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Unit 3 Part B Question & Ans

 UNIT – III

CHEMICAL PROCESS INDUSTRIES IN INDIA.

            The effective production executive knows the value of organization. He realizes that no objective can be attained, whether it be for production, training, inspection, selling or accident prevention or elimination does not come about unless all levels of people of the organizatiion are tuned towards that objective.

            A recent review of plants indicates many differences in safety organixations and a wide variance of authority and interest from top management down through the organization.

            The following points should be considered first.

(1)   Safety must have top management approval, sanction and support

(2)   Responsibility for safety must restwith the supervisory personnel.

(3)   Safety must be given an equally important consideration with other factors and

(4)   Provision must be made for prompt action in the elimination of mechanical and personal hazards.

            Whatever may be the size of the firm, the principle and the purpose should be indentical, “Within each and everyone, at all levels of the organization, a safety consciousness”.

            For this a definite programme should be developed to interest and educate all employees in safety and to secure their active cooperation to eliminate accidents. Such a programme must be based on the full assumption of its responsibilities by the management. Safety must be included in all phases of planning, purchasing, supervision and operation.

            We may classify the safety organization in three general types, namely

(1)   Type A firms. (2) Type B firms (3) Type C firms

TYPE – A FIRMS

            Those in which the safety work is  carried by the functional head of that particular firm.

            If no full time safety personnel are available, the production executives must become expert in their knowledge in safety problems involved in their particular establishment.

            The strength of Type A setup lies on the fact that it  centers its entire responsibility for all safety effort within each operating unit. It is his duty to incorporatesafety into each and every part of the day by day activities of his unit. He must become the best informed andmost safety minded person in his unit.

            The drawback in this type of organizations is that the supervisory staff occupied with other production problems finds it difficult to acquire the special knowledge needed to reach a high standard of safety performance. This means that the knowledge of how to prevent accidents is gained from the accidents that occur. So the progress is likely to be slow.

            This kind of setup is found more commonly in firms too small to employ a full time safety engineer.

TYPE – B FIRMS

            Those in which the safety work is directed by a safety engineer reporting to a major executive.

            Very large firms use this type of setup. Its effectiveness depends on two things.

            (a) The attitude of the top management and

            (b) The competency and ability of the safety director.

            In such type of industries, the safety director must first think of the help he can render to each supervisory staff, second he must try to determine the viewpoint of each so that his help will be accepted, third he must be sure of his facts and careful in drawing conclusions and fourth he must keep the boss informed.

TYPE – C FIRMS

            Those in which the safety work is carried out by committees setup for that purpose.

            Safety work governed by committees usually found in establishments too small to justify a full time safety engineer and where the management prefers the work to be directed by the members of his staff.

            It has the advantage of bringing together the viewpoints of the group and it’s joint judgement is better than that of any individual in the group. The disadvantage is the fact that a committee is the weakest in execution. The prompt, effective& orderly execution depends on placing the authority in the hands of one person and faithful discharge by him.

CHEMICAL HAZARDS

CLASSIFICATION OF HAZARDS

            Chemicals are classified on the basis of the danger properties. These dangerous properties are

            (1) Explosivity, (2) Flammability, (3)Oxidisability, (4) Toxicity, (5) Corrosivity, (6) Reactivity, (7) Compressibility.

EXPLOSIVITY

            Explosive materials under certain conditions of temperature shock or chemical action decompose rapidly and evolve large volumes of gas or excessive heat, thus causing the surround atmosphere to expand suddenly resulting in explosion. Such inherent explosive materials aregenerally not handled in the chemical industry except those manufacturing high explosives.

FLAMMABILITY

            Combustioin of materials occur due to reaction between oxygen and the combustibles present in the materials in the vaporised or finely divided state. The ease of  burning reduces progressively from gases to dusts to liquids and to solids.

            The index of flammability of a liquid is called the FLASH POINT which is the lowest temperature at which a liquid will give off enough vapour and can ignite from a spark or open flame.

            FIRE POINT is the lowest temperature at which a mixture of air and vapour continues to burn when an open container ignited.

            AUTO IGNITION TEMPERATURE is the temperature at which a material will self ignite and sustain  combustion without any initiation by spark or flame.

            A flammable liquid with a low boiling point is much more hazardous than a liquid with a higher boiling point.

