HAZARDS OF USING PNEUMATIC TOOLS BASIC INFORMATION AND TUTORIALS

WHAT ARE THE PNEUMATIC TOOLS HAZARD WHEN WORKING?
Hazard of Pneumatic Tools



Pneumatic tools are powered by compressed air and include chippers, drills, hammers, and sanders.
There are several dangers associated with the use of pneumatic tools. First and foremost is the danger of getting hit by one of the tool's attachments or by some kind of fastener the worker is using with the tool.

Pneumatic tools must be checked to see that the tools are fastened securely to the air hose to prevent them from becoming disconnected.

A short wire or positive locking device attaching the air hose to the tool must also be used and will serve as an added safeguard.

If an air hose is more than 12.7 millimeters in diameter, a safety excess flow valve must be installed at the source of the air supply to reduce pressure in case of hose failure.

In general, the same precautions should be taken with an air hose that are recommended for electric cords, because the hose is subject to the same kind of damage or accidental striking, and because it also presents tripping hazards.

When using pneumatic tools, a safety clip or retainer must be installed to prevent attachments such as chisels on a chipping hammer from being ejected during tool operation.

Pneumatic tools that shoot nails, rivets, staples, or similar fasteners and operate at pressures more than 6,890 kPa, must be equipped with a special device to keep fasteners from being ejected, unless the muzzle is pressed against the work surface.

Airless spray guns that atomize paints and fluids at pressures of 6,890 kPa or more must be equipped with automatic or visible manual safety devices that will prevent pulling the trigger until the safety device is manually released.

Eye protection is required, and head and face protection is recommended for employees working with pneumatic tools.

Screens must also be set up to protect nearby workers from being struck by flying fragments around chippers, riveting guns, staplers, or air drills.

Compressed air guns should never be pointed toward anyone. Workers should never "dead-end" them against themselves or anyone else. A chip guard must be used when compressed air is used for cleaning.

Use of heavy jackhammers can cause fatigue and strains. Heavy rubber grips reduce these effects by providing a secure handhold.

Workers operating a jackhammer must wear safety glasses and safety shoes that protect them against injury if the jackhammer slips or falls.

A face shield also should be used. Noise is another hazard associated with pneumatic tools. Working with noisy tools such as jackhammers requires proper, effective use of appropriate hearing protection.

HAZARD CLASSIFICATION IN WORKPLACE SAFETY BASIC INFORMATION AND TUTORIALS

HOW TO CLASSIFY HAZARDS IN WORKPLACE?
Hazard Classifications



Hazards found during an inspection shall be classified so that managers can allocate time and dollars for their correction in order of priority based on the degree of danger present.

Hazards shall be classified as: imminent danger, serious, and non-serious based on the following criteria.

• Imminent danger hazards would likely cause death, severe injury or high property losses immediately, or before the hazard can be eliminated through normal procedures. Immediate employee protection and abatement is required.

An example is a leaking propane gas cylinder in crew quarters.

• Serious hazards are those in which there is high probability that serious injury, illness, ör extensive property damage would result unless corrective action is taken. Abatement shall be accomplished within 14 days.

An example is a broken stair tread.

• Non-serious hazards are those that could cause injury, illness, or property damage. Abatement shall be accomplished in 30 days.

An example is a broken window in a workshop.

HEALTH EFFECTS TO EXPOSURE OF INDUSTRIAL CHEMICALS BASIC INFORMATION AND TUTORIALS

WHAT ARE EFFECTS TO EXPOSURE OF CHEMICALS?
Toxicology and Health Information

The consequences of exposure, if any, by inhalation, skin or eye contact, or ingestion are outlined in this section. The signs, symptoms and effects that the exposure could produce are described so that any exposure would be recognized as quickly as possible and the appropriate action taken.

The organs that are more susceptible to attack are referred to as target organs. The effects and damage that exposure could produce on these organs are given together with the symptoms. Some of the terms used that may be less familiar or which may have a specific inference in MSDS are defined below:

• Acute Effect: An adverse effect on a human or animal resulting from a single exposure with symptoms developing almost immediately after exposure. The effect is often of short duration.

• Chronic Effect: An adverse effect on a human or animal body resulting from repeated low level exposure, with symptoms that develop slowly over a long period of time or that reoccur frequently.

• Corrosive: A liquid or solid that causes visible destruction or irreversible alterations in human or animal tissue.

