Safety, Health & Environment Management

Engineering controls

Index

• Controlling hazards

• Control measure

• Engineering controls

• Enclosure

• Isolation

• Ventilation

• Points to remember

Controlling hazards…!!!• All workplace hazards (chemical, physical, etc.)

can be controlled by a variety of methods.

• The most effective method of controlling hazardsis to control at the source by eliminating thehazard or by substituting a hazardous agent orwork process with a less dangerous one.

• Some methods of hazard control are moreefficient than others, but a combination ofmethods usually provides a safer workplace thanrelying on only one method.

Goal …!!!

• The goal of controlling hazards is to preventworkers from being exposed to occupationalhazards.

• observe your workplace;• investigate complaints from workers;• examine accident and near-miss records;• examine sickness figures;• use simple surveys to ask your co-workers about

their health and safety concerns;• use check-lists to help you inspect your workplace;• learn the results of inspections that are done by the

employer, the union or anyone else;• read reports or other information about your

workplace.

How can you identify health and

safety problems ?

Major categories of control measures

• Elimination

• Substitution

• Engineering controls

• Administrative controls

• Personal protective equipment.

Engineering controls…!!!

• An engineering control may mean changing a pieceof machinery (for example, using proper machineguards) or a work process to reduce exposure to ahazard.

• There are a number of common control measureswhich are called “engineering controls”. Theseinclude

1. Enclosure2. Isolation3. Ventilation.

is Enclosure…?

• If a hazardous substance or work process cannot be eliminated or substituted, then enclosing it so workers are not exposed to the hazard is the next best method of control.

• Enclosing hazards can minimize possible exposures, but does not eliminate them.

• Machine guarding is another form of enclosure that prevents workers from coming into contact with dangerous parts of machines.

Machine Guarding…!!!

• Crushed hands and arms, severed fingers, blindness - the list of possible machinery-related injuries is as long as it is horrifying. Safeguards are essential for protecting workers from needless and preventable injuries.

• A good rule to remember is: Any machine part, function, or process which may cause injury must be safeguarded.

• Goals :

• Describe the basic hazards involving machinery including point of operation and power transmission devices.

• Introduce control measures through effective machine guarding principles and methods.

Where Mechanical Hazards Occur..?

• Point of Operation

Rotating parts

In-Running Nip PointsRotating cylinders

Chain and sprocket

Belt and pulley

Rack and pinion

Methods of Machine Safeguarding• Guards

▫ fixed▫ interlocked▫ adjustable▫ self-adjusting

• Devices▫ presence sensing▫ pullback▫ restraint▫ safety controls (tripwire

cable, two-hand control, etc.)

▫ gates

Location/distance

Feeding and ejection methods

automatic and/or semi-automatic feed and ejection

robots

Miscellaneous aids

awareness barriers

protective shields

hand-feeding tools

Some examples of guards• Fixed Guard Interlocked Guard

Interlocked guard on revolving drum

Some examples of guards

Examples of devices• Pullback Device Restraint Device Two-Hand

Control

Examples of devices

Designing machine guards

• Complete enclosure is preferable to a partialenclosure. A partial guard should be avoided.

• Guards should fit the danger areas as closelyas possible. Caution: a moving belt rubbingagainst a fixed guard can not only damage thebelt but may also be a potential source of fire.

• Guards should be combined with feeding andejection where possible.

• Guards should leave the operation easy tosee.

Unguarded machines are hazardous

Coming to isolation..!!!

• Isolation can be an effective method of control if ahazardous job can be moved to a part of theworkplace where fewer people will be exposed, or if ajob can be changed to a shift when fewer people areexposed (such as a weekend or midnight shift).

• The worker can also be isolated from a hazardousjob, for example by working in an air-conditionedcontrol booth.

• For example, dust-producing work should be isolatedfrom other work areas to prevent other workers frombeing exposed. At the same time, workers in the dustyareas must be protected and restricted to only a shorttime working in those areas.

Safety devices on machinery

No single isolation method is effective on its

own. Isolation methods should be used in

combination to minimize the chance of

exposure.

Next is Ventilation…!!!

• Ventilation in the workplace can be used for two reasons:

(1) to prevent the work environment from being too hot, cold, dry or humid.

(2) to prevent contaminants in the air from getting into the area where workers breathe.

• Generally there are two categories of ventilation: local exhaust ventilation and general ventilation.

• Whatever the type, ventilation should be used together with other methods of control.

Local exhaust ventilation• The control of potentially hazardous airborne contaminants

such as dusts, gases, vapours and fumes, etc. can beaccomplished by capturing and removing the contaminant ator near its source or point of generation, thus preventing therelease of the contaminant into the workroom.

• There are two common types of local exhaust ventilation usedin industry today:

(1) fumes are sucked into an open tank with side slotsand into a closed system, through which they are thentransferred to a disposal point away from the workers (adegreasing tank is an example of this).

(2) fumes are sucked into a canopy hood which hangsover a contaminant and forced out through a ventilation duct.

Components of a LEV

1.Hoods or enclosures to capture the air contaminant.

2.Ductwork leading to an exhaust fan to transport the contaminant.

3.A collection unit for particulate contaminants, or an air cleaning device for gases before discharge to the outside air.

LEV in a work station• Exhaust ventilation can also include the use of flexible piping. The end of

the pipe that draws in the contaminants (the inlet) must be placed as close as possible to the source of the hazard in order to be effective. Flexible piping is often used to draw welding fumes away from the worker and to draw away contaminants in work areas that are hard to reach.

General ventilation :

• It is generally used for keeping the workplacecomfortable, is one of the least effective methodsof controlling hazards but one of the mostcommonly .

• Air-bricks, windows and doors may be opened toincrease the general flow of air.

• The effectiveness of a general ventilation systemdepends on several things, including:

1.how quickly the hazardous agent is being releasedinto the air.

2. how much and how quickly fresh air is coming in.

3. how the contaminated air is being removed.

Points to remember

about engineering controls• Engineering controls include enclosure, isolation

and ventilation. • If a hazardous substance or work process cannot

be eliminated or substituted, then fully enclosing it so workers do not come into contact with it is the next best method of control.

• Enclosing hazards can minimize possible exposures, but does not eliminate them.

• isolating the work process or the worker does not eliminate the hazard, which means workers can still be exposed.

• it is always better to control the hazard as close to the source as possible. Using personal protection is the least acceptable and least effective of all control measures.

Choosing methods of control

which control

method to use?

Role of the health and safety

representative

• Your role is to work proactively (to take action before hazards become a problem) to prevent workers from occupational exposure by making sure hazards are controlled and kept under control.

• It is best to enclose all toxic materials or work processes using toxic materials. However, since this is often not possible, try to get the employer to enclose at least all highly toxic materials.

• Work with the union and employer to make sure the atmosphere in the workplace is monitored regularly for levels of hazardous materials.