Majority of fire accidents occur as a result of carelessness and elimination of carelessness is a major problem. The problems can be best avoided by in-depth study and understanding of the manufacturing process and the environment.
Hazards in Cotton Industry start right from the inception, i.e. from cotton in its fully compressed form (bales) and extends till its finishing process but its presence during each process is of varying degree.
Hazards in cotton industry can be discussed out of the following broad headlines :
(1) Raw materials used in the process;
(2) Construction;
(3) Nature of Process and Machinery;
(4) Electrical Installation; and
(5) House-keeping
(1) RAW MATERIALS
The basic raw material is cotton which is the most hazardous of all fibres from the fire point of view. When in damp condition or in contact with oils or facts, it is liable to spontaneous combustion. If cotton is pressed when damp, the baled cotton generates heat at the centre which, when in favourable circumstances, may ignite and start the fire. Also when in loose state, the heaps must be small and well-spaced and when in baled condition the stacking should not be very high or subject to dampness. This is because the fire tends to smoulder in bales of cotton and it will make itself evident only when it has attained a strong form.
Being cellulose fibre, cotton is capable of igniting even with a small spark as is found in the process of Ginning, Mixing, etc. The cotton fire spreads rapidly and unless attacked at inception, the consequence will be of serious proportion.
Fire in cotton godowns may be caused due to the following reasons :
(a) Spark caused at the time of stacking them if the iron hoops collide with each other.
(b) Once the bales are stacked in the godown, due to heat, the hoops expand and collide against each other causing a spark.
(c) Due to inadequate ventilation and improper stacking of the bales.
(d) Due to electrostatic charges or some such causes resulting in spontaneous heat and combustion.
(e) Human negligence – such as throwing cigarettes etc.
Fire in cotton godowns are almost spontaneous and takes everybody unawares.
Other raw materials used are the bleaching agents, dyes and chemicals, all of which present fire probabilities to a varying degree. They are more hazardous during storage and the processes making use of these chemicals are wet processes. Care must be taken to prevent ingress of water as this is enemy of water-reacting chemicals which will readily start fire. Hazardous chemicals such as Sulphuric acid, Cuastic soda, etc., must be stored away from the non-hazardous goods.
In waste godowns, spontaneous combustion is a natural hazard which occurs as a result of gradual generation of heat by chemical changes. In particular when the waste is soaked in oil the combustion becomes inevitable.
Adequate precaution and sound knowledge of hazards would enable safety against such occurrences.
(2) CONSTRUCTION OF BUILDING
These type of hazards refer to the types of buildings and materials used in their construction. The buildings housing textile processes, having timber floors are more susceptible to the spread of fire than others. This is due to accumulation of cotton fluff under the floors which may be ignited spontaneously.
Right from breaking of cotton bales upto the finished cloth, the processes require a large number of departments. All the departments cannot be spread out horizontally as a very large floor area is required. Due to paucity of land, the departments grow vertically. In storied buildings, the supporting steel structures, if not encased in RCC work, would buckle with the heat generated during the serious fire. This would result in total collapse of the building. Wooden intermediate floors, which absorb oil, burn fiercely when ignited. The cotton fluff accumulated underneath such floors especially when impregnated with oil is another source of potential hazard.
The other disadvantages in storied structures are :
(a) Water used in extinguishing fires on the upper floors would percolate through the intermediate floors and damage the property in the floors below.
(b) High-speed machinery installed in the upper floors cause heavy vibrations which reduces the durability of the structure and a fire of even small magnitude may bring about a collapse of the structure.
(c) Fighting the fire becomes more and more difficult with increase in the height, with the result small fires in upper floors can attain a sizeable proportion.
(d) All upper floors are connected through staircases, lifts, chutes etc. In case of fire, these act as flues facilitating the spread.
Nature of construction of a Cotton Mill also presents a variety of hazards. It may not pose fire problems, but in the event of fire, it would be a contributory hazard. The various types of constructions adopted in our country are with A.C. sheet roofs on steel purlins and structures, Galvanised Iron Sheets superimposed by Mangalore tiles or with RCC roof. The external walls are of brick or RCC. In a country like ours blessed with abundance of day-light, North-light type of construction have a popular role in construction have a popular role in construction. The construction are classified by Underwriters commensurating with their nature and hazard and underwriting is done accordingly. There are classifications such as Class I, Class II and Class III (Fire-proff, non-fire proof and Inferior) types of constructions depending on nature of external walls and roof of a building. When the construction is down-graded, the premium is increased to accommodate the increase in risk. Usage of wooden partitions, roof linings, false ceilings and also usage of hessians and similar non-combustibles would aggravate the fire risk.