• Irritation: An inflammatory response or reaction of the eye, skin or respiratory system.

• Allergic Sensitization: A process whereby on first exposure a substance causes little or no reaction in humans or test animals, but which on repeated exposure may cause a marked response not necessarily limited to the contact site.

Skin sensitization is the most common form of sensitization in the industrial setting, although respiratory sensitization is also known to occur.

• Teratogen: A substance or agent to which exposure of a pregnant female can result in malformations (birth defects) to the skeleton and or soft tissue of the fetus.

• Mutagen: A substance or agent capable of altering the genetic material in a living organism.

• Carcinogen: A substance or agent capable of causing or producing cancer in humans or animals. Authorities/ organizations that have evaluated whether or not a substance is a carcinogen are the International Agency for Research on Cancer (IARC), the U.S. National Toxicology Program (NTP) and OSHA.

• Target Organ Effects: Chemically-caused effects upon organs and systems such as the liver, kidneys, nervous system, lungs, skin, and eyes from exposure to a material.

OCCUPATIONAL NOISE STANDARD ALLOWED LEVEL FOR SAFETY BASIC INFORMATION

NOISE STANDARD IN THE WORKPLACE
What is the Allowable Levels of Exposure for Noise in Workplace?

Protection against the effects of noise exposure shall be provided when the sound levels exceed those shown in Table 2.3 when measured on the A scale of a standard sound level meter at slow response.

1. When the daily noise exposure is composed of two or more periods of noise exposure of different levels, their combined effect should be considered, rather than the individual effect of each. If the sum of the following fractions:

C(l)/T(l) + C(2)/T(2) C(n)/T(n) exceeds unity, then, the mixed exposure should be considered to exceed the limit value. Cn indicates the total time of exposure at a specified noise level, and Tn indicates the total time of exposure permitted at that level. Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level.

When noise levels are determined by octave band analysis, the equivalent A-weighted sound level may be determined as follows.

When employees are subjected to sound exceeding those listed in Table 2.3, feasible administrative or engineering controls shall be utilized. If such controls fail to reduce sound levels within the levels of Table 2.3, personal protective equipment shall be provided and used to reduce sound levels within the levels of the table.

If the variations in noise level involve maxima at intervals of 1 second or less, it is to be considered continuous.

COMBUSTIBLE GAS METERS BASIC INFORMATION AND TUTORIALS

COMBUSTIBLE GAS METERS FOR SAFETY ENGINEERING
What Are Combustible Gas Meters?



These meters use elements which are made of various materials such as platinum or palladium as an oxidizing catalyst. The element is one leg of a Wheatstone bridge circuit. These meters measure gas concentration as a percentage of the lower explosive limit of the calibrated gas.

The oxygen meter displays the concentration of oxygen in percent by volume measured with a galvanic cell. Other electrochemical sensors are available to measure carbon monoxide, hydrogen sulfide, and other toxic gases. Some units have an audible alarm that warns of low oxygen levels or malfunction.

Calibration of Combustible Gas Meters 
Before using the monitor each day, calibrate the instrument to a known concentration of combustible gas (usually methane) equivalent to 25%-50% LEL full-scale concentration.

The monitor must be calibrated to the altitude at which it will be used. Changes in total atmospheric pressure from changes in altitude will influence the instrument's measurement of the air's oxygen content. The unit's instruction manual provides additional details on calibration of sensors.

Special Considerations.
• Silicone compound vapors, leaded gasoline, and sulfur compounds will cause desensitization of the combustible sensor and produce erroneous (low) readings.

• High relative humidity (90%-100%) causes hydroxylation, which reduces sensitivity and causes erratic behavior including inability to calibrate.

• Oxygen deficiency or enrichment such as in steam or inert atmospheres will cause erroneous readings for combustible gases.

• In drying ovens or unusually hot locations, solvent vapors with high boiling points may condense in the sampling lines and produce erroneous (low) readings.

• High concentrations of chlorinated hydrocarbons such as trichloroethylene or acid gases such as sulfur dioxide will depress the meter reading in the presence of a high concentration of combustible gas.

• High-molecular-weight alcohols can burn out the meters filaments.

• If the flash point is greater than the ambient temperature, an erroneous (low) concentration will be indicated.

If the closed vessel is then heated by welding or cutting, the vapors will increase and the atmosphere
may become explosive.

