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Flammable and Combustible Liquids
Flammable and Combustible Liquids
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Introduction
Introduction
The two primary hazards
associated with flammable and
combustible liquids are
explosion and fire
Safe handling and storage of
flammable liquids requires the
use of approved equipment and
practices per OSHA standards
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Flash Point
Flash Point
Flash point means the minimum temperature at which a
liquid gives off enough vapor to form an ignitable mixture
In general, the lower the flash point, the greater the
hazard
Flammable liquids have flash points below 100o
F, and are
more dangerous than combustible liquids, since they may
be ignited at room temperature
Combustible liquids have flash points at or above 100o
F
Although combustible liquids have higher flash points than
flammable liquids, they can pose serious fire and/or
explosion hazards when heated
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Classes of Flammable
Classes of Flammable
and Combustible Liquids
and Combustible Liquids
IIIA
II
IC
IA IB
200
140
100
73
Flash
Point
(
o
F)
100
Boiling Point (o
F)
Combustible
(FP > 100o
F)
Flammable
(FP < 100o
F)
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Classes of Some Flammable Liquids
Classes of Some Flammable Liquids
CLASS IA
CLASS IB
CLASS IC
Common Name Flash Point (o
F)
Ethyl Ether -49
Gasoline -45
Methyl Ethyl Ketone 21
Toluene 40
Xylene 81-115
Turpentine 95
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Program Components
Program Components
Control of ignition sources
Proper storage
Fire control
Safe handling
A good plan for safe use of flammable and
combustible liquids contains at least these
components:
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Sources of Ignition
Sources of Ignition
Open flames
Smoking
Static electricity
Cutting and welding
Hot surfaces
Electrical and mechanical sparks
Lightning
Must take adequate precautions to prevent ignition of
flammable vapors. Some sources of ignition include:
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Static Electricity
Static Electricity
Generated when a fluid flows through a
pipe or from an opening into a tank
Main hazards are fire and explosion from
sparks containing enough energy to
ignite flammable vapors
Bonding or grounding of flammable liquid
containers is necessary to prevent static
electricity from causing a spark
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Bonding
Bonding
Physically connect two
conductive objects together
with a bond wire to eliminate
a difference in static charge
potential between them
Must provide a bond wire
between containers during
flammable liquid filling
operations, unless a metallic
path between them is
otherwise present
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Grounding
Grounding
Eliminates a difference in static
charge potential between
conductive objects and ground
Although bonding will eliminate
a difference in potential
between objects, it will not
eliminate a difference in
potential between these objects
and earth unless one of the
objects is connected to earth
with a ground wire
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Ventilation
Ventilation
Always provide adequate ventilation
to reduce the potential for ignition of
flammable vapors.
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Storage Fundamentals
Storage Fundamentals
Identify incompatible chemicals – check the Material
Safety Data Sheet
Isolate and separate incompatible materials
Isolate by storing in another area or room
Degree of isolation depends on quantities,
chemical properties and packaging
Separate by storing in same area or room, but
apart from each other
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Storage of Flammable
Storage of Flammable
and Combustible Liquids
and Combustible Liquids
Storage must not limit the use of
exits, stairways, or areas normally
used for the safe egress of people
In office occupancies:
Storage prohibited except that
which is required for maintenance
and operation of equipment
Storage must be in:
closed metal containers inside
a storage cabinet, or
safety cans, or
an inside storage room
Inside storage room
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Safety Cans for Storage and Transfer
Safety Cans for Storage and Transfer
Approved container of not
more than 5 gallons capacity
Spring-closing lid and spout
cover
Safely relieves internal
pressure when exposed to fire
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Flame Arrester Screen
Flame Arrester Screen
Prevents fire flashback into
can contents
Double wire-mesh construction
Large surface area provides
rapid dissipation of heat from
fire so that vapor temperature
inside can remains below
ignition point
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Storage Cabinets
Storage Cabinets
Not more than 60 gal of Class I
and/or Class II liquids, or not more
than 120 gal of Class III liquids
permitted in a cabinet
Must be conspicuously labeled,
“Flammable - Keep Fire Away”
Doors on metal cabinets must
have a three-point lock (top, side,
and bottom), and the door sill
must be raised at least 2 inches
above the bottom of the cabinet
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Fire Control
Fire Control
Suitable fire control devices, such as
small hose or portable fire
extinguishers must be available
where flammable or combustible
liquids are stored
Open flames and smoking must not
be permitted in these storage areas
Materials which react with water must
not be stored in the same room with
flammable or combustible liquids
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Transferring Flammable Liquids
Transferring Flammable Liquids
1. Through a closed piping system
2. From safety cans
3. By gravity through an approved self-closing safety
faucet
4. By means of a safety pump
Since there is a sizeable risk whenever flammable
liquids are handled, OSHA allows only four
methods for transferring these materials:
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Self-Closing Safety Faucet
Self-Closing Safety Faucet
Bonding wire between
drum and container
Grounding wire between
drum and ground
Safety vent in drum
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Safety Pump
Safety Pump
Faster and safer than
using a faucet
Spills less likely
No separate safety vents
in drum required
Installed directly in drum
bung opening
Some pump hoses have
integral bonding wires
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Waste and Residue
Waste and Residue
Waste drum with
disposal funnel
Safety disposal can Oily-waste can
(self-closing lid)
Combustible waste and residue must be kept to a minimum,
stored in covered metal receptacles and disposed of daily.
