gasses

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What is 2ug/m3 ?

• Consider this If you take a grain of sugar
• (1 packet), pulverize it evenly disperse it
  throughout a large house (2,200 sq. ft.), the
  concentration would be about 2ug/m3. Now, take
  the OSHA PEL ( the single grain of sugar), then
  divide it by 10 to arrive at the proposed ACGIH
  TLV of 0.2 ugm3 . This exposure level is, for all
  practical purposes, invisible to the naked eye.
  What is the PEL
• for lead 0.05 ug/m3 or 50 mg/m3!

2
What is ppm / mg/m3 ? 1-24-2010

• Airborne pollutant concentration limits are
  usually expressed as parts per million by volume
  (i.e., ppmv) for gases and vapors, and mg/m3 for
  dusts, aerosols and mists.

3
PPM

• One ppm is equivalent to 1 milligram of something
  per liter of water (mg/l) or 1 milligram of
  something per kilogram soil (mg/kg).
• The common unit mg/liter is equal to ppm
• Four drops of ink in a 55-gallon barrel of water
  would produce an "ink concentration" of 1 ppm.

4

• One part per million is one pound in a million
  pounds, one ounce in a million ounces, one gram
  in a million grams, etc.  Therefore
• 1 ppm 1 pound per million pounds
• 120,000 gallons of water 1,000,000 pounds
• 1 ppm 1 pound per 120,000 gallons of water

5
PPB

• One part per billion is 1 part in 1,000,000,000.
  One drop of ink in one of the largest tanker
  trucks used to haul gasoline would represent 1
  ppb.
• The difference between 1 ppm and 1 ppb is
  important. A prestigious scientific journal
  recently reported the concentration of a
  substance as 0.5-1.5 ppm. The real value was
  0.5-1.5 ppb. The difference between 1 and 1000!

6
PPT

• A unit of concentration used to measure
  vanishingly small levels of pollutants or
  contaminants in, for example, body fluids. One
  ppt is 1 part in 1,000,000,000,000. One drop of
  ink distributed through the water contained in a
  total of 4 of the 3-million-gallon reservoirs
  pictured would result in a final concentration of
  1 ppt.

7
PPQ?

• One ppq is 1 part in 1,000,000,000,000,000 or 1
  in 1015.
• Even the most modern analytical techniques cannot
  measure a pollutant such as dioxin in this range.
  However, mathematical models based on the tiny
  amounts of dioxin still produced during the
  manufacture of paper suggest that dioxin is being
  released in the ppq range by paper mills in the
  state of Maine (U.S.

8
One part per million (ppm) denotes one part per
1,000,000 parts, one part in 106, and a value of
1  106.

• This is equivalent to one drop of water diluted
  into 50 liters (roughly the fuel tank capacity of
  a compact car), or about thirty seconds out of a
  year.

9
One part per billion (ppb) denotes one part per
1,000,000,000 parts, one part in 109, and a value
of 1  109.

• This is equivalent to 1 drop of water diluted
  into 250 chemical drums (50 m3), or about three
  seconds out of a century.

10
One part per trillion (ppt) denotes one part per
1,000,000,000,000 parts, one part in 1012, and a
value of 1  1012.

• This is equivalent to 1 drop of water diluted
  into 20, two-meter-deep Olympic-size swimming
  pools (50,000 m3), or about three seconds out of
  every hundred thousand years.

11

• Often, parts-per notation is the simplest and
  best measure. But other times, it is less
  suitable or even impossible. This sometimes
  results in agencies such as the World Health
  Organization or US EPA presenting entire tables
  of air concentrations that use the weight/volume
  method, when parts-per notation might have more
  readily worked for many (but not all) substances
  present. While many contaminants can be easily
  described using parts-per notation, a few of them
  present a much more complex picture.

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• A case in point is when measuring gasoline
  (a.k.a. petrol). It's a very complex mixture
  which might have dozens or hundreds of types of
  molecules present, in air. It would require
  sophisticated, extremely expensive analysis to
  enumerate all of a given sample's molecules and
  give it an accurate parts-per measurement - and
  that measurement would probably not be comparable
  to any other gasoline parts-per concentration,
  because the petroleum mixture of the second
  sample would be different. (Batches of petroleum
  product differ considerably as an extreme
  example, gasoline fractions have a far higher
  parts-per count - many more molecules per
  molecule of air - compared to a heavier petroleum
  product like diesel, for a given weight per
  volume measure at STP.) Therefore, a mass per
  volume concentration unit (such as mg/m3) is
  almost always used for petroleum vapors, as well
  as for certain other complex mixtures.
• If one is dealing with

13
1 ppm ?