(3) PROCESSES AND MACHINERY EMPLOYED
The fire hazards associated with the various processes are as under :
3.1 Blow & Mixing Rooms
Fires in these departments are very frequent and losses could be substantial in view of large quantities of cotton. The cotton bales contain a number of impurities like trash, broken seeds, stalk, rivets and at times iron particles. When cotton is fed into the opener, inspite of magnets provided in the machine, many a times the iron particles give a spark due to mechanical friction. The spiked lattices, heaters, openers, rollers, grid bars etc. are some of the vital areas in the machinery at which likelihood of spark can occur due to friction. The cellar where all the fluff and dirt is collected, is a source of potential hazard. The modern Blow Room is completely automated and a spark resulting from any of above machines spread amazingly fast to all parts of the room. The dust chimney and the Blow Room underground cellar are potentially hazardous as all dirt, fluff of cotton are accumulated therein or exhausted therefrom. All machines with spiked lattices and blades must be provided with automatic fusing sprinklers inside the machine and this sprinkler system backed up by a reliable water source. The dust cellar and chimney should also be sprinklered as these are potential hazard-prone zones.
3.2 Carding Department
Fire hazards in this department are caused due to :
(i) Hot pedestal bearings in the line shaft drive (if group drive is installed) which would ignite the accumulated fluff;
(ii) Hot licker-in side-bearing pedestals;
(iii) Friction between cylinders and doffers;
(iv) Friction between licker-in and undercasing;
(v) Friction between metallic belts, strap and pulley;
(vi) Electric spark due to a broken flexible, faulty starter, switch or stop motor mechanism and static charges.
Cotton being in the loose form, is susceptible to fire due to friction. The cotton moves through fillet in narrow clearances and likelihood of friction is not infrequent.
With continuous carding, wire points of cylinders and doffers become blunt and they have to be ground at regular intervals. The grinding operations must be carried out in a separate chamber. The wires in the Carding engine are susceptible to water-damage and this has to be taken care of. With the increased use of staple fibres, electrostatic charges cause frequent fires.
3.3 Spinning Preparatory and Spinning Department
The processes previous to spinning are comparatively innocuous, the machines being wholly metallic and spindle speeds being inexcessive. Majority of the modern machines have individual drives, electronic stop motion and versatile controls and hence fires due to mechanical friction are increasingly less. However, fires due to static charges, faulty wiring, overloading of motors and improper grounding are among the common causes.
Ring frame operation is not hazardous than the preparatory processes. Nevertheless, Underwriters have reservations about fires in this department as the sum insured of this block will be about one fourth of the whole Mill. Friction is a very common cause for the fire hazard as the machine works at high speeds. The frames are always covered with fluff and any spark either mechanical (due to friction) or electrical (due to defective electrical installation) would result in a flash fire across the machine. Particularly in storied structures with wooden floorings, any small spark may result in collapse of entire structure.
Static pressure is developed by pressure on fibres between rolls and friction on one another and with influence of out-side weather conditions, these charges can emit sparks.
Mule spinning is comparatively more hazardous because of number of high speed pulleys revolving at differential speeds in the headstick as well as the mule carriage and also because it has certain amount of timber in its construction. The mule spinning is rarely exercised these days.
3.4 Weaving Preparatory and Weaving Process
The above departments are not hazardous and yet fires are common due to bad house-keeping and electrical short circuits. Underside of winding machines are invariably covered with fluff and any small spark would cause a flash fire across the whole length of machine. Hence a cleaning system of lint, fluff and fly must be provided which should be of the higher order.
There has been instances of fires in yarn singeing machines where yarn is passed through electrical heating elements to remove and burn out the protruding fibres. This optional process is a little hazardous in presence of the electric spark that can be caused. By properly interlocking the main motor and the heating elements, accidental fires due to stoppage of motor can be avoided.
Weaving itself is not a hazardous process and yet it is not without its dangers. The looms should be adequately spaced.
