Anachem ChT 4

Minimum temperature required to initiate or cause self-sustained combustion independent of the heat source

Ignition temperature

Carbon disulfide has an ignition temperature of 90°C)– it can be set off by

a steamline or a glowing bulb

Diethyl ether has an ignition temperature of 160°C)– it can be ignited by

a hot plate

Takes place when a substance reaches its ignition temperature w/o the application of heat

Spontaneous combustions

Causes of spontaneous combustions:

* Oily rags
* Dust accumulations
* Alkali metals
* Phosphorus

Common ignition sources

* Torch and Bunsen burner
* Electrically powered sources

Hazards based on the physical or chemical properties of the material such as flammability

Physical hazards

Type of liquid that can be ignited at concentrations less than their lower flammable limits and at temp. below their flash points

Flammable liquids

Minimum conc. at which liquid releases flammable vapor in the atmosphere enough to ignite when mixed with air or upon application of source of temperature

Flash point

Major causes of ignition

* Spontaneous combustion
* Ignition sources
* Oxidants other than oxygen

Gas oxidant

Cl, Fl, N2O, O2, O3

Liquid oxidant

Bromides, H2O2, HNO3, H2SO4

Solid oxidants

Bromates, perchlorates, chlorates, chlorites, hypochlorites, chromates, peroxides, permanganates

Indicates the highest concentration of a substance in the air that will produce a fire or explosion when a source of ignition (heat, spark or flame) is present

Upper Limit

Indicates the lowest concentration of a substance in the air that will produce a fire or explosion when a source of ignition is present

Lower Limit

Though mixtures with concentrations above UEL are too rich to burn, why is it these mixtures are still very dangerous?

Concentrations above UEL are still very dangerous because if the concentration is lowered (by introducing fresh air), it will enter the explosive range

One of the most common fire-fighting equipment

Fire extinguisher

Has a red body and white band; used for A, B, C fires

Dry chemical

Has a Red body, black band; Used for B, C fires

Carbon dioxide

Has a red body, blue band; Used for A, B fires

Foam

Has a Light Green body, white band; Used for A, B, C fires

Halon substitute

Fires involving ordinary combustible solid materials such as wood, paper, rubber, plastic, cloth, etc.

Class A

Fires in flammable and combustible liquid and gas

Class B (Surface fire)

Fires involving energized electrical equipment

Class C (Electrical fire)

Fires involving combustible metals

Class D (Metallic fire)

According to Fire Safety Enforcement Manual 2012 provision/construction of ___________ remote

from each other, with travel distance of _______ less from standard requirements

* Minimum of (2) secondary fire exits
* 20%

Arises from the highly reactive nature of chemicals in which the presence of a stimulus, may cause sudden increase in temperature or explosion

Reactive hazards

Materials that react violently with water, like alkali metals, hydrides, and halides

Water reactive substances

Materials that ignite due to rapid oxidation by oxygen or moisture in the air

Pyrophoric substance

Include gases which are contained in receptacle at a pressure of 200 kPa (gauge) or more at 20c or which are liquefied or liquefied and refrigerated

Gases under pressure

Arises from explosion due to rapid expansion or evolution of gases usually in a closed or restricted system

Explosion hazards

Explosion hazard stimuli may include

* Heat
* Impact
* Friction
* Detonation

Reaction that result in sudden, rapid rise in temp. of the material that is being heated which may become violent

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Runaway reactions

Based on the ability of the material to cause a harmful health effect

Health Hazard

Risk of toxic effects is related to both the extent of exposure and the inherent toxicity of the substance

Toxic substances

Toxic , substances is evaluated by

Lethal dose

It is the amount of a chemical that when ingested, injected, or applied to the skin of a test animal under controlled laboratory conditions kill one-half (50%) of the animals

Lethal dose

Indicates the max. average concentration to which workers can safely be exposed for a normal 8-hr workday or 48-hr workweek

Time weighted average (TWA)

indicates the max. concentration to which workers can safely be exposed for a period of up to 15 min

Short-term exposure limit (STEL)

Describes the concentration that may not be safey exceeded at any time, even for an instant

Ceiling (C)In

Involve injury at the site of first contact (eyes, skin, nose, and lungs)

Local toxic effects

Occur after the toxicant has been absorbed from the site of contact into the bloodstream and distributed throughout the body

Systemic toxic effects

In some cases, tissues have the capacity to repair toxic damage, so that the damage disappears following cessation of exposure

Reversible toxic effects

persist even after cessation of exposure

Irreversible toxic effects

Are chemical agents that cause undesirable response of tissues upon contact or exposure

Irritant

Cause depletion of oxygen to tissues

Asphyxiants

Are agents that cause toxic action mainly on the internal organs

Systemic poisons

Chemical agents that may cause cancer

Carcinogens

Chemical agents that affect the cells of the person upon exposure that may lead into cancer or undesirable mutation to take place on later generation

Mutagens

Agents that cause birth defects upon exposure of the pregnant women

Teratogens

Agents that cause allergic or allergic-like reactions in the airways upon inhalation

Sensitizers

Extent to which a substance is taken up by an organism and distributed to an area within the organism

Bioavailability

Net result of uptake, transformation, and elimination of a substance in an organism due to all routes of exposure

B

Net result of uptake, transformation, and elimination of a substance in an organism due to waterborne exposure

Bioconcentration

Small solid wastes spills are removed by:

Sweeping together and brushed into dustpan

Large and potentially toxic solid spills are removed by:

Cleaning with a special vacuum cleaner equipped with a High Efficiency Particulate Air (HEPA)

Involve accidental release of hazardous solid materials

Solid chemical spills

Accidental spill of

Most commonly used absorbent for chemical spills (diatomaceous earth, vermiculite, expanded clay, sand, and etc.)

Spill pillows

Acid solution spills are treated with _________ to neutralize acid spills

Soda ash (Na2CO3)

Small acid solution spills are treated with _________ to neutralize acid spills

Baking soda ( NaHCO3)

Alkali acid solution spills are treated with ________ to neutralize base spills

Citric acid or dilute HCl

Small caustic spills are treated directly with _________

Solid Boric acid (H3BO3) or dilute acetic acid

Commonly used sorbent materials for volatile and flammable solvent spills are:

* Amorphous silicate
* Polypropylene
* Surfactant-treated propylene

Spilled mercury are cleaned by using _________

* Aspirator bulb
* Vacuum device

Mercury spills into floor cracks are made non-volatile by __________

Amalgamation with zinc dust