• One ppm is like
• one inch in 16 miles,
• one second in 11.5 days,
• one minute in two years, or
• one car in bumper-tobumper
• traffic from
• Cleveland to San Francisco.

14
ppm ?

• Four drops of ink in one 55-gallon barrel
• of water (mixed thoroughly) would produce
• an ink concentration of 1 ppm.

15
Because a ppb is a much lower concentration,
other analogies would be

• one silver dollar in roll stretching from Detroit
  to Salt Lake City,
• one sheet in a roll of toilet paper stretching
  from New York to London,
• one second in nearly 32 years, or
• one pinch of salt in 10 tons of potato chips.

16
Pure Water At 40 C
1 kg
17
A milligram is a thousandth of a thousandth, or
amillionth of a kilogram moving the decimal
point six places.

• So, a milligram is one ppm
• of a kilogram therefore, one
• ppm is the same as one milligram
• per kilogram.
• milligram/kilogram or
• mg/kg or
• 0.001/1,000 or
• 10-3/103

18

• As a ppm is equal to mg/L, then ppb is equal to
  microgram per liter (µg/L).
• A µg/L is 1 thousandth of a mg/L.
• Most water analysis will have the concentration
• reported in ppm or mg/L and/or ppb or µg/L.

19
Most water analysis will have the
concentrationreported in ppm or mg/L and/or ppb
or µg/L.

• For example
• 1 ppm 1 mg/L
• 1/1 million 0.000001
• 1 ppb 1 µg/L
• 1/1 billion 0.000000001

20

• 1 ppm
•     2.72 pounds per acre-foot
•     1,233 grams per acre-foot
•     1.233 kilograms per acre-foot
•     0.0283 grams per cubic foot
•     0.0000624 pounds per cubic foot
•     0.0038 grams per US gallon
•     0.058419 grains per US gallon
•     0.07016 grains per Imperial gallon
•     1 milligram per liter
•     1 microlitre ( µL ) per liter
•     0.001 gram per litre
•     8.345 pounds per million gallons of water

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• Some associated conversion factors-
• 1 acre-foot 43,560 cubic feet
• 1 acre-foot 325,850 gallons
• 1 acre-foot of water 2,718,144 pounds
• 1 cubic foot of water 62.4 pounds
• 1 cubic foot of water 6.24 Imperial gallons
• 1 US gallon of water 8.34 pounds
• 1 Imperial gallon of water 10 pounds
• 1 US gallon of water 3,785 grams or 3.785 kg
• 1 litre of water 1,000 grams 1 kg (approx)
• 1 litre of water 1,000 cubic centimetres (cc)
• 1 cubic metre 1,000 litre
• 1 cubic metre 1 metric tonne of water (appx.)
• 1 US fluid ounce 29.57 grams
• 1 US fluid ounce 1.043 ounces (av)

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Some abbreviations in common use

• g, gm gram
• gr grain
• in., ins inch, inches
• cu.in. in3, in3 cubic inch
• kg kilogram
• l b.lbs pound
• l L litre, lite
• rm metre, meter
• cu.m. , m3, m3 cubic metre
• oz., ozs ounce
• yd., yds yard

• av avoirdupois
• cm centimetres
• cc, cu.cm, cm3, cm3 cubic centimetre
• fl oz fluid ounce
• fl pt fluid pint
• fl qt fluid quart
• ft foot, feet
• cu.ft. , ft3, ft3 cubic foot
• gal., gals gallon

23

• Examples of the use of the formula are given
  below
• A plant which treats 200 gpm operated for 15
  hours and used 30 pounds of alum. How many ppm of
  alum was used
• pounds of chemical (alum) 30 constant
  120,000 number of gallons 200 (gpm)  x  60
  (min)  x  15 (hrs) 180,000 gallons

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• A tank holds 150,000 gallons and it is desired to
  disinfect it with 50 ppm of chlorine. HTH is to
  be used (HTH is 70 chlorine).  How much HTH will
  be needed?
•              Y amount of chlorine needed
  (pounds)
•              120,000 constant        150,000
  gallons amount of water to be
• treated        
• 50 ppm  

