|
|
| (One intermediate revision by one other user not shown) |
| Line 1: |
Line 1: |
| '''Air pollutant concentrations''', as measured or as calculated by [[air pollution dispersion modeling]], must often be converted or corrected to be expressed as required by the regulations issued by various governmental agencies. Regulations that define and limit the [[concentration]] of [[pollutant]]s in the ambient air or in gaseous [[Air pollutants|emission]]s to the ambient air are issued by various national and state (or provincial) [[United States Environmental Protection Agency|environmental protection]] and [[United States Occupational Safety and Health Administration|occupational health and safety]] agencies.
| |
|
| |
|
| Such regulations involve a number of different expressions of concentration. Some express the concentrations as ppmv ([[parts per million]] by volume) and some express the concentrations as mg/m<sup>3</sup> (milligrams per cubic meter), while others require adjusting or correcting the concentrations to reference conditions of moisture content, [[oxygen]] content or [[carbon dioxide]] content. This article presents methods for converting concentrations from ppmv to mg/m<sup>3</sup> (and vice versa) and for correcting the concentrations to the required reference conditions.
| |
|
| |
|
| All of the concentrations and concentration corrections in this article apply only to air and other gases. They are not applicable for liquids.
| | Everything appears to be very easy, whenever you were just getting started together with your company. You only concentrate on the key business activities. But as your business grows, things get more complicated. Rather than having the ability to focus on the key business, you feel more flooded with other aspects of the business which can be considered as non-core functions time consuming and sometimes irrelevant. One of these will be the payroll. <br><br>Payrolls, even for the experienced business proprietors, working with payrolls can be a tasking job. Keeping track of rules and payroll changes in withholding tables and determining amounts can be quite a frustrating and tedious job. Doing the payroll while working with the business core activities may often easily result in problems. Another purpose in preparing payrolls may be the preparing of federal, state and local taxes. <br><br>For small and getting started companies, it is perhaps not unusual for owners to invest two to ten hours planning the payroll this is if it is done manually. Errors are also unusual given the fact you"re multi-tasking. The implications of those errors are costly. An employee receiving assessments with errors may hold grudges against the administration, and may lead to decrease morale of employee. If you think any thing, you will seemingly require to check up about [http://www.changshengmao.com/payroll-outsourcing-a-must-or-a-break/ source]. <br><br>Errors in payrolls won"t only affect your employees but it may greatly affect the complete business. You"ll be asked to pay for a paycheck charge, when you file late or with mistakes. Keeping erroneous problems can lead to penalties that can total a huge selection of dollars. <br><br>Given how pro-cessing payroll in-house can impact the whole business, you might want to consider other choices. If you don"t want to handle things that are linked to payroll, you can choose to go out and give payroll outsourcing a shot. <br><br>Contemporary Paycheck Outsourcing <br><br>Payroll outsourcing is used by business for quite some time already. So has payroll processing, as technology has got better. One example of here is the Internet. Through the Web, you whilst the operator will have the ability to see, at the same time manipulate a companys payroll in real time. <br><br>Due to certain forms given by the outsourcing company, all you should do is input the needed knowledge and it will determine every thing for you automatically. This also includes breaks together with taxes. This type of payroll technology can greatly keep your time and can give you the comfort to be still able to have control