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% vol co2
http://lpgforum.co.uk/viewtopic.php?f=33&t=14152
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Author:  LPGmalta [ Tue Aug 23, 2016 4:02 am ]
Post subject:  % vol co2

Hi guys, this happened to me twice. After doing an Lpg conversion, the %vol co2 remained the same. Car is running fine and fuel trims are spot on. How can I drop this please by at least 10%?

Author:  LairdScooby [ Tue Aug 23, 2016 8:57 am ]
Post subject:  Re: % vol co2

As a general rule of thumb, carbon dioxide (CO2) peaks when combustion is at its most efficient. Reducing it would mean that the combustion is much less efficient.

Just to be sure, you're not confusing CO (Carbon Monoxide) with CO2 (Carbon dioxide) are you? Carbon Monoxide is lethal in relatively low concentrations whereas carbon dioxide is present in many everyday things including fizzy drinks (it's what makes the bubbles!) so to put that into perspective, CO2 isn't as much of a worry as CO.
If the cars you've converted have kept a similar CO reading (instead of CO2) then it could well be that's how they run - yes, LPG will often reduce the CO reading but sometimes it will stay the same or even go up slightly for the engine to run right.

Author:  Brian_H [ Tue Aug 23, 2016 6:11 pm ]
Post subject:  Re: % vol co2

LairdScooby wrote:
As a general rule of thumb, carbon dioxide (CO2) peaks when combustion is at its most efficient. Reducing it would mean that the combustion is much less efficient.

Just to be sure, you're not confusing CO (Carbon Monoxide) with CO2 (Carbon dioxide) are you? Carbon Monoxide is lethal in relatively low concentrations whereas carbon dioxide is present in many everyday things including fizzy drinks (it's what makes the bubbles!) so to put that into perspective, CO2 isn't as much of a worry as CO.
If the cars you've converted have kept a similar CO reading (instead of CO2) then it could well be that's how they run - yes, LPG will often reduce the CO reading but sometimes it will stay the same or even go up slightly for the engine to run right.


Depends what your burning - LPG should be lower CO2 producing than petrol actually. See below for more info, but thats part of the reason for the fuel duty level being set lower as its slightly better for the enviroment (the other emissions that aren't present are more of a benefit PM and HC etc as well).
http://www.dft.gov.uk/vca/fcb/cars-and-fuel-options.asp
https://www.eia.gov/tools/faqs/faq.cfm?id=73&t=11

I would wonder what state the air filter was in for a starting point, and if any EGR system etc is working as intended? Hard to advise much beyond that without giving an idea of what system is in use though, or what car (Those who may respond with more insight into it will probabbly have different advice for a single point system vs a sequential one, and without knowing whats being converted its hard to guess what you might be dealing with)

Author:  LairdScooby [ Wed Aug 24, 2016 1:06 am ]
Post subject:  Re: % vol co2

Hmm, interesting - i did wonder about that and also the EGR, air filter and if it was burning any oil. Regardless of the type of conversion i would think if it was burning oil the CO2 would be fairly high as would the HC figure.

As you say though, without knowing the car in question, type of conversion and so on it's nigh on impossible to even hazard a guess.

Author:  LPGmalta [ Wed Aug 24, 2016 7:27 pm ]
Post subject:  Re: % vol co2

Hi guys, government in Malta is expecting a reduction in %vol of co2 after conversion to Lpg. Have no idea what should actually happen. Co is usually very low, even on petrol, I just need to know from your experience the co2 %vol differences when running on petrol compared to when running on Lpg.

Author:  LPGmalta [ Wed Aug 24, 2016 7:38 pm ]
Post subject:  Re: % vol co2

apem-journal.org › APEM6-2_087-094

Author:  Brian_H [ Wed Aug 24, 2016 8:37 pm ]
Post subject:  Re: % vol co2

Never personally monitored it - Its not looked at with a UK MOT to check the co2 % level, Lambda is checked on petrol but not on Gaseous fuels. Hopefully one of the people who has access to a gas analyser will give you an answer.

Author:  Gilbertd [ Thu Aug 25, 2016 6:26 am ]
Post subject:  Re: % vol co2

Most gas analysers here don't check CO2, only CO, HC and Lambda as that is all that is tested in the MoT. I've been taking a few imported cars in for the Individual Vehicle Approval (IVA) test recently and they only check the same as the MoT so no CO2 checking there either. Biggest advantage is that a newish car registered with the Certificate of Conformity will have a CO2 figure so the road tax is based on that but an import registered through the IVA scheme is taxed on the old flat rate used for pre-2001 cars. So the road tax on a 2014 Bentley Continental GT with a 6.0 litre, W12 engine is only £235 a year compared to £515 a year if it is taxed on the CO2 figure.

