Document O3XwrkbDKzxMxpyMoMq6kyJ2Q

77(\ Silver Jubilee Safety Congress \V. II. Greenwai.t, Murray Wood I'roducts Co., Memphis, Tcnn. mll.\nttY Gcjuiert. Tfic Pullman Co., Chicago, W. Junks. The Surly Manufacturing Co_ Oiicago. Ill, Harry J. Keuxy, American Seating Co., Grand Rapids, Mich. Wai.tkk S. Paine, Aetna Casualty & Surety Co., Hartford. Conn. *). A. I'l Wrt', Michigan Mutual Liability Co., Detroit, Mich. ( i. K. Sanford. General-Electric Co.. Schenectady, N. Y. II. K. Sef.i.v. The Brunswick-Balkc-Collender Co.. Oiicago, 111. l*ut (ieneral Chairman MONDAY AFTERNOON SESSION October 10, 1938 The first sc-sion tva* called to order by General Chairman H. E. Seely, Insurance Department Manager. The Brunswicklalke-ColIcnder Company, Oiicago. He sketched in his opening remarks the prog ress of the Section during the past year, spoke oi the good work of all Officers ami Chairmen of Committees of the Section, and then introduced the first s(>enker. Wood Dust Hazards Control By H. H. VALIQUET Ventilating Engineer, Employers Mutual Liability Insurance Company of Wausau, Wis. Wood dust is a by-product of almost all woodworking oj>crations including chipping and larking in the wood pulp plant and fini-hing wooden parts hy sanding or sawing in rash and door, furniture, box. toy. and veneer factories. Processing in wood flour plants ami the use of wood dust in the plastic ami linoleum industries also present a dust problem. Since wood dust introduces the hazard of explosion and Are. dust con trol at the source is essential. The first attempt at wood dust control in this country was made in altoul 1850 near North Conway. N*cw Hampshire, where R. 1*\ S'urlevant was making wooden pegs for shot's. To handle the refuse, he devised a kou-itl centrifuza) fan to Mow- the trash away from the point oi generation to a di-po-al. Not until about 1906 did capacity tables for centrifugal fans fiecome available and method* of dust control l*cgin to develop. Today the degree oi dust control can be relatively adequate even though we have no definite standards by which we can judge result.* *** tope, however, to outline a general dust control program which will apply to most woodworking plants. Removal of wckhI dust at (he source ithe prime consideration. \Yc must not over look the fact that some plants sj*em! large sums of money for dust control. In the R. C. A. Victor Company's radio cabinet plant at Camden. New Jersey, I fa million cubic feet of air per minute are Used to handle the trash, conveying tons and tors of refuse to disjtosal from woodworking facilities. Ford Motor Company. Fisher ltodv, Briggs, the Mcngel Company. Westingheusc. General Electric Contianv. Globc- Werneckc and others are doing an exten sive job of controlling dust at its source. In (he near future ue hope to scr the average and small plant provided with fa cilities tor wood dust control and safe guarded in this way from fires and explo sions such as the following. In a Detroit woodworking plant a steam pij>c passed through a brick flue u-cd to convey trash from various floors to the point of disposal. Some flammable dust thrown down the flue ignited, and the ex plosion resulted in injury to eleven raeu. Wood Products 777 Another accident occurred in a Sander finishing room at Appleton, Wisconsin, where wood dust on ratters liecame dis lodged and fell onto live coals that had accidentally rolled out of a stove onto the hearth. An o|icn lantern similar to those com monly used bv night watchmen, a leaky dust pipe which caused a dust cloud in an engine room, sparks drawn front a grinder into a dust collecting system, spontaneous combustion of an oily rag. and lack fire through a furnace feeder pipe which started fire in a sharings storage vault, arc a tew cau-cs of destruction and suffering. Static electricity is a hazard in industrial plants, larticularlv where flammable dusts or gases are present. Not every individual discliarge of static electricity will ignite a dust or ga> mixture because the ignition depend* ujmn the nature of the flammable material, the amount of it which i< mixed with the air at the point of static discharge, and the nature of the static discharge. CarlMinaceous dusts are explosive, and the enormously increased electrical capacity of matter in a finely divided condition is often a contributory cause of the explosion of combustible dust. Twenty per cent of a .-ample tested was of a fineness to pass through 20G me>h screen. Such particles arc aiiout A/1000 of an inch, or 74 microns, tn greatest dimension. Wood subjected to prolonged exposure to lemjH-ratures of a low* order (such as that <>f steam pij*cs) may ignite sjH>ntaneously. Wood flour ignites at a temperature no higher than that of a lighted match. The exact combination of dust concen tration. flame temperature, etc. may seldom occur. Reasonably safe conditions arc the imiKirtant criteria, and to make conditions <atc we must have good housekeeping and carefully observed safety precautions. Four steps arc necessary: (11 Enclose the operation: (2) Ventilate al (he source of the du.-r; (3) Remove possible sources of ignition; (4) Provide safe disposal of waste. As an example of enclosing operation?, we found a vertical sandcr belt completely hooded. The du?t control here was good Ifcratt'ic ventilation was effective at the point of dust generation. However, even this set-up was not functioning correctly for, in the first place, the fan was running in the wrong direction, and in the second place, its j>ccd was not sufficient to add effort to the air movement Itecausc its discharge was con nected to a dust disj>osal system already stronger titan the fan effort. The suction of the main system was greater than that of the small fan in line with the vertical suriaccr; therefore, the fan acted like a valve and restricted the natural flow of air and dust. This was an example of lack of thorough analysis of the facts. The hood was good, but the ventilation was poor. In another ca-c we found a vertical sandcr under partial enclosure with sub-standard dust control. The lower side of the belt should liavc been enclosed with the top and bottom pulleys. Not all the dust could lie caught because a large section of the licit was not enclosed. To fuvsh.complctclv such a crooked piece of wooo as a bow* lack of a chair, a large opening is necessary. The hood which is more nearly enclosed fur nishes the licst dust control for most work. A much neglected unit from the standjxiint of dust control is the wood sandcr. A hood developed by the Sheboygan Fibre Furniture Company not only accommodates awkward work, but produces excellent dust control. Unfavorable drafts cause little in terference with the mechanical ventilation. A 3 inch pipe connection has 2S inches total suction finches of water). This reading is taken 12 inches from the hood through a *.$ inch dean drilled hole in S inch pipe. Such a suction would indicate that results on the 24 inch drum arc excellent. A horizontal sandcr should have a- com plete enclosure of. sandcr bd! as possible. Such a device used In* Kirk and Blum of Cincinnati is very satisfactory*. Too many liclts lack endowing hoods and good ventilation. The cost of the sheet metal enclosure, once it is installed, is amortized over the uual period for such major expenses; hut ventilation equipment costs money day in and day out as long as it is in operation. Consequently, ventila tion carried on without an enclosing hood is more expensive and (ess satisfactory than ventilation carried on within a suitable hood. When a belt sandcr is completely covered except at the point of operation, ventila tion applied parallel to belt movement pro duces reasonable dust control. Not enough sander belts are guarded for dust control, but we are fast approaching the time when tentative hood standards should be set. S-FORD-058