over it. <br><br>Advantages of Paycheck Outsourcing <br><br>The same as with any type of outsourcing, paycheck outsourcing also can save your self an organization from wasting time and money. Because you do not have-to change your structure, hire new people and train them you can save money. Having new individuals with not that much knowledge is prone to committing errors. Exactly the same can be said why paycheck outsourcing can save yourself time. <br><br>Providing you with more time and energy to concentrate on more crucial issues related to the key of the business is another great advantage of payroll outsourcing. This may not only help you save time and money, but growth of your company could be expected. <br><br>A-must Or Perhaps A Bust <br><br>Ultimately, the choice will still rely on your preference and analysis of your company. If you wish to avail of the huge benefits that payroll outsourcing will give you, then it"s essential. <br><br>However if, basing in your examination, there"s really no need to hre 3rd-party businesses to the payroll for you because you can do it your self efficiently then there is no need to outsource..<br><br>If you loved this article and you would like to get far more facts regarding family health insurance plans ([http://hungryspoof8873.jigsy.com http://hungryspoof8873.jigsy.com]) kindly stop by the website. |
| | |
| ==Converting air pollutant concentrations==
| |
| | |
| The conversion equations depend on the temperature at which the conversion is wanted (usually about 20 to 25 °C). At an ambient sea level atmospheric pressure of 1 [[atmosphere (unit)|atm]] (101.325 [[Pascal (unit)|kPa]] or [[Bar (unit)|1.01325 bar]]), the general equation is:
| |
| | |
| :<math>\mathrm{ppmv} = \mathrm{mg}/\mathrm{m}^3\cdot \frac{(0.08205\cdot T)}{M}</math>
| |
| | |
| and for the reverse conversion:
| |
| | |
| :<math>\mathrm{mg}/\mathrm{m}^3 = \mathrm{ppmv}\cdot \frac{M}{(0.08205\cdot T)}</math>
| |
| | |
| {| border="0" cellpadding="2"
| |
| |-
| |
| |align=right|where:
| |
| |
| |
| |-
| |
| |align=right| '''mg/m<sup>3</sup>'''
| |
| |align=left|= milligrams of pollutant per cubic meter of air at sea level atmospheric pressure and '''''T'''''
| |
| |-
| |
| |align=right| '''ppmv'''
| |
| |align=left|= air pollutant concentration, in parts per million by volume
| |
| |-
| |
| |align=right| '''''T'''''
| |
| |align=left|= ambient temperature in K = 273.15 + °C
| |
| |-
| |
| |align=right| '''0.08205'''
| |
| |align=left|= [[Molar gas constant|Universal gas constant]] in atm·m<sup>3</sup>/(kmol·K)
| |
| |-
| |
| |align=right| '''''M'''''
| |
| |align=left|= [[molecular mass]] (or molecular weight) of the air pollutant
| |
| |}
| |
| | |
| Notes:
| |
| * 1 atm = absolute pressure of 101.325 kPa or 1.01325 [[bar (unit)|bar]]
| |
| * mol = [[mole (unit)|gram mole]] and kmol = 1000 gram moles
| |
| * Pollution regulations in the United States typically reference their pollutant limits to an ambient temperature of 20 to 25 °C as noted above. In most other nations, the reference ambient temperature for pollutant limits may be 0 °C or other values.
| |
| * Although ppmv and mg/m<sup>3</sup> have been used for the examples in all of the following sections, concentrations such as ppbv (i.e., parts per billion by volume), volume percent, mole percent and many others may also be used for gaseous pollutants.
| |
| *[[Atmospheric particulate matter|Particulate matter]] (PM) in the atmospheric air or in any other gas cannot be expressed in terms of ppmv, ppbv, volume percent or mole percent. PM is most usually (but not always) expressed as mg/m<sup>3</sup> of air or other gas at a specified temperature and pressure.
| |
| * For gases, volume percent = mole percent
| |
| * 1 volume percent = 10,000 ppmv (i.e., parts per million by volume) with a million being defined as 10<sup>6</sup>.
| |
| * Care must be taken with the concentrations expressed as ppbv to differentiate between the British billion which is 10<sup>12</sup> and the USA billion which is 10<sup>9</sup> (also referred to as the long scale and short scale billion, respectively).