            Limits of flammability are also known as explosive limits. These represent the percentage by volume of flammable vapour or gas in air will burn when ignited. Between the lower and upper limits, fuel- air mixtures are flammable and such mixtures should be avoided in the normal course.

OXIDISABILITY

            Oxidising agents are sources of oxygen which can sustain fire. Air is the most common oxidising agent. Some chemicals evolve oxygen at room temperature or on heating.(eg) Peroxides, Chlorates, Permanganates, nitrites ect fail in this category. It’s always advisable to segregate oxidising agents from flammable substances so as to avoid accidental fires.

TOXICITY

            Toxic properties of chemicals create hazardous conditions for life. The chemical may be inherently toxic or decompose to give toxic chemicals on heating or burning. Toxic substances enter the human body through the nose during inhalation and through the mouth during ingestion. The hazard due to toxic nature of chemicals is quantified by some well publicised methods such as Threshold limit values and Lethal dose.

(eg) Lead, Arsenic, Silica along with cyanides and isocyanides.

            Threshold limit values : These are expressed as mg/kg of gas or vapour in air. This is the level to which nearly all workers may be repeatedly exposed day in and day out without adverse effects.

            Lethal dose: Minimum lethal doseis defined asthe minimum quantity in milligrams per kilogram of bodyness which can cause fatality among a group of experimental animalas.

CORROSIVITY

            Corrosive materials are to be handled in specific containers and adequate precautions should betaken to avoid severe burns while handling these liquids. Sometimes dangerous gases can be evolved due to corrosive action of chemicals or metals.

REACTIVITY

            Certain chemicals can react violently with water or acids and alkalis with evolutioin of gases, heat and  fumes. Reactions with other substances can also cause similar disastrous effects. Some chemicals undergo chain reactions such as polymerisation on application of heat. Such reactions can also create unsafe conditions.

COMPRESSIBILITY

            This propertyi is present to a very limited extent in liquids. But when liquids in enclosed spaces are heated, very high pressures can develop which can rupture the equipment unless pressure is relieved safely.

            In case of gases, application of pressure compresses the gases considerably and it is normal practice to store gases under pressure. Some gases liquetyi at moderate pressures and temperatures and can be stored in properly designed containers as liquefied gases. A small amount of liquefied gas on vapourising creates a very large volume of gas which may be toxic or flammable.

            In site selection, plant layout and plot planning. It is possible to make allowances for only certain types of hazards. For only certain types of hazards.  For this, we breakdown these hazards into first degree hazards and second degree hazards.

            First degree hazards are those which provide the potential for trouble.Under normal conditions, these hazards do not cause any damage to either persons or property, but they set stage for accidents that can cause injury, fire or explosions.

(1)   The presence of flammable or combustible materials

(2)   The presence of heat

(3)   The presence of ignition sources

(4)   The presence of oxygen

(5)   The presence of compressed materials

(6)   The presence to toxic materials

(7)   The possibility of human error

(8)   The possibility of mechanical failure

(9)   The movement of people and equipment through the plant

            When first degree of hazards get out of hand, the result may be second degree hazards which are capable of directly inflicting damage to life, limb and property. The second degree hazards are

(a)    fire, (b) explosion, (c) release of toxic chemicals, (d) stumbling, (e) falling and (f) collision.

            In combating all of these hazards, we draw the lines of defense. The first line of defense consists of trying to deal the first degree hazards in such a way to avoid the occurrence of second degree hazards. Success here depends mostly on careful engineering of the equipment we use. The things we have to consider during plot planning to assist in first line of defense are

            (1) Locating ignition sources upwind from plants of possible releaseof flammablematerials.

            (2) Providing adequate accesways for movement of equipment and people,

            Despite all such efforts, there are occasions, when second degree hazards, such as fire occur. In the event of a second degree hazard, how can we minimize the extent of damage to limb, life and property, is the second line of defense. Here again, we have to look in for certain things during plot planning itselt.

            (1) Separating the most hazardous areas from areas which are most occupied by people

            (2) Strategically locating the fire fighting equipments

            But even then, some damages will result from these hazards. People do get hurt in modern chemical industries no matter how carefully we plan against accidents. The third line of defense is to provide efficient first aid and hospital facilities to care for those who are all hurt. The essence of the third line of defense is to repair thedamage we have not been able to prevent.

