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Both machines and
operators need the proper attention to function well in the hot,
dusty conditions of summer.
By Paul Hull
For many North American
contractors, work slows or even stops during the winter months,
so it is not surprising that they look forward to the warmth and
sunshine of summer. Machines seem to react in the same way. They
don't enjoy starting on cold mornings (although most manufacturers
have solved the worst start-up problems), but they purr along cheerfully
when they can feel the sun's warmth on their hoods. There are,
however, dangers for these machines and their operators: Both do
not function well when overheated.
The Dangers of Heatstroke
Heat can cause discomfort
and exhaustion, but heatstroke is even worse. It happens when the
body cannot produce enough sweat to stay cool. It dehydrates and
stops sweating. If not treated, a person with heatstroke can die
within one hour. As a test, a group of East Coast researchers parked
a car in the sun on a hot afternoon. By using the air conditioner,
the researchers brought the interior temperature of the car to a
comfortable 75ºF. Within 15 minutes of turning off the
air conditioner, the temperature inside the car rose to 115ºF;
the glass and steel of the car turned it into an oven. High humidity
can make the situation worse.
According to Claire Spiro,
a physician's assistant in Birmingham, AL, "Heatstroke
is a potentially fatal disorder that generally occurs in people
who are not acclimated to hot weather, older people, alcoholics,
and people who take certain medications called anticholinergics.
Those medications include antihistamines [which dry you out even
more], certain asthma medications, or diuretics [water pills]. The
key difference is that people who have heatstroke don't sweat
or they have an impaired ability to sweat because of medications
or other neurological problems. Thus, their body temperature gets
very high, which can lead to brain damage, heart failure, and death.
People with heatstroke typically are very hot, have dry skin, and
generally are confused."
An Ounce of Prevention
Spiro suggests that the
best prevention for heatstroke includes:
- frequently replenishing
the body with water containing sodium and electrolytes, such as
Gatorade or other sports drinks,
- taking breaks to avoid
becoming overly hot,
- designating a "cool
area" at the work site,
- trying to acclimate
to an area before beginning to work,
- considering not
taking your allergy pill (or other anticholinergic medication)
after checking with your physician,
- knowing the warning
signs of heat exhaustion and heatstroke: muscle cramps, extreme
heat, confusion, dizziness, and so on.
If these symptoms occur,
get out of the heat. Spiro adds that work sites should have a plan
for dealing with heat exhaustion and heatstroke. "Be prepared
to cool a worker down with ice and cold water. Be able to call for
emergency help and arrange for transport if needed." Good airflow
for the operators of your grading and excavation equipment is essential,
but you should also encourage your operators to drink plenty of
water. Keeping a bottle or jug of water in the cab makes sense,
but having a supply of water that is kept cool and in a centrally
located place might be a better plan.
Air-conditioned cabs
are fairly standard these days, but not everyone has that luxury.
Many grader and scraper operators working on those summer projects,
for example, still rely on the most basic ventilation. Some of us
remember the 4-70 automobile air conditioning of yesteryear: four
windows down while traveling 70 mph. Some operators must rely on
similar methods. So if you notice workers sweating profusely, make
sure they are drinking enough water to replace what their bodies
have lost. The body can only produce sweat if it has the water to
do so.
What you wear also affects
your efficiency in the sun. Being fashionable has never been a serious
consideration for outdoor construction workers. Loose-fitting, light-colored
clothing is best because dark colors absorb the heat and light of
the sun, and tight clothing restricts the body's ability to
breathe naturally and cool itself. Here's a point you might
have never thought of: A hat can shield you from the sun, but if
you start feeling too warm, it is better to remove any head covering
unless it is required for safety's sake.
Kristin Hawbaker of Imprint
Technologies based in Roseville, MN, where it can be very cold but
also very hot and humid, had some interesting observations on the
subject: "There are several ways to remain cool and still keep
your hat on. American Allsafe [in Tonawanda, New York] makes some
products called ‘Icy Ones.' You soak them in cool water
and wrap one around your neck or one inside your hat. They help
keep your body temperature down. Another way is a vented hat. MSA
[in Pittsburgh, Pennsylvania] manufactures them for Australia, but
they may not meet American Safety Standards yet. Such products would
be worth investigation by contractors."