| |
| | |
| ==Correcting concentrations for altitude==
| |
| | |
| Air pollutant concentrations expressed as mass per unit volume of atmospheric air (e.g., mg/m<sup>3</sup>, µg/m<sup>3</sup>, etc.) at sea level will decrease with increasing [[altitude]]. The concentration decrease is directly proportional to the pressure decrease with increasing altitude. Some governmental regulatory jurisdictions require industrial sources of air pollution to comply with sea level standards corrected for altitude. In other words, industrial air pollution sources located at altitudes well above sea level must comply with significantly more stringent air quality standards than sources located at sea level (since it is more difficult to comply with lower standards). For example, [[New Mexico]]'s Department of the Environment has a regulation with such a requirement.<ref>[http://www.complextransformationspeis.com/eis0236/vol4/v4c3.htm Draft Programmatic Environmental Impact Statement (EIS) for Stockpile Stewardship and Management](See section 03.05 of the EIS which involves the [[Los Alamos National Laboratory]] in New Mexico)</ref><ref>[http://www.blm.gov/pgdata/etc/medialib/blm/nm/field_offices/socorro/socorro_planning/socorro.Par.77588.File.dat/Final_Air_Quality_Impact_Analysis.pdf Air Quality Impact Analysis] (Developed for the [[United States Bureau of Land Management]], Socorro Field Office, New Mexico)</ref>
| |
| | |
| The change of atmospheric pressure with altitude (<20km) can be obtained from this equation:<ref>[http://www.atec.army.mil/publications/Mil-Std-810F/Mil-Std-810F.pdf United States Department of Defense MIL-STD-810F], 1 January, 2000. (See: Annex A, page 520.2A5 )</ref>
| |
| | |
| :<math>P_\mathrm h = P\,\cdot\bigg(\frac{288 - 6.5 h}{288}\bigg)^{5.2558}</math>
| |
| | |
| Given an air pollutant concentration at sea-level atmospheric pressure, the concentration at higher altitudes can be obtained from this equation: | |
| | |
| :<math>C_\mathrm h = C\,\cdot\bigg(\frac{288 - 6.5 h}{288}\bigg)^{5.2558}</math>
| |
| | |
| {| border="0" cellpadding="2"
| |
| |-
| |
| |align=right|where:
| |
| |
| |
| |-
| |
| !align=right| '''h'''
| |
| |align=left|= altitude, in km
| |
| |-
| |
| !align=right| '''''P'''''
| |
| |align=left|= atmospheric pressure at sea level
| |
| |-
| |
| !align=right| '''''P'''''<sub>'''h'''</sub>
| |
| |align=left|= atmospheric pressure at altitude '''h'''
| |
| |-
| |
| !align=right| '''''C'''''<br>
| |
| |align=left|= Air pollutant concentration, in mass per unit volume at sea level atmospheric pressure and specified temperature T
| |
| |-
| |
| !align=right| '''''C'''''<sub>'''h'''</sub>
| |
| |align=left|= Concentration, in mass per unit volume at altitude '''h''' and specified temperature T
| |
| |}
| |
| | |
| As an example, given an air pollutant concentration of 260 mg/m<sup>3</sup> at sea level, calculate the equivalent pollutant concentration at an altitude of 2800 meters:
| |
| | |
| :'''''C'''''<sub>'''h'''</sub> = 260 × [ { 288 - (6.5)(2.8) } / 288]<sup> 5.2558</sup> = 260 × 0.71 = 185 mg/m<sup>3</sup>
| |
| | |
| Note:
| |
| * The above equation for the decrease of air pollution concentrations with increasing altitude is applicable only for about the first 10 km of altitude in the [[troposphere]] (the lowest atmospheric layer) and is estimated to have a maximum error of about 3 percent. However, 10 km of altitude is sufficient for most purposes involving air pollutant concentrations.
| |
| | |
| ==Correcting concentrations for reference conditions==
| |
| | |
| Many environmental protection agencies have issued regulations that limit the concentration of pollutants in gaseous [[Emission standards|emissions]] and define the reference conditions applicable to those concentration limits. For example, such a regulation might limit the concentration of [[Nitrogen oxide|NOx]] to 55 ppmv in a dry combustion exhaust gas (at a specified reference temperature and pressure) corrected to 3 volume percent [[Oxygen|O<sub>2</sub>]] in the dry gas. As another example, a regulation might limit the concentration of total particulate matter to 200 mg/m<sup>3</sup> of an emitted gas (at a specified reference temperature and pressure) corrected to a dry basis and further corrected to 12 volume percent [[Carbon dioxide|CO<sub>2</sub>]] in the dry gas.