JOB SAFETY ANALYSIS

            A job is a sequence of seperate steps or activities that when put together accomplish the work goal. Identifying the hazards and stressing safe procedures are the part of safety analysis and should be one of the first steps taken where there is a possibility of injury to worker.

            Here are the steps to follow when analysing a job.

(1)   Select the job.

(2)   Break the job down

(3)   Identify the hazards and potential accidents

(4)   Develop solutions

SELECT THE JOB

            Job suitable for job safetyi analysis are those assignments that a line supervisor may make. (eg) Operating a machine, tapping a furnace or piling ware house goods. They are neither too broad nor too narrow.

            Jobs should not be selected at random. Those with worst accident experience should be analysed first if JSA is to yield quickest possible return. In fact some companies make this the local point of their accident prevention programme.

BREAK THE JOB DOWN

            Before the search for hazards begin, a job should be broken into a sequence of steps, each one describing what is being done. Avoiding the two common errors (a) making the breakdown so detail that an unnecessarily large number of steps result. (b) making the breakdown so general that basic steps are not recorded.

            The technique of making a job safety analysis should involve these steps

(1)   Selecting the right person for observing

(2)   Briefing him on the purpose

(3)   Observing his for the job and trying to break it into basic steps

(4)   Recording each step in the breakdown

(5)   Checking the breakdown with the employee who was observed

            While doing so, we have to select a person who is experienced, capable, cooperative and willing to share ideas. This person will be easy to work with.

            If the person whom we have selected for job safety analysis is not cooperating, he should be informed about the purpose (ie) to make a job safe by identifying and eliminating hazards or controlling hazards. We should explain him that we are going to studyi the job alone and he is selected on the basis of experience and capability alone.

IDENTIFY HAZARDS AND POTENTIAL ACCIDENTS

            The purpose is to identity all hazards – both those produced by the environment and those connected with the job procedure. Each step and thus the entire job must be made safer and more efficient.

            For this, the following observations should be made.

            (a) Is there a danger of striking against, being struck by or otherwise making injurious contact with an object.

            (b) Can he slip or trip? Can he fall on the same level or to another?

            (c) Can the person be caught in,on, or between the objects?

            (d) Can he strain himself by pushing, pulling or lifting?

            (e) Is the observing atmosphere hazardous? (toxic gas, vapour, mist, fume or dust, heat or radiation.)

            We should make close observatiions and knowledge of the job is required. We have to repeat the job observations as often as necessary until all the hazards have been identified. We have to include hazards that can happen as a result of the job. We should make a record of the type of accident and the cause of it. We have to check with the employee observed after making the records. We should cross check, with other employees also, the same. Through observation and discussion we should develop a reliable list of hazards and potential accidents.

DEVELOP SOLUTIONS

            These solutions are based on the fact that these should prevent the occurrence of poential accidents. The principal solutions are

(1)   Find a new way to do the job

(2)   Change the physical conditions that create the hazards and

(3)   to eliminate hazards still present, change the job or stleast the frequency that is must be performed. This solution is particularly helpful in maintenance.

            To find a new way to do the job, we should first determine the work goal of the job and we should see that the work goal is not altered while trying for newer ways. We should attain is with the safest way. If we have found a new way to do a job, we should study it carefully that what are all the other benefits that can occrue. (such as increased production, less time etc.) These benefits should also be pointed to the higher management when proposing for change.

            It the new way is not found, then we should try to change the physical condition so that we can eliminate the hazard or prevent the accident. (such as change in tools, materials, equipment or location. The third step is to investigate changes in the job procedure. We should note down what the worker need to do or the worker need not to do to eliminate the hazards or any potential accidents?If possible, we should try to analyse how should it be done.

BENEFITS OF JOB SAFETY ANALYSIS

(1)   Giving the individual training in safe efficient procedures

(2)   Giving pre-job instructions

(3)   Instructing the new man on the job

(4)   Making employee safe contacts

(5)   Preparing for planned safety observations

(6)   Reviewing job procedures after occurrence of  accidents

(7)   Studying the jobs for possible improvement in job methods

APPRAISALS

            It is a process of evaluation of the employee. This process involves 6 steps

1.      Establish performance standards

2.      Communicate performance standards and expectations to the employee

3.      Measure the performance of individuals

4.      Compare the actual performance of the individual with the standard

5.      Discuss the appraisal with the employee

6.      Initiate corrective actions if any

            Appraisals may be of the following types.