The probable hazards in this department are due to (a) healds which are composed of varnished chords and hence are inflammable. If metal healds are used this can be avoided. (b) Hazard in picking mechanism getting jammed due to accumulation These processes were once upon a time considered as least hazardous. However, with the introduction of modern machinery such as screen Printing, Polymerising etc., the statement will be no longer accurate. However, specific areas where element of fire risk is present are discussed as under : In a hot air stenter machine, fabrics are treated for thermo-soling or heat sttting the fabrics at a high temperature. If the machine stops all of a sudden due to some reason or other, the cloth inside the chamber catches fire. This machine is hazardous and is usually segregated from all the neighbouring blocks to check the fire spread. The spark, sometimes from the gas or petrol burner ignites the fluff and causes fire. Interlocking arrangement will be required so that the machine would not start up unless the exhaust fan and blower fan are brought into operation beforehand. The gas cylinders or other burning media would be located outside. It is also necessary to install electrical control gear outside and the local control push buttons be of flame-proof type. This is to ensure that any leakage of gas would not get ignited due to electric sparks. The light fittings in this department must also be of protected type. Only the main motor can be of ordinary type, subject to provisions of satisfactory interlocking arrangement. This is because, before main motor starts, the exhaust fan would remove the traces of gas. If petrol is used as a source, the installation of petrol tank must comply with relevant rules to prevent undue hazards. It is a practice to spread out loose. Cotton in vacant space inside or outside the department. Colour and chemical stores inside this department would also present a hazard. Rotary and Flat bed screen printing machine are now in vogue on which multi-colour heavy designs are printed. In preparing pigment colour paste, for printing the fabric, about 70% of kerosene if used together with other binders. The printed fabric, containing this percentage of kerosene, is then evaporated and fabric is dried in a Drier called “Float Drier”. Probabilities of disastrous explosions with resulting fires exist in the process. Several explosions and fires have occurred in the “Polymerising” or “Curing” machines. These machines are meant for fixation of colours on the fabrics. For this purpose, hydrocarbon resins and kerosene are used as binders. The various preventive measures prescribed must be strictly adhered to, failing which, explosion hazards are inevitable. The measures include provision of exhaust fans and ensuring their interlocking arrangement, electrical heaters to be synchoronised with main motors and exhaust fans, provision of thermostats to regulate temperature, provision of safety flaps to exhaust fumes, assurance of free circulating air, cleaning of exhaust system, etc. The raised fibres from the surface of the cloth are susceptible to fire. Sparks, emitted by rollers from Raising machine which rotate in opposite direction, are the source of ignition. Fluff accumulation on machinery and the surroundings are to be periodically removed. Spontaneous combustion of coal in the coal yard. It is a practice to keep coal storage in open 50 feet away form all the surroundings. Boiler Houses are usually segregated from adjoining blocks. In process house, thermic fluid heaters are installed for treatment of cloth at a very high temperature during various processes. In this system, oil is heated and circulated through the various machinery which is then recovered and re-circulated. Here also the probabilities of explosion hazard and subsequent fire are present. As far as humidification plants and system is concerned, these are non-hazardous. The entire process of humidification is wet. But the conspicuous hazard arises in return air system where all the dirt, fluff and flying matter will be sucked from the department and the entire return air path will be full of such refuses. Any accidental fire in the return air path would, thus, be not only hazardous but also pose the problem that being a confined area, its detection would be at a very later stage. As humidification ductings pass from place to place and sometimes floor to floor, these ducts would act as flues at the time of fire. Fires due to electrical faults have been more in cotton industry than any other industry. Cotton fluff is easily ignited by a spark by a faulty installation, which could be the cause of a serious fire. Modern machinery are driven by electricity & requires power at high pressure. Therefore, it is necessary that installation must comply with the standard requirements. The more frequent causes of electrical fires may be listed under three general classes : Arcs, Sparks and Overheating. When an electric circuit which is carrying current is interrupted, either intentionally as by a switch, or accidentally, as where a contact at a terminal becomes loosened, an arc is produced the intensity of which depends in a great measure on the current and voltage of the circuit. The temperature of the electric arc is very high and any combustible material in the vicinity may be ignited by the heat. An electric arc may ignite not only combustible material in its vicinity, such as the insulating covering of the conductor but it usually fuses the metal