• For gases and vapors other than those for which a device was calibrated, users should consult the manufacturer's instructions and correction curves.

Maintenance of Combustible Gas Meters
The instrument requires no short-term maintenance other than regular calibration and recharging of batteries. Use a soft cloth to wipe dirt, oil, moisture, or foreign material from the instrument. Check the bridge sensors periodically, at least every six months, for proper functioning.

A thermal combustion-oxygen sensor uses electrochemical cells to measure combustible gases and
oxygen. It is not widely used in the area offices.

PORTABLE FIRE EXTINGUISHER SAFETY TIPS BASIC INFORMATION AND TUTORIALS

SAFETY TIPS ON THE USE OF PORTABLE FIRE EXTINGUISHERS



A portable fire extinguisher can save lives and property by putting out a small fire or containing it until the fire department arrives; but portable extinguishers have limitations. Because fire grows and spreads so rapidly, the number one priority for residents is to get out safely.

Safety tips
Use a portable fire extinguisher when the fire is confined to a small area, such as a wastebasket, and is not growing; everyone has exited the building; the fire department has been called or is being called; and the room is not filled with smoke.

To operate a fire extinguisher, remember the word PASS:
 - Pull the pin. Hold the extinguisher with the nozzle pointing away from you,  and release the locking mechanism.
 - Aim low. Point the extinguisher at the base of the fire.
 - Squeeze the lever slowly and evenly.
 - Sweep the nozzle from side-to-side.

For the home, select a multi-purpose extinguisher (can be used on all types of home fires) that is large enough to put out a small fire, but not so heavy as to be difficult to handle.

Choose a fire extinguisher that carries the label of an independent testing laboratory.

Read the instructions that come with the fire extinguisher and become familiar with its parts and operation before a fire breaks out.

Install fire extinguishers close to an exit and keep your back to a clear exit when you use the
device so you can make an easy escape if the fire cannot be controlled. If the room fills with smoke, leave immediately.

Know when to go.
Fire extinguishers are one element of a fire response plan, but the primary element is safe escape. Every household should have a home fire escape plan and working smoke alarms.

WORKING ON OR NEAR DE-ENERGIZED EQUIPMENT AS SUGGESTED BY IEEE STD 902-1998

WHY WE SHOULD WORK ON NEAR OR DE-ENERGIZED EQUIPMENT?

Working on or near de-energized equipment.

The definition of the term de-energized can be found in IEEE Std 100-1996 and in several other documents. It is defined as "free from any electrical connection to a source of potential difference and from electric charge; not having a potential different from that of the earth".

At first thought, some people might think that they are safe if the electrical equipment on which they are going to work is de-energized. However, things are not always as they appear.

The unexpected happens. A person should think, "What if...?." What if the wrong disconnect switch was opened? Or, since you can't watch the switch and work at the same time, what if someone turns the switch back on while you are busy working?

What if a source of voltage from another circuit somehow gets accidentally connected onto the conductors on which you are going to work? What if a very large induced voltage is present? The point is that there are several things to consider to ensure a person's safety while working. De energizing is only one part of creating an electrically safe work condition.

Establishing an electrically safe work condition
In the past, the methods that electrical personnel followed to protect themselves were lumped into a term called clearance procedures. In some cases, clearance simply meant permission to work on a particular system, whether it was energized or not.

In other cases, clearance meant taking measures to ensure that equipment is de-energized, and to reinforce those measures with formal safeguards against altering that de-energized status for as long as clearance is required. The latter use of the word clearance is closer to the hazardous energy control requirements in place today.

The term clearance is falling out of use in modern electrical safety terminology because it does not mean safety. Clearance (for work) is defined in 29 CFR 1910.269 as "authorization to perform specified work or permission to enter a restricted area."

Today, for safety purposes, the phrase "establish an electrically safe work condition" is preferred. An electrically safe work condition is defined in Part II of NFPA 70E- 1995. Section 2-3.1.3 of that document states

An electrically safe work condition shall be achieved and verified by the following process:

a) Determine all possible sources of electrical supply to the specifc equipment. Check applicable up-to-date drawings, diagrams, and identifcation tags.

b) After properly interrupting the load current, open the disconnecting device(s) for each source.

c) Where it is possible, visually verify that all blades of the disconnecting devices are fully open, or that drawout type circuit breakers are withdrawn to the fully disconnected position.

d) Apply lockout/tagout devices in accordance with a documented and established  policy.

e) Use an adequately rated voltage detector to test each phase conductor or circuit part to verify that it is de-energized. Before and after each test, determine that the voltage detector is operating satisfactorily.

f) Where the possibility of induced voltages or stored electrical energy exists, ground the phase conductors or circuit parts before touching them. Where it could be reasonably anticipated that the conductors or circuit parts being de-energized could contact other exposed energized conductors or circuit parts, apply ground connecting devices rated for the available fault duty.

