Internal Combustion (Gasoline and Diesel) Engines☆
R.N. Brady , in Reference Module in Earth Systems and Environmental Sciences, 2013
Propane (C3H8)
LPG (liquefied petroleum gas) is commonly referred to in many overseas countries as 'autogas' and is a propane and butane mixture. It is a tri-carbon alkane that is in gaseous form at atmospheric pressure, but becomes a liquid at normal temperatures and low pressure. Produced from natural gas processing and crude oil refining, LPG is non-toxic, colorless and virtually odorless. Propane contains more energy than does NG and has been used for years in light-duty vehicles while producing fewer emissions than gasoline. In North America propane conversion truck packages for Ford, GM and Dodge Ram as well as some smaller buses are readily available. LNG should not be confused with LPG.
LPG is converted from its liquid form in the tank to gaseous form prior to injection. The evaporation cooling effect caused by the expanding propane-butane mix tends to reduce the charge-air temperature. This permits use of a higher compression ratio and also improves the energy density within the combustion chamber. LPG also offers reduced CO2 emissions with lower fuel cost.
National Fire Protection Association Standards in Fire Litigation
James A. Petersen , in Engineering Standards for Forensic Application, 2019
NFPA 58 and the History of Odorization
Definition: Odorization (Odorize)20: To make odorous. [Our note: Propane, which is colorless, odorless, and tasteless, will have a distinctive odor when certain chemicals are mixed with it.]
Any matter involving liquefied petroleum (LP) gas should include an early review of NFPA 58, LP-Gas Code.21 This standard covers the handling (e.g., transfer, storage, and transportation) of LP gas and the installation of LP gas systems. It does not cover the portion of the system after the final pressure regulator (e.g., inside residences).22 NFPA 58 has been adopted by virtually every state, sometimes with minor additions or deletions. A state may not have adopted the latest edition, however.23 In addition, unless stated otherwise, there is no requirement to update a system to the latest edition of NFPA 58 after it is installed. For example, if a system was installed in 1970, it would be covered by the edition adopted at that time. A significant modification to the system would require an update to the current requirements, however. The history of NFPA 58 regarding the addition of odorants, chemicals, the odor from which warn consumers of gas leaks, is quite complex. We produce a condensed version of the history here to give the reader a background in how ethyl mercaptan, aka "skunk oil," became the common odorant in the propane industry.
Burn Management in Disasters and Humanitarian Crises
Herbert L. Haller , ... Leopoldo C. Cancio , in Total Burn Care (Fifth Edition), 2018
Lyce Diyarbakir, Turkey—July 21, 201427
A driver of a liquid petroleum gas tanker lost control over the vehicle and caused an over roll followed by a boiling liquid expanding vapor explosion after 15 minutes. Sixty-nine patients were admitted mainly to Dicle University Faculty of Medicine and Diyarbakir Training and Research Hospital, including 62 male and 7 female patients. The average TBSA was 51 ± 32%, including 4 patients with minor burns (<2%), 9 with moderate burns (2–10%), and 56 with severe burns (>10%). In 75%, fasciotomies had to be performed. Twenty-seven (48%) required endotracheal intubation, and 13 (23%) needed tracheostomy. A total of 76% of the patients with severe burns had to be transferred to a burn ICU. Forty-seven (68%) of the patients were distributed to 14 different locations. The overall mortality rate was 49%. The length of hospital stay was 19.4 ± 19.8 days for the survivors and 6.4 ± 4.2 days for those who died.
Anas A. Khan , Michael I. Greenberg , in Ciottone's Disaster Medicine (Second Edition), 2016
Pitfalls
It is common to confuse LNG with liquefied petroleum gas (LPG) or compressed natural gas (CNG). LPG is a mixture of propane and butane in a liquid state at room temperature and moderate pressure. LPG is highly flammable and requires storage far from sources of ignition and in a well-ventilated area, so that any leak can disperse safely away from populated areas. An additive, mercaptan, is mixed in to give LPG a distinctive and unpleasant smell, making leaks readily detectable. The concentration of the added mercaptan is such that an LPG leak can be detected when the concentration is below the lower limit of flammability.5
LNG also differs from the material known as CNG. CNG is a form of pressurized natural gas and is usually the same composition as pipeline-quality natural gas. CNG is often misrepresented as the only form of natural gas that can be used as vehicle fuel. However, LPG and LNG may also be used as transport fuels.5
DANIEL A. VALLERO , in Fundamentals of Air Pollution (Fourth Edition), 2008
II. GASOLINE-POWERED VEHICLES
Gasoline-powered motor vehicles outnumber all other mobile sources combined in the number of vehicles, the amount of energy consumed, and the mass of air pollutants emitted. It is not surprising that they have received the greatest share of attention regarding emission standards and air pollution control systems. Table 27.2 shows the US federal emission control requirements for gasoline-powered passenger vehicles.