Individual appraisal : The shortcoimng of an individual atpraisal are apparent. It is one man’s opinion and may be biased. Companies with formal plans usually protect themselves by seeing to it that if individual appraisal is used, the results are reviewed by the superior of the person who is appraising, in some formal way. This serves as a definite check against the possibilities of irresponsible evaluation that may step in the records.

Group appraisal : In group appraisal the judgement of the immediate superior is supplemented by the different slants of other executives. The obvious advantages are counter points to most of the disadvantages cited for individual appraisal.

Multiple appraisal : In multiple appraisal the suberdinate personnel is appraised independently by several other qualified officers. The results of such multiple evaluations are generally consolidated by a staff personnel.

Appraisal by subordinates : Here employees evluate superiors. In most of the cases they are in no position to know what is expected of their executives. They may be too young or too inexperienced to realise the extent of their officer’s responsibility.

PERIODIC STUDY OF PLANT LAYOUT INSPECTION AND CONSTANT MAINTENANCE :

            In a well organized industry, safety inspections are constantly made. Plant engineers, supervisors and chief of the workmen all constantly watch over the performance of the workers under their control. The operations which they perform regularly make them over confident and sometimes they may neglect the safety regulations in the job. The safety engineer by inspectioin corrects the worker on the spot. He inspects as a specialist, keeping his thoughts concentrated on the work and detects and corrects the unsafe practices and conditions.

            Adequate planning and instruction, training and supervision minimize the hazards. But well planned routine inspection by a competednt person will discover the hazardous situations promptly upon their development.

            Safety inspections are classified into 2 types.

            1 General safety inspection. 2. Selective safety inspection

            The first type is carried out in most of the plants as a routine accivity. Inspection is carried out in all the departments and is done rapidly but not haphazardly. The safety engineer is through and familiar with the conditions of the plat. He looks for conditions that may carry hazards and which was absent during their previous inspection.

            In the second type he concentrates on one set of circustances closely and get very effective results. The objective of an ideal inspection is

1.      To go to the spot directly

2.      To look, observe and learn

3.      To correct as you inspect and

4.      To report to make records constructively

            The plant inspection is done with the aim of finding unsafe conditions both for workers and eachines. The plant inspector hence concentrates on good house keeping, material handling methods, adequacy of working space between machines guarding for rotating and revolving machineries, upkeep of hand tools, proper location of ladder, steps, lifts, hoists etc. And safe handling them, floors, plat forms, railing etc, electrical equipments and their switches, lighting, dusts, fumes, gases and vapours, dangerous substances like acards, location of explosive materials, access to overhead equipments, location of pressure vessels, compressors and any other conditions that lead to hazardous conditions.

            The inspection must be of continued plant activity and integrated with production processes. A definite shedule is drawn regarding what to inspect and how frequently it should be inspected. After inspection, notes and records are made and corrective actions immediately initiated.

            Inspection of plants are done by factory safety engineers, government and insurance agencies, factory inspectors, specialist consultants either regularly or periodically to assess the needs of safety, proper working area and welfare of personnel.

Plant maintenance From Safety Point of view:

            Proper plant maintenance specifically preventive plant maintenance is essential in continuing production safely and profitably. Maintenance is required for plant machines, tools, equipments, portable tools and buildings. Safely operated machine will never stop work or bring sudden failures. The cheapest way to operate any machine is to keep it in good condition as new until obsolescence justifies it’s replacement.

            Safety mindeness in operation and maintenance are the motto of a good management. Maintenance men should be experienced engineers and mechanics. They should be alers, capable of learning the characteristics of machines and show good judgement. Maintenance men should be trained well in their jobs and safety motivated. In maintenance the following aspects are given importance.

1.      Careful planning

2.      Hazards anticipated and provisions made there of

3.      Proper selection of men of the job.

            Accidents due to improper maintenance results in moving machinery, cables breaking, heavy loading, dizziness and uncosciousness from breathing of fumes and gases and short circuit of electrical wires. A maintenance job is never completed until the entire area is restored to order and the machine is kept in operating condition with all safe guards in place. Loose materials in the floor, grease or oil clean up are all given importance.