| |
| | |
| Environmental agencies in the USA often use the terms "dscf" or "scfd" to denote a "standard" cubic foot of dry gas. Likewise, they often use the terms "dscm" or "scmd" to denote a "standard" cubic meter of gas. Since there is no universally accepted set of "standard" temperature and pressure, such usage can be and is very confusing. It is strongly recommended that the reference temperature and pressure always be clearly specified when stating gas volumes or gas flow rates.
| |
| | |
| ===Correcting to a dry basis===
| |
| | |
| If a gaseous emission sample is analyzed and found to contain water vapor and a pollutant concentration of say 40 ppmv, then 40 ppmv should be designated as the "wet basis" pollutant concentration. The following equation can be used to correct the measured "wet basis" concentration to a "[[dry basis]]" concentration:
| |
| | |
| :<math>C_\mathrm{dry\, basis} = \frac{C_\mathrm{wet\, basis}}{1 - w}</math>
| |
| | |
| {| border="0" cellpadding="2"
| |
| |-
| |
| |align=right|where:
| |
| |
| |
| |-
| |
| !align=right|'''''C'''''
| |
| |align left|= Concentration of the air pollutant in the emitted gas
| |
| |-
| |
| !align=right|'''''w'''''
| |
| |align=left|= fraction, by volume, of the emitted gas
| |
| |}
| |
| | |
| As an example, a wet basis concentration of 40 ppmv in a gas having 10 volume percent water vapor would have a:
| |
| | |
| :'''''C'''''<sub>'''dry basis'''</sub> = 40 ÷ ( 1 - 0.10 ) = 44.4 ppmv.
| |
| | |
| ===Correcting to a reference oxygen content===
| |
| | |
| The following equation can be used to correct a measured pollutant concentration in a dry emitted gas with a measured O<sub>2</sub> content to an equivalent pollutant concentration in a dry emitted gas with a specified reference amount of O<sub>2</sub>:<ref name=Lewandowski>{{cite book|author=David A. Lewandowski|title=Design of Thermal Oxidation Systems for Volatile Organic Compounds|edition=1st Edition|publisher=CRC Press|year=1999|isbn=1-56670-410-3}}</ref>
| |
| | |
| :<math>C_\mathrm r = C_\mathrm m\cdot\frac{(20.9 - \mathrm{reference\,volume\, %\, O_2})}{(20.9 - \mathrm {measured\,volume\, %\, O_2})}</math>
| |
| | |
| {| border="0" cellpadding="2"
| |
| |-
| |
| |align=right|where:
| |
| |
| |
| |-
| |
| !align=right| '''''C'''''<sub>'''r'''</sub>
| |
| |align=left|= corrected concentration of a dry gas with a specified reference volume % O<sub>2</sub>
| |
| |-
| |
| !align=right| '''''C'''''<sub>'''m'''</sub>
| |
| |align=left|= measured concentration in a dry gas having a measured volume % O<sub>2</sub>
| |
| |}
| |
| | |
| As an example, a measured NOx concentration of 45 ppmv in a dry gas having 5 volume % O<sub>2</sub> is:
| |
| | |
| :45 × ( 20.9 - 3 ) ÷ ( 20.9 - 5 ) = 50.7 ppmv of NOx
| |
| | |
| when corrected to a dry gas having a specified reference O<sub>2</sub> content of 3 volume %.
| |
| | |
| Note:
| |
| * The measured gas concentration '''''C'''''<sub>'''m'''</sub> must first be corrected to a dry basis before using the above equation.
