Safe use of power saws
By:Captain James Benjamin,
MS, CSHM, CFEI
We have all seen the drastic increase
in the use of power saws on the fireground. They are used commonly
for ventilation, forcible entry, as well as a plethora of other activities
and tasks. As you can imagine, this has created numerous problems
regarding how to carry, properly handle and use different saws.
The saw hanging this low may be a problem
for some shorter firefighters and may make them feel like the saw is going
to swing out and cause it to fall off the shoulder. However, passing
the sling over the head, which would cause the saw to ride higher and alongside
the SCBA, can eliminate this problem.
|ACCESSING THE ROOF
Before you ever think about climbing a
ladder with a saw, take a few extra seconds to start it and make sure that
it will run. A smoky rooftop is not the place to find out that your
saw is not operating correctly. It is much easier to transport a
power saw, whether rotary or chain, and place that saw in service, if a
strap or sling is used. This is especially true when trying to climb
or navigate on a portable ground ladder or aerial unit. Having a
sling on the saw allows the firefighter the ability to still have the use
of both hands, thus allowing them to have four points of contact with the
ladder while climbing. As you can imagine, different lengths of straps
are needed for different saws. The sling must be long enough so that
it rides down off the firefighter’s back, does not interfere with the SCBA
and allows the firefighter to carry the saw comfortably.
|photo by R. Scollan,
Anyone who has ever worked on a ventilation
crew will tell you that one of the most nerve-racking operations on the
fire-ground is moving from point to point on a smoky roof, especially when
there are multiple saws running. Not only is the rooftop a hazard
(i.e., not knowing exactly where the edges of the roof are located, structural
integrity, etc.), but the other ventilation crews and their equipment are
as well. You can hear the saws and you know they are close, but you
are not exactly sure where they are. This is especially true during
major ventilation operations
MOVING ON THE ROOF
What is the proper way to move on a smoky
roof when you have a saw? There is no one correct way to move on
a roof. However, there are a number of factors to keep in mind.
Sounding the roof is an extremely important and, often times, overlooked
step. Before leaving the relative safety of the ladder, make sure
you have a tool to sound the roof with (i.e., an axe, Halligan tool, etc.)
and remember to sound the roof early and often. Once you have determined
the roof is safe, you have a couple of choices on how to move with your
power saw. If the saw is not yet running, you can simply carry it
slung over your shoulder or in your hand. However, if the saw is
running, it is usually best to place the blade of a rotary saw against
the roof’s surface in order to stop its rotation. Even if the tension
on the belt is improperly adjusted, the spinning blade will stop spinning
once contact is made with the roof. If you are using a chain saw,
it is best to engage the blade break before moving.
If additional ventilation is needed, there
are two basic options. The first and fastest is to remove the top-floor
windows from the roof level. This can be accomplished in a number
of ways, such as reaching over the side of the building with a pike pole
and busting the windows out (again, primarily used while operating at commercial
structures) or using a Halligan tool or axe and a rope (it always pays
to have the irons with you). If this additional ventilation is not
sufficient (or feasible i.e., operating at most residential structures)
to remedy the smoke condition, then the roof must be cut.
|photo by Normal FD
Once on the roof ask yourself, “is cutting
the roof necessary?” If you are operating at a residential structure,
the answer is probably yes. However, in many cases (i.e., commercial
structures), opening up scuttles, bulkheads, and/or removing skylights
can accomplish initial vertical ventilation. As a general rule, the
opening or removal of the above listed items should be completed before
commencing saw operations (if the structure is equipped with such items).
Once the initial vertical ventilation is completed, the firefighters on
the roof should evaluate the smoke conditions and any radio reports to
determine if additional ventilation is necessary. Positive Pressure
Ventilation (PPV) is an excellent way to increase the effectiveness of
ventilation whether the opening is natural (i.e., skylight, etc.) or manmade.
CUTTING THE ROOF
Many times, ventilation crews are assigned
to cut an opening at a specific location (i.e., E-45’s crew has been assigned
to ventilation, open the roof on the South East side, or A, D side, etc.).
However, if you are operating at a commercial structure, finding the seat
of the fire will be more challenging. In these instances, several
different visual indicators can help you determine the location of the
fire. Indicators may include but are not limited too: bubbling
tar on the roof’s surface as well as smoke pushing through seams in the
roof or around vent pipes. Employing the use of a thermal camera
is another excellent way to find the seat of a fire. Example - if
the fire is now blowing out of several windows on the top floor of a building,
it should be fairly easy to narrow down the location for the ventilation
|photo courtesy of SJFD
||So where should you place the ventilation
cut? The proper placement of the ventilation hole depends on several
factors, with the most important factor being the fire’s location within
the building. The opening needs to be cut where it will provide the
most effective escape route for the fire’s heat and toxic gases.
With this in mind, it is easy to see why the ventilation opening must be
as close as possible to the main body of fire. The seat of the fire may
already be known (i.e., reports from the interior crew, visual observations
of the fire, etc.) if you happen to be operating at a residential structure
Watch out for what I like to call the “parapet
paradigm.” This paradigm refers to the frequently made mistake of
cutting the ventilation hole too close to the outside or parapet wall.
With fire showing from multiple windows, the ventilation opening should
be placed farther in toward the middle of the roof’s surface. Why?
The rooms that have fire emanating from the windows already have plenty
of ventilation and cutting too close to these exterior walls would only
vent the same area that is already being vented by the windows. The
rest of the floor, especially the hallways, has limited ventilation.
However, this lack of ventilation can be eliminated by pulling back from
the exterior walls (location of windows) between 10-15 feet and then opening
up the roof. The location of this opening will allow for venting
of the fire’s gases and heat and aid the interior crews in their efforts.
DOES SIZE REALLY MATTER?
As we all know, much has been written
about what the size of the ventilation opening should be (and you thought
I was talking about something else… shame on you). Over the years,
you have heard quoted dimensions of 8’x8’ or 12’x12’, or as an old friend
of mine used to put it, “if you can’t drive a small automobile though the
opening, it’s too small!” Although it is ideal to end up with the
above-mentioned sizes, it is impractical to initially try to cut the ventilation
opening to those sizes. It is the author’s opinion that cutting smaller,
more manageable openings (4’x4’) not only saves time over cutting the traditional
8’x8’ or 12’x’12’, but it is also much easier to pull.
Time and speed are of the utmost importance
during ventilation operations, especially when cutting the original ventilation
opening. The quicker the opening is made and pulled, the faster the
fire floor will be vented. Again, it is prudent, not to mention advantageous,
to cut and pull a 4’x4’ opening and then add to that size if needed, than
it is to cut an 8’x8’ opening. Your interior crews will thank you!
(See, sometimes smaller and quicker is better!)