Air Quality Standards

The following Air Quality Standards are offered as a guide only.  Specifiers and users of compressed breathing air are cautioned to read the most current specifications as supplied by OSHA, NFPA and  CGA.   Contact these organizations directly for their up to date specifications.

 

 There are many standards relative to the purity of compressed air used for breathing purposes.  However, the most generally accepted are those set forth by the Compressed Gas Association in its Pamphlet G-7.1.  These standards are incorporated by reference in OSHA 29 CFR 1910.134 as well as in NFPA 1500.

                                                                      CGA (1)

Contaminant

Grade D

Grade E

Grade H

Z180.1

Carbon Monoxide, PPM/v

10

10

5

5

Carbon Dioxide, PPM/v

1000

500

500

500

Condensed Hydrocarbons, mg/m³

5

5

-

1

Gaseous Hydrocarbons as methane, PPM/v

-

-

10

10

Water Vapor, PPM/v, dewpoint

(3)

(3)

(3)

-63°F

Objectionable Odors

None

None

None

None

Nitrogen Dioxide (NO²), PPM/v

-

-

0.5

0.2

Nitrous Oxide (N²O), PPM/v

-

-

-

5

Sulfur Dioxide (SO²), PPM/v

-

-

0.5

-

Halogenated solvents, PPM/v

-

-

1

-

Other gaseous contaminants

-

-

-

(4)

Inorganic particulates, mg/m³

-

-

-

1

 Notes:

 (1)  Compressed Gas Association, Inc., New York, Pamphlet  G-7 1973, Compressed Air for Human Respiration, and Specification G-7.1, Commodity Specification for Air.

Grade D is the minimum grade for routine use in self-contained or supplied-air protective breathing air equipment, as used in industry, fire fighting or general respiratory use.

Grade E is the minimum grade to be used for sports diving to 125 feet.

Grade H is a more stringent specification which is met by most manufactures Purifiers when installed, operated, and maintained in accordance with their recommendations.

 (2)  Canadian Standards Association, Rexdale, Ontario, Standard Z180.1-1978, Compressed Breathing Air.

 (3)  The CGA standards do not call out a specific moisture limit when the ambient temperature is above freezing.  However, NFPA 1500 requires a water vapor level of less than 25 ppm.

Since a moisture content no greater that -50º F dew point (66 ppm/v) is necessary for catalytic conversion of carbon monoxide to carbon dioxide, carbon monoxide limits could not be met unless air is dried to a -50º F dew point or better.  

(4)  Maximum allowable content of tricholotrifluorethane, dichlorodifluoromethane, and chlorodifluoromethane is 2PPM/v for each.  Unlisted contaminants shall not exceed one-tenth of the Threshold Limit Valves (TLV’s) for Chemical Substances in Workroom Air adopted by the American Conference of Governmental Industrial Hygienists (ACGIH).

 

Moisture Conversion Data

(All referred to 70º F and 14.7 psia)

Dew Point (ºF)

Dew Point (ºC)

PPM (v/v)

Mg/liter

-110

-78.9

0.58

.00045

-105

-76.1

0.94

.00070

-100

-73.3

1.5

.0011

-95

-70.5

2.3

.0017

-90

-67.8

3.2

.0024

-85

-65.0

5.0

.0037

-80

-62.2

7.1

.0055

-75

-39.4

10.6

.0079

-70

-56.7

16.1

.012

-65

-53.9

24.2

.018

-60

-51.1

30.9

.023

-55

-48.3

43.0

.032

-50

-45.6

60.5

.045

-45

-42.8

87.3

.065

-40

-40.0

121.0

.09

-35

-37.2

161.0

.12

-30

-34.4

229.0

.17

-25

-31.6

382.0

.21

-20

-28.9

403.0

.30

-15

26.1

538.0

.40

-10

-23.3

685.0

.51

-5

20.5

900.0

.67

0

-17.8

1180.0

.88

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Compressed Gas Association

Commodity G-7-1990

February, 1990

6.1.4    Quality Verification level D

The quality verification level D indicates the minimum requirements or air routinely used in self-contained or supplied-air protective breathing air equipment, as used in industry, fire fighting, or general respiratory use.  For use at temperatures below freezing, excess water content should be reduced (see 3,1,9).  All quality verification levels of higher quality than level D are considered breathable.  The specific quality verification level desired should be requested by the user.

6.1.5 Quality verification Level E  

This quality verification level is the minimum for diving to a depth of 130 feet.

7.3 Compressed air Cylinders

Compressed air cylinders should not be dropped, dragged, rolled or allowed to strike each other or to be struck violently.  Such treatment can result in damage which could cause failure of the cylinder or valve allowing violent release of gas with possible damage to property and injury to personnel.