| |
| | |
| ===Correcting to a reference carbon dioxide content===
| |
| | |
| The following equation can be used to correct a measured pollutant concentration in an emitted gas (containing a measured CO<sub>2</sub> content) to an equivalent pollutant concentration in an emitted gas containing a specified reference amount of CO<sub>2</sub>:<ref name=Lewandowski/>
| |
| | |
| :<math>C_\mathrm r = C_\mathrm m\cdot\frac {(\mathrm{reference\,volume\,%\,CO_2})}{(\mathrm{measured\,volume\,%\,CO_2})}</math>
| |
| | |
| {| border="0" cellpadding="2"
| |
| |-
| |
| |align=right|where:
| |
| |
| |
| |-
| |
| !align=right| '''''C'''''<sub>'''r'''</sub>
| |
| |align=left|= corrected concentration of a dry gas having a specified reference volume % CO<sub>2</sub>
| |
| |-
| |
| !align=right| '''''C'''''<sub>'''m'''</sub>
| |
| |align=left|= measured concentration of a dry gas having a measured volume % CO<sub>2</sub>
| |
| |}
| |
|
| |
| As an example, a measured particulates concentration of 200 mg/m<sup>3</sup> in a dry gas that has a measured 8 volume % CO<sub>2</sub> is:
| |
| | |
| :200 × ( 12 ÷ 8 ) = 300 mg/m<sup>3</sup> | |
| | |
| when corrected to a dry gas having a specified reference CO<sub>2</sub> content of 12 volume %.
| |
| | |
| ==References==
| |
| {{Citizendium}}
| |
| {{reflist}}
| |
| | |
| {{DEFAULTSORT:Air Pollutant Concentrations}}
| |
| [[Category:Chemical engineering]]
| |
| [[Category:Air pollution]]
| |
| [[Category:Environmental engineering]]
| |
Everything appears to be very easy, whenever you were just getting started together with your company. You only concentrate on the key business activities. But as your business grows, things get more complicated. Rather than having the ability to focus on the key business, you feel more flooded with other aspects of the business which can be considered as non-core functions time consuming and sometimes irrelevant. One of these will be the payroll.
Payrolls, even for the experienced business proprietors, working with payrolls can be a tasking job. Keeping track of rules and payroll changes in withholding tables and determining amounts can be quite a frustrating and tedious job. Doing the payroll while working with the business core activities may often easily result in problems. Another purpose in preparing payrolls may be the preparing of federal, state and local taxes.
For small and getting started companies, it is perhaps not unusual for owners to invest two to ten hours planning the payroll this is if it is done manually. Errors are also unusual given the fact you"re multi-tasking. The implications of those errors are costly. An employee receiving assessments with errors may hold grudges against the administration, and may lead to decrease morale of employee. If you think any thing, you will seemingly require to check up about source.
Errors in payrolls won"t only affect your employees but it may greatly affect the complete business. You"ll be asked to pay for a paycheck charge, when you file late or with mistakes. Keeping erroneous problems can lead to penalties that can total a huge selection of dollars.
Given how pro-cessing payroll in-house can impact the whole business, you might want to consider other choices. If you don"t want to handle things that are linked to payroll, you can choose to go out and give payroll outsourcing a shot.
Contemporary Paycheck Outsourcing
Payroll outsourcing is used by business for quite some time already. So has payroll processing, as technology has got better. One example of here is the Internet. Through the Web, you whilst the operator will have the ability to see, at the same time manipulate a companys payroll in real time.
Due to certain forms given by the outsourcing company, all you should do is input the needed knowledge and it will determine every thing for you automatically. This also includes breaks together with taxes. This type of payroll technology can greatly keep your time and can give you the comfort to be still able to have control over it.
Advantages of Paycheck Outsourcing
The same as with any type of outsourcing, paycheck outsourcing also can save your self an organization from wasting time and money. Because you do not have-to change your structure, hire new people and train them you can save money. Having new individuals with not that much knowledge is prone to committing errors. Exactly the same can be said why paycheck outsourcing can save yourself time.
Providing you with more time and energy to concentrate on more crucial issues related to the key of the business is another great advantage of payroll outsourcing. This may not only help you save time and money, but growth of your company could be expected.
A-must Or Perhaps A Bust
Ultimately, the choice will still rely on your preference and analysis of your company. If you wish to avail of the huge benefits that payroll outsourcing will give you, then it"s essential.
However if, basing in your examination, there"s really no need to hre 3rd-party businesses to the payroll for you because you can do it your self efficiently then there is no need to outsource..
If you loved this article and you would like to get far more facts regarding family health insurance plans (http://hungryspoof8873.jigsy.com) kindly stop by the website.