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Milligrams Per Liter

• Milligrams per liter also refers to a weight
  ratio.  One milligram per liter is the same as
  one part per million when the reference volume is
  water because,

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• 1 gram (weight) 1,000 milligrams  and
• 1 liter of water weighs 1,000 grams
  therefore, 1 liter of water
  1,000,000 milligrams
• (1,000  x  1,000) so,
• 1 milligram in one liter of water 1 milligram
  per liter or one part in a million parts

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If one is dealing with a single known diluent
(contaminant), it is easy to convert from
parts-per notation to weight per volume
concentration, using the substance's molecular
weight in the following types of equations

• mg/m 3 ppm MW ppm Mg/m 3 24.45
• 24.45
  MW
• For example, 1 ppm of toluene (MW 92.15) is
  equivalent to a 3.8 mg/m3 concentration.

29

• What is gram molecular weight?
• Gram molecular weight is the molecular weight
  (MW) expressed in grams. For example, the gram
  molecular weight for toluene is 92.13 g. since
  the molecular weight is 92.13. A gram molecular
  weight is also called a gram mole.

30

• How do I convert mg/m3 to ppm at different
  temperatures and pressures?
• The number 24.45 in the equations above is the
  volume (liters) of a mole (gram molecular weight)
  of a gas or vapour when the pressure is at 1
  atmosphere (760 torr or 760 mm Hg) and at 25C.

31

• To convert mg/m3 to ppm at other temperatures and
  pressures, one must calculate the volume of 1
  gram molecular weight of an airborne contaminant
  (e.g. 92.13 grams of toluene) by using the
  formula
• V (RT/ P)
• where R is the ideal gas constant T, the
  temperature in  kelvins (273.16 TC) and P,
  the pressure in mm Hg. This information can be
  substituted in the formulas for converting
  between mg/m3 and ppm.

32

• TLV in mg/m3
• (P/RT) x MW x (TLV in ppm)
• P x MW x (TLV in ppm) 
  62.4 x (273.2 TC)
• and
•  TLV in ppm  62.4 x (273.2 TX) x (TLV in
• mg/m3) P x MW

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• where the value of R is 62.4 when the temperature
  (T) is in kelvins, K (273.16 TC), the
  pressure is expressed in units of mm Hg and the
  volume is in liters. There are different values
  for the gas constant R if the temperature is
  expressed degrees Fahrenheit (F) or if other
  units of pressure (e.g., atmospheres,
  kilopascals) are used. b

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Ie.

• The molecular weight of benzene is 78. If the
  concentration of benzene in air is 10 mg/m3,
  convert to the units of ppm by multiplying 24.45
  x 10 mg/m3 78 3.13 ppm.
• Note Sometimes you will see chemical
  concentrations in air given in concentration per
  cubic feet (ft3) instead of concentration per
  cubic meter (m3). The conversion from cubic feet
  to cubic meter and vice versa is as follows 1
  ft3 0.02832 m3 and 1 m3 35.31 ft3.

36
One part per quadrillion (ppq) denotes one part
per 1,000,000,000,000,000 parts, one part in
1015, and a value of 1  1015.

• This is equivalent to 1 drop of water diluted
  into a cube of water measuring approximately 368
  meters on a side (fifty million cubic meters,
  which is a cube about as tall as the roof of the
  Empire State Building), or two and a half minutes
  out of the age of the Earth (4.5 billion years).
  Although relatively uncommon in analytic
  chemistry, measurements at the ppq level are
  performed.4

37

• Dosages of pharmaceutical drugs 5 mg/kg (i.e.
  milligrams of medication per kilogram of body
  weight)  but not  5 ppb
• Particulate matter in the air 50 µg/m3  but
  not  50 ppb. Also see Air measurements, below.
• A stepper motor/gear system that produces a
  motion of 1 µm/pulse  but not  1 ppm
• Mercury vapor concentration in air 0.6 ng/L  but
  not  0.6 ppt

38

• Note however, that it is not uncommon to
  express aqueous concentrationsparticularly in
  drinking-water reports intended for the general
  publicusing parts-per notation (2.1 ppm,
  0.8 ppb, etc.) and further, for those reports to
  state that the notations denote milligrams per
  liter or micrograms per liter. Whereas 2.1 mg/L
  is technically not a dimensionless quantity on
  the face of it, it is well understood in
  scientific circles that one liter of water has a
  mass of one kilogram and that 2.1 mg/kg
  (2.1 ppm) is the true measure.

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