SDSRP Practice - Rubric 6 Industrial Hygiene and Safety

Fire Ingredients

• Heat or ignition source

• Fuel (Combustible material and reducing agent)

• Oxygen or oxidant or oxidizer

• Chain reaction through free radicals to maintain the fire

Class A

Classification of fuels: Wood, paper, cloth

Class B

Classification of fuels: Flammable liquids

Class C

Classification of fuels: Electrical, energized equipment

Class D

Classification of fuels: Metals

Class K

Classification of fuels: Oils and fats

Water

Extinguishing Agents

• Mainly effective for class A fires

• Works by cooling

• May spread flammable liquid fires

• Can be used to cool containers and structures and disperse smoke and vapors

Carbon Dioxide

Extinguishing Agents

• Works well for class B and C fires

• Works by displacing oxygen

  • Also has a limited cooling effect

• Not effective for class A fires

Dry Chemicals

Extinguishing Agents

Regular type: Class B and C fires. Consists mainly of sodium bicarbonate. Works by excluding oxygen and interrupting the chemical reaction of fire. Not effective on Class A fires

Multi-purpose: Class A, B, and C fires. Consists mainly of monoammonium phosphate. Works by excluding oxygen and interrupting the chemical chain reaction of fire

Halons

Extinguishing Agents

• Class A, B, and C fires

• Interrupts chemical reactions

Foam

Extinguishing Agents

Works by excluding oxygen

• Aqueous film forming (AFFF): for non-water soluble materials

• Alcohol-resistant (AR-AFFF): For alcohols and other water-soluble materials

Special Dry Powders

Extinguishing Agents

Used for class D fires

Chemical Stability

The resistance of a compound or a mixture to chemical change

Unstable or Reactive

A chemical which (in the pure state, or as produced or transported) will vigorously polymerize, decompose, condense, or will become self-reactive under conditions of shocks, pressure, or temperature

Chemical Incompability

Types of reactions between chemicals that may generate:

• Heat (acids and bases, oxidizers and combustibles)

• Unstable materials (metallic azides, peroxides)

• Toxic gases or vapors (hydrogen sulfide)

• Corrosive materials (acids, bases)

• Flammable gases or vapors (hydrogen, methane)

• Asphyxiant gases (carbon dioxide, nitrogen)

• Pressure (rupture containers)

Decomposition

Types:

• Spontaneous decay

• Thermal

• Chemical

• Oxidation

• Electrolysis

Products of this may be irritating, toxic, corrosive, flammable, chronic health hazards, etc.

Decomposition may generate heat and pressure

Time Weighted Average (TWA)

Sampling represents exposure averaged over a work shift (8 hours).

This is either one long sample or several shorter samples combinen using the formula: (Ca*Ta) + (Cb*Tb) + (Cc*Tc)/total time.

Short Term Exposure Limit (STEL)

A 15-minute TWA.

Should never be exceeded over any 15-minute time frame during a shift.

Ceiling Limit

An instantaneous limit

• At no point should the exposure exceed the ceiling limit

• For peak exposures (no STEL) see TLV booklet

• Never more than 5 x TWA

• No more than 3 x TWA, if limited to 30 min/day

• TWA must not exceed TLV-TWA

Inhalable Fraction and Vapor (IFV)

Chemicals that can be present in both particulate and vapor phases

• Sample to collect both phases

  • Use filter followed by a sorbent tube

Respirable Fibers

A fiber must meet these criteria;

• Length > 5 u

• Aspect ratio ≥ 3:1

Total Particulate

All sizes of particles

Inhalable Particulate Matter

For materials hazardous when deposited anywhere in the respiratory tract (≤ 100 um)

Thoracic Particulate Matter

Deposited in the lung airways and gas exchange area (≤ 25 um)

Respirable Particulate Matter

Deposited in the gas exchange area (≤ 10 um; ~ 4 um median)

PPM Conversion Formula

ppm = (mg/m³ * 24.45)/MW

Hierarchy of Controls

Elimination > Engineering Controls > Administrative Controls and Work Practices > PPE

Elimination

Number one preference in hierarchy of controls

For chemical exposure, that might mean substituting a less hazardous substance for a more hazardous substance

Engineering Controls

Minimize chemical or physical hazards. Built-in controls that prevent exposure

Engineering Controls: Ventilation

General ventilation < Local Exhaust Ventilation < Process Enclosure

Administrative Controls and Work Practices

Examples:

• Use of wet methods to suppress dust

• Equipment maintenance

• Vacuum (not sweeping)

• Closed containers

• Personal hygiene

• Housekeeping and maintenance

• Job rotation of workers

Personal Protective Equipment (PPE)

Guidance on selection is needed to minimize potential for illness or injury

Includes:

• Eye and face protection

• Skin protection

• Respiratory protection

• Thermal hazards

Respirator Cartridge Ratings

N for Not resistant to oil

R for Resistant to oil

P for oil-Proof

Chemical Cartridge Types

• Black for organic vapors

• White for acid gases, chlorine, chlorine dioxide, sulfur dioxide, hydrogen chloride, or hydrogen sulfide (for escape only)

• Yellow for organic vapor or acid gas

• Green for ammonia or methylamine

• Olive for formaldehyde

• Orange for mercury or chlorine vapor

Maximum Use Concentration (MUC)

The maximum atmospheric concentration of a hazardous substance from which an employee can be expected to be protected when wearing a respirator

• Determined by the assigned protection factor of the respirator (or class of respirators) and the exposure limit of the hazardous substance

Assigned Protection Factor (APF)

The workplace level of respiratory protection that a respirator (or class of respirators) is expected to provide to employees, when the employer implements a continuing, effective respiratory protection program

Respirator Hierarchy

Filtering Facepiece < Air-Purifying Respirator < Powered Air-Purifying Respiratory < Self-Contained Breathing Apparatus (SCBA)

Skin Protection

• Specify equipment to be worn

• To the extent possible, identify recommended materials of construction and unacceptable materials

• Selection should be based on lab data and field experience

Permeation

A process by which a chemical can pass through a protective film of glove material without going through pinholes, pores, or other visible openings.

Individual molecules of the chemical enter the film and “squirm” through by passing between the molecules of the glove material.

In many cases, the permeated material may appear unchanged to the human eye.

Breakthrough Time

The time observed from the start of the test to first detection of the chemical on the other side of the sample barrier

• Represents how long a glove can be expected to provide effective permeation resistance when totally immersed in the test chemical.

Permeation Rate

The highest flow rates recorded for the permeating chemicals during a six-hour test. These qualitative ratings are comparisons against each other.

Degradation

A reduction in one or more physical properties of a glove material due to contact with a chemical

• Certain glove materials may become hard, stiff, brittle, or they may grow softer, weaker, and swell to several times their original size.

• If a chemical has a significant impact on the physical properties of a glove material, its permeation resistance is quickly impaired.

Penetration

The movement of the chemical through pores, holes, stitching, etc.

Is prevented by good quality control initially and frequent inspection once the gloves are in use.

Gloves and other PPE that show damage or degradation should be discarded.