of conductor. Hot sparks from burning combustible materials and hot metals are thrown about and may set fires to other combustible material like cotton. When an electric conductor carries a current, heat is generated. This heat depends upon the size of conductor and type of insulating material. Where the limiting currents are exceeded, or where the conductor is ‘overloaded’ the generation of heat becomes a hazard in the following two ways : First through deterioration of the insulation, and second through the excess heat generated. All regulations governing the installation and maintenance of electrical equipments are designed fundamentally to prevent fires from these three major causes arcs, sparks and overheating and the prevent accidental contact which may cause a shock. In the installation, maintenance and inspection or re-inspection of electrical equipment, these primary sources of electrical fires and shock should be kept clearly in mind. An orderly, tidy and clean risk denotes good management and suggests a less moral hazard. Conversely, an untidy, dirty risk not only indicates careless management, but engenders carelessness in both management and employees, and carelessness is the prime cause of fires. This is true of all risks, but it is of special importance in cotton mills owing to the inflammable nature of cotton itself and the tendency of dust and fluff to collect. Waste should be swept up and removed from the premises daily, particular attention being paid to inaccessible places where there is a danger of accumulation, for example, a round heating apparatus, of which mention has already been made. Looms should be regularly swept down, and all other machinery, particularly in the winding and warping departments, together with shafting and gearing, should be kept clean. Any accumulation of “down” or “fly” easily becomes saturated with oil and thus aids the rapid spread moveable parts of machines increases the friction hazard with its attendant generation of heat ever-present where moving machinery is in use. This raises a second point calling for attention throughout the mill – the need for adequate lubrication of all machinery and gearing with a fast-moving machinery. The use of sight feed lubricators on the taping and sizing machine should be encouraged. The importance of good house-keeping for elimination of hazards needs no emphasis. To ensure good house-keeping both inside the department of the mills and in the compound not only a good lay-out of the plant is necessary but it also becomes a management responsibility. In cotton textile mills cleanliness inside the department is of prime importance as cotton “fluff” accumulates and settles on machines, shafts and pedestals, switches and starters, ceiling, floor and what not. In Process house, drums of hydro should not be stored in the department below the sprinkler or leaky pipes because if a sprinkler bursts, it will ignite hydro. It is also a general practice in the mill to hang hessian bags on walls and pillars to collect and store cotton waste. This is a hazardous practice. For this, metallic boxes conventiently placed far away from electrical appliances should be used. Oily waste must not be collected and stored, specially below the electrical distribution boards but should be removed and put in the bins provided at the entrance of the department. Lighting fixtures, supply air ducts, return air ducts in case of all air system of humidification, bare overhead steam pipes, walls, ceilings and suspensions must also be periodically cleaned. Inside the department, special bins must also be provided for storage of scrap materials. Flammable items in the mills’ compound such as empty wooden cases, oil drums etc. should be kept in properly marked out locations. All grass adjoining the department in the compound should be cut and removed after the monsoon. Cement bunkers should be provided for collection of waste products from the departments, in the compound. Waste and rubbish should not be allowed in the compound. Good house-keeping both inside the mills and outside must be observed if fires are to be avoided and it is the duty, both of the management and the workers to ensure a high standard of house-keeping in the whole factory and its compound. 1. What do you understand by location hazard in Cotton Ginning & Pressing industry? 2. Describe the hazards involved in Cotton Ginning & Pressing processes. 3. Describe the hazards involving in storage of cotton (loose and in bales) in godowns and in open. 4. Describe the common factors responsible for fire in cotton godowns. 5. Describe how construction plays a vital role in making a textile mill a good risk. 6. Discuss the fire hazards present in Blow and Mixing Rooms and Carding sections of a textile mill. 7. Discuss the fire hazards present in Spinning and Weaving sections of a textile mill. 8. Singeing, Polymerising, Raising and Steam Generation processes endanger the textile processing plant to a large extent. Discuss. 9. Discuss the needs and requirements of a good electrical installation in a textile mill. 10. House-keeping is the key to fire safety particularly in textile risks. Elaborate.3.5.1 Finishing Department
3.5.2 Singeing Department
3.5.3 Dyeing Department
3.5.4. Printing Department
3.5.5 Polymerising Section
3.5.6 Raising Department
3.5.7 Other types of hazards include fires originating from explosion of Boiler.
4. ELECTRICAL INSTALLATION
Causes of Electric Fires :
5. HOUSE-KEEPING
House-Keeping : (Moral Hazard) :
COTTON MILLS