Advantages of plant maintenance :

1.      Reduced break down and downtime of machines and labours

2.      Greater safety for worker

3.      Low maintenance and repair costs compared to break down maintenance

4.      Less stand by or reserve equipments

5.      Better product quality and fewer rejects

6.      Increased equipment life

7.      Better individual morale and industrial relationship because production workers do not face lay –off or less incentive due to break down

EFFECTIVE STEPS TO IMPLEMENT SAFETY PROCEDURES:

            Safety education and safety training are the two modes by which the management can effectively implement the safety procedures.

Safety Education :

            Safety education deals primarily with the development of mind, broadening one’s knowledge and understanding. Education in a specific subject means acquisition of information and elucidation relating to the subject. Training deals primarily with the development of skill in performance.

            Safety education develops safety consciousness – a vivid awareness on the importance of eliminating accidents and creating a mental alertness in identifying conditions and actions that might cause injury. Safety education of the general working personnel is valuable in promoting the interest, understanding and active participation of the workers in safety activities. It improves plant plant performance, adds to the efficiency and generally adds to a sense of satisfaction in making operations successfully without losses. Since safety is an intimate part of all activities it may be integrated right from the school education onwards and carried out in all training courses for specific tasks, jobs, operations and professions. Every human activity has some safety incorporated in it and which must be known to him.

Safety education lies in effectively

1.      Teaching the essentials of, safe practices

2.      Organising safety programmes

3.      Appraising human attitude and

4.      Fitting new employees to the job

            Getting men to work safely is the motive of safety education. The workmen must be first prepared to accept the safety codes. Then the information must be present in a powerful manner and also methodically. Safety posters, films, various types of hazards must be exhibited and demonstrated to make an impression in the minds of employees.

Safety Training :

            In applying the principles of accident prevention, it is sometimes found that is is better to train the inexperienced worker rather than to search for the unsafe acts that have accumulated over a period of time and caused the injury. Sometimes employees are inherently unsuited to the work they are expected to perform. If a job study has been made it will indicate the characteristics to look in for men such as strength, height, weight, skill, judgement of distance, speed of hand or eye, versatility, perseverance and physical or other qualities. Added to this the details of operatiion will bring out the specific hazards so that in the training process they may be given proper instructions on now to avoid the injury.

            Each person starting a job should be given instructioins to do it properly. Even if he has performed similar type of job, he needs to know the expectations because each supervisor will have his own idea of how to do the job. A safety conscious supervisor wants to make sure the new person is going to work in the safest possible environment and this might not have been emphasized where the person worked before.

            Good instructions contribute to safety even if is is not specifically on the safe practices. Good instruction makes an employee a better worker, more satisfied with his company and his job and more willing to go along with programmes which his company and supervisor talks more about safety. He also makes his own suggestions to avoid hazards. In such cases the accidents occurring will be less.

PROPER SELECTION AND REPLACEMENT OF HANDLING ITEMS:

            The subject of handling items is an exceedingly broad one . All raw matereails parts finished products and wastes produced or used in the industry must be handled. The handling equipments may be selected on facters such as characters of materials, size, weight, rate of handling, distances to be moved , and the purpose of moving. The methods and procedures used not only vary as between plants but also as between departments within the plants so that the handling materials is an important function of over all planning.

            Accident experience also shows that the substitution of suitable mechanical handling for manual methods reduce accidents to a greate extent. Also the time consumed will be comparatively less. The volume material to be handled is of greater importance.

Methods of handling objects:

            General methods of moving materials commonly used industries are

1.      Hand lift trucks

2.      Wheel barrows

3.      Overhead travelling creanes

4.      Conveyours

5.      Shovels and

6.      Elevators

            The basic that unsafe acts of individual are a factor in majority of the accidents justifies the needs of mechanical operation wherever possible. The mechanical means must be of safer design and proper construction and that the personnel selected to operate them be properly qualified and adequately supervised. Typical hazards are overloading, poor arrangement of material, operating excessive speeds, lack of adequate space for operation and lack skill on the part of the operator.

Use of hand tools:

            Hand tools of one or the other type are used in every industry, more particularly in metal working areas, in maintenance and construction works. We can control accidents directly attributed to safety and improper hand tools, but we have more difficulty in controlling the action of the worker who might get injury by way of his improper work and cause injury to his eye. In such cases, accidents cannot be avoided but the extent of injury can be avoided by use of goggles.

