Environmental Engineering Reference
In-Depth Information
tABle 25.1
Permissible Plank spans for scaffolds
maximum Permissible span using
Full-maximum Intended load
(lb per sq ft)
maximum Permissible span using
thickness, undressed lumber
(feet)
normal thickness lumber
(feet)
..25
10
8
..50
..8
6
756
Not.Applicable
The.maximum.permissible.span.for.a.1
1
/
4
-inch.by.9-inch.or.wider.plank.for.full.
thickness. is. 4. feet,. with. medium. loading. of. 50. pounds. per. square. foot.. Scaffold.
planks.must.extend.over.their.supports.not.less.than.6.inches.or.more.than.18.inches..
Scaffold.planking.must.overlap.a.minimum.of.12.inches.or.secured.from.movement.
skylIghts (29 cFr 1910.23)
Over.a.number.of.years,.many.workers.have.fallen.through.skylights.after.assuming.
they. were. designed. to. support. human. weight.. This. misconception. has. resulted. in.
many.deaths.and.injuries..Every.skylight.loor.opening.and.hole.is.to.be.guarded.by.
a.standard.skylight.screen.or.a.ixed.standard.railing.on.all.exposed.sides.
sPrAy-FInIshIng oPerAtIons (29 cFr 1910.107)
In.conventional.dry-type.spray.booths,.over-spray.dry.ilters.or.rolls,.if.installed,.are.
to.conform.to.the.following..The.spraying.operations,.except.electrostatic.spraying,.
must.ensure.an.average.air.velocity.over.the.open.face.of.the.booth.of.not.less.than.
100. feet. per. minute.. Electrostatic. spraying. operations. may. be. conducted. with. an.
air.velocity.of.not.less.than.60.feet.per.minute,.depending.on.the.volume.of.inish-
ing. material. being. applied,. its. lammability,. and. explosive. characteristics.. Visible.
gauges,.or.audible.alarm,.or.pressure-activated.devices.must.be.installed.to.indicate.
or.ensure.that.the.required.air.velocity.is.maintained..Filter.pads.must.be.inspected.
after.each.period.of.use,.and.clogged.ilter.pads.discarded.and.replaced..Inspections.
are.to.ensure.proper.replacement.of.ilter.media.
Spray.booths.must.be.installed.so.that.all.portions.are.readily.accessible.for.clean-
ing..A.clear.space.of.not.less.than.3.feet.on.all.sides.must.be.kept.free.from..storage.
or.combustible.construction..Space.within.the.spray.booth.on.the.downstream.and.
upstream. sides. of. ilters. must. be. protected. with. approved. automatic. sprinklers..
There.shall.be.no.open.lame-.or.spark-producing.equipment.present.in.any.spraying.
area.or.within.20.feet.thereof,.unless.separated.by.a.partition..Electrical.wiring.and.
equipment.not.subject.to.deposits.of.combustible.residues,.but.located.in.a.spraying.
area,.must.be.explosion.proof.
The. quantity. of. lammable. or. combustible. liquids. kept. in. the. vicinity. of. spray-
ing. operations. must. be. the. minimum. required. for. operations. and. should. ordinarily.
not.exceed.a.supply.for.one.day.or.one.shift..Bulk.storage.of.portable.containers.of.