Crankcase emissions in the United States have been effectively controlled since 1963 by positive crankcase ventilation (PCV) systems which take the gases from the crankcase, through a flow control valve, and into the intake manifold. The gases then enter the combustion chamber with the fuel–air mixture, where they are burned.
Figure 35.1 shows a cross section of a gasoline engine with the PCV system.
Evaporative emissions from the fuel tank and carburetor have been controlled on all 1971 and later model automobiles sold in the United States. This has been accomplished by either a vapor recovery system which uses the crankcase of the engine for the storage of the hydrocarbon vapors or an adsorption and regeneration system using a canister of activated carbon to trap the vapors and hold them until such time as a fresh air purge through the canister carries the vapors to the induction system for burning in the combustion chamber.
The exhaust emissions from gasoline-powered vehicles are the most difficult to control. These emissions are influenced by such factors as gasoline formulation, air–fuel ratio, ignition timing, compression ratio, engine speed and load, engine deposits, engine condition, coolant temperature, and combustion chamber configuration. Consideration of control methods must be based on elimination or destruction of unburned hydrocarbons, carbon monoxide, and oxides of nitrogen. Methods used to control one pollutant may actually increase the emission of another requiring even more extensive controls.
Control of exhaust emissions for unburned hydrocarbons and carbon monoxide has followed three routes:
1.
Fuel modification in terms of volatility, hydrocarbon types, or additive content. Some of the fuels currently being used are liquefied petroleum gas (LPG), liquefied natural gas (LNG), compressed natural gas (CNG), fuels with alcohol additives, and unleaded gasoline. The supply of some of these fuels is very limited. Other fuel problems involving storage, distribution, and power requirements have to be considered.
2.
Minimization of pollutants from the combustion chamber. This approach consists of designing the engine with improved fuel–air distribution systems, ignition timing, fuel–air ratios, coolant and mixture temperatures, and engine speeds for minimum emissions. The majority of automobiles sold in the United States now use an electronic sensor/control system to adjust these variables for maximum engine performance with minimum pollutant emissions.
3.
Further oxidation of the pollutants outside the combustion chamber. This oxidation may be either by normal combustion or by catalytic oxidation. These systems require the addition of air into the exhaust manifold at a point downstream from the exhaust valve. An air pump is employed to provide this air. Figure 35.2 illustrates an engine with an air pump and distribution manifold for the oxidation of CO and hydrocarbons (HC) outside the engine.
Fig. 35.2.. Manifold air oxidation system.
Beginning with the 1975 US automobiles, catalytic converters were added to nearly all models to meet the more restrictive emission standards. Since the lead used in gasoline is a poison to the catalyst used in the converter, a scheduled introduction of unleaded gasoline was also required. The US petroleum industry simultaneously introduced unleaded gasoline into the marketplace.
In order to lower emissions of oxides of nitrogen from gasoline engines, two general systems were developed. The first is exhaust gas recirculation (EGR), which mixes a portion of the exhaust gas with the incoming fuel–air charge, thus reducing temperatures within the combustion chamber. This recirculation is controlled by valving and associated plumbing and electronics, so that it occurs during periods of highest NOx production, when some power reduction can be tolerated: a cruising condition at highway speed. Other alternatives are to use another catalytic converter, in series with the HC/CO converter, which decomposes the oxides of nitrogen to oxygen and nitrogen before the gases are exhausted from the tailpipe.