When nondrawout, molded-case circuit breakers are being used as the disconnecting device mentioned in item b), visual verification of an open circuit, as suggested in item c), cannot be made.

One technique that could be used to verify true opening is to have a voltmeter, or other voltage indicating device, safely applied somewhere away from the breaker enclosure itself on the load side of the breaker before the breaker is opened.

Always try to place the voltmeter at a point where exposure to energized conductors is minimized. Then, have someone watch the meter as the breaker is being opened. Simultaneous opening of the breaker and disappearance of voltage is generally a good indicator of disconnection.

If that can't be done, the next best way is to measure load-side voltage (using safe practices and appropriate protective and test equipment), remove the meter, open the breaker, and measure again immediately. With multiple pole systems, all load-side poles should be verified to have voltage prior to disconnection.

Again, apply a voltmeter to one of the poles. After the breaker is opened and the first pole is verified, move the meter, as safely and quickly as possible, to verify deenergization of the other poles.

POWER SYSTEM PROTECTION COORDINATION AND SAFETY ENGINEERING

THE IMPORTANCE OF SYSTEM PROTECTION COORDINATION WITH REGARDS TO PERSONNEL SAFETY

How system protection coordination serve its safety purpose?



System protection coordination
When an electrical distribution system is designed and constructed, a fault-current coordination study should be conducted, and circuit protective devices should be sized and set according to the results of the study.

In time, however, the electrical system configurations are often changed due to the changing needs of the end users. If the coordination and capability of the electrical equipment are not reviewed at the time of the changes, faults could result in unnecessary tripping of a main breaker or, even worse, an explosion of equipment that was thought to be in good condition.

When system conditions change, the results that were obtained in the original fault-current coordination study may no longer apply to the current system. Unnecessary tripping, known as lack of selectivity, could be caused by poor coordination.

An equipment explosion could result from the interrupting capability of the circuit breaker being exceeded. Both indicate a clear need for an updated fault-current coordination study.

Utility systems delivering higher fault currents
The demand for electricity, particularly in the industrial and commercial environment, has been steadily increasing. Consequently, utility systems have grown much larger and have become capable of delivering much higher fault-currents at service points than in the past.

Therefore, protective devices that were properly applied at the time they were installed may have become inadequate after system changes, and the protective system may no longer be coordinated. When available fault current increases to the point at which it exceeds protective device interrupting and withstand ratings, violent failure is possible, regardless of how well the devices are maintained.

Protection in an electrical distribution system
System and equipment protective devices are a form of insurance. This insurance pays nothing as long as there is no fault or other emergency.

When a fault occurs, however, properly applied protective devices reduce the extent and duration of the interruption, thereby reducing the exposure to personal injury and property damage. If, however, the protective system does not match system needs, just as an insurance policy should keep up with inflation, it is no help at all. It is the responsibility of the system operator to ensure proper system protection and coordination.

Protective equipment set to sense and remove short circuits
In medium-voltage systems, the protective equipment for feeder conductors is often set to sense and remove short circuits, but not necessarily to provide overload protection of circuits. Device settings sometimes are purposely chosen low enough to sense and provide a degree of overload protection.

Operators should be aware of this so that a protective device that is set lower than necessary for coordination does not cause a false tripping action during system switching procedures. System protection coordination is an important consideration in switching systems with loop feeds and alternate sources.

To avoid false tripping action, operators should be aware of the settings and any probable temporary overloads or circulating currents during switching.

ELECTRICAL SAFETY HAZARDS THAT NEEDS TO BE IDENTIFIED ON ELECTRICAL SAFETY WORKS

WHAT ARE THE DIFFERENT ELECTRICAL SAFETY HAZARDS?

Identifying electrical safety hazards.