Author:  rich r [ Thu Aug 25, 2016 7:09 am ]
Post subject:  Re: % vol co2

Measuring the CO2 in vehicle exhaust is more complicated than measuring more reactive gases such as CO, NOx and O2. Also as it's present in a non-negligible percentage in the intake air you really need to measure that too to work out what the increase in CO2 at the exhaust is. Hence it's generally done thoroughly for new models only (at least in the UK and most of Europe from what I can see) during the expensive one off testing phase at specialist laboratories. The above linked document (direct link http://apem-journal.org/Archives/2011/A ... 87-094.pdf ) details their lab setup, which includes an exhaust gas heater and collection system then a series of gas analysers a bit more bulky and complex than the usual exhaust pipe probe.

Cheaper CO2 exhaust gas analysers do exist but do they meet the standards the Malta government want it tested against? I can't find a link to the Maltese test requirements.

But yes, the document does show a big reduction in CO2 for LPG compared to petrol on the same engine.

Author:  LPGC [ Thu Aug 25, 2016 4:37 pm ]
Post subject:  Re: % vol co2

Bit unusual to need to know CO2 output figures. Since CO2 + water (steam) are the resultant gasses produced during complete combustion, the ideal situation regards other arguably (not really even an argument) more harmful emissions is to have CO2 and water vapour exhaust gasses total 100% of emissions, because that will mean there's 0% CO emission, 0% HC emission, 0% NOx emission, etc..

I'm not a chemist but I'd bet that given the above situation, since both petrol and LPG are HC fuels, since H forms with O to produce water and C bonds with O to produce CO/2, since the engine must need similar amounts of H and/or C to produce similar amounts of heat (that will see the engine produce similar amounts of power - the conditions needed for a fair test) - that where CO2 emission is lower running on LPG, water vapour emission must increase... but water vapour emission isn't depicted in any emissions stats. That might be the next thing - vehicle drivers causing increasing sea levels.

But you're not talking % of emissions, you're talking volume of emissions - Volume of all emissions is likely to increase with engine size, engine load and with decreasing engine efficiency (many aspects to engine efficiency). If CO, HC, NOx etc are good then there's probably not much you can do to lower CO2 (or at least combined CO2 and H2O). If CO or HC increase when running on LPG that would point to a problem with the LPG setup, or the ignition system, or some other aspect of the engine (perhaps compression), any of which could cause the engine to need to use greater quantities of air/fuel to create the same power, including when the engine is just idling.

If nothing is found to be wrong with other emissions, a simple way of decreasing CO2 emissions would be to fit a smaller or more efficient engine but that won't suit your purpose. Another way is to make sure your engine is running under as little load as possible, test done with engine fully warmed up, use thinner oil, turn off all electrical loads and aircon etc. If the test is comparative between petrol and LPG with back to back tests on your car, could cheat by increasing CO2 emissions when running on petrol by turning on aircon and electrical items such as the heater fan and heated rear window.. turning everything off while testing on LPG! :lol:

Simon

Author:  rich r [ Fri Aug 26, 2016 7:00 am ]
Post subject:  Re: % vol co2

I've found this document from the Malta Transport Authority: http://www.transport.gov.mt/admin/uploa ... 131521.pdf

Nowhere does it ask for proof of reduction of CO2 after an LPG conversion, but in fact it looks to be the other way round - if you can prove your car has been converted to LPG then they will automatically reduce it's CO2 output for the purposes of tax etc by 10%.

Author:  LPGC [ Fri Aug 26, 2016 8:57 am ]
Post subject:  Re: % vol co2

That's good Rich. Seems more intuitive and is a better position for LPG installers / owners to be in.

Simon

Author:  rich r [ Fri Aug 26, 2016 9:00 am ]
Post subject:  Re: % vol co2

Which reminds me - it's been some time since mine was converted. I wonder if I ought to get round to telling the DVLA?

Author:  Gilbertd [ Fri Aug 26, 2016 9:37 am ]
Post subject:  Re: % vol co2

You'll get 10% knocked off your road tax on both post 2001 cars. Fill in the change of fuel bit on your V5 and send that in along with the invoice from whoever converted it (or, the invoice for the bits if you did it yourself).

Author:  hitman [ Fri Aug 26, 2016 9:51 am ]
Post subject:  Re: % vol co2

Its not 10% Gilbert

its a tenner - hardly worth bothering telling dvla about the conversion

Author:  LPGC [ Fri Aug 26, 2016 10:29 am ]
Post subject:  Re: % vol co2

Following dieselgate I contacted Mike Chapman of UKLPG to ask if they were leaning on government to increase incentives for LPG conversions - converted vehicles being the cleanest burning low emission vehicles... I would want to become a member if they could pull off government introducing decent road fund licence concessions! No surprise, perhaps a missed opportunity, nothing happened, still not a member. Government taxing cars according to emissions a load of rubbish when it comes to the most damaging emissions, especially for the local environment - Kyoto agreement (for instance) does nothing for local health, it's all about CO2, diesels kick out all sorts of nasty emissions but can be a bit lower on CO2.. Not the best policies if we want to avoid local health problems due to emissions.

Edit - forgot to mention, I converted Rich's car and yes he could send off the paperwork I supplied, maybe get a tenner's road fund discount. But the concession ought to be a lot more!

Simon

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