ACtion Magazine - July/August 2017 - 26

Stephen Petit

Positive pressure for operator cabins

Enginaire

Figure 1: New OSHA standards that take effect in September
emphasize the need for clean air in heavy-equipment cabs,
especially at sites with respirable silica.

Stephen Petit

Figure 3: This diagram shows how a combination of centrifugal force and ﬁltration can pre-clean the air before it reaches
the A/C system and cab interior.

Figure 2: A supplemental pre-cleaner and pressurizer like
the one mounted on the rear of this orchard tractor can
provide HEPA-level ﬁltration for air coming into the cab and
use positive pressure as a barrier to keep dust out. The result
is a healthier environment for the operator and better A/C
performance.

Powering up
Most heavy-equipment cabs have one or more fresh air
intake filters, and the modes should be familiar to anyone
who does A/C work: pleated paper or cellulose to collect
dirt, dust, and hair; charcoal-impregnated foam to neutralize odors and gases; and HEPA (High-Efficiency Particulate Air) filters to capture extremely small particles.
By itself, the intake filter won't be sufficient to meet
the new OSHA standard or, for that matter, to handle the
high volume of dirty air that gets kicked up at construction
sites, farms, mines, mills, quarries, and logging areas.

26

ACTION * July/August 2017

A powered air pre-cleaner actively removes more than
90% of contaminants before they reach the intake filter.
The most effective designs mount on the outside of the
cab, draw in dirty air, and use a centrifuge to spin the
heaviest particles back out into the environment. This
"pre-cleaned" air is pumped through a paper or charcoal
filter for a general level of protection or a high-efficiency
filter that can trap 99.97% of particles down to 0.3 microns-HEPA-level filtration.
"In the case of silica, a particle can be 100 times smaller than a grain of beach sand," says Mark Losching of
Enginaire Clean Air Systems, which supplies powered filtration systems for heavy-duty vehicles. "You can be sitting in a cloud of silica dust and not know it because it's
too small to see. A high-efficiency filter will trap minute
contaminants that can do the most harm to the operator."
The unit blows the filtered air into the cab through the
air conditioner's air intake duct, creating a positive pressure that forces dirt out through exhaust vents on the cab
or leaky areas like door and window seals.
If you work on heavy equipment, or you're an HVAC
distributor or specialty OE, the OSHA rule can be a conversation starter about the advantages of powered filtra-

Table of Contents for the Digital Edition of ACtion Magazine - July/August 2017

Outlook
Service Port
Leonard's Law
Virtual View
Cooling Corner
HD and OTR vehicle Service: Keep it Clean
Positive Pressure dor operator cabins
Industry News
Association News
New Products and Services
Last Watch
ACtion Magazine - July/August 2017 - Cover1
ACtion Magazine - July/August 2017 - Cover2
ACtion Magazine - July/August 2017 - 3
ACtion Magazine - July/August 2017 - 4
ACtion Magazine - July/August 2017 - 5
ACtion Magazine - July/August 2017 - Outlook
ACtion Magazine - July/August 2017 - 7
ACtion Magazine - July/August 2017 - Service Port
ACtion Magazine - July/August 2017 - 9
ACtion Magazine - July/August 2017 - Leonard's Law
ACtion Magazine - July/August 2017 - 11
ACtion Magazine - July/August 2017 - Virtual View
ACtion Magazine - July/August 2017 - 13
ACtion Magazine - July/August 2017 - Cooling Corner
ACtion Magazine - July/August 2017 - 15
ACtion Magazine - July/August 2017 - HD and OTR vehicle Service: Keep it Clean
ACtion Magazine - July/August 2017 - 17
ACtion Magazine - July/August 2017 - 18
ACtion Magazine - July/August 2017 - 19
ACtion Magazine - July/August 2017 - 20
ACtion Magazine - July/August 2017 - 21
ACtion Magazine - July/August 2017 - 22
ACtion Magazine - July/August 2017 - 23
ACtion Magazine - July/August 2017 - Positive Pressure dor operator cabins
ACtion Magazine - July/August 2017 - 25
ACtion Magazine - July/August 2017 - 26
ACtion Magazine - July/August 2017 - 27
ACtion Magazine - July/August 2017 - Industry News
ACtion Magazine - July/August 2017 - 29
ACtion Magazine - July/August 2017 - 30
ACtion Magazine - July/August 2017 - 31
ACtion Magazine - July/August 2017 - 32
ACtion Magazine - July/August 2017 - Association News
ACtion Magazine - July/August 2017 - 34
ACtion Magazine - July/August 2017 - New Products and Services
ACtion Magazine - July/August 2017 - 36
ACtion Magazine - July/August 2017 - 37
ACtion Magazine - July/August 2017 - Last Watch
ACtion Magazine - July/August 2017 - Cover3
ACtion Magazine - July/August 2017 - Cover4
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