping the extinguisher aimed at the base of the fire. Sweep back and forth until the fire is out.

NEVER TURN YOUR BACK ON THE FIRE!



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