Katherine Newell , ... Om P. Kurmi , in Encyclopedia of Respiratory Medicine(Second Edition), 2022
Adoption of Cleaner Fuel
Switching to cleaner fuels is deemed the most effective but not necessarily the most feasible intervention strategy to reduce HAP exposure in LMICs. Adopting cleaner household fuels are beneficial and increasingly appealing as an intervention since it requires relatively little behavioral change at the level of the individual. It's an intervention reflected in the UN sustainable development goal (SDG) of "access to affordable, reliable, sustainable and modern energy for all" (Mitter et al., 2016), which recognizes the harmful effects of HAP, and the role limited access to clean fuels has in forcing households use of more primitive solid fuels.
Examples of cleaner fuels include ethanol, liquid petroleum gas (LPG), biogas, and solar cooking. Studies have shown these cleaner fuels associated with decreased levels of HAP exposure as well as adverse health effects. A recent RCT of ethanol stove and fuel distribution in Nigeria found a 2.8-mm Hg reduction in diastolic blood pressure and a 4.5% reduction in the prevalence of systemic hypertension among pregnant women randomized to ethanol stoves compared to those randomized to the control arm (Thompson et al., 2011). Similarly, a study in Sudan evaluated the impact of LPG use on HAP concentrations, reporting substantial reductions in kitchen PM (51–80%) and CO (74–80%) levels (Alexander et al., 2018). A meta-analysis of ethanol stoves in LMICs also found pooled reductions in kitchen PM2.5 and CO concentrations of 83% and 82%, respectively, following implementation of ethanol stoves. Ethanol as a clean fuel showed the most substantial reduction in HAP exposure, but only one identified study compared multiple types of clean fuel (Wang et al., 1997).
It's important to note that not all clean fuels are equally "clean" nor are they equal in reducing HAP exposure. Kerosene is often referenced in earlier studies as a "clean fuel," however evidence has emerged linking kerosene to PM concentrations which exceed the WHO indoor air quality guidelines. Kerosene has also been linked with tuberculosis and respiratory infections at an order of magnitude similar to that of solid fuels. Similarly, natural gas, although deemed a "clean" fuel has also now been associated with HAP exposure. A systematic review reported there is "good evidence" that the use of gas for cooking and heating can result in levels of pollutants exceeding WHO indoor air-quality guidelines, increased risk of asthma and wheezing also observed for users of gas, relative to that of electricity (Amegah et al., 2014). Further research on this is needed but, even if it's not as clean as electricity, natural gas has a low risk of adverse health outcomes relative to solid fuel use.
An essential and constricting factor for cleaner fuel access is its accessibility as an intervention. Current fuel users in poorer, more rural settings are unlikely to be able to access exclusively clean fuels for many years, with widespread dissemination of clean fuels in LMICs hampered by poverty and supply chain issues. Start-up costs for cleaner fuels are too high for LMIC households and expanding clean fuel production, and distribution facilities and networks such as LPG requires a significant financial commitment, with often private sector involvement and government facilitation. For clean fuel adoption to work as an intervention, it must be provided affordably to LMICs which is both economically and ecologically sustainable for LMIC populations. These initiatives usually need governmental support to be successful. A recent initiative "Ujjwala Yogana" by the Indian government since May 2016 to distribute free LPG stove and LPG cylinder to household below poverty line has been highly successful. The government has in the last 3 years have distributed over 7 million LPG stoves and cylinders and it has been reported that over 82% of these household continue to use it.
Therefore, improved solid-fuel stoves will likely continue as the most common widespread HAP intervention until such these challenges for clean fuel adoption are addressed.
R.J. Flanagan , D.S. Fisher , in Encyclopedia of Forensic Sciences (Second Edition), 2013
Abstract
Acute poisoning with volatile substances is usually encountered following the deliberate inhalation of vapor in order to become intoxicated ('glue sniffing,' 'huffing,' 'dusting,' 'bagging,' inhalant abuse, solvent abuse, volatile substance abuse (VSA), volatile substance misuse). A wide range of substances/products may be misused in this way, but purified liquefied petroleum gas found in cigarette lighter refills and most aerosol propellants is the most common. The major risk is sudden death, which may be secondary to an event such as inhalation of vomit, but is most likely to result from a fatal arrhythmia ('sudden sniffing death'). VSA is often a solitary pastime and the intent to achieve intoxication may be clear, but sometimes it is necessary to exclude criminal involvement in a death. However, there are special problems. Many volatiles are excreted unchanged via the lungs and thus whole blood and not urine is usually the sample of choice. Collection, storage, and transport of biological sample(s) must be tightly controlled in order to minimize sample contamination on the one hand, and loss of analyte on the other. Finally, the interpretation of results can be difficult, especially if legitimate exposure to solvent vapor is a possibility.
