OK Folks, really dull stuff here. EPA and others regulate emissions of CO and NOx in terms of grams per kilometer. That's an odd unit. I want to compare in terms of PPM out the tailpipe. I have a conversion, but those in the know say my numbers don't come out right. Care to help? Tell me what I did wrong. Here it is:
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I probably couldn't help with the conversion even if I could see that. I can't see it though, which probably means anyone who can help can't see it.
It's true; I can't see a thing. Er, at least partly true. It's totally true that I can't see anything, but that's not necessarily a proof that anyone who can help can't see it... But I'd love to have a go.
All I see is this:〖
And I know I can't help.
Parts per million is a completely different scale than grams per mile- PPM is unconcerned with overall volume. It is merely a measurement of the percentage of a specific gas. Grams per mile measures the quantity of a specific gas.
Therefore: A 2008 Ford Expedition with a 10 cylinder gas engine will produce a lower ppm reading of CO than a 1979 1.6 Escort, due to the much improved fuel management and emission controls.
A 1979 1.6 Ford Escort has a much lower grams per mile reading than the Expedition because of the smaller quantity of fuel and air consumed.
If a government agency starts to measure grams per mile, its because their current cultural manifesto states that people need to drive smaller cars.
Streetwiseguy wrote:Parts per million is a completely different scale than grams per mile- PPM is unconcerned with overall volume. It is merely a measurement of the percentage of a specific gas. Grams per mile measures the quantity of a specific gas.
Therefore: A 2008 Ford Expedition with a 10 cylinder gas engine will produce a lower ppm reading of CO than a 1979 1.6 Escort, due to the much improved fuel management and emission controls.
A 1979 1.6 Ford Escort has a much lower grams per mile reading than the Expedition because of the smaller quantity of fuel and air consumed.
If a government agency starts to measure grams per mile, its because their current cultural manifesto states that people need to drive smaller cars.
I know this. I am trying to convert between the two using an example of a 40 mpg diesel modern car. I'll work on getting the equation somewhere that can be read.
All of the emissions laws are in g/mile... or g/km
The standard is based on a speed and load, all specified in the NVFEL protocols for new engines, or the IM-240 protocol for post-production vehicles. It does not directly cross over to a simple PPM. You have to account for engine load vs speed.
I'm the one who didn't think it was correct. The way cars are tested is with a diluter taking a sample which is then sampled at the end of a phase and then turned into a mass value based on the dilution and an exhaust measurement.
At the end of the test, each phase mass is corrected for distance and then weighted for a final result.
I think the reason for the bag measurement is because the emissions change a lot with the condition, from a cold start to a 70mph cruise, so a constant ppm does not work to cover it all.
I'll have to check with some of the diesel guys to see if they have a feel for a translation between the two.
And it's been g/mi for 40 years now.
