Kyle Jefferson, VP of sales and engineering at Ventaire, echoes the need to have
exhaust fans properly sized to ensure that VE systems are not compromised by
extreme temperatures, and he goes a step beyond. “For existing systems, a
portion of all of the flexible hose may need to be upgraded to one that carries
a higher temperature rating.” Are there ways to economize?
“Yes,” says Jefferson. “The first 10 feet of flexible hose takes the brunt of
the heat since the exhaust gases cool quickly after they enter the exhaust
capture system. Hoses with different temperature ratings can be spliced together
with the section near the inlet carrying the highest temperature rating,” he
explains. “We supplied a system for a bus manufacturer that utilized 10 feet of
hose rated to 2,010 F coupled to 25 feet of hose rated to 1,200 F,” Jefferson
says to further illustrate the example.
“Another way to keep the cost of engine exhaust removal systems down is to
increase the volume of air moved by the fan,” Jefferson continues. “The fan can
be oversized to draw room temperature air into the system, which mixes with the
hot exhaust gases to keep the overall temperature to a level where
cost-effective components can be used,” he suggests.
Adding to the discussion, Monoxivent national sales manager Erik Swanson
endorses the idea of adding more ambient air into the system in order to keep it
cool, while suggesting other VE system changes, as well. “We may also add
high-temperature accessories to the exhaust fan such as heat slingers,
high-temperature paint and other suggestions,” Swanson explains.
“In an extreme case, where the vehicles may go into regeneration mode while
attached to the vehicle exhaust system, we could possibly recommend utilizing a
2,000 F flex hose,” he adds.
Toward a Safer Work Environment
Monoxivent’s Swanson looks to overall safety as part of the VE system
improvements that can enhance the working environment. “We can put
heat-resistant handles on our tailpipe adaptors to help prevent the mechanics
from getting burned,” he suggests. “Mechanics have to keep in mind that today’s
engines are running hotter, which creates more heat in the vehicle exhaust
system. They must exercise care when removing the VE system from the vehicle,
because it may be hot, especially right after the vehicle is shut down,” Swanson
adds. He even suggests that vehicles be pulled outdoors to conduct certain
engine tests that will definitely create high exhaust gas temperatures, and that
the vehicle be disconnected from the VE system to do so.
Combining Old Engines with New Engine Maintenance Ops
“For the time being, service managers could designate one or two work bays of
their facility for the service of new vehicles,” Swanson suggests. “These bays
could be outfitted or retrofitted with higher temperature, higher air volume
exhaust extraction equipment and leave the rest of the facility as is,” he
reasons. “As more of the higher temp engines are introduced into the fleet, more
bays can be retrofitted with high-temperature exhaust hoses and equipment,”
VE System Design Refinements Sense Load Capacity
Shawn Smith, vice president of Operations at Plymovent, Cranbury, N.J., urges a
thorough understanding of usage capacity for the VE system, including
considering the percentage of drops that will be in use at a given time.
“Service managers need to get a clear snapshot of all types of vehicles that
move through the service area,” he recommends. “Planning should include a
temperature monitor at each of the extraction points to ensure that no vehicle
in maintenance reaches or exceeds an approved temperature level,” Smith says.
Outsourcing Regeneration Servicing
Car-Mon’s president, Fred Imming, points to an industry trend that is
influencing maintenance of higher temperature bus engines: outsourcing
maintenance services to engine manufacturers. The Chicago Transit Authority
(CTA) designates two bays in at least one of its bus barns for regeneration and
subcontracts the maintenance work out to engine companies, he says. “Normally,
they have two people from Cummins designated to come out and evaluate the
catalytic convertor maintenance,” Imming says. “You have to plug regeneration by
laptop link to a computer program,” for scheduled maintenance, he explains.
Otherwise, catalytic converter regeneration can occur on the road, he adds.
All the more reason to have VE systems checked for extremely high-temperature
performance ability in those bus bays where regeneration maintenance is
scheduled, Imming suggests. In a world where technical improvements in engines
are taking place, engine service managers need to review the basics and ante up
for vehicle exhaust systems that will match the oncoming requirements while
providing improved safety and security in their operations.
Management of exhaust is one of the key components to any service function. New
VE systems solve a practical problem and they are affordable and available