            All heat treating should be done by those skilled in the art, who understands the properties of the materials used and know how to apply the required treatment in each case. Materials from the which hand tools are made should be of good quality and appropriate for the use to which hand tools will put. A periodic inspection of all tools would include the collection of those that need dressing, repairing and replacement of tools, this work should be done only to persons qualified to do it. Tools not in use should be stored safely on racks designed for them or should be placed in tool boxes.

RESPIRATORY PROTECTIVE EQUIPMENTS

REQUIREMENTS OF PERSONAL PROTECTIVE EQUIPMENTS:

            (1) Adequate protection against the hazards to which the worker will be exposed

            (2) Maximum comfort and minimum weight compatible for protective efficiency.

            (3) No restriction of essential movements

            (4) Durability and susceptibility of maintenance on the premises where it is used.

            (5) Construction in accordance with acceptable standards of performance and material

NEED FOR PERSONAL PROTECTIVE EQUIPMENTS:

            In industry it may be possible to substitute dangerous chemicals by a safer one or to have automatic and mechanical handling of the substance or to have controlled ventilation of the processes or to plan and arrange operations such that the personal protective equipments are not necessary. But sometimes it may not be possible to introduce such measures and there may be breakdown in the plant. In such cases the use of protective equipments become necessary. It should be kept in mind that the usage of these equipments do not eliminate the hazard. These devices are designed to interpose an effective barrier between a person and harmful objects or radiations.

TYPES OF PERSONAL PROTECTIVE EQUIPMENTS:

            These are divided into 2 broad groups

(1)   Respiratory protective equipments

(2)   Non- respiratory protective equipments.

RESPIRATORY PROTECTIVE EQUIPMENTS:

            The atmospheric contaminants may vary from the relatively harmful substances to toxic dusts fumes smokes mists and vapours and gases. Processes which present hazards of exposure to dangerous substances should be enclosed or ventilated to minimize the hazard. In enclosed systems,  ventilation is not possible or become very costly to apply to the degree of safety required. Respiratory protective equipments should be provided to workers exposed to such hazards. In any case the usage of respiratory protective equipments should e considered the last resort or as a stand by protection and never a substitute for effective engineering control.

CLASSIFICATION OF HAZARDS:

            Types of hazards to which the worker will be exposed is the basis of selection of the right type of respiratory protective equipments. Hazards may be classified under

            (1) OXYGEN DEFICIENCY : Atmosphere in confined spaces such as vats, tanks holds of ships etc, may contain air with oxygen content much lower than the normal. (21% by  volume) It may be ude to dilution or displacement of the air by other gasesor vapours or because of loss of oxygen due to decay of organic mateer, chemical reaction and oxidation over a long period of time. A person breathing air with oxygen content of 16% or less may exhibit symptoms ranging from increased rate of breathing, acceleration of pulse rate of unconsciousness and death. Such cases, the respiratory protective equipment should supply normal air or oxygen to the water.

            (2) GASEOUS CONTAMINANTS : These may be toxic gases. The toxic gases may produce harmful effect even as they are present in relatively low concentrations. These gases produce undersirable effects mainly by displacement of oxygen.

            (a) Immediately dangerous to life : These contaminants are gases present in concentrations that would enganger life of a person breathing them even for a small period of time.

            (b) Not immediately dangerous to life : These are gases present in concentrations that could be breathed by a person for a short time without endangering life but which may cause possible injury on a prolonged single exposure or repeated short exposures.

            (3) PARTICULATE CONTAMINANTS : These are all not immediately dangerous to life. They may be solid or liquid or a mixture of solid and liquid and may be classified into three broad groups.

            (a) Toxic particulate contaminants : These when inhaled may pass from the lungs into the blood stream and are thus carried to various parts of the body. The effect may be chemical irritation, systematic poisoning or allergic reactions. Some common examples are Antimony, Arsenic, Cadmium, Chromic acid, Lead, Mangenese and Chromates.

            (b) Fibrous producing dusts: These dusts do not pass into the blood stream but remain in the lungs and may cause pulmonary impairment. The common examples are Asbestos, Coal, Bauxite and Free silica.

            (c) Nuisance dusts : These may dissolve and pass directly into the blood stream or may remain in lungs neither producing local nor systematic effects.

AIR LINE RESPIRATORS :

            It consists of a face piece to which air is supplied through a small diameter hose. It may be a continuous flow or demand type.