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Safe Handling Fundamentals
Safe Handling Fundamentals
Carefully read the manufacturer’s label on the flammable
liquid container before storing or using it
Practice good housekeeping in flammable liquid storage
areas
Clean up spills immediately, then place the cleanup rags in
a covered metal container
Only use approved metal safety containers or original
manufacturer’s container to store flammable liquids
Keep the containers closed when not in use and store away
from exits or passageways
Use flammable liquids only where there is plenty of
ventilation
Keep flammable liquids away from ignition sources such as
open flames, sparks, smoking, cutting, welding, etc.
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Summary
Summary
The two primary hazards associated with flammable
and combustible liquids are explosion and fire
Safe handling and storage of flammable liquids
requires the use of approved equipment and
practices per OSHA standards
An excellent reference on this topic is National Fire
Protection Association Standard No. 30, Flammable
and Combustible Liquids Code
Editor's Notes
#1:This presentation is designed to assist trainers conducting OSHA 10-hour General Industry outreach training for workers. Since workers are the target audience, this presentation emphasizes hazard identification, avoidance, and control – not standards. No attempt has been made to treat the topic exhaustively. It is essential that trainers tailor their presentations to the needs and understanding of their audience.
This presentation is not a substitute for any of the provisions of the Occupational Safety and Health Act of 1970 or for any standards issued by the U.S. Department of Labor. Mention of trade names, commercial products, or organizations does not imply endorsement by the U.S. Department of Labor.
#3:1910.106(a)(14)
Flash point means the minimum temperature at which a liquid gives off vapor within a test vessel in sufficient concentration to form an ignitable mixture with air near the surface of the liquid.
Flammable liquids themselves will not burn, but as the liquid evaporates, it gives off vapors that mix with the air to form dangerous gases that can be set off by a small spark. Gasoline, for example, evaporates at temperatures as low as 45 degrees Fahrenheit below zero. As the temperature rises, the rate of evaporation increases and more and more vapors are given off. Flammable vapors are usually heavier than air so they collect in the lowest areas they can reach. Without good ventilation to dissipate them, a small spark can set off a big disaster.
#4:1910.106(a)(18) and (19)
Flammable and combustible liquids are classified primarily according to their flash point to indicate the danger they pose as a fire hazard. Flash point is directly related to a liquid’s ability to generate vapor. Since it is the vapor of a liquid, not the liquid itself, that burns, vapor generation becomes a primary factor in determining the fire hazard.
Flammable liquids have flash points below 100oF and are classified as Class I liquids. Flammable liquids are sub-divided into three subclasses: IA, IB, and IC. Class IA liquids have flash points below 73oF and boiling points below 100oF. Class 1B liquids have flash points below 73oF and boiling points at or above 100oF. Class IC liquids have flash points at or above 73oF and below 100oF.
Combustible liquids have flash points at or above 100oF and are classified as Class II and Class III liquids. Class II liquids have flash points at or above 100oF and below 140oF. Class III liquids are sub-divided into two subclasses: IIIA and IIIB. Class IIIA liquids have flash points at or above 140oF and below 200oF. Class IIIB liquids have flash points at or above 200oF, and are not regulated by 1910.106.
#5:Other common flammable and combustible liquids and their flash points are shown below:
Flash Point (oF)
CLASS IA Pentane < -40
CLASS IB Acetone 0
VM&P Naptha 20-45 (Typical)
Ethyl Alcohol 55
CLASS IC Mineral Spirits 85-110
CLASS II Fuel Oils 100-130
Kerosene 110-150
CLASS III Ethylene Glycol 232
#8:Static electricity can be generated by the contact and separation of dissimilar materials. For example: belts and pulleys, tires and the road, fluid flow through a pipe, agitation and mixing of fluids, and splash filling of flammable liquids.
For more information, see NFPA 77, Static Electricity.
One of the primary means of reducing the hazard of static electricity when transferring flammable liquids into/from containers is through the use of bonding and grounding, which is discussed in this program.
#9:1910.106(e)(6)(ii)
Both objects bonded share the same charge and have no potential difference, BUT there still is a potential difference between the conductive objects and ground. Thus, there is danger of a spark from one of the conductive objects to grounded objects.
#10:1910.106(e)(6)(i)
Both objects bonded and grounded permit charge to flow to ground.
#11:1910.106(a)(31)
Ventilation for the prevention of fire and explosion is considered adequate if it is sufficient to prevent accumulation of significant quantities of vapor-air mixtures in concentration over one-fourth of the lower flammable limit.
For additional information on ventilation, see OSHA’s web site at:
http://www.osha-slc.gov/SLTC/ventilation/index.html
#13:1910.106(d)(5)(i) and (iii)
In office occupancies, the inside storage room must not have a door that opens into that portion of the building used by the public.
#16:1910.106(d)(3)(i) and (ii) and (ii)(a)
Three-point lock on metal cabinet doors prevents buckling, which would expose contents to fire.
Raised door sill contains leaks.
#22:Spills or Leaks
First, eliminate all sources of ignition, then
Stop the leak, if possible
Contain the material
Isolate the area
Avoid direct contact with the material
Use appropriate fire control procedures
