Methods of Control

Page 1

CONTROL

Topic covered under various titles

CONTROL of airborne hazards

CONTROL of workplace contaminants/pollutants

CONTROL of emissions and hazardous conditions

CONTROL of emissions/hazards and worker conditions

Prevention/Control of workplace hazards

5 Fundamental control ASSUMPTIONS

All hazards can be controlled

Alternative approaches

More than one control

Some control are cost effective

May not completely control the hazard

Factors to consider in SELECTION of controls

Effectiveness of controls

Ease of use by worker

Cost of controls

Adequacy of warning properties of the material

Acceptable level of exposure - TLV

Frequency of exposure

Route(s) of exposure

Regulatory requirements for specific controls

3 CATEGORIES OF CONTROL METHODS

Engineering - physical changes in machine, materials, process or operation

Administrative - focus on the workers and policies

Personal Protective Equipment - devices that protect certain parts of body from the hazard

VENTILATION

add or remove air from work areas; utilization of controlled flows flows of air

Importance of ventilation in the workplace

Control of health hazards (e.g. chemicals)

Control of safety hazards (fire & explosion)

Comfort

Types of Ventilation as to SOURCE

Natural

Artificial

Types of Ventilation SYSTEMS

Supply

Exhaust (Suction)

Dilution Ventilation Application

- General ventilation

Principles

Determine amount of air required for satisfactory dilution of air contaminant

Locate the exhaust opening of the system near the source of contamination

Locate the air supply and exhaust outlets such that air passes through zone of contamination

Replace exhausted air by use of a replacement air system

Avoid re-entry of the exhausted air by discharging it high above the roof line

Exhaust Ventilation System

Many hazards to be driven away

Types and shapes of hoods

Selection of hood type

Type of contaminant, mechanism for its generation

Physical characteristics

Interface: operator (worker) and equipment

Hood design principles

Captures hazard that needs to be eliminated

Enclose operations

Locate hood such as that the contaminant is moved away from the breathing zone of operator

Shape hood such so the initial velocity directs or facilitates contaminant entry into hood (opening)

Capture contaminant with the hood positioned as close as possible to the source

Hood should be designed NOT to interfere with movements of the operator

Hood Type

Slot

Flanged slot

Plain opening

Planged opening

Booth

Canopy