In continuous flow type, air is supplied to the face piece continuously. Exhaled air or excess air entering the face piece escapes to the surrounding atmosphere. Air supplied should be atleast 110 1pm to enter the face piece. In demand type, air is supplied to the face piece, when the wearer inhales and the rate is governed by his volume of breathing. Air from an air compressor or cylinder is supplied to the face piece through a demand hose which is actuated by the slight negative pressure created when the wearer inhales. In exhalation, demand valve closes and exhaled air escapes to the surrounding atmosphere through exhalation valve.

            Air line respirators provide protection so long as the air supply is maintained. But the wearer’s travel is limited by the length of the hose. Care should be taken to ensure that the air supply is respirable and is not contaminated and is free from any objectionable odours, oil or water mist and rust particles from the supply line.

SUCTION HOSE MASK:

            It consists of a full face piece connected to a larger diameter flexible hose. The wearer draws air by his own breathing effort. The hose is atached to the wearer’s body by a suitable safety harness with safety line and inlet end is provided with a filter to arrest particulate matter. Air can be drawn in by the werer upto 30 ft. Length of the hose.

PRESSURE HOSE MASK:

            This hose mask is similar to suction hose mask except that air is forced through a large diameter hose by a hand or motor operated blower. This should be operated until the mask is in use.

SELF CONTAINED COMPRESSED AIR OR OXYGEN BREATHING APPARATUS:

            This is a device by means of which the use r obtains respirable air or oxygen from compressed air or oxygen cylinder which is an integral part of the apparatus. In demand type self-contained breathing apparatus, air or oxygen is admitted to the face piece through a two stage pressure reducing mechanism, only when the wearer inhales and the quantity of air or oxygen admitted is governed by his  breathing . The wearer’s exhaled breath escapes to the atmosphere.

            In compressed oxygen cylinder recirculating apparatus high pressure oxygen from the cylinder passes through a pressure reducing and regulating valve into a breathing bag. The wearer inhales the oxygen through a one way breathing valve and his exhaled breath passes into the canister containing chemicals to absorb exhaled carbon-di-oxide and moisture and then through a cooler into the same breathing bag. Oxygen requirement of the wearer is taken from the supply cylinder only when the volume of the gas in the bag has decreased sufficiently to allow the supply valve to open.

            From respiratory point of view, self- contained breathing apparatus has no limitations as to the concentration of the gas or deficiency of oxygen in the surrounding atmosphere but other factors may limit. The time that the wearer can remain in a contaminated atmosphere since many gases are irritating to the skin and can be absorbed in dangerous amounts through the skin.

OXYGEN REGENERATING TYPE- RECIRCULATING SELF CONTAINED BREATHING APPARATUS:

            In this type apparatus, the moisture content from the wearer’s exhaled breath reacts with granular chemical in a cannister to liberate oxygen. Also the exhaled Co₂ is absorbed by the chemicals in the cannister. This oxygen enters the breathing apparatus from which the wearer inhales through a corrugated breathing tube connecting the bag to the face piece.

AIR PURIFVING RESPIRATORS

CANNISTER GAS MASK:

            This consists of a cannister, containing appropriate chemical, a full face piece and body barness to hold the apparatus on the body of the wearer. Air is drawn through the cannister by the wearer and during it’s passage through the chemical in the cannister, the contaminant present in the incoming air is absorbed, reacted with a neutraliser. The cannisters are designed for specific gases and it is important that the appropriate type is used.

            The cannister gas mask can be used only in atmosphere not deficient in oxygen and not containing more than 2% by volume of most toxic gases. Also the life of the cannister will depend upon the type of cannister, the concentration of gas and the activity of the wearer.

CHEMICAL CARTRIDGE RESPIRATORS:

            This consists of a half mask attached to one or two cartidges. Like cannisters, the cartridge are filled with appropriate chemicals to absorb gases or vapours drawn through them. This one is a non- emergency gas respirator and it should not be used in an atmosphere deficient in oxygen. Like cannister gas mask, chemical cartridge respirator provides respiratory protection for a period that depends on the type of cartridge used, the concentration of gases or vapour and the wearer’s activity. It’s recommended for low concentrations of gases or vapours (about 0.1% of organic vapours)

SELF RESCUE TYPE RESPIRATORS:

            This is designed to provide the greatest possible respiratory protection consistent with the practicability of carrying the device at all times so that it is always available for use during escape. It consists of a small filter element, a mouth piece, a nose clip and means of carrying conveniently on the body. The filter elements are similar to chemical cartridge. The extent of protection afforded is between that provided by canister gas mask and that provided by a chemical cartridge respirator.