Inside the Machine
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| In some states,
hot weather can cause flashfloods. |
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| Manufacturers
often incorporate features into their excavators to allay the
attacks of heat and dust. |
Previous issues of Grading
& Excavation Contractor have discussed the good ergonomic
designs of today's equipment. Those designs involve the positions
of controls, the seat configuration, and all of the engineering
that makes operation of the machine simple, comfortable, and more
productive. Hands, wrists, arms, legs, feet, and backs seem to be
the body parts that benefit most from good ergonomic design. But
when the weather is hot, atmospheric control becomes even more important–for
the whole person.
You might assume that
air conditioning in, say, a new loader or excavator will work as
it should. Your best sources for practical information about the
merits of different manufacturers' systems might be your fellow
contractors. Ask them about the pros and cons of their system. Are
they having any problems with it? Is the cab air conditioner well
protected enough? Bobcat places its air-conditioning system for
the 863, 864, 873, and 963 loaders inside the engine compartment
and behind the seat pan.
Not all skid-steer loaders
have cabs, however, and air conditioning is still quite a new feature–but
that is changing. If you need to rent a skid-steer, you should be
able to find one with all the comforts your operators need. You
don't have to settle for a noisier model without cab and atmospheric
control.
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| Summer work can
be enjoyable - if machines and workers are prepared.
|
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| Heat and dust
can affect people and machines at small sites. |
Edgar Gonzalez at Rebel
Rents, which works with contractors in most of southern California
where heat and dust are commonplace, confirms that the company offers
good atmospheric control options on its loaders and excavators that
you would expect in such a territory. At John Deere Commercial Worksite
Products in Moline, IL, Product Manager Larry Foster says noise
reduction and better visibility are already popular. He sees enclosed
cabs becoming more and more popular too. "I see manufacturers
offering a total climate-control system. This will involve heaters
and air conditioners for the temperature, but also better air filtration
to keep dust levels down in the cab."
In terms of air conditioning,
the 621D wheel loader from Case Corporation offers a midmount, cube-shaped
module for its cooling system. The manufacturer claims that this
system produces the cleanest air and offers improved efficiency
for cooling the engine and components. It has no stacked coolers,
a design that prevents debris from plugging between the coolers.
The hydraulically driven fan runs independently of the engine, and
an optional, reversible fan is available for extremely dusty
applications. The operator can reverse the fan and airflow by simply
engaging a switch in the cab, purging in just a few seconds any
material stuck in the coolers. With that capability, the wheel loader
does not have to leave the job site for cooler cleaning.
"Contractors who
anticipate hot and humid weather for their work should ascertain
what is available in optional hydraulic oil coolers and hydraulically
driven fans," advises David Wolf, product manager at Case.
"The benefits from our cube module with the reversible fan
are quite dramatic. In hot, humid Georgia, at a cottonseed delineation
plant–you can imagine what dust there is like–the normal
routine was to run a loader for two hours and then have it purged.
This meant taking the machine off-site too. With the 621D, they
run the machine for 14 hours before they need to purge it. They
reverse the fan, and it takes 30 seconds or less."
Excavators offer more
fresh air than they used to, with sliding windows, roof hatches,
and skylights. Many offer air conditioning as well. Introduced in
2001, the CX excavators from Case have what the manufacturer calls
"a climate-control system like those found in luxury automobiles."
The system maintains a comfortable temperature for the operator
regardless of the outside temperature. According to Caterpillar,
one of the features of its 311C Utility Hydraulic Excavator, introduced
in 2001, is a fully automatic climate control that adjusts temperature
and airflow and determines which outlet is best in each situation.
There is also a large polycarbonate skylight that allows natural
light to enter the cab and opens for ventilation.
