220 



THE INDIA RUBBER WORLD 



[February 1, 1916. 



the benches. This would seem to present a needless hazard, for 

 the cement is easily made of the proper consistency, and if used 

 in small quantities at a time there should be very little evaporation 

 and thus no call for the addition of naphtha. 



Lighting here should be incandescent electric. The making 

 room should have at least half of its fire pails filled with sand 

 and supplied with a scoop for using it, as cement fires are best 

 put out by smothering. 



Some of the hazards above mentioned are also applicable to 

 varnish. Some factories manufacture their own varnish. This 

 should always be made in a well-detached building. The build- 

 ing used for the manufacture of cement could be made large 

 and a section of this building could be used, cut off by parapet 

 fire walls, with no openings into the cement section. The varnish 

 is made from linseed oil, which is bought, generally, in the raw 

 state and boiled here. 



It is the opinion of this investigator that this section should 

 be made thoroughly fireproof, and that sprinklers might be 

 omitted. Floor should be concrete and fitted with a drain lead- 

 ing to a blind pit of ample capacity, located 50 feet or more 

 from any build- 

 ing. 



The vessels in 

 which the oil is 

 boiled should be 

 suflSciently large, 

 so that the oil 

 can in no way 

 boil over. Coke 

 or hard coal, it 

 is believed, is best 

 for fuel. Gas is 

 sometimes used, 

 but might cause 

 danger, owing to 

 drafts. 



Varnish also 

 contains rosin or 

 some cheap var- 

 nish gum ; also 

 sulphur in small 

 amounts. 



After the var- 

 nish is boiled for 

 a proper length 

 of time it is thinned down with naphtha. This hazard is similar 

 to the cement hazard, and the naphtha should receive the same 

 treatment here. 



Varnish should be stored in strong metal tanks, and pumped 

 out as needed. It is often brought to the factory in pails. The 

 best way would seem to be a system by which it can be pumped 

 to the place where it is used. The investigator has seen an in- 

 stallation where the pump is controlled by an electric device in 

 the varnish room, arranged so that the pump can be started up 

 or shut down at will. The piping is arranged to pitch back to 

 the pump, so all varnish drains back to storage tank when pump 

 is stopped. The amount of varnish in the factory should be 

 limited to a day's supply. 



Lighting in this department should be incandescent electric. 

 Varnish room should be well ventilated and cut ofif from the 

 main plant and vulcanizer room. Dip tanks, if used, should be 

 installed to conform, where practicable, to the rules and re- 

 quirements of the National Fire Protection Association. 



Dry heaters for vulcanizing should be located in a well cut-off 

 section. The tin lining should be standard, and attention should 

 be given steam pipes to prevent contact with all inflammable 

 material. They should be provided with a steam jet having an 

 easily accessible valve, so they could be flooded with steam if 

 necessary. 



They should also be protected by a standard system of auto- 

 matic sprinklers, although the manufacturers, almost without 

 exception, take issue to this, owing to the fear of premature 

 opening of the sprinklers, as the presence of water during the 

 vulcanization process would ruin the goods. 



The foregoing hazards, or some of them, and the precautions 

 recommended apply practically to all rubber factories. But 

 besides these are others applicable to the manufacture of rubber- 

 coated fabrics. Our readers are familiar with the operation of 

 the spreading machines, and know of the danger of ignition of 

 the naphtha fumes from sparks of static electricity, which is 

 generated in the fabric by friction and pressure. This, according 

 to another investigator, has been found to be very largely a 

 matter of humidity, which will be referred to later. 



The dough or spreading mixture is simply compounded rubber 

 which by means of naphtha and churning has been made of a 

 dough or cement-like consistency. The hazard of manufacture 

 of this material should be safeguarded in the same manner as 

 described for the manufacture of cement. 



Spreading machines should be located in a detached or well 

 cut-off section of 

 the plant. The 

 hazard of the 

 operation is en- 

 tirely due to the 

 presence of the 

 naphtha used in 

 t h e spreading 

 compound. Rub- 

 ber being easily 

 electrified by fric- 

 tion and pressure. 



wall 



The Chapman Neutralizer 



of the Chapman neutralizer to spreading macl 



T 

 The i 

 of 



preading machine is fitted with t\ 

 placed iust back of the spreading 

 IS of these inductors are shown abi 

 ese inductors are placed so that th 

 Buence of the inductors 

 fast as it come 



electr 



result 



insulated 

 "inducto 

 nife and the othei 



fabric passes them 

 igh the air for sev 

 legion of influenc 



the inducto 



ndmg 



ends thr 





e head end of the spreader 



neutralizes every part of the fabric as tast as it leaves the spreading knife, befon 



the fabric can accumulate sufficiently to discharge to the roll, knife, frame or pipe; 



The obiect of the other inductor, treating the fabric just before it is rolled uj 



charge redeveloped by the other rolls over which the fabric passes before winding 



)m two to four inches, 

 lem, and every portion 

 It instantly deprived of 



nstantly and completely 

 any charge imparted to 

 in the form of a spark, 

 is to remove any slight 



thought by some 

 engineers that the 

 evaporation o f 

 naphtha also 

 causes this phe- 

 n o m e n o n, the 

 spreading m a - 

 chine should be 

 equipped with de- 

 vices for remov- 

 ing these static 

 charges. 



The methods in use for guarding this hazard are as follows: 

 All metal and moving parts of the machine are well grounded. 

 Directly in front of the knife is located a steam jet. Bearing on 

 the underside of the fabric is a wire which collects any charge 

 which is not broken up by the steam jet. 



In some factories the speed machines are equipped with an 

 electric device know-n as the Chapman Electric Neutralizer, which 

 distributes alternating charges at high voltages in minute quanti- 

 ties to the places where the static charges collect. This works 

 on the principle of the simple law of attraction and repulsion, 

 that the static charge in any insulating material selects for itself 

 the kind and quantity to exactly neutralize itself. 



According to investigation made by the Inspection Department 

 of the Associated Factory Mutual Fire Insurance Com- 

 panies, it has been concluded that if the humidity of the room 

 where the spreading machine is conducted is kept at about forty 

 per cent., there will be little danger of fire from this cause. 



As a proof that the chief hazard in rubber factories is due to 

 ignition of the spreading material through sparks of static elec- 

 tricity F. J. Hoxie, a well-known insurance inspector and en- 

 gineer, gives in graphic form the number of all fires in twelve 

 factories during the seven years previous to 1915, and the number 

 of spreader fires in seven factories during that same period. It 

 will be seen that a very large percentage of all occurring in the 