When electrical systems break down what are the primary hazards and what are the consequences to personnel? Electric shock Exposure to Arc-Flash Exposure to Arc-Blast Exposure to excessive light and sound energies

Secondary hazards may include burns, the release of toxic gases, molten metal, airborne debris and shrapnel. Unexpected events can cause startled workers to lose their balance and fall from ladders or jerk their muscles possibly causing whiplash or other injuries.

Electric Shock
When personnel come in contact with energized conductors they receive a shock with current flowing through their skin, muscles and vital organs. The severity of the shock depends on the current’s path through the body, the current intensity, and the duration of the contact.

They may only experience a mild tingling sensation or it could result in serious injury or death. As voltage levels increase, the effects of electric shock escalate. Current may also cause an erratic heartbeat known as ventricular fibrillation.

If fibrillation occurs even briefly and goes untreated, the effects are usually fatal. A clear understanding of how electric current travels through the body can help minimize injury if such contact occurs. The table below outlines the effects that various values of electrical current have on the human body.

There are three basic pathways electric current travels through the body;

1) Touch Potential (hand/hand path)

2) Step Potential (foot/foot path)

3) Touch/Step Potential (hand/foot path)



1) In a touch potential contact, current travels from one hand through the heart and out through the other hand. Because the heart and lungs are in the path of current, ventricular fibrillation, difficulty in breathing, unconsciousness, or death may occur.

2) In a step potential contact, current travels from one foot through the legs, and out of the other foot. The heart is not in the direct path of current but the leg muscles may contract, causing the victim to collapse or be momentarily paralyzed.

3) In a touch/step potential contact, current travels from one hand, through the heart, down the leg, and out of the foot. The heart and lungs are in the direct path of current so ventricular fibrillation, difficulty in breathing, collapse, unconsciousness, or death may occur.

Even though there may be no external signs from the electrical shock, internal tissue or organ damage may have occurred. Signs of internal damage may not surface immediately; and when it does, it may be too late.

Any person experiencing any kind of electrical shock should seek immediate medical attention. Using the correct personal protective equipment (PPE) and following safe work practices will minimize risk of electrical shock hazards.

Arc-Flash and Arc Blasts 

An Arc-Flash is an unexpected sudden release of heat and light energy produced by electricity traveling through air, usually caused by accidental contact between live conductors. Temperatures at the arc terminals can reach or exceed 35,000 degrees Fahrenheit (F), or four times the temperature of the sun’s surface.

The air and gases surrounding the arc are instantly heated and the conductors are vaporized causing a pressure wave called an Arc Blast. Personnel directly exposed to an Arc-Flash and Arc-Blast events are subject to third degree burns, possible blindness, shock, blast effects and hearing loss. Even relatively small arcs can cause severe injury.

The secondary effect of arcs includes toxic gases, airborne debris, and potential damage to electrical equipment, enclosures and raceways. The high temperatures of the arc and the molten and vaporized metals quickly ignite any flammable materials.

While these fires may cause extensive property damage and loss of production, the hazards to personnel are even greater. Any energized electrical conductor that makes accidental contact with another conductor or with ground will produce an Arc-Flash.

The arcing current will continue to flow until the overcurrent protective device used upstream opens the circuit or until something else causes the current to stop flowing. The arc current can vary up to the maximum available bolted fault current

CIRCUIT PROTECTION CHECKLIST ESSENTIAL FOR ELECTRICAL SAFETY

THE IMPORTANCE OF HAVING A CIRCUIT PROTECTION CHECKLIST IN ELECTRICAL SAFETY

Before a system is designed or when unexpected events may occur, circuit designers should ask themselves the following questions:

What is the normal or average current expected?

What is the maximum continuous (three hours or more) current expected?

What inrush or temporary surge currents can be expected?

Are the overcurrent protective devices able to distinguish between expected inrush and surge currents and open under sustained overloads and fault conditions?

What kind of environmental extremes are possible? Dust, humidity, temperature extremes and other factors need to be considered.

What is the maximum available fault current the protective device may have to interrupt? Is the overcurrent protective device rated for the system voltage?

Will the overcurrent protective device provide the safest and most reliable protection for the specific equipment?

Under short-circuit conditions, will the overcurrent protective device minimize the possibility of a fire or explosion?

Does the overcurrent protective device meet all the applicable safety standards and installation requirements?

Answers to these questions and other criteria will help to determine the type of overcurrent protective device to use for optimum safety and reliability.