"Kobelco has several
features built into its excavators to protect the operator from
the heat and dust," points out Brian Conrad at Kobelco. "We
offer a climate-controlled cab that keeps dust out and maintains
a comfortable working environment for the operator." Several
Kobelco cabs have five vents: placed at foot level, at chest level,
and to the rear, with one vent located at the front right portion
of the cab that can be directed to cool the operator's face
and another vent at the window, which works similar to a defroster.
Kobelco also uses a tinted skylight with a sliding cover that can
be closed to keep out the heat on extremely hot days. Also helpful
for operators in hot climates is the substitution of hydraulic oil
for normal formula.
Outside the Machine
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| Operators in
machines without air conditioning should be especially alert
to the dangers of overheating. |
Water trucks, a common
sight at road construction projects, keep down the dust stirred
up by scrapers, graders, and heavy vehicles. Dust that is controlled
and lies quietly on the ground does less harm and causes fewer accidents
from poor visibility than those clouds that swirl around people
and machines, getting inside clothing and engine components.
There are many types
of pumps available for pulling water to fill the tanks. Keep in
mind that some of the water used for dust and dirt control is taken
from ponds, lakes, or even big puddles and is not clean, so select
your pumps accordingly; they should be able to pass small solids.
If the water is sprayed through nozzles from the truck, the water
should be solids-free. In an increasing number of communities, all
the water used in water trucks is potable, taken from public hydrants.
In addition to the water being easier to spray, the advantages are
readily available water and a quicker fill from hydrant to truck.
For determining payment to the municipality or county, the trucks
have their own water meters.
Last year was especially
dry for much of the country, so water trucks were in action more
often than usual. Many people might imagine that water trucks are
seasonal in most states, but Kathy Bradley of Bradley Metals Company
in Canon City, CO, points out that subdivision projects in Canon
City have continued into the snow-free days of late November. "They
use water to settle the dust there all the time, at all times of
the year. Much of that is due to environmental regulations, of course,
and is intended to protect the general public as well as the construction
workers at the site. But having the ground you're working unimpeded
by dust or flying dirt is a definite advantage for a contractor.
Most of our trucks are purchased by contractors because they
now use them regularly, but we have heard of some who will rent
a water truck if the job is unusual for them and has only a short
time span." You can rent protection from dust and heat as well.
The water trucks from Bradley Metals have capacities of 2,000-4,000
gal., with controls for the power take-off and spray heads inside
the cabs.
One part of a rental
contract for water trucks dictates who drives them. In some
contracts, the driver is an employee of the truck owner, and his
or her pay is either included in the rental fee or billed separately
(to include wages and fringe benefits) to the contractor. At other
locations, the contractor provides his own driver, but be prepared
to provide evidence that your driver is perfectly qualified for
the job.
"Most of our rentals
of water trucks tend to be long term," explains Gonzalez at
Rebel Rents. "They are used on road construction projects,
but not only for that. They are also at housing developments–anywhere
the contractors need to keep down the dust and dirt." Some
manufacturers also recommend spraying water on the outside of machines
to cool them down.
But is water enough?
Those who live in dry climates, such as Arizona, Nevada, and Montana,
know that water sprayed onto the surface on a hot summer's
day can evaporate in minutes. Sometimes it seems like seconds! "Controlling
dust at construction sites via water only is a Band-Aid, not a cure,"
comments Lou Snow, vice president and owner of Dust Pro Inc. in
Phoenix, AZ. "Historically, water usage at construction sites
is for either a surface dust control or stabilizing soils to temporarily
increase soil strengths. Depending on soil type, questions of water
usage and ambient temperature times determine the longevity and
performance of soil/water combinations. Millions of gallons of potential
drinking water are used to no avail." Snow points out that
by adding concentrated, environmentally friendly soil binders, water
usage is reduced and soil strength can be increased and stabilized.
The overall cost of using soil stabilization products is almost
always less than using water alone, he adds.
A major political issue
is present here too. Many government facilities pay or in some way
compensate those contractors who use drinking water for temporary
soil stabilization and that, states Snow, offers no incentive for
contractors to consider alternatives that really provide a better
solution.