MECHANICAL FILTER RESPIRATORS:

            These remove particulate matter from the inspired air which passes through a filter. These filters may be of the single use or reusable type. If these respirators are used in heavy concentrations of particulate matter, the filter will be clogged with gust particles too quickly and they may have to be replaced every now and then.

            Micro filters are special filters designed to arrest ultra microscopic size of dust particles and these are used where extra fine dusts are encountered.

COMBINATION OF CHEMICAL AND MECHANICAL FILTER RESPIRATORS:

            They remove toxic gases and vapours and particulate matter from the inspired air.

SELECTION OF RESPIRATOR:

(1)   Nature of hazard

(2)   Severity of hazard

(3)   Type of contaminant

(4)   Concentration of the contaminant

(5)   Period for which respiratory protection must be provided

(6)   Location of the contaminated area with respect to a source of respirable air

(7)   Expected activity of the wearer and

(8)   Operating characteristics and limitations of the available respirator

CARE OF RESPIRATORS:

            Instructions in the use of respirators, among other things, should include the following.

(1)   When it is to be used

(2)   How it is to be used

(3)   Checking that it is in good operating condition

(4)   Fitting of respirator on the wearer

(5)   Proper use and maintenance of the respirator

NON-RESPIRATORY PROTECTIVE EQUIPMENTS

HEAD PROTECTION:

            Head protectors must be hard hats and caps made of aluminium, PVC, fiber glass, laminated plastic or vulcanised fiber.They may be fitted with brackets, welding masks, protective face screen or lamp. These caps are provided with replaceable harness which provide sufficient clearance between the top of the head and shell.

            Soft caps and hood are also used for protection from heat, spark and other dangerous materials and are made of appropriate materials.

EYE AND FACE PROTECTION:

            Numerous eye and face injuries are caused dusts, flying particles, splashes and harmful radiations. It is difficult to cover precisely. The various processes in which the worker will be required to wear goggles. The hazards encountered are

            Relatively large flying objects            -----      chipping, caulking, sledging

            Dust and small flying objects             ----       scaling, grinding, woodworking

            Splashing of metals                             ----       casting of metals, vanishing and dipping                                                                                of molten metals

            Splashing of gases, fumes & liquids   ----       handling of acids and chemicals

            Reflected light, glare & radiant energy --       Foundry work, furnaces, gas welding &                                                                                cutting, arc welding

            Eye protectors must be safety spectacles, mano goggles, welding goggles, foundry goggles, chemical goggles, welding helmets, face shields and gas tight goggles etc.

HAND AND BODY PROTECTION:

            Protection of hands and arms become necessary hence workers have to handle materials having sharp edges or when hot and molten metals, chemicals and corrosive substances are to be handled. The protective substances may be gauntlet gloves, wrist gloves, mittens, hand pads and thumb and finger guards and sleeves. It is important that not only the various parts of the arm and hand are adequately covered but that they should be covered by a material suitable of with standing the specific hazards involved.

FOOT AND LEG PROTECTION:

            Adequate foot protection may have to be provided to the workers employed in certain jobs. Risks of injury may be in handling of heavy materials, caustic and corrosive liquids, wet conditions, molten metals etc.Common leg and foot protective devices are safety shoes and boots, foot guards and leg guards. Shoes and boots may be provided with steel toe- box and inner steel sale and they may be ankle, calf or thigh or hip high. They may be made of asbestos, neoprene, natural rubber & synthetic rubber.

            Leg protectors may be in the form of leggings which may be knee high and they may be spats which should be lower shin, ankle and instep. They may be held in position by straps or spring lips or snap fasteners.

BODY PROTECTION

            Sometimes it become necessary to provide special protective equipment for the body in the form of aprons, jackets and complete head to toe protective suits. Nature of potential hazard, degree of hazard involved and nature of activities of the person involved are important considerations in the selection of safety clothing.

            Besides the above five groups, there are devices for protection against noise in the form of ear- muffs and safety belts for working in the pits or in confined spaces.