Bezalel Bacon , ... Elizabeth Boon , in Advances in Microbial Physiology, 2017
6.1 H-NOX and HaCE Signalling
Although they are in the minority, some facultative aerobic bacteria code for an H-NOX domain in the same operon as a cyclic-di-GMP synthase and/or phosphodiesterase. We have recently termed these enzymes, collectively, HaCEs for H-NOX-associated cyclic-di-GMP processing enzymes. This category of H-NOX domains is of particular interest as they directly implicate NO/H-NOX signalling in the regulation of cyclic-di-GMP, a secondary messenger molecule in bacteria that regulates biofilm formation (Ross et al., 1987).
HaCE enzymes generally have one or both of two enzymatic domains that directly participate in cyclic-di-GMP regulation: a diguanylate cyclase domain that synthesizes cyclic-di-GMP from two molecules of GTP and/or a cyclic-di-GMP phosphodiesterase domain that hydrolyzes cyclic-di-GMP into pGpG (5′-phosphoguanylyl-(3′-5′)-guanosine) or GMP (guanosine-5′-monophosphate). H-NOX/HaCE complexes have been shown to link NO detection with regulation of HaCE activity, leading to intracellular changes in the concentration of cyclic-di-GMP and biofilm formation.
H-NOX regulation of HaCE activity has been biochemically observed in the bacteria L. pneumophila (Carlson et al., 2010), S. woodyi (Liu et al., 2012), and more recently, Agrobacterium vitis (Nesbitt et al., unpublished data) (Fig. 5). In L. pneumophila, Lpg-HaCE has only cyclic-di-GMP synthase activity (although it contains a phosphodiesterase domain, it is inactive) (Carlson et al., 2010). In both S. woodyi and A. vitis, however, Sw-HaCE (Liu et al., 2012) and Av-HaCE (Nesbitt et al., unpublished data) proteins were found to exhibit both cyclic-di-GMP synthase and phosphodiesterase activities in vitro. In L. pneumophila, Lpg-HaCE cyclic-di-GMP synthase activity is unaffected in the presence of Fe(II)-unligated L1-H-NOX (Carlson et al., 2010), while in S. woodyi, Sw-HaCE cyclic-di-GMP synthase activity is upregulated (by ~ 10-fold) in the presence of Fe(II)-unligated Sw-H-NOX and phosphodiesterase activity remains unchanged (Liu et al., 2012). Thus, it appears that NO-free H-NOX variably affects HaCE activity; NO-bound H-NOX, however, universally results in changes in HaCE activity. In L. pneumophila, NO-bound L1-H-NOX causes a decrease in Lpg-HaCE cyclic-di-GMP synthase activity, leading to a decrease in cyclic-di-GMP concentration in vitro (Carlson et al., 2010). In S. woodyi, Sw-HaCE cyclic-di-GMP production is also downregulated in the presence of Fe(II)-NO bound Sw-H-NOX, but by an slightly different mechanism. Here, in addition to decreasing HaCE cyclic-di-GMP synthase activity, the phosphodiesterase activity of Sw-HaCE is increased (Liu et al., 2012), leading to a dramatic decrease in c-di-GMP concentration.
Fig. 5. NO regulates HaCE activity through ligation to H-NOX. (A) NO bound H-NOX only affects cyclic-di-GMP production in Legionella pneumophila as Lpg-HaCE is only functional as a cyclic-di-GMP synthase. (B) Fe(II)-NO bound H-NOX directly influences both the production and hydrolysis of cyclic-di-GMP in Shewanella woodyi and Agrobacterium vitis.