Filtering the Attackers
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| The heart of
every machine - its engine - deserves special care. |
Experienced contractors
know that keeping hydraulic lines clean is dramatically less expensive
than emptying and refilling them. Maintaining other components of
your machines is, of course, similarly worthwhile. One area of disagreement,
however, is in the selection and use of oil filters for engines.
Engine manufacturers have warned that advanced filtration is not
a substitute for proper, timely maintenance. With new systems designed
to give better protection against contaminants–and there could
be even more of those after the new regulations for engines take
effect in October of this year–it might be tempting to assume
that cleaner oil will always last longer and, in turn, service intervals
can be extended.
Contamination, however,
is not the only reason for changing oil. The additives in oil are
depleted with use and can be replaced only by new oil, say some
engineers, including Jim Pirie with International Engine Engineering.
Merely putting in new additives does not work as well, according
to some scientists, such as Ross Iwamoto, product development scientist
at 76 Lubricants, because we cannot hope to match the original,
carefully researched formula. The oil-change intervals recommended
by engine makers vary considerably and must include consideration
of such aspects as idle time, operating conditions, and the quality
of the fuel, filters, and oil used. These consideration are particularly
important in hot, dusty conditions. So again, simple maintenance
is much less expensive than engine repairs or replacement.
Fleetguard (a division
of Cummins, manufacturer of diesel engines for construction machinery)
now offers centrifuge-filtering technology in a system called Centriguard.
"This year's engines make the technology more timely,"
comments John Clevenger, a product group manager at Fleetguard.
The technology is not new–the Spinner II product division of
T.F. Hudgins has been making successful, reusable centrifugal bypass
filters for some time–but Fleetguard waited to introduce its
version because there were less expensive solutions for users until
recently. "We think that multistage filters will be necessary,
and Centriguard offers that with bypass, full-flow, and centrifugal
areas in the same can," maintains Clevenger. He adds that meeting
the minimum flow-rate standards of engine manufacturers is important,
and some aftermarket bypass filters might not do that even though
the filters clean the oil very well.
Perhaps the most obvious
part of your machine that needs special attention in hot weather
and for hot operations is the cooling system. Checking your heavy-duty
diesel coolant at least once a year is a good practice in any climate.
More frequent attention is recommended in hot, dusty conditions.
"Even the highest-quality precharged and extended-service coolant
can be degraded if engine head gaskets leak and allow combustion
gases to contaminate the coolant," notes Clevenger. Fleetguard
also offers Quik-Chek, an easy-to-use product that helps contractors
know when to replace coolant. The system comprises test strips that
monitor coolant pH, chloride, and sulfate levels. You take a coolant
sample, dip the Quik-Chek test strip in it, and within 45-75 seconds,
you can read the levels. If any of the readings fail, you should
consider the coolant "no go," drain the system, and refill
it with new, precharged coolant. As with all the techniques mentioned
for beating the threats of heat and dust, it's simple. And
it works.
All these precautions
and preparations are affirmed by John Frame, product manager for
New Holland Construction excavators. "For machines that will
work constantly in dust and heat, a centrifugal-type air precleaner
should be considered," observes Frame. "Some manufacturers
offer clog-resistant radiator/cooler options for work in applications
subject to high levels of dust and debris." He adds that the
greenhouse effect of having more glass in cabs for improved visibility
can increase the inside temperature.
New Holland also points
out an easily forgotten point: The air inside tires expands as the
temperature increases. Contractors should discuss this issue with
their tire dealers before the advent of summer heat and dust. "Due
to the higher ambient temperatures and dry conditions experienced
in many parts of North America, users should make sure that the
equipment's coolant, lubricants, and hydraulic fluids are rated
for the likely temperature range," advises Frame.
It all seems to come
down to that famous Boy Scout motto of "Be prepared."
Venturing into the heat and dust of summer will pose few problems
for those who have planned ahead and made sure that both their equipment
and workers are ready.
Frequent contributor
Paul Hull writes on construction and environmental topics for several
international magazines.
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