Testing for gas helps meet Enviso targets

Remember when buses spewing black diesel smoke were just part of urban life?

That was then. This is now.

These days, the last thing ETS or the City’s Fleet Services Branch want to see is anything at all emitting from a bus exhaust pipe. They don’t even want certain gases that you can’t see to be emitted in unsafe concentrations.

That’s why Fleet Services is using an emissions detection technology that’s been around for a while in the form of large gas analyzer machines, but which has recently been downsized into convenient hand-held units called The Green Thing.

The unit’s working end is attached to a long pole so it can be held high and inserted in an idling bus’ tailpipe. Very quickly it produces readouts of the parts-per-million concentration of carbon monoxide, hydrocarbons and oxides of nitrogen, the gases that form awful-looking yellow smog hanging over polluted urban areas.

“We use it to analyze 10% of ETS buses every six months,” says Bart Agate, Fleet Services’ senior industrial engineer.

The program recently won the competition for Charles Labatiuk Award for Environmental Excellence.

“Our results serve two purposes; they enable us to verify that we’re meeting our Enviso emission standards, and if we do find a bus that is generating unacceptable levels of specific gases, we can locate the problem and correct it right away.”

Too many oxides of nitrogen can mean something’s wrong with the engine management computer or with the selective catalytic reduction system which breaks down oxides of nitrogen into harmless oxygen and nitrogen.

Too-high levels of carbon monoxide or hydrocarbons can be signs of a plugged air filter, or an engine that’s running with too rich a fuel-air mix.

“If that continues, the exhaust will be smoky. Over time, it can create costly mechanical problems because if  too much fuel in the cylinders remains unburned, it washes out oil and intensifies metal-to-metal wear. That causes overheating and increases future chances of expensive repairs.

“Buses with improper fuel/air mixes also lose engine power. They’re sluggish,” says Bart. “Improper mixture can also cause both high fuel consumption and contamination of the engine intake system due to exhaust gas recirculation.”

Fleet Services is an enthusiastic participant in Edmonton’s Community Energy Transition Strategy, an eight-year plan to reduce greenhouse gas emissions by 35% and reduce the energy used by every citizen by 25%, among other things.

Among the plan’s many goals are to avoid wasteful energy and carbon-intensive practices, improve energy efficiency and replace high carbon energy sources with low carbon sources.

City of Edmonton Fleet Services’ Mechanical Coordinator Ray Petlock holding a Green Thing gas emissions analyzer. Its probe is inserted into a bus’ exhaust pipe, and parts-per-million readouts for various gas levels are instant.

City of Edmonton Fleet Services’ Mechanical Coordinator Ray Petlock holding a Green Thing gas emissions analyzer. Its probe is inserted into a bus’ exhaust pipe, and parts-per-million readouts for various gas levels are instant.

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