Finally, in light of the S. oneidensis H-NOX NMR solution structures and the C. subterraneus crystal structures revealing that NO-haem binding may induce haem flattening and subsequent protein conformational changes (Erbil et al., 2009; Olea et al., 2008; Olea, Kuriyan, et al., 2010), it has been hypothesized that changes in both haem and protein conformation may directly translate into changes in downstream signalling events in H-NOX signalling pathways (as discussed in Section 5). Since there was no direct evidence in support of this hypothesis, however, our lab investigated the role of the H-NOX haem structure in the H-NOX/HaCE signalling pathway from S. woodyi. In this study, as expected, the relaxed haem proline mutant of Sw-H-NOX led to upregulation of the phosphodiesterase activity of Sw-HaCE (Muralidharan & Boon, 2012), which is the very same effect that NO-bound H-NOX has on HaCE activity (Liu et al., 2012). This study, therefore, provided the first direct evidence for the role of haem relaxation in H-NOX signal transduction.
R.J. Flanagan , in Encyclopedia of Analytical Science (Second Edition), 2005
Introduction
Acute poisoning with volatile substances usually follows the deliberate inhalation of vapor in order to become intoxicated ['glue sniffing', inhalant abuse, solvent abuse, volatile substance abuse (VSA)]. Solvents from adhesives, notably toluene, some correcting fluids and thinners, hydrocarbons such as those found in cigarette lighter refills [usually liquefied petroleum gas (LPG)], aerosol propellants, and anesthetic gases such as nitrous oxide are amongst the compounds/products that may be abused in this way (Tables 1 and 2). Nail varnish/varnish remover (acetone and esters) and felt-tip marker pen fluids, although strong smelling, are probably too water soluble to be intoxicants. Methanol, ethanol, 2-propanol, and ethylene glycol, and also diesel fuel, aviation fuel (kerosene, Avgas), white spirit, turpentine (or substitute), and paraffin are not sufficiently volatile to be abused by inhalation. Petrol (gasoline), on the other hand, is often abused, especially in less well-off communities. Isobutyl and isopentyl ('amyl') nitrites are also inhaled in order to experience their vasodilator properties, sometimes by male homosexuals. In addition, those who ingest, or even more rarely inject, solvents or solvent-containing products, either accidentally or deliberately, and the victims of clinical, industrial, and domestic accidents may be poisoned by the compounds under consideration. Finally, chloroform, diethyl ether, and other volatiles are still used occasionally during crimes such as rape and murder, whilst a further volatile compound, chlorobutanol (1,1,1-trichloro-2-methyl-2-propanol), sometimes employed as a sedative and a preservative, has been used in doping racing greyhounds.
Table 1. Some volatile substances that may be abused by inhalation
Mike Joffe , in International Encyclopedia of Public Health (Second Edition), 2017
Fuel Poverty and Health
The health benefits of energy use are most clearly seen in mirror image, among those populations that are excluded from this affluent lifestyle – the majority of humankind. One of the main disadvantages of poverty is lack of access to energy, or access only at high financial and health cost. Even in the developed world, fuel poverty is not uncommon, in the sense of households spending more than 10% of their income on energy. This is likely to increase as fuel costs rise.
The situation is far worse for those on a medium or low income in the developing world. Even in urban areas, access to network electricity or other sources of clean energy, such as off-grid electricity or a supply of natural gas or liquefied petroleum gas, is limited by its expense, even when it is physically available (not necessarily true, for example in peri-urban slums). In rural areas, fuel typically needs to be gathered, often from far away, and the time cost can add significantly to the household burden of toil and drudgery (see Figure 3); the task tends to fall to women and girls and, as well as exposing them to risk of attack, can be a factor in reducing female schooling, which has a major health impact. In some regions fuel is scarce, leading to a vicious cycle of deforestation/environmental degradation and poverty. For the majority of people in the world, therefore, the costs of obtaining fuel are high and this carries a health burden.
Figure 3. Two women with wood, Nepal: Female drudgery.
Photograph courtesy of Nigel Bruce/Practical Action.
The benefits of access to energy, or rather the lack thereof, are also important to health. This is an area in which public health research could produce findings that would lead to major improvements in public policy. In practice, the available evidence merely points to this as an important issue, but without disaggregation in the sense of knowing which interventions produce the best outcomes at lowest investment cost. We need to know the potential health impacts of energy for clean water and sewage disposal, for health care, for domestic electricity such as refrigeration and indoor lighting, and for transport. Energy can also be a limiting factor in the availability and nature of livelihoods, the major determinant of living standards, with some occupations such as mining that use raw human labor being not only atrocious but also outright dangerous.
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